optodyne argonne national laboratory applicazioni dell'interferometria laser ad alta...

OPTODYNE

OPTODYNE Argonne NationalLaboratory

Applicazioni dell'interferometria laser ad alta risoluzione

Applications of high-resolution laser interferometry

Gianmarco Liotto

Optodyne Laser Metrology srl

Via Veneto,5 20044-Bernareggio (MI )+39 039 6093618

[email protected]://www.optodyne.com/

A linear actuator system with 1-angstrom resolution and 50-millimeter travel

mailto:[email protected]





http://www.optodyne.com/







Argonne National Laboratory


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OUTLINE

Introduction

Laser Doppler Encoder with Sub-Angstrom Sensitivity

High-Stiffness Weak-Link Linear Motion Reduction Mechanism

One-dimensional Laser Doppler Linear Actuator Design

One-dimensional Laser Doppler Linear Actuator Test

Optics for Two-dimensional Laser Doppler Encoder

Two-dimensional Laser Doppler Linear Actuator Design

Discussion and Conclusions



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Since 1997 an ultraprecision motion control techniques have been developed at the APS, Argonne National Laboratory with the support of OPTODYNE, inc.

The novel laser Doppler encoder system;

is a valuable measuring tool in the study of a crystal’s vibrational behavior because it has nanoradian sensitivity.



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A commercial Laser Doppler Displacement Meter (LDDM) system includes four components: a laser head, a processor module, a display module, and a target reflector. The laser head houses a frequency-stabilized HeNe laser, an electro-optic assembly and a photodetector, which functions as a receiver. The laser light reflected by the target is frequency shifted by the motion of the target. The photodetector measures the phase variation caused by the frequency shift, which corresponds to the displacement of the target.

When the displacement is larger than the half-wavelength, /2, a counter records the total phase changes

as:total

where N is the number of half-wavelengths, and is the phase angle less than 2.



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The total target displacement, z, can be expressed as:

c z = ------ (N +/2) (2)

2f0 ,

where f0 is the frequency of the laser, and c is the speed of the light.

If we make the laser light reflecting back and forth M times between the fixed base and the target before it finally reach the photodetector, then introducing equation (2) gives

c z = --------- (N + /2) (3)

2f0 M ,

which indicates that the multiple-reflection optics provides M-times resolution extension power for the system.



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Multiple-reflection optics for the laser Doppler displacement meter (LDDM)

The laser Doppler displacement meter is based on the principles of radar, the Doppler effect, and optical heterodyning. We have chosen a LDDM as our basic system, not only because of its high resolution (2 nm typically) and high measuring speed (2 m/s) but also because of its unique performance independent of polarization, which provides the convenience to create a novel multiple-reflection-based optical design to attain sub-Angstrom linear resolution extension.



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Multiple-reflection optics for the laser Doppler displacement meter (LDDM)



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Test of a Laser Doppler Linear Encoder (LDLE)

A prototype LDLE system having an extension with optical resolution from twenty-four multiple A prototype LDLE system having an extension with optical resolution from twenty-four multiple reflections has been developed and tested at the Advanced Photon Source. A precision reflections has been developed and tested at the Advanced Photon Source. A precision stepping-motor-driven stage has been used to test the LDLE over a 300-mm measuring stepping-motor-driven stage has been used to test the LDLE over a 300-mm measuring range.range.

Measuring Range Test for LDLE with Optical Resolution Extension

0

50

100

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0 5 10 15 20 25 30

Readout from Commercial LDDM (cm)

Rea

do

ut

wit

h O

pti

cal R

eso

luti

on

Ext

ensi

on

(1

= 0

.083

3333

cm

)



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The resolution of the custom-made commercial LDDM system, which was used during this test, was 2 nm (1 nm LSB), so that, theoretically, a 0.166 nm resolution (0.083 nm LSB) was reached by the prototype LDLE system.

LDLE Test with Queensgate PZT Driver 6.8 nm Jumps

8.00E+02

9.00E+02

1.00E+03

1.10E+03

1.20E+03

1.30E+03

56 66 76 86 96

Time (1 unit = 0.2 sec)

LD

LE

Rea

do

ut

(1 u

nit

= 0

.083

3 n

m)

Test of a Laser Doppler Linear Encoder (LDLE)



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Calibration for a High-stiffness Weak-link Linear Motion Reduction Mechanism



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Prototype of a laser Doppler linear actuator system (LDLA) with sub-angstrom sensor resolution and positioning resolution over a 50-mm travel range.



