Common-channel OCT (optical coherence tomography) ultra-large range space measurement system and method

Abstract

The invention discloses a common-channel OCT (optical coherence tomography) ultra-large range space measurement system and method. A gain compensation type polarization-maintaining fiber optical circulation cavity is arranged in a sweep frequency OCT imaging system, and the optical circulation of the P-channel light and the S-channel light with different optical paths in the same polarization-maintaining fiber is realized based on the birefringence effect of the polarization-maintaining fiber. The low-coherence interference between the sample lights of different depth areas and the reference light with the ultra-large range is realized based on the hypervelocity stepping change of the optical path difference between the P-channel light and S-channel light. The coding of the interference signals of different depth areas within the ultra-large range is realized based on different carrier frequencies of an electrooptical modulator on the P-channel light and S-channel light in the optical circulation cavity of the polarization-maintaining fiber. A wave plate is arranged in front of the sample surface so as to realize the common channel of the reference light and the sample light; and the common-mode rejection of DC (direct current) term in the interference signal is realized by use of the dual-channel balance detection of the polarization light split. The system disclosed by the invention has a compact structure and high stability, and effectively improves the quantization precision and dynamic range of the interference signal.

Description

technical field

[0001] The invention belongs to optical coherence measurement, and in particular relates to a common-path OCT ultra-large-range distance measurement system and method. Background technique

[0002] The distance between each lens in a modern optical system is a key indicator that determines the performance of the optical system and directly affects the imaging quality of the optical system. Therefore, people have proposed a method based on optical interference to measure the distance between lenses in an optical system, such as Time Domain Optical Coherence Tomography (TDOCT) adopted by the LenScan mirror locator of Fogale Company in France. The coherent light source and high-precision delay optical path obtain more accurate optical distance measurement results. However, the measurement speed and measurement accuracy of this system are limited by the speed and accuracy of mechanical movement in the high-precision delay optical path. The measurement speed is sl...

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