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We developed a micro optical scanning sensor with the dimension of 2.0 mm X 4.0 mm X 3.0 mm for a micro inspection robot. In this sensor, the functional elements such as a laser diode (light source), photo diodes, pin-holes, a beam splitter, a ball lens, and a PZT thin film actuator driven micro optical scanner are integrated on separate substrates each consisting a functional modules and the substrates are stacked. Performance of the optical sensor depends on its optical characteristics. This sensor has spot size of output beam is 256 micrometer X 580 micrometer at 60 mm from the sensor, output power is 0.5 mW, optical scanning angles are plus or minus 10 deg. two-dimensionally, and detecting sensitivity of photo diodes are 0.3 A/W. The sensor is capable of distance measurement between the sensor and an object at 50 mm plus or minus 10 mm and the object shape recognition two-dimensionally based on the optical scanning method. By using these functions, the sensor can measure dimensions of the object and measuring resolution is less than 0.5 mm.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

For achieving higher performance and for miniaturizing the size of an optical scanning sensor, raising the scanning angle response, increasing the accuracy of detection of the scanning location independent from the environmental temperature, and miniaturizing an optical-scanning sensor were considered. And the silicon micromachined 2D optical scanner integrated with a piezoresistor for scanning location detection and a photodiode for optical intensity detection was newly designed and fabricated. The obtained results with the fabricated scanner are following. The scanner is capable of scanning a light beam more than 40 degrees 2D. The scanning angle sensitivities are 4.8 deg/V for horizontal direction and 10.5 deg/V for vertical direction. The scanning location detection sensitivity for each horizontal and vertical directions are 21 mV/deg and 26 mV/deg., respectively. The decrease of detection accuracy of scanning location has been reduced to less than 1 percent within +/- 10 degrees C temperature shift. And the photodetector has a photosensitivity of 0.33 A/W which allows the optical-scanning sensor to detect the reflected light intensity from an object which is 200 mm away from the sensor.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We have newly developed a miniature optical scanning sensor capable of three dimensional recognition for pipe-inspection. The sensor. the size of 2 I mrn. consists of a miniature two dimensional optical scanner integrated with photo detector and piezoresistor. a laser diode with collimating lens and an amplifier circuit. The two dimensional optical scanner actuated • by piezoelectric actuator was applied to the sensor for miniaturization of thescanning mechanism. In order to detect on surface in pipe three dimensionally. circular scanning pattern with variablescanning range. such as spiral pattern. was adopted. Reflected beam intensity from surface in pipe at each scanningposition is detected by the photo detector. When scratches or obstructions exist on surface in pipe. the detected signalis changed. Shape recognition of the surface in pipe can he realized by detecting the change signals and its eachscanning position information. In this case. piezoresistor fabricated on the torsional spring of the scanner was appliedfor detection of scanning position. Sensing range of I 00 to 200 mm and resolution of less than 1 mm was obtainedin 1 inch diameter pipe. This sensor could be useful for recognition sensors of miniature mobile robot in manyinspection fields.Key words: pipe-inspection. 3D shape recognition, optical scanning. micro sensor. micro robot. micromachine

Piezoelectric thin films are very promising materials for MEMS applications because they have application flexibility and compatibility with semiconductor and micromachining processes. How to design MEMS devices with piezoelectric thin films, the mechanical characteristics, and how those characteristics can be controlled by process conditions is discussed in this paper. In addition, piezoelectric/electric characteristics must be understood. With this background, mechanical characteristics (Young's modulus and built-in stress) measurements of sputtered Pb(Zrx, Ti1 - x) O3 thin film, one of piezoelectric materials, have been carried out using the load-deflection method. Relationships between post anneal conditions and those characteristics are discussed. It was shown from the experiment results that Young's modulus increases as anneal temperature/time increases. The maximum value was 76.6 GPa(700 degrees C/3600 sec) which is more than three times larger than that of as-depo film. Built-in stress is also affected by post anneal process and ranges from 0.04 GPa(as-depo) to 0.41 GPa(700 degrees C/60 sec). SEM observation results made it clear that it was caused by film shrinkage due to grain enlargement during anneal process.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A highly miniaturized optical scanner integrated with a photo detector has been developed for miniaturization of scanning type of optical sensors. The scanner is fabricated by silicon micromachining technologies and is driven by a piezoelectric actuator. It is capable of two dimensional scanning and photo detection. The scanning angle is over 40 deg X 30 deg and the photo detecting sensitivity is 0.49 A/W for 680 nm wavelength light.

A novel micro focusing optical device controlled by a piezoelectric thin film micro actuator has been presented. This device is provided by bonding two micromachined substrates, which are a glass substrate integrated with a surface emitting light element and a micro Fresnel lens on each surface, and a silicon substrate with a diaphragm type of piezoelectric thin film actuator on it. The surface of the thin film is used as a movable reflection mirror. Focusing is performed by changing position of the mirror surface along the optical axis. In the case of applying the micro lens with 1.3 mm of diameter and 0.33 of N.A. to this focusing device and the thin film actuator capable of several micron displacement, focal point shifting of over 100 mm is obtained. Applying the device to optical senors such as a barcode reader, miniaturization of the light source and high resolution detecting for wide range could be possible.