| 摘要 |
PURPOSE:To eliminate the need for an expensive diffraction grating, etc., by arranging a micro Fresnel lens which has concentric circular gratings for an optical system after the projection of laser light from a semiconductor laser chip, and obtaining laser light and parallel luminous flux. CONSTITUTION:The micro Fresnel lens 18 has three concentric circular gratings 3 in parallel, and their cross section is rectangular and triangular. Thin-film material or resist 17 is provided on a transparent substrate 16 of glass or plastic, and the concentric circular gratings decrease in interval from the centers to the circumferences and have hundreds of cycles. |
