English - EduKit Handbook

8/8/2019 English - EduKit Handbook

1/48

English:a better wordingHeriot-Watt-University

Edukit p. 1


2/48

Preface

NEMO is the Network of Excellence in Micro-Optics constructed under theEuropean Sixth Framework Programme. It aims at providing Europe with acomplete Micro-Optics food-chain, by setting up centres for optical modellingand design; measurement and instrumentation; mastering, prototyping andreplication; integration and packaging and reliability and standardization.More than 300 researchers from 30 groups in 12 countries are participating inthe project. One of the objectives of NEMO is to spread excellence anddisseminate knowledge on micro-optics and micro-photonics.

To convince pupils, already from secondary school level on, about the crucialrole of light and micro-optics and the opportunities this combination holds,several partners of NEMO have collaborate to create this Educational Kit. In part 7: NEMO: Network of Excellence on Micro-Opticsyou can read more

about the goals, activities and partners of NEMO.

In the introduction of this manual you will find a short description of micro-optical elements and a few examples of their applications.

The micro-optical elements you will find on the plastic card of the EduKit aredetailed in Part 1: Description of layout of the card with micro-opticalelements.

Part 2: How to perform the experimentsshould be read before starting the

experiments. It describes the basic rules to be observed for performing theexperiments, and also a few words about laser safety.

The experiments which can be performed with each of the optical elementson the plastic card are explained in Part 3: Description of individualexperiments.

The experiments are grouped as follows:Experiment 1: experiments with linear gratings

Experiment 2: experiments with crossed gratings

Experiment 3: experiments with pattern forming DOEs Experiment 4: experiments with the Fresnel zone platesEach experiment starts with a link to Part 2, where the general experimentalset up is given, and also a link to the basic theory (Part 4). Each experimentis also linked to the LTG-tutorial.

In Part 4: Basic Theorythe basic concepts of (light) waves, interference anddiffraction are explained. If students are already familiar with these concepts,they can skip it. However, for most students, this part is the basic part to

study before performing the experiments. In the explanation of each of the

Edukit p. 2


3/48

experiments, there should be a link "back to the theory", in case the readerhas problems understanding the theory behind the experiments.

If more sophisticated optical hardware is available, some advancedexperiments can be performed with the diffractive optical elements. Those

are described in Part 5: Advanced experiments.

Three such experiments are described:

Experiment 5: Fourier transform with a single lens Experiment 6: Optical filtering with a 4-f processor Experiment 7: Experiments with micro-lensesTo learn more about the design, fabrication and replication of such micro-optical elements please go to Part 6: Fabrication of the micro-optical

elements.

Part 8: Worksheets of experimentscan be used directly as instruction notesfor the pupils.

Some interesting web links to SPIE, Society for Optical Engineering, are listedin Part 9.

At the end of this document you will find an Evaluation Form, we would askyou to send us as much feedback as possible on your experience with this

EduKit. Your feedback (both positive and negative) will be invaluable to usimproving future editions of the EduKit towards your needs. Please send thisevaluation form by mail to [email protected]. We thank you in advance.

Please also note that the text between two vertical lines in this manual is alittle bit more complicated, and may be omitted at first reading.

We hope to increase your fascination for light with this EduKit.

Please do not hesitate to contact us in case of questions:

[email protected]

Edukit p. 3


4/48

Content table:

Preface.............................................................................................. 1Content table: .................................................................................... 4Introduction ....................................................................................... 5

What is a micro-optics ? ................................................................ 5What are ROEs? ........................................................................... 5What are DOEs? ........................................................................... 5What are specific applications of DOEs? ...........................................6

PART 1: Description of the layout of the card with micro-optical elements 8PART 2: How to perform the experiments .......................................... 10

The laser................................................................................... 10Laser safety............................................................................... 10Experimental set up .................................................................... 11

PART 3: Description of individual experiments.................................... 13

Experiment 1 : Linear Gratings..................................................... 13Experiment 2 : Crossed gratings................................................... 16Experiment 3 : Pattern Forming DOE............................................. 17Experiment 4 : Diffractive Lens..................................................... 19

PART 4: Basic theory .................................................................... 22Diffraction and Interference of Light a simple approach .......................... 22

1. What is diffraction? ................................................................. 222. More about waves................................................................... 253. Interference........................................................................... 27

PART 5: Advanced experiments ........................................................ 30

Experiment 5 : Fourier-transform set up ........................................ 30Experiment 6 : 4-f processor........................................................ 31Experiment 7 : Experiments with micro-lenses................................ 32

PART 6: Fabrication of the micro-optical elements............................... 34PART 7: NEMO : Network of Excellence on Micro-Optics ....................... 39What is NEMO ? ................................................................................ 39

Objectives of NEMO .................................................................... 40Activities ................................................................................... 40

PART 8: Worksheets ....................................................................... 41Experiment A : Project image with the EduKit ................................. 41

Experiment B : Focussing with a diffractive lens from de EduKit ....... 42Experiment C : Optics rodeo: hit the targets! ................................. 43

PART 9: SPIE : International Society for Optical Engineering................. 44PART 10: Evaluation form.................................................................. 45

Edukit p. 4


5/48

Introduction

What is a micro-optics?Micro-optics is a collective term for very small optical structures andcomponents (around the magnitude of the thickness of a human hair) whichenable the manipulation, collection and distribution of light. They are used inmany products encountered in daily life:e.g.

Micro-optics in displays on mobile phones on GPS modules on digital camera's

Micro-optics for sensing applications in car distance control in windshield wiper activators in structural health monitoring systems in food quality control in barcode readers in novel surgical and medical instruments

Micro-optics for computing and data storage in CD- and DVD- players in optical data communications

From this non-exhaustive list it can be send that micro-optics is a keytechnology that satisfies the increasing demand for miniaturization, costreduction and improved performance in manyproducts.

What are ROEs?ROEs or Refractive Optical Elements areelements based on the phenomenon that lightrays are broken when transferring from one medium to another. This

phenomenon is called refraction. Examples of refractive optical elements arelenses and prisms.

What are DOEs?DOEs or Diffractive OpticalElements are optical com-ponents containing microscopicstructures not larger than thethickness of a hair. Themicroscopic structures diffract

incident light (generally amonochromatic laser beam),

Edukit p. 5


6/48

such that a desired light pattern is generated at a distance from the DOE.They have the advantage of combining more than one optical functionality ina single component. Moreover they are so small and light that they can berealized on flexible and thin materials.

What are specific applications of DOEs?DOEs can be used for a variety of different applications. Some examples :

Project a line for measuring the height

Convert a single laser beam into a square grid or fan-out of beams

A reading head of a CD or DVD with DOE ( left) is much lighter and compacter than

a classical one ( right)

Edukit p. 6


7/48

Project your logo

Edukit p. 7


8/48

PART 1: Description of the layout of the card with

micro-optical elements

On the small plastic card, provided with this EduKit, you find different kinds of

diffractive optical elements or DOEs, and also refractive opticalelements or ROEs namely arrays of micro-lenses, [see Figure 6 below].

a) Elements number A1 and A2 are simple lineargratings, with different pitch. There are about60 lines per millimetre (lpmm) in A1, andabout 30 lpmm in A2.

