Abstract：This paper introduces a new laser detecting instrument for railway track flatness, it takes a silicon photocell as photoelectric receiver, and then the laser signal is converted into electric signal.In the instrument, the weak electrical signal is amplified by high power low noise amplifier, in which the variable magnification is controled by single chip microcomputer, thereby successfully solved the difficult problem that such as the different light source modulation signal amplitude, near and distant light signal strength caused by different signal magnitude varying considerably. Thus, the high accuracy detection has been achieved for different kinds of laser light source and light intensity changes in far and near distance. The adaptability and the detection performance of the receiver are ensured.
