Gain-programmable acousto-optic spectroscopy detection system based on variable osk radio frequency modulation

Abstract

The invention discloses a gain program-controlled acousto-optic spectral detection system based on variable OSK radio frequency modulation. The system shares a pre-positioned optical path, uses a plurality of AOTFs as light splitting elements, based on electric tuning characteristics of the AOTFs, performs OSK modulation on radio frequency signals synthesized by the AOTFs by utilizing an OSK function of an AD9910, and achieves electrical modulation of single-spectral signals by utilizing a radio frequency relay to time-sharing drive the plurality of AOTFs. The system post-positions detectors of corresponding spectral sections and pre-amplifying circuits, matches gating by utilizing an analog channel selector, shares an analog spectral signal processing and acquiring circuit, compensates phase shifts produced in a circuit of the signals to be detected by performing digital phase shift on OSK modulated signals, then performs mutual phase locking with the signals to be detected. The system controls gain coarse tuning and fine tuning based on the program-controlled amplifier which is in cascade connection with a voltage-controlled amplifier, and achieves gain self-adaptation by a closed-loop control. The system increases optical efficiency and signal-to-noise ratio of a wide spectrum detection, reduces system scale and power consumption, and achieves large dynamic range detection of a target spectral energy.

Description

[0001] Technical field: [0002] The invention relates to an acousto-optic spectrum detection system, aiming at the specific requirements of outdoor or space material spectrum passive detection, using a broadband Acousto-optic tunable filter (AOTF) as a spectroscopic element, based on a variable OSK ( Output shift keying (Output Shift Keying) radio frequency drive modulation and gain program-controlled wide-spectrum, large dynamic range, high signal-to-noise ratio acousto-optic spectroscopy detection system, suitable for detection system design of various infrared spectroscopy instruments, especially in When the light source irradiance changes greatly and the spectral detection range is wide, it can effectively improve the output signal-to-noise ratio of the system, increase the spectral range to be detected, and realize the large dynamic range detection of the system input spectral energy. [0003] Background technique: [0004] Infrared spectroscopy instrument uses its spectr...

AI Technical Summary

Problems solved by technology

The spectrometer mentioned in patent CN102928081 and patent CN102967370 uses lock-in amplification technology to improve the output signal-to-noise ratio of the system, and the electrical modulation method it adopts can effectively avoid the traditional spectral signal modulation method to be measured: such as mechanical modulation (about The optical chopper is placed between the light source and the light splitting element) and the light source modulation (that is, the use of pulse signals to control the light source switch) may cause problems such as jitter and modulation frequency limitations; but both patents use autonomous light sources, which are not suitable for passive detection , especially wide-spectrum spectral detection with a large dynamic range; in addition, the modulation of the radio frequency signal in the two patents is completed by additionally regulating electronic devices such as a pulse generator or a digital frequency synthesizer, and the signal to be tested and the reference signal The synchronization accuracy is low, and it increases the system cost and affects the working efficiency of the system

Patent CN104748851 proposes to improve the working efficiency of the spectrometer through the method of variable gain. The design uses an analog channel selector to select different feedback resistors to change the gain. Although the system gain can be expanded to a certain extent, the optional gain is very limited, and the increase in system burden

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