OPTICAL PARTS

PURPOSE:To form falsely a sand grinding surface as a mirror surface and to improve light transmissivity by applying ultraviolet curing type light transmissible adhesives to the sand grinding surface extracted as a chip like a film and curing the adhesives. CONSTITUTION:For instance, a prism 1 is formed so that four faces A-D are sand grinding surfaces with chip extracting states and a face E is a full reflection mirror. Since an apparatus in which the prism 1 is to be built may be used under severe environmental temperature change, it is necessary to use flexible adhesives in order to absorb stress due to the difference of linear expansion coefficients between a glass material for the prism 1 and an aluminum material for a holding tool 2. The transparent ultraviolet curing type adhesives 4 with light transmissivity is applied to the face A capable of transmitting light so as to form 0.1-0.3mm thickness and then cured to form a false mirror surface based on the adhesives. The face B is formed as a false mirror surface by applying similar ahdesives to transmit ultraviolet rays. Namely, the faces A, B can be provided with light transmissivity without grinding both the faces A, B.