Terahertz (THz) waves have characteristics such as low energy, strong penetration, and high resolution. Therefore, THz imaging technology has broad prospects in areas such as security inspection, medical diagnosis, and non-destructive testing. As an important component of THz imaging systems, the performance of THz detectors has a significant impact on imaging resolution and speed. Field effect transistor (FET) THz detectors, due to their characteristics of room temperature operation, easy large-scale integration, and fast response speed, have enormous potential in imaging applications. This paper reviews the research progress of FET THz detectors in the field of THz imaging in recent years, including advances in imaging arrays, material selection, and analysis of existing design and manufacturing issues It points out that the antenna and pixel spacing are important factors limiting large-scale arraying. Based on this, it provides an outlook on future research directions, indicating that new materials and structural designs will further improve device performance,achieving faster and dearer THz imaging
A multispectral time delay integration (TDI) line array cooled infrared detector is developed. The detector array has a scale of 1024×4X6 and a pixel size of 20 umX20 um. The readout circuit has the function of serial output of analog signals that are converted into electrical signals through spectral segmentation,and integrating while reading (IWR), TDI, and blind/flash element elimination. The detector chip is made of HgCdTe epitaxial material to manufacture a photovoltaic diode array, packaged with a highly reliable all-metal vacuum dewar, and cooled using a small split Stirling refrigerator. The whole machine has advantages such as small size, low power consumption, wide response band, high integration, and short startup time The test results show that the blind element rate of each spectral segment of the device is less than 1%, and the noise equivalent temperature difference (NETD) is less than 30 mK, the dynamic range of each spectral segment is greater than 70 dB, the non-uniformity of the response rate of each spectral segment is less than 5%, the nonlinearity of each spectral segment is less than 2%, and the device line frequency is greater than 20 kHz.
Aiming at the problems of unclear texture, low brightness and high noise of infrared images, an adaptive multi-feature fusion algorithm for infrared image enhancement is proposed in this paper. Firstly, the automatic linear mapping method is used to extract 16-bit infrared images from 14-bit infrared images, which improves the visual effect. Secondly, the combined processing method of GUM and MSRCR is introduced to obtain effective information on different scales of the image and improve the contrast of the image Finally, the adaptive weight map is designed and combined with the characteristics of the image pyramid structure to complement and fuse the effective information of different feature layers, which improves the brightness of the image and enriches the texture information of the image. Experimental results show that this algorithm can effectively improve the contrast and visual effect of infrared images, and its AG is increased by about 0.6% compared with the existing algorithms. The PSNR is about 10% higher, the image edge information efficiency is about 11% higher, and the image sharpness is about 10% higher.
Deep convolutional neural networks (CNNs) have attracted much attention in the field of image denoising. However, with the increase in network depth, most deep CNNs have problems such as performance saturation and learning decline. In this paper, a dual-path denoising network combining local and global features is proposed. Two networks with different structures are combined to form a dual path model, and the width of the network is increased to obtain more different features. The global and local features are integrated through long path connections to enhance interlayer correlation. The attention mechanism uses the current stage to guide the input of the previous stage to obtain more features. The experimental results show that the PSNR values of the proposed network model reach 32. 95 dB and 31.74 dB in Set12 and BSD68 datasets, respectively. At the same time, the subjective visual effects such as image edges and other details are recovered better and clearer.
The influence of refrigerant pressure on the refrigeration performance of a corrugated tube self-adjusting J-T coder was studied through specific experiments. The conclusion of the experimental conditions is that within a certain pressure range (11 MPa≤P23 MPa), as the working fluid pressure increases, the start-up time of the infrared system using this refrigeration device gradually shortens, but the rate of accelerated startup will decrease with the increase of working fluid pressure. When the working fluid pressure increases to a certain extent (23 MPa≤P27 MPa), the startup time will tend to stabilize. Within a certain pressure range (11 MPa≤P<15 MPa), as the working fluid pressure increases, the storage time of the infrared system using this type of cooler gradually increases But when the working fluid pressure increases to a certain extent (15 MPa≤P≤27 MPa), the cold storage time will tend to stabilize. Within a certain pressure range(11 MPa≤P≤27 MPa), with the increase of working fluid pressure, the maximum flow rate of the refrigerator increases linearly during startup, and the stable flow rate gradually increases during operation. The process, methods, and research results of this experimental study have reference significance for engineering practice.
In order to meet the requirements of data acquisition, nonlinear fitting compensation, signal preprocessing and Fourier spectrum inversion of transmission rotary mirror Fourier spectrometer, a set of transmission rotary mirror Fourier spectrum analysis software integrating data acquisition and signal analysis is designed based on LabVIEW. By calling the physical channel interface of NI data acquisition card, the software collects the interferogram data of the amplitude of interference signal changing with time, and restores the spectrum information of infrared signal by signal processing program. It can realize automatic storage of waveform files and visualization of important data processing processes, which is suitable for industrial computer applications The spectral curve of blackbody radiation source is measured. The wavelength accuracy is measured by polystyrene absorption spectrum, and the spectral half-height width is measured by water vapor spectrum curve.By using the spectral analysis software designed in this paper, the spectral distribution of infrared signal is recovered. The wavelength accuracy of 0. 40% and the spectral resolution of 0. 88 cm-1 are achieved, which verifies the uability of the systemn.