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Testing and applicability of the UPC-ZEBRA interferometer as a phasing system in segmented-mirror telescopes
Agustí Pintó1, Ferran Laguarta, Roger Artigas
1Center for Sensors, Instruments and Systems Development (CD6), Universitat Politècnica de Catalunya (UPC) Rambla Sant Nebridi, 10, E-08222 Terrassa, Spain.
Applied Optics
|March 11, 2004
Summary
UPC-ZEBRA precisely measures telescope segment piston errors using a novel interferometric technique. This advancement offers a 5 nm uncertainty for daytime phasing calibration, crucial for optical performance.
Area of Science:
- Optical Engineering
- Telescope Technology
- Metrology
Background:
- Segmented-mirror telescopes suffer performance degradation due to wave-front discontinuities from segment misalignment.
- Measuring vertical discontinuities (pistons) is critical for maintaining optical quality in large telescopes.
- Existing methods for piston error measurement have limitations, necessitating new approaches.
Purpose of the Study:
- To present key results from the testing phase of the UPC-ZEBRA instrument.
- To provide a detailed analysis of error sources affecting the UPC-ZEBRA's piston measurement accuracy.
- To outline modifications for integrating UPC-ZEBRA into a telescope phasing calibration system.
Main Methods:
- Utilizes a novel interferometric technique for measuring piston error.
- Instrument tested for daytime operation with high precision requirements.
- Error sources analyzed to understand measurement uncertainties.
Main Results:
- Demonstrated a measurement uncertainty of 5 nm within a 30-microm range for piston error.
- Representative testing results confirm the instrument's capability.
- Identified and analyzed key error sources impacting measurement precision.
Conclusions:
- The UPC-ZEBRA instrument effectively measures piston errors in segmented telescopes with high accuracy.
- The analysis of error sources provides a foundation for further instrument refinement.
- Modifications are proposed to adapt UPC-ZEBRA for operational phasing calibration systems.