Research And Implementation Of Infrared Thermal Imager Based On Uncooled Infrared Focal Plane

Infrared thermal imager is widely used in power monitoring and industrial production.The main reason is that it can efficiently measure the temperature of large areas.With the breakthrough of domestic manufacturers in the manufacturing technology of uncooled infrared focal planes,the use cost of high-resolution uncooled infrared focal plane detectors is rapidly decreasing,and the demand for high-resolution infrared cameras has increased.Higher resolution places higher demands on the design method of the infrared camera.In response to this problem,this paper proposes a highresolution infrared camera design.The key components of the thermal imaging camera design are uncooled infrared focal plane detectors(detectors)and ZYNQ processors.In addition,the hardware platform also includes a detector temperature adjustment circuit,a signal preprocessing circuit,an analog to digital conversion(ADC)circuit,and a video output circuit.The ZYNQ processor has two main functions in the system.The first is to generate the driving signals required by the respective circuits,and to receive the signals output by the ADC,the second is to process the obtained image information.Aiming at the problem of generating the driving signal and receiving the output of the analog-to-digital converter,the design scheme of the signal generation circuit and data format conversion circuit based on ZYNQ internal FPGA is studied and proposed.The signal generation circuit is composed of a Mixed-Mode Clock Manager(MMCM),a BRAM,a FIFO,a counter,and a state machine.The circuit can drive the detector to operate and generate the phase-adjustable sampling clock required by the ADC.The data format conversion circuit consists of SerDes and FIFO,which converts the parallel data input from the ADC into the data format of the AXI-Stream protocol.Aiming at the problems of non-uniformity correction,temperature measurement and image enhancement in image processing,the image processing unit design scheme is proposed.The scheme uses an on-chip FPGA and an on-chip ARM.For nonuniformity correction,an on-chip FPFA resource design is used to implement a twopoint correction and blind element compensation circuit;For temperature measurement,the target area gray level statistics circuit is designed using on-chip FPGA resources,and the statistical results are calculated as temperature values using on-chip ARM;Image enhancements include contrast stretching,pseudo color coding,and on screen display.Contrast stretching operation using a double plateaus histogram equalization circuit implemented by an on-chip FPGA.A pseudo color coding circuit and a on screen display circuit are implemented using an on-chip FPGA,and a pseudo color coding table and displayed information are generated using ARM.After the system design is completed,the system calibration scheme is designed according to the characteristics of the system and the system is calibrated using the scheme.Imaging and temperature measurement experiments were carried out using the calibrated system.The experimental results obtained showed that the imaging effect of the scheme was good and the temperature measurement accuracy met the requirements.