Building and Testing a Laser Balance Detector
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Building and Testing a Laser Balance Detector David Grayson ([email protected]) University of Illinois at Urbana-Champaign and University of Rochester PowerPoint PPT Presentation


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Building and Testing a Laser Balance Detector David Grayson ([email protected]) University of Illinois at Urbana-Champaign and University of Rochester. Table top test of general relativity. Balance detectors are simple to build. Response near zero test.

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Building and Testing a Laser Balance Detector David Grayson ([email protected]) University of Illinois at Urbana-Champaign and University of Rochester

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Building and testing a laser balance detector david grayson graysonuiuc university of illinois at urbana champaign and u

Building and Testing a Laser Balance Detector

David Grayson([email protected])

University of Illinois at Urbana-Champaign and University of Rochester

Table top test of general relativity

Balance detectors are simple to build

Response near zero test

Dispersive medium + gravity + light => phase shift [1].

Dr. John Howell’s group @ University of Rochester:

Sagnac interferometer + dispersive slow-light medium in one

arm  measure phase shift.

Control beam and balance detector used to minimize

mechanical fluctuations.

Other balance detector measures phase shift of signal beam.

[1] S. Manly and E. Page, Phys. Rev. D 63,062003 (2001)

Laser, Intensity I1

Ideal Balance Detector: Voltage = 0

if and only if intensities are equal.

Procedure: Make voltage zero.

Measure intensities.

Results: Detectors can measure differences as small as 2µW as long as average intensity is less than 120µW.

Voltage V proportional to (I1-I2)

(up to ±15V)

Balance detectors measure laserbeam intensity difference

Laser, Intensity I2

Conclusions

Sensitivity test

Five detectors were built and tested. Two are now being used in the experiment.

Intensity I2

Ideal Balance Detector:

Voltage(I1, I2) = k(I1 – I2)

Real Results:

Detectors behave linearly.

Sensitivity k ~ .25 V/µW.

Acknowledgments

-15 V

Laser beams (same color)

0 V

+15 V

Intensity I1

My Advisor: Professor John Howell. Program Coordinator: Connie Jones, John Gresty, David Starling, Ben Dixon. The Research Experience in Physics and Astronomy for Undergraduates at the University of Rochester, funded by National Science Foundation

Grant No. PHY-0552695.

Input Power

Output: Voltage V proportional to (I1-I2)

(up to ±15V)


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