| 摘要 |
PURPOSE:To record spectra always at an optimum gain with high accuracy by automatically changing over the gain of a photelectric signal amplifier according to the intensity of photoelectric signal. CONSTITUTION:Light signal out from a spectroscope 1 is converted to a photoelectric signal by a photo detector 2. After this signal is amplified with a multistage gain amplifier 3, it is converted to a digital signal by an AD converter 4. This signal enters a bus line 11. A CPU 6 compares the signal from the AD converter 4 with the reference value H of a memory 7 and emits the control signal to an amplifier gain controller 5 through the bus line 11 so as to lower the amplifier gain when the signal is larger than H. If the signal is not larger than H, the CPU compares the same with another reference value L and when it is smaller than L, the CPU emits the control signal to the gain controller 5 so as to increase the gain. If the signal is between H and L, the CPU multiplies the signal by a coefficient inversely proportional to the amplifier gain to let the magnitude of the signal be proportional approximately to the mecha photoelectric signal. This signal is outputted to a DA converter 9 and is recorded in a recorder 10. |
