Small laser interferometer linked to laser source with an optical fiber.

In a present laser interferometer system it is necessary to adjust the alignment between a laser source and a laser interferometer. The laser source is a heat source to be a disturbance in a precise length measurement, while the laser interferometer itself is large and its setting lacks flexibility. This study is performed in order to solve the practical disadvantage mentioned above, in which the small laser interferometer is linked to the laser source with an optical fiber so as to give full play to the flexibility in the case of the precise length measurement. The results of this study are shown as follows. (1) The influence of the disturbance mixing into the optical fiber can be cancelled by making differential interference signals by means of an electronic instrument. As a result, the resolution of the interferometer becomes high and the length measurement stable. (2) A small laser interferometer with an optical fiber has been developed with 10mm in measurable length and 0.05μm in resolution as a kind of contact type indicator. The length measurement error of the present interferometer is 0.13μm in 10mm. Another non-contact type laser interferometer has also been developed for vacuum.