The Highlight Protection's Circuit Design Of The Low-light Level Night-vision Device

With the rapid development of modern photoelectronic technology,the performance of LLL night vision device has been greatly improved,and it has been widely used in military,civilian and other fields.But the core device—the image intensifier is easy to defocus after it is exposured by highlight,which the image is blurry.The continuous highlight will seriously damage the image intensifier so that the instrument runs out completely.Therefore,it is of great practical significance to study the highlight protection device of LLL night vision device.Based on the study of the fatigue and damaged mechanism of the LLL night vision device in the effect of the bright light,the light protection equipment of the LLL night vision device under the the technology of the “gating power” is studied,and the actual application and detection are carried out.On the basis of firstly researching a large number of relevant literatures at home and abroad and probing into the technology index and the realization principle of the product,the author demonstrates the main technical way of the highlight protection equipment of the LLL night vision device and investigates the highlight protection schemes of the LLL night vision device with the gating power technology.When the highlight irradiates,the electric current of fluorescent screen is large,regarding the sample as a signal to feedback that the continuous power supply time of the control cathode working voltage is short;when it is in low light irradiation,the feedback signal is weak,and the working voltage is approximate to the direct current high voltage.At the aim of the image intensifier circuit system,the design of auto-gated power achieves the transformation to the image intensifier in the mirror through the helmet-mounted glimmer observation.In the case of ensuring the overall structure unchanged and making full use of the original circuit meter,the PWM signal output is achieved with the FPGA technology controlling the gating power technology.Utilizing the TTL signal of the pulse width modulation to control the output of the IGBT device that is approximately the 240 V direct current high voltage of the rectangular flat,the highlight protection is achieved.Focus on studying the MTF inspect methods of image intensifier,conducting the comparison test to the MTF of image intensifier remoulded before and after,and comparing the detection on the performance of the improved helmet-mounted LLL night vision device of complete machine with that of the unmodified LLL night vision device to test,the results meet the design requirements.