Large-scale optical delay line design for axial parameter measurement of the eye

Abstract

The performance of an optical delay line is important for an accurate and wide-range measurement of the axial parameters of the human eye, in particular in coherence tomography. In order to improve its performance, a rotating optical delay line device based on the equidifference fiber group is proposed by analyzing the optical path delay principle of the rotating mirror type delay line and the optical path multiplication principle of the equidifference fiber group. The delay distance formula is theoretically derived and a self-calibration method for the optical path difference of the fiber group is proposed. Finally, an experiment system was built to test and evaluate the characteristics of the delay distance, delay linearity, and self-calibration repeatability for the optical path difference of the fiber group. The measurement results show that the maximum delay optical path is 128.094 mm and the delay linearity error is 0.17%. The repeatability is better than 0.036 mm. This can meet the requirements of human eye axial parameters for accurate and wide-range measurement.