PURPOSE: To lessen the movement of an image plane with a temp. change by setting the distance between a light source and a collimator lens in such a manner that the distance is adequately changed by temp.
CONSTITUTION: The change in the distance between the light source (semiconductor laser 11) and the collimator lens 21 affects most the movement of the image plane. The material of the part coupling both is, therefore, adequately selected, by which the movement of the image plane by the temp. change of the optical characteristics is confined within the permissible value or below even in the absence of special mechanisms. Namely, the semiconductor laser 11 is inserted into an LD holder 12 and the collimator lens 21 are mounted at a collimator lens barrel 23. The LD holder 12 is fixed by screwing to an optical base 91 and the collimator lens barrel 23 by an adhesive thereto. The movement of the image plane is minimized by selecting the structure and the material of the mechanisms parts in such a manner that the distance between the semiconductor laser 11 and the collimator lens 21 is changed under a specified condition by the temp. in such a manner.
HAMA TAKASHI
NOMURA YUJIRO
TAKADA KIYUU
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