They give a row of equidistant points on theprojection screen.

b) B1 and B2 are crossed grating, once againwith decreasing spatial frequency, the same astheir corresponding A number. Their far-field diffraction pattern consistsof a regular grid of points.

Figure 1:Crossedgrating

c) Next we have a set of PF-DOE's (= Pattern

Forming Diffractive Optical Elements), whichproduce the following patterns:

PF1 and PF2 are array generators or "fan-out"

elements: the incident laser beam is split intoa regular square grid of 4x4 (for PF1) or 8x8(for PF2) points of equal intensity. Figure 2: DOE

PF3 transforms the incoming laser beam into acircular disc of constant intensity. This is calleda flattop generator

PF4 gives a square gridPF5 shows the logo of the NEMO networkPF6 produces a European flag

Also on the card you will find three FZPs or FresnelZone Plates: FZP1 to FZP3. These are circularstructures which focus light, just as a normal lens would do. They have focallengths of respectively 10, 50 and 250 mm.

Figure 3: Fresnel Zone Plate

Edukit p. 8


9/48

Finally elements L1 till L6 are arrays of very smalllenses, so-called micro-lenses (refractive elements).

L1 and L2 are square packed arrays of sphericalmicro-lenses,

L3 and L4 are arrays of cylindrical lenses, whichonly focus the light in one direction,L5 and L6 are hexagonally packed arrays ofspherical micro-lenses. Figure 4: square arrays of

micro-lensesThe distance between neighbouring lenses is 0.1 mmfor L1, L3, L5 and 0.05 mm for L2, L4 and L6.

Figure 5:cylindrical micro-lenses

PF6

FZP1 FZP2 FZP3

L6

L5

L4

L3

A2 A1B1B2PF1

L2

L1

PF5PF4PF2 PF3

refractive structuresdiffractive structures

Figure 6: Layout of the elements on the card

Edukit p. 9


10/48

PART 2: How to perform the experiments

This section gives general information about the experiments.We first say a few words about the laser to be used, and explain then theexperimental set up.

The laserThe DOEs are designed to be used with a low-power semiconductor laser,giving a red beam with wavelength of 635 nm; that is about the wavelengthof the light emitted by the laser pointer provided with this EduKit. If you useanother laser, be sure that it has about the same wavelength or you willobserve some changes in the output patterns.

You can also use a He-Ne gas laser if you have one available. The wavelengthof 633 nm is almost the same as the design wavelength. Moreover these

lasers can give you much more power than your laser-pointer, and hence youobtain a much brighter image.

Laser safetyLaser light can be dangerous for the eyes; hence laser safety rules should bestrictly followed.

In Europe, safety standards are given in the European Norm EN-60 825-1. Inthat norm, lasers are classified in different "laser-safety classes", dependingon their power and emitted wavelength (= colour).

The laser which is included with the EduKit emits visible light, and has lessthan 1 mW power. According to the norm it belongs to safety class 2. Thoselasers are considered to be eye-safe, and normal exposure to the laser beamwill cause no permanent damage to the eye. Indeed, when exposed to thislaser, the eye immediately closes. This "blink reflex" takes about a quarter ofa second, and this is fast enough to avoid any damage to the eye (taking intoaccount the low power of the beam). Consequently no safety goggles areneeded.

However, it could be dangerous if you look orstare intentionally longer than a quarter of asecond in the beam: this should be avoided inany case.

Lasers of class 2 carry a black and yellow labelwith the word "CAUTION", and of course thelaser-pictogram.

Edukit p.10


11/48

Experimental set upWhen you shine a laser beam through one of the diffractive optical elementsin the card, light will be diffracted by the microscopic structures and you canobserve, on a screen at large distance, the so-called far-field diffractionpattern. In principle the screen should be positioned at infinity, but if you putit at about 1 metre from the DOE, then you will find acceptable images.

Direct projection of the image of the DOEs on a screen

You can improve the quality of the image by using a focused beam. First(step 1) position a lens between the laser and the screen, such that the laserbeam (without DOE) is focused on the screen. Then (step 2) put the DOE inthe converging beam.

Step 1: first focus the laser beam (without DOE) on the screen

Step 2: put the DOE in the convergent laser beam

Edukit p.11


12/48

Questions: what happens when you change the distance between the DOEand the screen?

Remark: some laser-pointers are equipped with a convergent lens. So if youuse another laser than the one which is delivered with this kit, first check

whether or not your laser has a lens included. If this is the case, be sure thatyou position your screen such that the laser beam (when used without aDOE) is focused on the projection screen.

It may look strange that light, after it is diffracted at the DOE, finally formsuch a sharp image; however, this is what really happens!

You can convince yourself by moving a paper or cardboard screen along thepath of the beam and observing the evolution of the light distribution, fromthe lens to the final image. A numerical simulation of this is provided with this

CD-ROM.

Edukit p.12


13/48

PART 3: Description of individual experiments

Here we describe each of the experiments which can be performed with theelements of the card.

Experiment 1: Linear Gratings

You will find the linear gratings at positions A1 and A2 on your card.

Inpart 2 of this textyou find the general description "How to perform the experiments".The basic theory can be found inpart 4.

Suppose that we shine coherent light through a transparency representing agrating i.e. a set of alternating absorbing and transparent lines, and look atthe image on a distant screen.

General view of set up

It is clear that such a grating can be considered as a repetition of Young'stwo-slits set up. Consequently Huygens Principle implies that each point Pon the screen receives light from each of the slits. All those light wavesinterfere together.

towards point P on a

distant screen

Top view of grating

If the position of the point P on the distant screen is chosen such that allwaves interfere constructively, then P is a bright point. If this condition is notsatisfied, P is a weak or even a dark point. In real gratings, there arehundreds of lines per millimetre, so in each bright point hundreds of wavescome together. All this implies that the difference in brightness between the

Edukit p.13
http://young2.jar/http://young2.jar/http://young2.jar/http://young2.jar/


14/48

points of constructive interference and all other points is so large, that youonly see the bright points.

Positions of the bright spotsThe figure below shows the light rays coming out of the grating. Two

successive rays will amplify each other when their path difference is amultiple of the wavelength: = m (basic theory). When this condition isfulfilled between two successive rays, it is automatically fulfilled for allrays.Hence the positions of the bright spots are given by the same equation as ina two-slit experiment:

ymax = mD

d m = 0, 1, 2, ...

D

towards P

d

= d sind

P

0

Phase gratingIn a "normal" grating, as the one described above, half of the light is

absorbed by the dark lines of the transparency; therefore this kind of gratingis called an absorption grating.

Edukit p.14


15/48

Edukit p.15

One can improve the brightness of the spots on the screen by using instead aphase grating.

