According to the requirement of rapid,nondestructive and continuous measurement of fruit sugar content, we designed nondestructive fruit sugar content detecting device based on near infrared spectroscopy. The device used a semiconductor laser as light source,photocell to receive signal,digital lock-in amplifier to extract fruit signal. And from the comparison of the calibrations,curves fitting and other data processing methods the calculation formula of sugar content of fruit can be obtained. The actual measurement error was less than 3％. The test showed that the disturbance and temperature drift from the common light emitting tube and analogy detection circuit was solved,and the stability of device was improved. The measurement error was consistent with the design requirements.%针对水果糖度快速、无损和连续测量的要求,设计了一套基于近红外光谱原理的无损水果糖度检测装置.该装置采用半导体激光器作为发射光源,光电管接收信号,数字锁相放大器提取微弱信号,并通过校准对比、曲线拟合等数据处理方法,得到了水果糖度的计算公式,实际测量误差在3％以内.试验表明:该装置解决了普通发光管和模拟检测电路带来的干扰和温漂等问题,提高了装置稳定性,测量误差满足装置设计要求.
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