Abstract: An optical device comprises an optical lens and a mounting assembly for securing the optical lens to a support surface. The optical lens has a longitudinal axis and has first and second projections; the mounting assembly includes a clamp member which has a clamp surface and depresses the optical lens downwardly through contact of the clamp surface with the optical lens so as to mount the optical lens on the support surface. The clamp member is formed, on the clamp surface, with first and second holes engageable with the first and second projections of the optical lens, respectively; the second hole is an elongated opening extending in the longitudinal direction of the optical lens.

Abstract: An image reading apparatus for reading a projected image by a line sensor formed in a linear shape. An image reading apparatus has an illumination system, an original supporting member, a projection lens and a line sensor formed in a linear shape. The illumination system includes a light guide formed of a cylindrically shaped light-transmitting material, a light source for introducing light into the light guide from the lengthwise direction of the light guide, a light-diffusing portion formed on the circumference of the light guide in the lengthwise direction of the light guide and a slit portion positioned opposite the light-diffusing portion.

Abstract: A mirror which is incorporated in an optical device and is made of plastic, comprising: an effective portion which has a constant thickness and a reflecting surface; and a reinforcing portion which is so provided as to enclose the effective portion and reinforces the effective portion from a periphery of the effective portion; the reinforcing portion being formed integrally with the effective portion; the reinforcing portion having a thickness equal to the thickness of the effective portion; the reinforcing portion having a constant width.