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Updated: Jun 2, 2026
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Characterization of SiN Integrated Optical Phased Arrays on a Wafer-Scale Test Station
Published on: April 1, 2020
On-sky performances of an optical phasing sensor based on a cylindrical lenslet array for segmented telescopes
F Gonte1, R Mazzoleni, I Surdej
1European Southern Observatory, Karl Schwarzschildstr 2, Garching 85748, Germany. fgonte@eso.org
Applied Optics
|April 22, 2011
Summary
New optical phasing sensors achieved high precision measurements for telescope mirror alignment. The Active Phasing Experiment demonstrated sub-10 nm wavefront RMS accuracy, even with dimmer stars.
Area of Science:
- Optical astronomy
- Adaptive optics
- Optical metrology
Background:
- Precise alignment of segmented telescope mirrors is crucial for optimal performance.
- Existing optical phasing sensor technologies require further validation and improvement.
Purpose of the Study:
- To evaluate the performance of new optical phasing sensor technologies.
- To measure the precision of wavefront error measurements and closed-loop corrections.
Main Methods:
- Utilized the Active Phasing Experiment (APE) on-sky at the European Southern Observatory Very Large Telescope (VLT).
- Employed a Shack-Hartmann type sensor with cylindrical lenslets across segment borders to measure phasing errors.
- Conducted measurements using both bright and dimmer stars (up to magnitude 14.5).
Main Results:
- Achieved better than 9 nm wavefront root mean square (RMS) precision for piston step measurements at a single border with bright stars.
- Demonstrated better than 10 nm wavefront RMS precision for closed-loop correction of piston errors across the entire mirror.
- Obtained precisions of approximately 22 nm wavefront RMS with dimmer stars up to magnitude 14.5.
Conclusions:
- The tested optical phasing sensor technology shows high precision for astronomical applications.
- The Shack-Hartmann sensor effectively measures and corrects mirror phasing errors, even under challenging light conditions.
