Abstract:For the shortcomings of the interference fringe difficult to read and adjust in an Ubbelohde interferometer, a He-Ne laser was used in the Ubbelohde interferometer as the source to offer interference fringe signals with high quality. Then, the fringe signals were transform into electron signals to implement the micro-displacement measurement precisely. A detection circuit was designed and the square wave signal was extracted by using a dual-threshold shaping circuit, which solveed the error processing problem when signals jittered near the set comparison value. A discerning direction and subdividing circuit was designed and the orthogonal electron signals were extracted to achieve the discerning direction of interference fringe movement and the subdivision of interference signals. On the schemes above, a laser interference detection device was designed and built. The device was calibrated by two standard gauge blocks with a difference value of 5 m. Under four subdividing circuits, the resolution of the detecting device is 79 nm. Therefore, the Ubbelohde interferometer achieveds automatic reading and improves its measurement precision.