PURPOSE: To make an optical scanning carriage generate no vibration, by coupling an illumination light source supporting body and the optical scanning carriage, through an elastic member for absorbing the vibration.

CONSTITUTION: An optical scanning carriage 21 and a passive reflector 24 are coupled through an elastic member 70, and this elastic member 70 is constituted so as to absorbe vibration generated when the optical scanning carriage 21 runs. That is to say, the upper end and the lower end of the elastic member 70 are fixed to mounts 71, 72 made of a metal, etc., and through both these mounts 71, 72, and passive reflector 24 and the optical scanning carriage 21 are coupled by rivets 73, 74, respectively. The elastic member 70 consists of elastic rubber having an attenuation characteristic, can be deformed elastically in its shearing direction as shown by a 2 dot chain line in the figure, and this deforming direction is made to coincide with the moving direction of the optical scanning carriage 21.