| 摘要 |
<p>Device for detecting a focus (1) which detects a state of focusing of an optical recording medium, wherein, in order that said device for detecting a focus (1) has a small size and is inexpensive, detection of a focus employing two photodetectors (33), (34) respectively located before and behind the point of convergence of beams (45) from the optical recording medium is made possible by means of a single prism (37), further, a plurality of optical parts (31), (33), (34), and (37) being formed into one body, moreover, mounting these optical parts (31), (33), (34), (37) on a single plane of a semiconductor substrate (32) being made possible, therefore, said device (1) can be applicable to an optical head which particularly requires a small size, light weight, low cost, and high performance.</p> |