In a phase grating the dark bands are replaced by elevations, the thickness ofwhich equals half a wavelength.

Transforming an absorption grating (left)into a phase grating (right); top view.

3-D view of a linear phase grating

It is clear that waves number and give constructive interference in pointP because their path difference, in point P, equals one wavelength. This is

also true for waves number

and

. Moreover, because the "bump" is halfa wavelength high, wave number travels the same distance towards P as

does wave number; and wave number travels the same distance as

wave number . Hence those waves will also amplify each other.Consequently in each point of constructive interference, we have now twiceas many waves as compared to an absorption grating. Hence the light pointson the screen are much brighter.

All the gratings on the EduKit are phase gratings.

TUTORIAL: these experiments are also simulated on a computer tutorialavailable on this CD.

height of bump = /2

towards point P

on distant screen


16/48

Experiment 2: Crossed gratings

You will find the crossed gratings at positions B1 and B2 on your card.

Inpart 2 of this text you find the general description "How to perform the experiments".

The basic theory can be found inpart 4.

A crossed grating is a diffractive optical element in which two lineargratings are combined; they are usually drawn perpendicular to each other.Each of the gratings gives, at a distant screen, a set of evenly spaced dots.The diffraction pattern of a crossed grating then consists of a multiplication intwo dimensions of an array of dots, which is nothing else than a square gridof dots.

Diffraction pattern (right) of a crossed grating (left)

The figure above shows a crossed grating made of a grid of absorbing lines.We have seen that gratings can also be produced as phase gratings, which isa transparent plate in which the thickness changes periodically. This can also

be done with a crossed grating.

A linear phase grating

A crossed phase grating

From this figure one sees that such a crossed grating can also be consideredas a periodic repetition, in both the horizontal and vertical directions, of asquare elevation on the transparent substrate.

Some properties of the diffraction pattern are illustrated in the numericaltutorial also available on this CD.

Edukit p.16


17/48

Experiment 3: Pattern Forming DOE

You find the Pattern Forming Diffractive Optical Elements (PF-DOEs) atpositions PF1 to PF6 on your card.

Inpart 2of this textyou will find the general description "How to perform the experiments".The basic theory can be found inpart 4.

In experiment 2 we have seen that a crossed grating gives a square array ofdots on the projection screen. Those dots are strongest in the middle, andfade off slightly towards the edges. The grating itself consists of a repetition,in horizontal and vertical direction of a so-called unit cell. In the simplestphase grating the unit cell is nothing else than an elevated plateau on thetransparent plate.

More complicated pictures can be produced on the projection screen byrealizing more complicated unit cells in the diffractive element. The unit cell isno simple plateau anymore, but can be a complete "town of sky-scrapers", asit is sometimes called.

the unit cell of a simple crossed grating;a "sky-scrapers" unit cell of a more sophisticated DOE.

The final image on the projection screen is again a regular set of points, butnow the points have not the same intensity anymore: some points are (very)bright, some are (very) weak.

By carefully designing the structure of the unit cell, it is possible to arrangethings such that the light dots on the screen form a certain pattern. This isthen called a Pattern Forming DOE, or a PFD.

The pattern forming process is illustrated in the numerical tutorial alsoavailable on this CD.

Examples are given below.The pictures on the left ("phase profile") show a magnified view of the

diffractive elements, the pictures on the right ("output profile") show the finalimages on the projection screen.

Edukit p.17


18/48

Element Name Phase Profile Output Profile Description

8x8 Increased fan-outelement binary

EOM.

Period is 256m.

EU outline

16 phase levelpattern formationDOE (PF-DOE)generating theoutline of the EU

flag.

Period is 512 m.

NEMO outline 16 level PF-DOEgenerating theNEMO logo.

Period is 512m.

On-axis Flattop On-axis flattopgenerator. 16phase levels.

Period is 512m.

Grid 16 level PF-DOEwhich generatesa grid pattern.

Period =512m.

PF2

PF6

PF5

PF3

PF4

Edukit p.18


19/48

Edukit p.19

Experiment 4: Diffractive Lens

You will find the diffractive lenses at positions FZP1, FZP2 and FZP3 on yourcard.

Inpart 2 of this text you find the general description "How to perform the experiments".

The basic theory can be found inpart 4.

A lens is an optical component which focuses an incident light beam towardsa point F, which is consequently called the focal point. A usual lens does thisby refracting the light; in a diffractive lens it is done with diffraction.

Such a diffractive lens is made of transparent material (glass or plastic) withconcentric rings on it; they divide the surface into so-called zones. In itssimplest form the zones are alternatively opaque and transparent. The radiiof the different zones are designed such that the distances from successive

zones towards the point F each time increases with half a wavelength.

Incident light will of course only be transmitted through the transparent

zones: zones number and in the picture. When these light waves cometogether in point F, their difference in distance is twice half a wavelength; thisimplies that, in F, they give constructive interference. The same is true forthe light waves coming from all other transparent zones. Consequently pointF is a brightpoint. In other words: this component indeed works as a lens.

Diffractive lenses are often called Fresnel Zone Plates or FZP, after AugustFresnel (1788-1827), a French scientist who did much research on diffraction.


20/48

Edukit p.20

f

towards F

= /2

F


21/48

Edukit p.21

The FZPs on your card are slightly different: they are phase FZPs. Here thedifferent zones are not alternatively transparent and opaque, but they differin thickness.

All those steps are equal to half a wavelength. This implies that wave number

now travels the same distance towards F as does wave number . Hence

waves number and , when arriving in point F, will give constructive

interference. Of course: wave number still gives constructive interference

with wave for the same reason as before. Hence in a phase FZP more lightwaves will give constructive interference than in a transparent/opaque one,and the focal point F is consequently brighter.

It can be shown that the radius rn of zone number n is given by

rn2 = n f n = 1, 2, 3, ....

with = the wavelength of lightf= the distance towards the "focal" point F

This explains why the zones become smaller towards the edge of the FZP.

The three FZPs on your card are designed such that, when illuminated with aparallel beam of red light with wavelength = 635 nm, they have a focaldistance of respectively f= 10, 50 and 250 mm.

height of bump = /2

towards point F


22/48

PART 4: Basic theory Diffraction and Interference of

Light a simple approach

1. What is diffraction?

Light propagates in straight lines!

When you look at the shadow of an object cast on the ground, or theformation of a mirror image, it immediately becomes clear that lightpropagates in straight lines. People have realized this for thousands of years.Those straight lines are called light rays.

Figure 1: The shadow of an object (left) or the mirror image (right) are formed by light rays

Later on, in the early 17-th century, simple optical instruments weredeveloped, such as eye glasses and simple telescopes or microscopes. It soonbecame clear that the working of those instruments could be understood ifyou suppose that, next to linear propagation, the light rays are broken whenentering or leaving the lenses; this phenomenon is called refraction.

