Piezoelectric type dispenser

Precision Metrology Lab.

Piezoelectric type dispenser The principle is to actuate a disk type PZT to push the liquid and make the drop to perform a linearly stable ejection behavior.

Glue dispenser The step motor applies a force to a valve that forces the valve toward the liquid container so as to open the opening. After opening the valve, the dispensing apparatus control the dropping amounts using the air pressure.


Measured weights of 1000 drops by the subpixel method(a) A schematic diagram of a droplet flying in free space

(b), (c), (d) Image processing

In situ volume measurement of micro droplets The system developed utilizes a stroboscopic technique to synchronize the triggering of a strobe light and a CCD camera. A steady image of the droplet flying in free space can be captured in situ by the CCD camera. The method of precise volume estimation is based on a rotationally symmetric model of the droplet’s shape.


3-color LED

40X microscope

Focus lens

Beam splitter

60X microscope

Color CCD

Beam splitter

Depth response curve

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

-20 -15 -10 -5

Z (µm)

Nor

mal

izat

ion

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

RG ration

The nominal dimension of the grating: the pitch is 5.0 µm and the height is 2.5 µm.

To get the RG-ratio via the depth response curve could determine the height of work

piece.


Introduction During machining, feed force, cutting force and the self weight of machine tool applied to the contact surface, such as the slide way and the linear slide, will cause friction and wear. For improper assembled parts, it will incur loose contact. The accuracy of machine tool will be degraded. This research is to develop a monitoring system of machine tool accuracy degradation. One object is to develop a software, under known cutting conditions, this software can predict the slider displacements, feed force, reaction force of contact surfaces and wear of slideways. Another to reconstruct the commercial DVD pick-up head to be a precision angular probe. It can measure three angular errors of working stage, and the angular errors can be real-time processed by embedded system, and then angular errors can be displayed on PC that user can know the machining condition. The advantages of this system are high precision, low cost and monitoring immediately, so that can improve industry‘s competitiveness.


Optical system of DVD pick-up head Residual of angular calibration


The software of the machine tool accuracy degradation


Disc

Voice coil motor

Objective lensCollimator lens

Polarization beam splitter and λ/4 plate

Laser diode

Grating

Photodiode IC

Cylindrical lens

Quadrant detector

and arm springs

AC DB

FE

Plane1

Plane2Plane3

Y

X

Z

Plane1

Plane2

Plane3

V

-

0

+

0

+

-

mμCD : 20

m

A

B

C

D

A

A

B

B

C

C

D

D

DVD : 7 mμ

Basic structure of DVD pick-up head Schematic representation of astigmatic auto-focusing method

10um

FES curve


The micro meter scratches on the scraping work pieces can measure by the DVD probe’s Focus Error Signal can be find out.

DVD Laser Probe

Objective lens

Scraping work piece

Moving work plate


Introduce Rectangular type of the bridge is always employed in the precision CMM structure for mounting the Z-axis probe. The deformation in the center of the bridge is very critical because of the concentrated load from the spindle. The research proposes a fixed pagoda structure. Under the same dimension and the same spindle load, the maximum deflection at the center of the bridge can be reduced Abbe free in all axes.


Introduction Conventional XY stage is stacked up by two linear stages. The Abbe’ error of the lower stage is high. An innovation co-planar stage is thus proposed in this study. The stage motion is actuated by a ultrasonic motor, the opposite side set the motion sensor of LDGI.


Introduction A compact micro interferometer LDGI (Laser Diffraction Grating Interferometer), could generate interference fringe in half pitch (416.5nm). With signal interpolation at 360 degree, the resolution can reach to 1nm. The principle of LDGI with a 1nm resolution, as show in Figure. Through a series polarization phenomenon, the beam will eventually arrive at PD1, PD2, PD3 and PD4. The intensity of each PD can be expressed by:


Tip ball with 30 μm diameter made with melt-drawn technique

Tip ball attached to the CMM probe Fiber probe

Probe stem

Introduction The cleaning feature of a commercial optical fiber fusion splicer is used to manufacture a micro probe. Due to the surface tension , the fiber melt by the arc energy will shrink as a ball at the tip. Typically , the diameter of tip ball is 300 μm while fusing the tip ball with 125 μm fiber. Furthermore, with the melt-drawn technique , the diameter of the tip ball was down to 30 μm.Connecting with the plate of the sensor mechanism , the tip ball fiber can be used as a CMM touch probe.


Orthogonal circuit

Signal_1Signal_2

Analog output

AD converter

FPGA circuit

Linear Guide Motor

Displacement Display

LDGI Grating Displacement Transducer

Current to Voltage

Converter

DifferentialAmplifier

Auto-Orthogonal

Circuit

Signal input

Probe

LDGI Grating

Motor

Screw thread

Stylus

Linear guide

Pivot

Inside screw

The flow diagram of the system

To calculate and analysis the Geometry of the Mechanism.

Introduction Using the motor to drive the mechanism of the probe . To measure and calculate the x-axis and y-axis displacement by LDGI , and can return to the original condition in the profile of inside screw.

Piezoelectric type dispenser

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