对数积分放大器在弱光检测中的研究与应用

为解决微弱光信号检测中信号动态范围宽、噪声大等难点，利用对数积分放大原理设计了微弱光信号检测电路。并利用2种不同特性的硅光电二极管（PN和PIN）作为光电转换器件验证电路的性能。实际结果表明:在入射光功率特性上，2种光电二极管电路输出相似，对信号具有压缩作用。在入射光频率特性上，f20 Hz时PN型电路输出幅值是PIN型的1.2倍以上；f40 Hz时PN型电路输出幅值变化约90%，PIN型电路输出更稳定，最大变化约50%。在光谱测量上，2种光电二极管测得的光谱与实际光谱相比变化趋势相同，峰值波长一致。

Research and application of logarithmic integral amplifier in weak optical detection

In order to solve the problems in weak optical signal detection with wide dynamic range and high background noise, a circuit for detecting weak light based on the principle of logarithmic integral amplification was designed and fabricated. And the Si photodiodes with two different properties (PN and PIN) were used as the photoelectric conversion element to verify the circuit characteristics. Measurement results show that for the incident light power characteristics, the two photodiodes- output are similar and have signal compression. For the incident light frequency characteristics, when f<20 Hz, the output amplitude of PN type is 1.2 times more than PIN type, the PN type has higher sensitivity; when f>40 Hz, the output amplitude of PN type varied about 90%, the PIN type output is more stable with about 50% maximum variation. Additional, the spectra measured by two photodiodes have the same trend and peak wavelength as the actual spectra.