Study on a Ultra-precisely Joining Method using a Shrink Fitter

微机械是未来机械工程师所能做出贡献的高新技术之一。问题是没有足够的设备来检查微型机器的形状和功能。现在我们可以用光学显微镜或扫描电子显微镜（SEM）来观察这些微机械。扫描电镜具有聚焦深度的优势。然而，扫描电镜的视野很窄，试样的尺寸受其真空室的限制。如果研制出高精度的激光扫描仪，这些问题就迎刃而解。在30毫米宽的扫描宽度上，如何将光斑控制在几微米以内，是激光扫描仪发展的挑战。要做到这一点，几个扫描透镜必须组装在外壳中，它们的光学轴高度重合。本研究的目的是利用我们开发的收缩滤镜，建立将多个光学透镜以超高精度组装到外壳上的技术。去年用三维有限元法计算了收缩滤器贴合的每个光学透镜的变形。得到了透镜在光轴方向上的变形不超过半波长时每个光学透镜的极限干涉量e/2。在极限干涉的基础上，确定了收缩滤器和壳体的尺寸。在室温下使用的收缩过滤器的材料是我们之前使用的聚酰亚胺和丙烯酸酯。在室温下，我们成功地获得了直径约为6μm的光斑，扫描宽度为30mm。同样的实验在当年进行，温度在5 ~ 70℃之间变化。由于尼龙的耐热性，这次我们使用了它作为收缩过滤器的材料。结果表明，即使在5℃和70℃的温度范围内，在扫描宽度为30mm的范围内，也能获得并保持6μm的光斑直径。

A micro machine is one of the high technology for mechanical engineers to give a contribution in the future. The problem is that there is no sufficient equipment to check shapes and functions of the micro machines. Now we can observed the micro machines by an optical microscope or a scanning electron microscope(SEM). The SEM has an advantage of the depth of focus. However the field of view of the SEM is narrow and the sizes of specimens are limited to its vacuum chamber. If a highly accurate laser scanner is developed, these problems are solved. The challenging thing for the development of the laser scanner is to keep the laser spot within several micrometers over a wide scanning width of 30 mm. To do this, several scanning lenses have to be assembled in the housing with their optical axises highly coincided.The purpose of this research is to establish the technology to assemble several optical lenses to the housing in super-high accuracy by using a shrink fitter that we have developed.Last year the deformation of each optical lens fitted by the shrink fitter was calculated by three dimensional finite element method. The limit interference for each optical lens by which the deformation of the lens in the direction of the optical axis did not exceed half wavelength, e/2 was obtained. On the basis of the limit interference, the sizes of both the shrink fitter and housing were determined. The materials of the shrink fitter used at room temperature were polyimide and acryl which we used before. We succeeded in obtaining spot diameter about 6μm over the scanning width of 30mm only at the room temperature. The same experiments have been carried out at current year with the temperature changed between 5℃ and 70℃. This time we used cast-nylon for the materials of the shrink fitters because of its heat resistance property. As a result, the spot diameter of 6μm could be obtained and maintained over the scanning width of 30mm even at the temperature range of 5℃ and 70℃.