| 摘要 |
PURPOSE: To accurately detect the degree of deterioration in each of a laser diode, a testing LED and a photodiode. CONSTITUTION: A laser diode(LD) 3 and a testing LED 4 are driven by a prescribed current value in every fixed period, the characteristic values of the LD 3 and the LED 4 and a characteristic value at the time of simultaneously driving the LD 3 and the LED 4 are respectively measured, current characteristic values are divided by the preceding characteristic values to find out respective deterioration degrees KL, KE, KLE and the deteriorationαof a light emitting part, the deteriorationβof a test light emitting part and the deteriorationγof the light receiving part are respectively calculated fromα=KLE/KE,β=KLE/ KL andγ=KL.KE/KLE.
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