Research On High Sensitivity Detection Technology Of Laser Pulse

The pulsed laser signal has the advantages of narrow pulse width,wide frequency range and high peak power,therefore,it has a good application prospects in military and communication fields.System of high-performance pulse signal detection has been gotten more and more domestic,which is popular with more and more domestic and foreign scientific research workers.Detection sensitivity is the key technical indexes of the receiving system,which is described as the minimum peak optical power received by the device under certain false alarm probabilities.For the weak laser pulse signal detection scene,through the study of pulse width and other parameters,detection sensitivity and other technical indexes can be further adjusted and optimized.Therefore,based on the theoretical calculation,the detection system of pulse laser which is based on the direct detection scheme is designed in this thesis.Laser pulse signal detection can be divided into direct detection and coherent detection,these two detection schemes are compared with their advantages and disadvantages in this thesis.In addition,the noise of each module of the pulse detection system is described and analyzed,and the detection sensitivity index is calculated in detail.Secondly,for direct detection system of laser pulse signal,conventional photoelectric conversion devices and APD which has internal gain are compared in detection efficiency and technical indexes.Finally,several design ideas of the preamplifier circuit are summarized and the pulsed laser detection system under certain false alarm probabilities is built in this thesis.Finally,on a certain theoretical analysis in this thesis,the experiment of the pulsed laser direct detection scheme was built and completed,at the same time welding and commissioning work are completed.The structural elements for each circuit module are fabricated to achieve the purpose of shielding noise.On the basis of the calculation that the false alarm probability less than 1%,sensitivity test task is completed.The test result is-37.1 dBm and the theoretical calculated in this paper difference is 7.4 dB.The difference between the test result and the theoretical calculation value is mainly due to the lack of accurate measurement of the system noise of the detection circuit.The chip or peripheral circuit will generate some noise when the power is applied.Therefore,the sensitivity optimization scheme needs to be carried out.The adjustment of the field of view is completed to ensure uniformity of the receiving field of view and the emission field.By analyzing the amplifier circuit parameters,the filter circuit is designed.In addition,according to the principle of correlation detection,the theoretical correctness is verified by software simulation.