Research on piston error sensing for segmented mirrors under atmospheric turbulence
Optics Express
|October 20, 2023
Summary
Optical piston error detection offers a solution for calibrating edge sensors in segmented telescopes, mitigating zero-point drift. This method maintains high accuracy even with atmospheric turbulence, suggesting potential for real-time piston error detection.
Area of Science:
- Optical astronomy
- Adaptive optics
- Telescope engineering
Background:
- Large ground-based segmented telescopes rely on electrical edge sensors for co-phase error detection.
- Zero-point drift in edge sensors due to complex environments challenges long-term primary mirror co-phasing.
- Optical piston error detection can calibrate edge sensors, addressing drift issues.
Purpose of the Study:
- Investigate the impact of atmospheric turbulence on optical piston error detection accuracy.
- Determine optimal parameters for optical piston error detection under turbulent conditions.
- Assess the feasibility of optical methods for short-term edge sensor calibration and potential real-time application.
Main Methods:
- Simulated atmospheric turbulence to analyze piston error measurement.
- Conducted optical piston error detection experiments on a segmented mirror system under simulated turbulence.
- Varied turbulence intensities, detection aperture size, and exposure times during experiments.
Main Results:
- Simulated results show measured piston error equals the difference between segment average phases under turbulence.
- Experimental detection accuracy closely matches non-turbulent conditions with a 0.82 atmospheric coherence length aperture and >=40 ms exposure.
- Achieved a cross-calibration root mean square better than 3 nm.
Conclusions:
- Optical piston error detection meets short-term edge sensor calibration needs under good atmospheric seeing with optimized parameters.
- The method shows potential for direct, real-time piston error detection, possibly replacing electrical edge sensors.
