为提高金属线胀系数的测量精度和灵敏度，以方便数字化测量与微机处理，以PSD 光电传感器为核心实现微位移 测量，采用光学放大机构提高微位移分辨率，利用BOS-PSD0018 芯片实现微位移转换，并用单片机系统实现金属线胀系数的数字化处理与显示. 用铜棒进行了标定测试，用铁棒进行检测试验，检测试验表明金属线胀系数最大相对误差为±2. 3%，用光学放大机构使微位移分辨率比提高4 倍.

In order to improve measurement precision and sensitivity of metal linear expansion coefficient，thus simplify digital measurement and computer processing，the micrometric displacement is completed by using the core element of PSD photoelectric sensor. An optical enlargement device is employed to advance micromovement resolution ratio. The chip BOS-PSD0018 is employed to achieve micromovement conversion. A microprocessor is utilized to realize digital procession and display for metal linear expansion coefficient. The standardization test is completed by using a copper rod; the detection test is conducted by using iron rod. The results show that the maximum relative error of metal linear expansion coefficient is less than ±2. 3%，the optical enlargement device can 　　increase 4 times for the resolution ratio of micromovement.