| 摘要 |
PROBLEM TO BE SOLVED: To suppress decrease in picture quality due to vibration of, specially, the center part of an Fθmirror along the optical axis, etc., by providing a supporting method for a plasticθmirror when high precision is needed. SOLUTION: This device consists of a light source 1, which emits a light beam, a converging lens group 2, which converges the light beam, a rotary polygon mirror 3, which makes a scan with the light beam, reflecting mirrors 4, 6, and 8, which reflect the said scanning light beam, and an optical housing 5 which stores and supports those optical elements. The device which uses a plastic concave mirror 6 as one of those optical elements is provided with a projection part 20 on a nearly center back surface of the plastic concave mirror and this projection part is fixed to the optical housing. |