Figure 2: In optical instruments (here two Galilean telescopes) light rays are refracted whenentering or leaving the lenses

Edukit p.22


23/48

Nowadays more complicatedinstruments exist. Althoughcomputers are used tocalculate the propagation oflight rays, the design is still

based on those two sameprinciples: refraction at thesurfaces and rectilinearpropagation between them.

Figure 3: Light rays in a complex optical system

...but that's not the whole storyShine a parallel beam of light on a screen with a small hole ("pinhole") in it.On the basis of the "light-ray-model' of optics, one would expect a parallellight beam behind the screen, and consequently a sharp shadow on a distant

wall. This can indeed be observed.

But around 1800 peoplediscovered that (under certainconditions - to be discussedlater on) strange thingshappened. The shadow wasnot sharply defined anymore:it was rather a diffuse disc,surrounded by light and dark

circles [Figure 4]. After itsEnglish discoverer theastronomer George Bidell Airy(1801-1892) this disc is calledthe Airy disc. This strangeeffect is called diffraction: wecan say that diffraction is thedeviation from linearpropagation.

Figure 4: Diffraction at a circular pinhole;the Airy disc

People found out that this strange effect could only be explained bysupposing that light behaves as it was a wave.You are already familiar with the concept ofwaves. You can produce a simple one bydropping a stone in a pool, creating ripples onthe water surface. Those ripples are calledwavefronts; they are circles, originating at thepoint of impact, which is then called the sourceof the wave. Hence we say that a point sourceproduces spherical waves

Figure 5: Spherical waves on awater surface

Edukit p.23


24/48

Moreover we see that, at each point, the direction of propagation isperpendicular to the wavefront. In a previous section we introduced theconcept of the light ray, by saying that it gives the direction of propagation oflight. So we can conclude that lightrays are perpendicular to their

wavefronts, as can be seen infigure 5.

When you add two or more sphericalwaves together, you obtain of coursea more complicated one; this additionof waves is called their superposition.The Dutch scientist ChristiaanHuygens (1629-1695) found that thereverse is also true: any complicated

wave can always be considered as asuperposition of (spherical) waves.Those spherical components arecalled the Huygens wavelets. Huygensused this construction to successfullyexplain the propagation of waves (seefigure 6).

A century later it was discovered thatthis same principle could also explain

diffraction at an aperture in a screenif one assumes that each point of theaperture sends waves in all directions; in other words: each point is thesource of a spherical wave (as in the lower part of figure 6). The total lightdistribution at the distant wall is then found by adding together all thoseHuygens wavelets, and indeed one finally finds the light distribution of Airy! Itturns out that the same trick also works perfectly when considering otherapertures then circular ones: squares, triangles, etc.

Conditions for diffraction

We have mentioned that certain conditions should befulfilled in order to realize diffraction. Thoseconditions can be summarized in one word: the lightshould be coherent. What's this all about?Light originates at a light source; each atom of thesource emits a small light wave. A light beam thenconsists of millions of those small waves [figure 7].Usually the emission from individual atoms runscompletely randomly. This "normal'' behaviour

produces what is known as an

incoherent beam. This givesproblems when adding the Huygens

Figure 6: The propagation of waves can beexplained by adding the Huygens

wavelets

Figure 7: Coherent light of a laser (upper)

versus incoherent light (lowerfigure).

Edukit p.24


25/48

wavelets: adding incoherent light waves gives you only rubbish; thats why itis very difficult to realize diffraction with "normal" light sources.In order to obtain a beautiful diffraction pattern, all those small waves shouldgo up and down together, as shown in the upper part of figure 7. We call thislight coherent light. Light from a laser is almost completely coherent. So in a

practical set up, one will use a laser for realizing diffraction.

SummaryDiffraction is the deviation from rectilinear propagation of light; it is due to itswave character. In practical set ups it can only be observed with laser light.

2. More about waves

Now that we know that light is a wave, let's look at some properties of waves.

We will concentrate on light waves, although most of the properties apply toall kinds of waves. So, in order to visualize the things, we can use the pictureof the water wave of figure 5.

WavelengthThe distance between two crests in figure 5 is called the wavelength; it isabbreviated with the Greek letter (= lambda). This wavelength is very smallfor light waves: it is less than one micron. A micron or micrometre (m) isone thousandth of a millimetre, or one millionth of a meter. The colourdepends upon the wavelength: it varies between 0.4 m for blue and 0.8 m

for red light. A picture showing this colour dependence is called the spectrumof light; see figure 8.

Figure 8: The spectrum of electromagnetic waves, including the spectrum of light

Edukit p.25


26/48

FrequencyEach point of the wave of figure 5 moves up and down. The number ofmovements or oscillations per second is called the frequency f of the wave. Itis measured in hertz, abbreviated as Hz; one hertz equals one oscillation persecond. This number is very high for light waves: about 1014 Hz or 100 times

one million times one million oscillations per second!

Velocity of propagationThe velocity of propagation of a light wave is called c, and it is about 3108m/s. This is an enormous value: indeed, each second a light wave advancesover 300 000 km {this equals more than seven times the circumference ofthe earth}. Moreover, Albert Einstein showed in his relativity theory that c isthe highest possible velocity: nothing can move faster than light!

The three parameters we have introduced so far are not independent; it can

indeed be proven that frequency times wavelength equals velocity, or insymbols

f = c (1)

Light is an electromagnetic waveIn the previous section it was said that light behaves as a wave, but it is notyet clear what kind of wave we are talking about. In other words: what ismoving up and down in a light wave?For simple waves the answer is obvious. In a water wave, for instance, it is ofcourse the surface of the water that oscillates; in a sound wave propagating

through air, the air molecules oscillate. But what is oscillating in a light wave?It was shown by the Scottish mathematician and physicist James ClerkMaxwell (1831-1879) around 1850 that light is an oscillating electric field.Because a changing electric field always creates a magnetic field, theoscillating electric field is accompanied by an oscillating magnetic field. Hencelight waves are called electromagnetic waves. Later on it was discovered thatother electromagnetic waves exist in nature; each having their ownwavelength range. Figure 8 shows this whole family as a function of theirwavelength; this is called the spectrum of electromagnetic waves. They rangefrom radio waves (for very long wavelengths), over microwaves, light waves

(infrared, visible, ultraviolet) up to X-rays and radioactive (= gamma) raysfor very short wavelengths.

Light waves have moreover a strange property; whereas "normal" wavesneed some matter to propagate trough (water waves in water, sound wavesin air....), which is called the medium of propagation, electromagnetic wavesdon't need this! Electromagnetic waves can propagate through empty space{of course: otherwise you would never see the light from distant stars!}.Matter on the other hand always retards and absorbs light. That is why youcannot see trough a wall. The velocity we called c in the previous section is

then the velocity in vacuum; all electromagnetic waves propagate with thissame velocity trough vacuum.

