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Updated: Jul 7, 2026
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Implementation of a Reference Interferometer for Nanodetection
Published on: April 26, 2014
Measurement of large cryogenic structures using a spatially phase-shifted digital speckle pattern interferometer
Babak Saif1, Marcel Bluth, Perry Greenfield
1Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, Maryland 21218, USA.
Applied Optics
|February 22, 2008
Summary
The James Webb Space Telescope (JWST) Backplane Stability Test Article (BSTA) proved large cryogenic structures are ready for space. Advanced interferometry precisely measured its stability at cryogenic temperatures.
Area of Science:
- Aerospace Engineering
- Cryogenics
- Optical Metrology
Background:
- The James Webb Space Telescope (JWST) requires highly stable, large-precision cryogenic structures.
- The Backplane Stability Test Article (BSTA) is a representative section of the JWST primary mirror backplane assembly (PMBA).
Purpose of the Study:
- To demonstrate the technology readiness of large precision cryogenic structures for the JWST.
- To measure the thermal stability and deformations of the BSTA at cryogenic temperatures.
Main Methods:
- Utilized a spatially phase-shifted digital speckle pattern interferometer (SPS-DSPI) for high-accuracy measurements.
- Conducted nearly continuous measurements over six weeks at cryogenic temperatures (down to 30 K).
- Measured rigid body motion and deformations of the BSTA to nanometer-level accuracy.
Main Results:
- Successfully demonstrated the technology readiness of the BSTA for JWST.
- Achieved nanometer-level accuracy in measuring rigid body motion and deformations.
- The BSTA, a 3m structure, is the largest tested with SPS-DSPI under cryogenic conditions.
Conclusions:
- The BSTA successfully validated the performance of large cryogenic structures for the JWST.
- The developed SPS-DSPI is effective for testing large cryogenic structures.
- Confirmed the technological readiness of critical JWST components for cryogenic operation.
