| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical element in simple structure that causes small stray light. SOLUTION: Incident light having a wavelength range ofλ1 toλ3 is incident on an incidence surface 3 of a photonic crystal structure part from above, travels through the crystal in different directions for each wavelength and exits from the photonic crystal structure on a projection surface 4 of a photonic crystal part at positions different for each wavelength. In this chromatic dispersion element, only an optical path of a part A is needed, but the light is reflected by the crystal structure and the projection surface 4 as a usual medium interface actually as shown by a broken line to become stray light. This stray light travels straight at the part A, but the travel direction is bent at a part B as shown in Fig. as the light travels and stray lineλ'<SB>1</SB>reflected by the incidence surface 3 never enters the part A. Characteristics of the spectral element can be deterred from degradation owing to the stray light. COPYRIGHT: (C)2005,JPO&NCIPI |
