Basic research of a laser scanner having a wide field of view with the almost same resolution as a scanning electron microscope

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A laser scanner we have developed consists of a semiconductor laser, collimator lens, a rotating flat plane mirror, a fe lens and a photodiode. It has adopted a scanning con focal microscope system. The fe lens consists of several optical lenses. They were fixed in an aluminum housing with a shrink fitter, a new machine element we have already developed. By using the fe lens with the shrink fitter we made it possible to keep the diameter of the laser spot constant at almost 3_1 m over a wide scanning width of 10mm at any temperature from 0 degrees C to +60 degrees C. A test chart was observed to estimate the magnification of our laser scanner. Then it could be found that the magnification of the laser scanner was almost x20 by conversion of it to that of an objective lens of an optical microscope.We have almost succeeded in trail production of the laser scanner except for one thing. That was a vertical jitter of the image captured by the laser scanner. This was because of the vibration caused by the ball bearing which supported the rotating flat plane mirror. Thus a self-acting air bearing was used instead of the ball bearing. After the flat plane mirror was adhered to the air bearing, the assembly was dynamically balanced by adjusting the weight of the mirror holder. As a result, the vertical jitter of the image captured by the scanner was able to be made below into a certain fixed value. In addition the software of the laser scanner was also improved to detect correctly the starting point of the laser scanning.The A/D converter board used in this research, which changes the catoptric light intensity into digitized data, was the high-speed type of 100MHz operation. Thus we could observe the object at intervals of 0.5 1 m over the wide scanning width of 10 mm. The laser scanner we made was installed on the anti-vibration device to make external influence of vibration minimum.