Abstract

Firstly, the basic theory of the optical coherence tomography (OCT) is reviewed. Optical delay line is one of important parts in OCT. Several types of optical delay lines which were proposed and demonstrated are briefly described including their advantages and disadvantages. In this work, a novel multiple-pass cavity optical delay line (MPC-ODL) is proposed and analyzed. The proposed delay line consists of four mirrors, one lens and one resonant scanner. In this proposed delay line, the path delay is obtained by scanning a tilting mirror and magnified by the multiple-pass optical cavity. Thus, for a small scanning angle, a large path delay can be obtained. This delay line is especially suitable for the OCT system that will generate the large dimension images at video rate with high resolution. However, due to multiple-pass cavity used in the proposed delay line, false interference signal may be created besides OCT signal. In order to reduce the false interference signal generation, some crucial parameters of the proposed delay line have to be carefully chosen. Principle of how to choose the optical component parameters is given. The proposed delay line combined with OCT is verified by computer simulation. Characterization of the delay line is done by simulation and it is shown that the scanning repetition rate of 16 kHz, the total path delay of 3 mm, and the scan velocity of 71.3 m/s can be achieved. The proposed delay line can support OCT system with dynamic range over 110 dB. The proposed delay line can support a further higher scanning repetition rate, such as 32kHz