| 摘要 |
PROBLEM TO BE SOLVED: To provide an image formation element and an image reader by which the wavelength characteristic and the viewing angle characteristic of diffraction efficiency are made excellent. SOLUTION: This image formation element having a diffraction optical device on which an off-axis luminous flux is made incident and a diaphragm, is provided with a restricting member at a position more separated from the diffraction optical device than the diaphragm, and the part of a luminous flux on the side that an incident angle is made larger than that of the main light beam of the luminous flux to the incident angle of the main light beam of the luminous flux made incident on the grating surface of the diffraction optical device out of the off-axis luminous flux made incident on the diffraction optical device is shielded by the restricting member. |
