Imaging with Waves

Creating images with light

camera obscura modern imaging device

Steering waves

Magnification with 2 lenses

Seeing small things

Antonie van Leeuwenhoek

The compound microscope

Seeing sharper

Modern optical microscopy

Focusing down

Airy Disk

0.61•/NANA = n•sin

2

The diffraction limit

Objects spaced apart by less than d~/2NA cannot be resolved individually!

Ernst Abbe (1840-1905)

Imaging with the diffraction limit

Object ImageFocal spot

Images can be improved by using shorter wavelengths

CD versus DVD

7x more data on DVD because of different wavelength!

780 nm 650 nm

(Blu-Ray DVD uses 405 nm, 6x more data than DVD)

UV lithography

Superresolution

Single molecules

Seeing single molecules at work

Seeing single molecules at work

QuickTime™ and aH.263 decompressor

are needed to see this picture.

Seeing smaller thingsusing particlesusing EM radiation

of particles:

€

= hmv

Electron with v = 1.0 x 105 m/s:

€

=6.626 ×10−34 Js

9.11×10−31kg( ) 1.0 ×105m /s( )

€

€

=7.3×10−9m

€

=7.3nm

Electron Microscopy

Resolution ~ 0.2 nm

Electron Microscopy

Cryo-Electron Microscopy

Cryo-Electron Microscopy

Cryo-Electron Microscopy

Viral DNA portal protein

What are X-rays?

Wilhelm Conrad Röntgen (1845-1923)

Electromagnetic radiation with wavelength of ~10-10 m

Focusing or diffracting?

Bragg diffraction Diffraction pattern

2d sin = n

X-ray crystallography

Protein structure determination

X-ray crystallography reveals electron densities

Protein structure determination

No longer a mystery

No longer a mystery

DNA polymerase on the DNA backbone