Edukit p.26


27/48

3. Interference

When you shine coherent light troughtwo neighbouring pinholes or slits, youwould expect to see, on a distant wallor screen, two overlapping bright spots.This happens indeed.

But around 1800 the English scientistThomas Young (1773-1829)discovered something strange: he found some dark bands, superposed onthose spots. This was not expected at all.

Edukit p.27

S1

S2

P Indeed, according to Huygens' principle,each of the two pinholes sends light wavesin all directions; hence in each point of thescreen two light waves come together, onefrom each pinhole or slit. How comes thenthat some points are dark? It looks as if, inthose dark points, the two waves destroyeach other.

This was indeed the explanation Young found out.

The two light rays coming together in point P have run a different distancebefore joining each other. Suppose that the wave from point S2 is retardedwith respect to the wave from point S1 by justhalf a wavelength, as in figure 11. So whenthe first wave goes up, the second goes down,and vice verse. When you add both wavesalgebraically together, they annihilate eachother.

This phenomenon is called destructive

interference; it is a typical wave phenomenon{in fact, the experiment of Young is thehistorical proof of the wave character of light}.What happens in point P can also happen inother points: in each point where thedifference between the two distances is half awavelength (up to a multiple of thewavelength, of course) the two wavesannihilate each other, end hence we find adark spot.

Figure 9:Young's experiment

Figure 10: at each point on the

screen, two waves cometogether

Figure 11: Destructiveinterference


28/48

On the other hand when the difference indistances is just a whole multiple of thewavelength, the two waves add constructivelytogether and consequently they reinforce

each other: one finds a bright spot at thosepoints, see figure 12. This is calledconstructive interference.

Between the points of constructive anddestructive interference, the two wavespartially reinforce or annihilate each other;hence the brightness varies continuously atthe screen, as is shown in the right part offigure 13. This image is called an interference

pattern; the bright and darks bands are calledthe fringes.

Interference: some numerical values

Let' s now return to the set up of Young's two-slit experiment, and let's lookat some typical numerical values; see figure 13 for a top view. Let us call thedistance between the two pinholes d, and the distance to the wall or screenD. In a real setup we always have D >> d.

Each of the two slits sends a light ray towards point P. When both rays cometogether they will interfere. We will now calculate the point(s) of maximumintensity, i.e. the points where the two waves add constructively together.This will happen each time the distance D2 - D1 equals a multiple of thewavelength

maximum : D2 - D1 = m m = 0 , 1, 2, 3, (2)

Because D >> d, the two light rays are (more or less) parallel. Then you see,in figure 13, that D2 - D1=d sin . Consequently we will have constructive

interference when

dsin= m (3)

The height of that point is called y, and you can see that y = D tan .

Combining this with (3) we find that the positions of the maxima are given by

Figure 12: Constructive interference

Edukit p.28


29/48

dmDy

== sinwithtanmax (4)

In real set ups, the angles are very small, and you know that for small

angles: sin tan (if you measure in radians, not in degrees!). So

finally we find the positions of the maxima

ymax = mD

d m = 0, 1, 2, ...

(5)

On the other hand, one has a minimum of intensity when the two wavesannihilate each other, and this happens when the difference between thedistances equal half a wavelength (plus possibly a multiple of the wavelength)

D2 D1 =

2+ m m = 0, 1, 2, ...

(6)

With analogous calculations as above this gives

ymin = m +1

2

D

d m = 0, 1, 2, ...

(7)

Between the maxima and the minima the light intensity varies continuously,

as shown in figure 13.

A pictorial representation of this is given in the companion tutorial alsoavailable on this CD; you can change the parameters of the set up and lookat their influence on the image.

Figure 13: details for the calculation of the interference fringes in Young's experiment

Edukit p.29


30/48

PART 5: Advanced experiments

The diffractive elements, provided with this EduKit, can also be used in moreelaborated experiments, if you have access to more complicated opticalhardware.

You will need a laser with more power than the laser pointer provided withthe EduKit: you will need several mW of power. A semiconductor laser with awavelength of about 635 nm is ideal, but a He-Ne laser (= 633 nm) is asgood. Moreover you will need a lens; a focal length of about 20 or 30 cm isconvenient for a laboratory set up.

Experiment 5: Fourier-transform set up

Illuminate the DOEs with a parallel beam, and position a lens between thecard with the DOEs and the screen, such that both distances equal the focallength f of the lens. You will find on the screen the same diffraction pattern asbefore. However, it is smaller: the dimensions of the diffraction pattern areindeed proportional to the focal length f of the lens.

f

f

Fourier-transform set up: diffraction pattern in the focal plane of a lens.

A diffraction pattern at a large distance is called a Fraunhofer diffractionpattern, after the German physicist Joseph von Fraunhofer (1787-1826). Themathematical operation which transforms the light distribution of the DOEinto the distribution on the screen is called a Fourier transform, after theFrench mathematician Joseph Fourier (1768-1830). This operation has beenextensively studied in mathematics, because it is not only important in optics,but it is also a basic mathematical tool for electronics.

That is why the set up above is called a Fourier transform set up.

Edukit p.30


31/48

Example.

Take for example DOE number FP4: this projects a square grid on theprojection screen. When using the set up of experiment # 3, with the screenat about one meter from the DOE, the overall width of the square grid is

about 15 cm.

When you use the "Fourier-transform" set up, with a lens of focal distance of15 cm, then the overall width of the grid is only 25 mm! With a lens with asmaller focal length, the image becomes even smaller.

One can prove, by theoretical calculations, that the position of the screen iscritical: you have to put it really at focal distance from the lens. On the otherhand: the distance between the DOE and the lens is not important; you canbring it close to the lens, or put it very far away: the image on the screen will

not change.

Check those theoretical predictions experimentally.

Experiment 6: 4-f processor

f

f

f

f

input

slide

Basic set up for a 4-f processor

When an optical bench with the necessary optical components is available,you can build more complicated set ups. A possible experiment is shown inthe figure above.

Position successively a slide, a lens, a filter, another lens (with the same focallength as the first one) and the screen. The distance between the

components is each time equal to the focal length f. This is why this set up is

Edukit p.31


32/48

called a "4-f processor". The input slide is illuminated with a parallel beam ofred light.

When you put no filter in the set up, you find the image of the slide (upsidedown) on the screen. If you put now a grating at the position "filter", then the

image will be multiplied on the screen.

For this experiment it is best to use a simple, small object at the input side;for example use an aperture of a few mm wide. For "filter" use the grating ofthe highest frequency available; in other words, use DOE number A1 or B1 ofyour card.

The theory behind this filtering is too complicated to be given in this simpletext; you have to look at books on Fourier optics.

