Paper
26 June 2017 Study on measurement accuracy of active optics null test systems based on liquid crystal spatial light modulator and laser interferometer
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Abstract
A common way to test high-quality aspherical lenses is to use a measurement system based on a set of null corrector and a laser interferometer. The null corrector can either be a combination of spherical lenses or be a computer generated hologram (CGH), which compensates the aspheric wave-front being tested. However, the null optics can’t be repeatedly used once the shape of tested optics changes. Alternative active null correctors have been proposed based on dynamic phase modulator devices. A typical dynamic phase modulator is liquid crystal spatial light modulator (LCSLM), which can spatially change the refractive index of the liquid crystal and thus modify the phase of the input wave-front. Even though the measurement method based on LCSLM and laser interferometer has been proposed and demonstrated for optical testing several years ago, it still can’t be used in the high quality measurement process due to its limited accuracy. In this paper, we systematically study the factors such as LCSLM structure parameters, encoding error and laser interferometer performance, which significantly affect the measurement accuracy. Some solutions will be proposed in order to improve the measurement accuracy based on LCSLM and laser interferometer.
© (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Shijie Liu, Longbo Xu, Xiao Ma, Zhigang Zhang, You Zhou, Qi Lu, Yunbo Bai, and Jianda Shao "Study on measurement accuracy of active optics null test systems based on liquid crystal spatial light modulator and laser interferometer", Proc. SPIE 10329, Optical Measurement Systems for Industrial Inspection X, 103290A (26 June 2017); https://doi.org/10.1117/12.2269435
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KEYWORDS
Interferometers

Liquid crystals

Optical testing

Active optics

Aspheric lenses

Computer generated holography

Modulators

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