Extremely weak optical signal detecting device and method

Abstract

The invention belongs to the field of signal detection, and particularly relates to a high-precision extremely weak optical signal detecting device and method based on a DSP. The device comprises a mechanical shutter, a photomultiplier, a low-noise preamplifier, a high-pass filter circuit, a high-resolution A / D conversion circuit, a DSP processing circuit, a shutter drive circuit and a computer. Processing of modulation, background noise elimination and digital sampling integration is carried out on extremely weak optical signals through the device, and precise detection on extremely weak incident light is achieved. Meanwhile, the extremely weak optical signal detecting device is low in production cost, simple in structure and convenient to use.

Description

technical field [0001] The invention belongs to the field of optical signal detection, and relates to an extremely weak optical signal detection device and method, in particular to a high-precision extremely weak optical signal detection device and method based on a digital signal processor (DSP). Background technique [0002] In the measurement of extremely weak optical signals, it often occurs that the background noise or interference is very large, but the measured signal is very weak or even obliterated by the noise. In this case, the traditional method of converting the weak light signal into a weak electrical signal through a photodetector and then amplifying the weak electrical signal through a low-noise preamplifier cannot extract and restore the measured signal from the noise. At present, the commonly used method is to realize the detection and extraction of extremely weak optical signals through a lock-in amplifier or a sampling integrator. [0003] The lock-in am...

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Problems solved by technology

Usually, a chopper that meets the above requirements is very expensive, increasing the cost of the development task

[0006] 2) Since the lock-in amplifier and the chopper are two independent devices, when the reference signal is transmitted to the reference terminal of the lock-in amplifier through the cable, the phase shift of the signal may be caused by the influence of the distribution parameters of the cable

However, this will limit the application of some special occasions, especially when the detector is placed far away from the preamplifier or the preamplifier is far away from the test instrument, the signal attenuation and the interference of the external electromagnetic environment will seriously affect the test results

[0010] 6) Usually when using a lock-in amplifier or a sampling integrator, it is often impossible to determine the noise of the signal preamplifier itself, because this part of the noise is not modulated and is not related to the measured signal, and belongs to the noise floor of the circuit

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