Alignment technology of portable Tyman-Green interferometer

In order to meet the requirements for high-precision test of optical components and systems, the paper researched the assorted alignment method based on the design of a new type of portable interferometer. This new type of interferometer with a theoretical precision of /10(PV, =630 nm) is developed from the improved Tyman-Green interference optical structure, it has several advantages such as off-axis reference mirror, small size, low cost and high accuracy. According to the structure of the portable Tyman-Green interferometer, the alignment method for the overall system with two vertical optical axes as the reference was studied. The interferometer was aligned by using this method. Then the measurement experiment and comparison experiment were carried out. The experiment which focuses on testing the standard spherical mirror with the peak value (PV) of /10 shows that the interferometer has a measurement precision of 0.09 (PV, =630 nm); and the comparison experiment shows that when measuring a regular standard spherical mirror in the same testing environment, the precision of the interferometer is 0.053 (root mean square, =630 nm), while the one of Zygo interferometer is 0.051 (RMS, =632.8 nm). The results indicate that the measurement accuracy of potable Tyman-Green interferometer aligned by the new alignment method is almost equal to the one of Zygo interferometer and closed to the theoretical limit, the new alignment method satisfies the demands of the portable Tyman-Green interferometer.