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矩形光栅1级和0级衍射效率之比对光栅的凹槽深度敏感,介绍了将其应用于聚合物光栅生物传感器的原理和光栅衍射光信号检测电路系统原理。设计了锁相放大器的信号通道滤波器,获得带宽不大于1kHz的窄带滤波特性;利用相敏检测器(PSD)结合二阶巴特沃思低通滤波器,使等效噪声带宽限制在20Hz以内,避免了工频干扰,实验结果表明系统输出信噪比SNR可达4 000以上。
The ratio of the 1st order and the 0th order diffraction efficiency of the rectangular grating is sensitive to the groove depth of the grating. The principle of its application to the polymer grating biosensor and the principle of the grating diffraction optical signal detection circuit are introduced. The signal path filter of the lock-in amplifier is designed to obtain the narrow-band filter with the bandwidth less than 1kHz. By using phase-sensitive detector (PSD) and the second-order Butterworth low-pass filter, the equivalent noise bandwidth is limited to within 20Hz. Avoid the frequency interference, the experimental results show that the system output SNR up to 4,000 above.