| 摘要 |
PROBLEM TO BE SOLVED: To provide a light receiving device where directivity is made wide and an S/N is satisfactory. SOLUTION: A light receiving device main body 1 is provided with a light receiving element 3, an IV converter converting current into voltage in accordance with the quantity of received light that the light receiving element 3 receives and that is converted into electricity, and with an amplifier amplifying voltage outputted from the IV converter. Then, directivity can be improved by arranging a light receiving element 5 in a position where a converging area is wider than a light receiving area. Since the light receiving element 5 whose element area is smaller than the light receiving element whose size is equal to the converging area is used, the S/N is improved in accordance with the reduction of dark current. Thus, the gain of the amplifier in a subsequent stage can be set large in accordance with the improved value. Then, the high sensitivity of the light receiving device 1, which can set the gain to be large, is realized.
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