Development of integrated optical measurement systems having layered structures

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Some integrated optical measurement systems are developed for realizing the small size but having practical performance. The research is both the development of elements and the packaging of optical setup.Laser interferometer: By introducing the photodiode with the thickness near to the optical wavelength, the standing wave detection-type interferometer is realized at the volume of fingertip (φ 〜 2.5cm). The optical setup is realized by stacking a polarizer, a quarter 2 plate, and the thin film photodiode on the housing of the collation lens of the laser diode. The interferometer signal magnitude is 1 μ A detecting the movement at the speed of 9cm/s. This is near to the practical specification. The standing wave in the speckle pattern is also measured realizing the measurement of the sample having rough surface. Now. Fabry-perot resonant cavity is combined for increasing the signal intensity and for purifying the interference signal. The effect is clearly observed, and tuning to the accurate resonant condition is aimed.Optical encoder: The grating can be combined on the Si microstructure realizing new types of encoder. The imaging type encoder has the problem that the optical setup becomes complicated with the increasing number of grating. Since the grating can be integrated at the aligned position, the alignment problem is reduced realizing the automatic setting at the position serving the high image contrast. Additionally, the modulated pitch of the detection grating can cancel the higher order noise. The total encoder system is demonstrated combining with the LED chip and the IC chip. At present, the emitting field is spatially narrow and optical averaging effect is limited. The illumination optics is under the revision.As scheduled, optical systems are demonstrated clearing the fundamental performance by stacking planer elements. Sensors are confirmed to be effective for realizing the integrated sensor systems.