Experiment 7: Experiments w ith micro-lenses

Elements L1 to L6 on your plastic card are arrays of "normal" or refractivelenses; however, they are very small therefore they are known as micro-lenses. L1 and L2 are square packed arrays of spherical micro-lenses, L3 andL4 are arrays of cylindrical micro-lenses, and L5 and L6 are hexagonallypacked arrays of spherical micro-lenses. The distance d betweenneighbouring lenses is 0.1 mm for L1, L3, L5 and 0.05 mm for L2, L4 and L6.

d

Magnified view of a square packed array of spherical refractive micro-lenses

Edukit p.32


33/48

If you shine a parallel beam of light onto these lenses, they focus the beamtowards their focal point. This gives an array of points (for L1, L2, L5 and L6)or an array of lines for the cylindrical lenses L2 and L4. However, the focaldistances are so small (only a few microns) that you need special equipmentto measure it.

On the other hand, if you look at the light pattern at a large distance, thenyou find a regular pattern of dots. It looks as if you have diffraction at alinear or a crossed grating!

You can easily understand this. An array of cylindrical lenses forms in fact alinear grating, whereas a square or hexagonal array of micro-lenses forms acrossed grating. The peculiarity that they are composed of individual micro-lenses turns out to be of minor importance - at least in this experiment.

Edukit p.33


34/48

PART 6: Design, Fabrication and Replication of the micro-

optical elements

Design and Fabrication of Diffractive and M icro-Optical Components.

The procedures used in the design of the micro-structured diffractive opticalelements (DOEs) are based around the relatively simple physicalphenomenon of diffraction. However, before the advent of powerfulcomputers, only the simplest DOE designs could be generated (for example,the simple 1x2 gratings contained in the EduKit). With the explosion inavailable computational power over the last twenty years, the complexity andefficiency of DOEs has increased commensurately. In this section we shalllook at the basic method used in the design of pattern formation DOEs andpresent some of the technologies used in the fabrication of the masters usedin the replication processes.

The design of DOEs exploits an area of computational mathematics known asoptimisation, where the inputs to some physical process (in this case,diffraction) are altered in some way to ensure the best possible output fromthe process.

Element Plane Output Plane

Edukit p.34

Element phasePerform Diffraction

Operation

Output intensityand phase

Apply output constraint

Recalculate complexamplitude

Generate phaserofile

Quantise phase

Perform Inverse

Diffraction Operation

Random PhaseProfile

Desired OutputPattern

Experimental Output

DOE OutputDOE Profile

Figure 1: Design cycle for diffractive optical element (DOE) using iterativeoptimization method.


35/48

The optimization, which takes a number of iterations to produce the bestresult, calculates the diffraction pattern produced by the input micro-structured profile, compares it to the desired output by calculating a meritfunction (relating the desired output to the actual output) and then makeschanges to the input micro-structured pattern such that the overall merit

function is lowered from one cycle to the next. Finally, the output is producedas a simple text file which can be used in the fabrication process. This methodis shown schematically in Figure 1 where movement between the elementplane (the structure of the DOE) and the output plane (the output from theDOE) is performed using the mathematical description of the physical processof diffraction.

The profile generated using the optimization procedure described above, isused to generate a set of binary amplitude masks, which are plates of glasscoated in a thin layer of highly reflective chrome with small holes selectively

opened in the chrome layer. These masks, which are fabricated on a machineknown as an electron-beam writer (which operates on a principle identical tothe scanning mechanism used in a cathode ray television), are then used toselectively pattern a glass substrate coated with a chemical known as aphotopolymer.

Figure 2: Layout of binary amplitude mask set for EduKit. Layout and designs Heriot-Watt

University, Edinburgh, Scotland.

This chemical is altered by exposure to ultra-violet light so that, once thephotopolymer has been developed, those areas that have been exposed to UVlight (where the chrome layer has been opened on the electron-beam mask)are washed away and the areas which have not been exposed remain. Thisprocess, known as photolithography, is used extensively in the fabrication of

the micro-electronic chips found in every electronic product. Once thephotopolymer has been patterned, the substrate containing the patterned

Edukit p.35


36/48

photopolymer is placed in an etching machine (known as a reactive ionetcher) and the remaining photopolymer and areas of exposed glass areremoved (etched) at a precisely controlled rate. The reactive ion etchingprocess is based around the acceleration of gas ions inside an electric fieldand produces very precise vertical etches ensuring the accurate

reconstruction of the DOE design.

UV

PMMA

Glass

RIE

)1(2 =

nd

Figure 3: Reactive Ion Etching of Multi-level Structure using photopolymer(PMMA) and binary amplitude masks.

In this way, the pattern which has been transferred from the computer to theelectron-beam mask to the photopolymer is now transferred to the glasssubstrate. The diffractive optical elements produced after this process arecomplete and are generally used in this form. However, in applications wherea large number of elements (>100) are needed, thephotolithographic/reactive ion etching mastering process is too slow andlabour intensive to be used and so the completed elements are used as amaster in the mass replication procedures described in the following section.

The refractive micro-lenses, which are fabricated using a thermal reflow

method, are designed using a simple disc pattern of photopolymer. The disc,which is typically of 50m to 150m diameter, is produced in photopolymerusing the standard photolithographic technique outlined above. Once theindividual discs of photopolymer are produced, the entire patterned substrateis heated (to approximately 200 C) allowing the photopolymer to go liquid.The effect of surface tension acting on the liquid photopolymer causes thedisc structures to form into a spherical surface. After the substrate coolsdown, the now spherical micro-lenses can be transferred into the glasssubstrate by the standard reactive ion etching technology described above.The different focal lengths of the lenses are achieved by using different

diameters of microlens disc and altering the etch procedure to ensure thephotopolymer etches at a faster (or slower) rate than the glass substrate.

Edukit p.36


37/48

Hot Embossing for Micro-optical Structures

The plastic parts of the educational kit are fabricated by hot embossing usingmoulding tools manufactured by lithography and etching methods andsubsequent electroforming. The principal process steps of hot embossing are:

A thermoplastic film is inserted into the moulding machine (see figure 4(a)),

a micro-structured tool (mould insert) in an evacuated chamber is pressedwith high force into the film, which has been heated above its softening

temperature. Thus the cavities of the mould insert are filled by the plasticmaterial replicating the microstructures in detail (figure 4(b)). After coolingdown the whole setup below the softening temperature of the polymer, theplastic film with microstructures on the surface is released from the mouldingtool (figure 4(c)).

(a) (b) (c)

Figure 4: Process steps of hot embossing

In contrast to injection moulding, during hot embossing the flow path of thepolymer is very short. As a result, very little stress is produced in the polymerand the moulded parts are well suited as optical components, such aswaveguides and lenses. As the moulding temperature is also smaller

compared to injection moulding the shrinkage during cooling and the frictionforces acting on the micro structures during mould release are reduced. Thusmore delicate micro structures with higher aspect ratios can be fabricated byhot embossing compared to injection moulding. Hot embossing is particularlysuited for forming thin sheets or foils, as a small amount of plastic has to bemoulded only.