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Setup for Large Field Atomic Probe Microscope Test with LDLA



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Test of a LDLA closed-loop feedback system

Comparison of Open loop and Closed loop

-15.0

-10.0

-5.0

0.0

5.0

10.0

15.0

20.0

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Time (s)

An

gs

tro

m

-1.0

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-0.4

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0.0

0.2

0.4

0.6

0.8

1.0

3 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4



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Laser Doppler Linear Actuator Test

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0

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9

0 10 20 30 40 50 60 70

Time (sec)

Dis

pla

cem

ent

(An

gst

orm

)

01928-52627pm.dat



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LDLA Active Vibration Control Test

-40

-30

-20

-10

0

10

20

30

40

92 93 94 95 96 97 98

Time (sec)

Dis

pla

cem

en

t (A

ng

stro

m)

0272-64210pm.dat



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Prototype of a two-dimensional laser Doppler linear actuator system (LDLA) with subnanometer positioning resolution over a 50 mm x 50 mm travel range



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MULTIPLE PASS ADAPTER

A 6-pass optical arrangement achieved by an optical adapter and a 25mm diameter retroreflector .



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Multi 6 Single

6 - p a s s v s s in g le

0 10 20 30 40 50 60 t i m e , s e c

0

-0,1

-0,5

MULTIPLE PASS ADAPTER

Effect of air circulation on a 6-pass optical arrangement and on a single pass optical arrangement.



OPTODYNE

OPTODYNE Laser Measuring System LDDM

•Includes:

•Retroreflector

•Processor box

•Laser Head

•Performances

•Resolution 1.2nm

•Speed 5m/s



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We have contributed to built a compact linear actuator system with 1-Angstrom closed-loop control resolution and 50-mm travel range.

Two special techniques were developed for this ultraprecision motion control system. A laser Doppler encoder system with multiple-reflection optics has demonstrated its sub-Angstrom linear sensitivity. A specially designed high-stiffness weak-link linear motion reduction mechanism provided sub-Angstrom driving sensitivity with high stability.

Further developments of the LDLA system are focused on the compactness of the two-dimensional system and optics for differential measurements for X-ray nanoprobe applications.



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References [1] Deming Shu, Yufeng Han, Thomas S. Toellner, and Esen E. Alp A linear actuator system with 1-angstrom

closed-loop control resolution and 50-millimeter travel range July 8, 2002 OPTOMECHANICS 2002, SPIE

[2] D. Shu, E. E. Alp, J. Barraza, and T. M. Kuzay, A Novel Laser Doppler Linear Encoder Using Multiple-Reflection Optical Design for High Resolution Linear Actuator, Proceedings of SPIE, Vol.3429 (1998)284-292.

[3] D. Shu, T. S. Toellner, and E. E. Alp, Ultraprecision Motion Control Technique for High-Resolution X-ray Instrumentation, Proceedings of the 1st International Workshop on Mechanical Engineering Design of Synchrotron Radiation Equipment and Instrumentation, July 14, 2000, PSI-SLS, Switzerland.

[4] D. Shu, T. Toellner, and E. E. Alp, Novel Miniature Multi-Axis Driving Structure with Nanometer Sensitivity for Artificial Channel-Cut Crystals, Synchrotron Radiation Instrumentation: Eleventh US National Conference, ed. P. Pianetta, Am. Inst. Physics, Conf. Proceedings vol 521 (2000) 219.

[5] D. Shu, T. S. Toellner, and E. E. Alp, Modular Overconstrained Weak-Link Mechanism for Ultraprecision Motion Control, Nucl. Instrum. and Methods A 467-468, 771-774 (2001).

[6] LDDM is a trademark of the Optodyne Inc., 1180 Mahalo Place, Compton, CA 90220, U.S.A.

[7] Wang C. P., (1987), Laser & Optronics, Sept., p69-71.

[8] Wang C. P., (1977), American Scientist, 65 (3), p289-293.

[9] D. Shu, (2001), Patent application in progress.

[10] U.S. Patent granted No. 5,896,200, Optical design for laser encoder resolution extension and angular measurement, D. Shu, 1999.

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