| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a high resolution optical encoder which can form a small spot using a semiconductor laser light source emitting a light with low divergence. SOLUTION: A microlens 4 is formed monolithically on the surface of a surface emission laser 1. Assuming the focal length (f) of microlens 4 is f=ma<2> /2λ(a is the width of light emitting window andλis the wavelength of laser light), m<2 is satisfied. Light transmitting parts and light shielding parts are arranged periodically, at a constant pitch, on a scale 2 disposed movably with respect to the surface emission laser 1. A light receiving element 3 receiving the light transmitted through the scale 2 is disposed on the opposite side to the surface emission laser 1 with reference to the scale 2.</p> |
