Stray light and ghosts in catadioptric spectrometers: incorporating grating scatter measurements into simulations and ghost sensitivity into system design
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Monika Kroneberger
Monika Kroneberger received her diploma in Physics in 1991 from the Johann Wolfgang Goethe University in Frankfurt/Main. Currently, she is working in the domain of optical system engineering for OHB System AG. Her main topic is stray light reduction and verification in the optical systems by simulation and measurement.
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Andreas Mezger
Andreas Mezger received his diploma in aerospace engineering in 2010 from the University of Stuttgart. Currently, he is working in the domain of optical mounting, metrology and validation for OHB System AG.
Stephanie Becker received her Master of Engineering of Laser and Optic Technology in 2013 from the University of Applied Sciences in Jena. She is currently working in the domain of optical analysis and optical engineering for OHB System AG.
Abstract
The accurate simulation of stray light is essential for the verification of the contrast requirements in optical instruments. In a spectrometer, the scattering from reflective gratings is difficult to characterize while contributing significantly to the overall system stray light and reduction of the spectrometer contrast. In addition, the multiple diffraction orders create a ghost sensitive environment, which must be considered in the design of the instrument. In this article, we present an experimental setup for, and measurement results from, the characterization of the bidirectional scattering distribution function (BSDF) of a holographic grating for a spectrometer applied in a typical earth observation mission with demanding stray light requirements. We observed distinct stray light peaks out of the diffraction plane, which are called ‘satellites.’ The main challenges in the measurement of grating BSDFs arise from the near angle limit, the determination of the instrument signature and the selection of the appropriate sampling (2D or 3D). Following the grating characterization, the next step is to introduce these measured BSDFs into stray light simulation. We have done that by fitting appropriate functions to the measured BSDF and defining them in the optical analysis software ASAP as a user-defined BSDF. Ghost analysis is done at the spectrometer level as a sensitivity analysis of the tilts of the optical elements. Due to the ghosting of higher diffraction orders of the grating, a high sensitivity to the tilts of some of the optical elements can be seen.
About the authors
Monika Kroneberger received her diploma in Physics in 1991 from the Johann Wolfgang Goethe University in Frankfurt/Main. Currently, she is working in the domain of optical system engineering for OHB System AG. Her main topic is stray light reduction and verification in the optical systems by simulation and measurement.
Andreas Mezger received his diploma in aerospace engineering in 2010 from the University of Stuttgart. Currently, he is working in the domain of optical mounting, metrology and validation for OHB System AG.
Stephanie Becker received her Master of Engineering of Laser and Optic Technology in 2013 from the University of Applied Sciences in Jena. She is currently working in the domain of optical analysis and optical engineering for OHB System AG.
Acknowledgements
The authors acknowledge that this work is supported by an ESA funding through the FLEX Mission development. We also wish to acknowledge the contribution of Riccardo Gabrieli of Leonardo S.p.A. in coming up with the new definition of the grating requirement.
References
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[6] M. Kroneberger, A. Mezger and J.-B. Volatier, ‘Scattering from Reflective Diffraction Gratings: The Challenges of Measurement and Verification’, Proc. SPIE 10692, 106920G (2018).10.1117/12.2312099Search in Google Scholar
©2018 THOSS Media & De Gruyter, Berlin/Boston
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- At odds with Nobel
- Community
- News
- Topical Issue: Space Optics
- Editorial
- Space optics
- Research Articles
- The European optical contribution to the James Webb Space Telescope
- The deployable telescope: a cutting-edge solution for high spatial and temporal resolved Earth observation
- Stray light and ghosts in catadioptric spectrometers: incorporating grating scatter measurements into simulations and ghost sensitivity into system design
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Articles in the same Issue
- Cover and Frontmatter
- Editorial
- At odds with Nobel
- Community
- News
- Topical Issue: Space Optics
- Editorial
- Space optics
- Research Articles
- The European optical contribution to the James Webb Space Telescope
- The deployable telescope: a cutting-edge solution for high spatial and temporal resolved Earth observation
- Stray light and ghosts in catadioptric spectrometers: incorporating grating scatter measurements into simulations and ghost sensitivity into system design
- Absorbing Aerosol Sensor on Gao-Fen 5B satellite
- A telescope for LISA – the Laser Interferometer Space Antenna
