Research of the Surface Roughness Optimization Techniques of 45 Degrees Thick-Film Polymers Micro Mirrors

• Main Authors: Jung-Chiang Liao, 廖容瑲
• Other Authors: Kuo-Yung Hung
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/73389963818099317465

碩士 === 明志科技大學 === 機電工程研究所 === 97 === In this paper we apply an inclined-exposure technology and a special design inclined-exposure aiming system to make a new optical micro-structure and replace the traditional mechanical extra work or injection molding optical component. The thick-film negative photoresist SU-8 was used in the experiment, because the polymer material have the feature of stronger and not easy to be changed shape in high temperature (~100°C). At the mean time, using inclined-exposure mechanism to help the angle accuracy to ±30’, and lower the surface roughness to in 300μm×300μm range. The structure of micro reflective mirror is using polymer material with a 1.4mm high micro structure, which is made by low spin and surface tension. In order to resolve the diffraction phenomenon bringing from the non flatness of thick-photoresist, we apply the material, which has the same refractove index as photoresist, to fill in between mask and photoresist, and make use of filter to filter out the UV light, which is lower than 365nm to improve the non parallel structure caused by the difference of the penetration depth of different wavelength. In this research we also developed the anti-reflection technology, and used Fresnel equation to solve the problem of second reflection from substrate surface caused by inclined-exposure. In order to deal with the difficulty of coating on micro mirror, we used optical UV tape as the material when coating and making a pair of mirror group, inaccuracy of shift can be reduced to 60μm-80μm. If this technology could be successfully developed, it can help to improve the design and fabricate of optical pick-up device.