Hot embossing allows for a very simple setup of the plant, which isparticularly advantageous if tool or plant reconstructions or modifications arenecessary. This results in very short set-up times. When using standardized

mould inserts, a few minutes are sufficient to exchange a tool. Moreover, foilsmade of various thermoplastic materials can be put into the machine

Edukit p.37


38/48

successively without any furthermodifications. Therefore, hotembossing makes the production ofsmall and medium-scale serieseconomically more efficient and is

especially suited for laboratoryapplications. On the other hand,relatively long cycle times of up to 30min may be required for somecomponents.

Figure 5: Hot embossing press

For some applications such a longtime can be advantageous if, e.g.,inner stress is reduced by extremeslow cooling rates. But long cycle

times are caused mainly by the factthat the heated polymer is notsupplied continuously by an injectionunit. Such problems can be reducedconsiderably by further developing hotembossing machines and theirperiphery.

The principal limit for shortening themoulding cycle of hot embossing is a

bit larger than for injection-moulding,because in injection-moulding themolten polymer can be filled into amould insert which is colder than thesoftening point of the polymer while inhot embossing the polymer needs tobe heated up and cooled down in themould insert (vario-term process).

This means that the thermal cycle of

a mould insert is usually smaller in aninjection moulding machine than in ahot embossing machine. Cycle timesare also strongly affected by the tool

design. For mass fabrication a tool can be designed with sophisticated heatingand cooling features and reduced thermal mass.

Figure 6: Typical large area hot embossing tool

For the moulding of the NEMO Educational Kit a new hot embossing tool with verylow cyclic heated thermal mass was used (see figure 6). The tool can carry up to fiveshim mould inserts. With this setup cycle times of six minutes were reached.Additionally an automated handling system was used to place the semi-finished

parts in the machine and to take the parts out of the tool.

Edukit p.38


39/48

PART 7: NEMO : Network of Excellence on Micro-Optics

What is NEMO ?

In its 2nd call under Framework 6, theEuropean Commission granted theNetwork of Excellence on Micro-Optics"NEMO" with 6.4 Million Euro.

NEMO is running since Sept. 1st 2004and aims at providing Europe with acomplete Micro-Optics food-chain bysetting up durable Service and

technology centres for Optical Modelling and Design; Measurement andInstrumentation, Mastering, Prototyping and Replication; Hybrid Integration

and Packaging; Reliability and Standardization.

NEMO will be the networking platform for 30 European partners for the next 4years. The network is co-ordinated by Prof. Hugo Thienpont from the VrijeUniversiteit Brussel, Belgium, by Prof. Malgorzata Kujawinska from WarsawUniversity of Technology, Poland, and by Dr. Juergen Mohr fromForschungsZentrum Karlsruhe, Germany. Each of the 30 institutes involved inNEMO is a key-role player in micro-optics.

NEMO's main objective is to structure and integrate the expertise and core-

competences of its partners while strengthening their R&D activities in theemerging field of micro-optics.More info about NEMO at www.micro-optics.org.

Edukit p.39
http://www.micro-optics.org/www/our_serviceshttp://www.micro-optics.org/www/our_serviceshttp://www.micro-optics.org/www/our_services/modelling_designhttp://www.micro-optics.org/www/our_services/measurement_instrumentationhttp://www.micro-optics.org/www/our_services/measurement_instrumentationhttp://www.micro-optics.org/www/our_services/prototypinghttp://www.micro-optics.org/www/our_services/packaging_integrationhttp://www.micro-optics.org/www/our_services/packaging_integrationhttp://www.micro-optics.org/www/our_services/reliabilityhttp://www.micro-optics.org/www/our_services/standardisationhttp://www.micro-optics.org/http://www.micro-optics.org/http://www.micro-optics.org/www/our_services/standardisationhttp://www.micro-optics.org/www/our_services/reliabilityhttp://www.micro-optics.org/www/our_services/packaging_integrationhttp://www.micro-optics.org/www/our_services/packaging_integrationhttp://www.micro-optics.org/www/our_services/prototypinghttp://www.micro-optics.org/www/our_services/measurement_instrumentationhttp://www.micro-optics.org/www/our_services/measurement_instrumentationhttp://www.micro-optics.org/www/our_services/modelling_designhttp://www.micro-optics.org/www/our_serviceshttp://www.micro-optics.org/www/our_services


40/48

Objectives of NEMO

NEMO's Mission Statement is to set up a world force on micro-optics researchand technology that strongly and constructively impacts:

the way micro-optics research will be structured and conducted inEurope's society of tomorrow

the competitiveness of European research, SMEs and companies the awareness of society for "optics for the quality of life" the world-wide recognition of European research in micro-optics the education of secondary school and university level students in

(micro)-optics and photonics women's involvement in optics and photonics employment in European research centres and high tech companies

Activities

Structuring and Integration

Setting up and sustaining 6 integrated Service and Technology ProvidingCentres that support an entire food chain of micro-optics, from modellingto standardisation. Their goal is the technological support of micro-opticsR&D for NEMO research centres and third-party industry.

Setting up a micro-optics multi-project wafer facility for refractive and

diffractive optics.

Creating a knowledge management centre to support e-collaboration anddissemination of knowledge on micro-optics.

Creating an Industrial Interface Centre and an Industrial Users Club formicro-optics to enhance interaction with industry and to initiate NEMO'scontract research with companies.

Jointly Executed Research Activities

Tackling 6 long-term application-oriented research topics on micro-optics, the outcome of which targets to increasing the quality of life.

Spreading of Excellence Activities

Creating optics-awareness by given secondary schools an educationaloptics kit.

Spreading promotional material to increase the involvement of women inoptics.

Restructuring and integrating optics and photonics conferences with afocus on the European optics and photonics research area.

Edukit p.40
http://www.micro-optics.org/www/our_serviceshttp://www.micro-optics.org/www/our_serviceshttps://industry.micro-optics.org/http://www.micro-optics.org/www/our_researchhttp://www.micro-optics.org/www/wonderful_lighthttp://www.micro-optics.org/www/wonderful_lighthttp://www.micro-optics.org/public/news/careers_in_optics_and_photonics_surveyhttp://www.micro-optics.org/public/news/careers_in_optics_and_photonics_surveyhttp://www.micro-optics.org/www/news_events/eventshttp://www.micro-optics.org/www/news_events/eventshttp://www.micro-optics.org/public/news/careers_in_optics_and_photonics_surveyhttp://www.micro-optics.org/public/news/careers_in_optics_and_photonics_surveyhttp://www.micro-optics.org/www/wonderful_lighthttp://www.micro-optics.org/www/wonderful_lighthttp://www.micro-optics.org/www/our_researchhttps://industry.micro-optics.org/http://www.micro-optics.org/www/our_serviceshttp://www.micro-optics.org/www/our_services


41/48

PART 8: Worksheets

Experiment A: Project image w ith the EduKit

What do you need?

1 laser or laser pen 1 card with diffractive components 1 screen

How do you perform the experiment?

Put the screen at about 1 metre behind the card with diffractive componentsand shine the laser through each of the DOEs in turn. Explain the observedimages.

