Design of a highly sensitive photoelectric detection circuit for TDLAS gas laser telemetry
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摘要:
针对气体 遥测光信号微弱、环境因素干扰强等特点，结合波长调制技术，设计和研究了用于TDLAS 遥测的高灵敏度光电探测电路(Highly Sensitive Photoelectric Detection Circuit, HSPDC)。基于波长调制技术，确定了TDLAS信号噪声抑制方法；采用光电二极管理想模型，分析了光电探测电路的线性响应特性并确定了光电二极管的关键参数；基于级联放大原理设计、仿真并对HSPDC进行测试。结果表明：所设计HSPDC的光功率检测下限为0.11 nW，信号衰减仅为0.79 dB(
f =10 kHz)，截止频率较现有108 V/A跨阻放大电路高一个数量级，可用于高速调制微弱光信号的探测。搭建了气体 遥测系统，当调制频率为3 kHz时， 遥测系统获得了良好的检测性能，检测灵敏度达到88.66 mV/ppm，检测限优于0.565 ppm，线性拟合度R 2为0.9996。研究表明，研制的HSPDC光电探测电路具有响应速度快、检测灵敏度高等优点，可集成化，能满足气体 遥测应用需求。Abstract:Aming at the characterstics of weak gas laser telemetry optical signals and strong interference from environmental factors, a Highly Sensitive Photoelectric Detection Circuit (HSPDC) for TDLAS laser telemetry based on wavelength modulation technology has been designed and investigated. In addition, a noise suppression method for TDLAS signals based on wavelength modulation technology was determined. The photodiode ideal model is utilized to analyze the linear response characteristics of the photodetector circuit and determine the essential photodiode parameters. Based on the cascade amplification principle, the HSPDC is designed, simulated, and tested, achieving a lower limit of optical power detection of 0.11 nW, a signal attenuation of 0.79 dB (
f =10 kHz). The cutoff frequency is one order of magnitude higher than the existing 108 V/A cross-impedance amplification circuit. Therefore, the HSPDC is applicable for high-speed modulation of weak optical signals. The laser telemetry system exhibits excellent detection performance at a modulation frequency of 3 kHz, with a detection sensitivity of 88.66 mV/ppm, a detection limit of less than 0.565 ppm, and a linear fitR 2 of 0.9996. The study demonstrates that the HSPDC photoelectric detection circuit has the advantages of fast response, high detection sensitivity and accuracy. Thus, it can be integrated to meet the needs of gas laser telemetry applications.-
Key words:
- photoelectric detection /
- transimpedance amplification /
- TDLAS /
- open light path /
- laser telemetry
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图 1 各次谐波信号。(a)奇次谐波信号；(b)偶次谐波信号
Figure 1. Each harmonic signal. (a) Odd harmonic signal; (b) even harmonic signals
图 3 不同Rd时I-IL 响应关系。(a) Rd=10 kΩ； (b) Rd=100 kΩ； (c) Rd=1 MΩ
Figure 3. I-IL response relationship with different Rd values. (a) Rd=10 kΩ; (b) Rd=100 kΩ; (c) Rd=1 MΩ
图 4 光电探测电路原理示意图。(a) 跨阻放大电路；(b) 负反馈放大电路；(c) BW滤波电路
Figure 4. Schematic diagram of photoelectric detection circuit. (a) Cross resistance amplification circuit; (b) negative feedback amplification circuit; (c) BW filtering circuit
图 5 光电探测电路仿真结果。(a) 各级放大电路输出信号；(b) 增益及相位频率响应特性
Figure 5. Photoelectric detection circuit simulation results. (a) Output signals of each stage of amplification circuit; (b) frequency response characteristic of gain and phase
图 7 暗电流噪声信号。(a) HSPDC噪声；(b) TLB PDC 噪声
Figure 7. Dark current noise signal. (a) HSPDC noise; (b) TLB PDC noise
图 8 遥测距离变化时系统输出信号。(a) HSPDC 输出信号；(b) TLB PDC 输出信号
Figure 8. System output signals when telemetry distance changes. (a) HSPDC output signal; (b) TLB PDC output signal
图 9 二次谐波峰峰值及标准偏差随距离变化曲线
Figure 9. Curves of the second harmonic peak-to-peak value and standard deviation changing with distance
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