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

我们研制的激光扫描仪由半导体激光器、准直透镜、旋转平面镜、fe透镜和光电二极管组成。采用扫描共焦显微镜系统。fe透镜由几个光学透镜组成。它们被固定在一个铝制的外壳里，里面有一个收缩过滤器，这是我们已经开发出来的一种新的机器元件。在0°C至+60°C的任意温度下，通过使用带收缩滤镜的fe透镜，我们可以在10mm的宽扫描宽度内保持激光光斑直径几乎恒定在3_1 m。然后将激光扫描器的放大倍率转换为光学显微镜物镜的放大倍率，可以发现激光扫描器的放大倍率几乎是20倍。除了一件事，我们的激光扫描仪的试生产几乎已经成功了。那是激光扫描仪捕捉到的图像的垂直抖动。这是由于支撑旋转平面镜的滚珠轴承引起的振动。因此，采用自动空气轴承代替滚珠轴承。将平面镜粘附在空气轴承上后，通过调整镜架的重量来实现总成的动态平衡。这样，扫描仪捕获的图像的垂直抖动就可以在下面变成一个固定的值。此外，还对激光扫描器的软件进行了改进，使其能够正确地检测激光扫描的起始点。本研究采用的A/D转换板为100MHz高速型，将反射光强度转换为数字化数据。因此，我们可以在10mm的宽扫描宽度上以0.5 m的间隔观察物体。我们制作的激光扫描器安装在防振装置上，使外界对振动的影响降到最低。

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.