What happens if you change the distance between the diffractive card and thescreen?

And what if you change the distance between laser and DOE ?

Edukit p.41


42/48

Experiment B: Focussing w ith a diffractive lens from de

EduKit

What do you need?

1 laser or laser pen 1 plastic card with diffractive components 1 white screen


Shine with the laser on each of the diffractive lenses (the FZP or Fresnel ZonePlates) from the EduKit. Position your card far enough from the laser, suchthat the whole FZP is illuminated. Put your screen immediately behind thecard, and then move it slowly backwards.At a certain distance you will see that the laser beam is focussed to a point,which gives you the focal distance

Improved experiment

The incident beam should be collimated and you can realize this in the wayshown below:

laser

FZP

Use a lens with a focal distance of about 10 cm.

Edukit p.42


43/48

Experiment C: Optics rodeo: hit the targets!

What do you need per group?

1 laser or laser pen 1 plastic card with diffractive components Some play-doh/ plasticine 10-15 small mirrors (2cm x 2cm) 10 targets to hang on the walls (sheets of paper with a logo)


The goal of this game is simple: hit as many targets hanging at the walls aspossible with a laser beam. Explore which diffractive element is the most

effective to split your laser beam and position your mirrors as such that theincoming laser beams are reflected onto a target. This is a fun activity whereteams can compete against each other to see who can measure mostaccurately or who can come up with the most effective method for hitting thetarget. This involves having several small groups working in isolated areas ofa classroom.

Improved experiment (alternative)

The targets on the walls might contain logos of varying size. Hitting small

logos gives more points than hitting large ones. Scoring could be forexample:

10 points for small targets 7 points for medium targets 4 points for large targets The number of targets hit at the same time could be multiplied by 2

and added to the total score.

You might also restrict the time that the laser beam can be ON to increasethe difficulty and the required cooperation in the group.

Edukit p.43


44/48

PART 9: SPIE: International Society for Optical

Engineering.

SPIE, the International Society for Optical Engineering, was founded in 1955 and is a

not-for-profit organization that has become the largest international force for theexchange, collection and dissemination of knowledge in optics, photonics andimaging. This is realized through the organization of conferences, variouspublications (conference proceedings, journals, and books), exhibitions andshowcases, education (short courses, videos) and different scholarships, awards,technical groups with discussion forums, career services, and so on.

One of the big action points of SPIE is the outreach towards youngsters. SPIEMembers, event participants, and volunteers, through their collective talents,influence the future of optical, technical, and scientific discovery. Their knowledgeand vision help to create a next generation of young scientists and engineers, whoare captivated by the extraordinary promise of light. To that end, the Societyprovides more than $700,000 annually in scholarships, grants, and financial supportto encourage scientific and technological education and innovation.

SPIE offers the resources of the Society to elementary and secondary educatorsinterested in using optics tools to interest young people in science. By doing this theSociety increases the number of teachers who use optics tools and providesresources to students on optics career opportunities and information. Moreinformation can be found on the following links:

Hands-on Optics - http://www.hands-on-optics.org/home/Hands-On Optics (HOO) helps kids learn by doing, making discoveries, andthinking like scientists. It nurtures their spirit of adventure and increases theirknowledge of science and technology. It opens the world of optics as adiscipline and potential career pathand broadens their perception of whatscience is about. It integrates a wide range of subjectsfrom biology and artto technology and engineeringto excite students about science, math, andlearning.

Light at Work - http://spie.org/x2650.xmlThink of optics as the science of lightwhat light is made of and how itbehaves. Light allows us to see, but it can also be used to transmit sounds,cut things and control electrical circuits. Optical Engineers helped design

things you use everyday...remote controls, DVD players, cell phones... eventhe Internet.

Optical engineers and scientists work by themselves and in teams to solvetoday's puzzles, they're working on cancer cures, clean energy, spacetelescopes, and more it's hard to imagine what the future of optics will be.Optics careers are as varied as they are exciting. The researchers anddevelopers featured in this video are travelling the world; making a differenceand seeing their creations come to life. Optical engineers are changing theworld with light.

Edukit p.44
http://www.hands-on-optics.org/home/http://spie.org/x2650.xmlhttp://spie.org/x2650.xmlhttp://www.hands-on-optics.org/home/


45/48

PART 10: Evaluation form

Thank you for you assistance to improve NEMOs Educational Kit (EduKit) bycompleting this form. In order to optimize the use of and work with the

EduKit your FEEDBACK is essential.

On these three pages you are kindly asked to give us your opinion regardingyour findings/experiences with NEMOs Educational Kit.

Please send us your evaluation to [email protected] or fax it to +32 2629 34 50. This form is also electronically available on the NEMO portal(www.micro-optics.org).

1 Basic information

First and last Name

Title

Email

Tel

Fax

Name ofschool/university

Address

2 Target group the EduKit was presented to

2.1 Number of people

/ pupils

2.2 Age of pupils /people

from to

2.3 Gender female male

Edukit p.45
http://www.micro-optics.org/http://www.micro-optics.org/


46/48

3 CD-ROM

verygood

good sufficient poor

3.1 How would yourank the CD-ROMmanual

3.2 What is to beimprovedregarding theexplanation of theopticalbackground?

3.3 Which type ofexperimentdescription wouldyou recommendto add to the CD-ROM?

3.4 Is there anotherchapter / topicyou would

recommend to bediscussed in theCD-ROM?

3.5 Was thereanything difficultto understand inthe CD-ROMdescription?

3.6 What is to beimproved with thesetup-explanationin general?

3.7 Do you have anyothersuggestions?

Edukit p.46


47/48

4 Setup

very good good sufficient poor

4.1 How would yourank theusability of theopticalelements?

Exp. 1

experimentswith lineargratingsExperiment

Exp. 2experimentswith crossedgratingsExperiment

Exp. 3experimentswith patternformingDOEs

Experiment

Exp. 4

experimentswith theFresnel zoneplates

Exp. 5

Fouriertransformwith a singlelensExperiment

Exp. 6

Opticalfiltering with a4-f processorExperiment

Exp.7Experimentswith micro-lenses

4.2 Which of thedescribedexperiments onthe CD-ROM did

you show inclass?

4.3 Which experiments didyou perform with theEduKit that were not yetdiscussed on the CD-ROM?

4.4 Are there additionalexperiments you wouldlike to show / ask thepupils to do? What kind

of optical elementswould you require forthat?

4.5 Do you have any othersuggestions?

Edukit p.47


48/48

5 Reaction

5.1 Please describebriefly the reaction

of the pupils /students to theEduKit.

5.2 What do youconsider to be theadded value of theEduKit for thestudents?

6 Open Comments

6.1 Do you have anyfurther comments,suggestions orrecommendationsto the use of theEduKit?

THANK YOU your feedback will help us to improve the understanding ofoptics for the pupils & students in Europe!

English - EduKit Handbook

Documents

Transcript of English - EduKit Handbook