Suppression of stray interference peaks of optical joint in white light interferometer

The stray interference peaks (SIPs) are an important factor resulting in the misjudgment of measurement information in white light interferometer (WLI). SIPs are generated by the residual reflected light beams. We theoretically analyze the interference conditions of the SIP. The analysis shows that these SIPs are discrete main interference peak outside and have different orders. We present a stagger optical path (SOP) method for suppressing or eliminating these SIP which will appear in the interference pattern. The SOP means that there is an appropriate fiber length determined by the delay amount of delay line between each joint. Moreover, an experiment with two joints, for simplicity, is given as an example. Experimental results show that the high-order SIP from the joints can be suppressed by the SOP to obtain a clean interference pattern.