With the responsibility for a manufacturer of length measuring instruments, a laser stabilized by the saturated absorbing molecule 127 I2, one of the light sources recommended by the Comite International des Poids et Measure, are made as length standard of Mitutoyo Corporation. It has been confirmed that this laser, when compared with that of the National Research Lab.of Metrology, Japan, meets the internationally required level of accuracy.This laser is used for calibrating both the light source of the interferometer for linear encoder scales and the laser wave length used for measurement in our plants. The results of laser frequency comparison shows that the differences of wave length and of its stability are large even in same type laser and the preheating time is different in individual laser.The efficient usage of laser is given by the comparison for traceability.

A new optical fiber sensor with 2 light beams is developped for detecting variation of scattered light distribution caused by surface defects, like flaws, surface inferiority, etc. Its feature consists in compact structure using only light transmission characteristic proper to the optical fiber, using no optical components like a lens. High response speed of maximum 2m/s is suited to purpose of non contact in-process or in-line defect detection and with automation of inspection process performed in the past visual or sampling method, the stabilization of inspection level is achieved and inspection eff iciency is improved by introduction of this sensor.In this paper, the principle of surface defect detection with the optical fiber sensor and the quantification of surface properties by conversion of detection output into arithmetical mean deviation are described, and the system structure on representative examples of practical application in actual inspection process is explained.

We are developing a bolometric astronomical interferometer in mm and submm wave bands by applying Martin-Puplett type fourier transform spectrometer to aperture synthesis technique. Since the spectroscopically resolved intensity distribution of four Stokes parameters are measurable by this instrument, we refer this to Multi-components Fourier Transform interferometer abbreviated as MuFT. Fundamentals of the MuFT with results of laboratory experiments and current status of astronomical observations with MuFT are summarized.

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