| 摘要 |
PROBLEM TO BE SOLVED: To provide a lens which will not be affected by aberration in its peripheral part, even if it is not attached to a frame having a diaphragm and can emit light of superior parallelism or of convergence. SOLUTION: For example, a collimator lens 30 comprising a gradient index rod lens can emit light which is superior in parallelism from a central region 32a within a prescribed distance from an optical axis in the emission surface 32 but cannot emit perfectly parallel light from a peripheral region 32b around the central region 32a. Thus by subjecting the peripheral region 32b to roughening, emission from the peripheral region 32b is prevented and light emitted from the emission surface 32 becomes only a light OP, passing through the central region 32a.
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