Dynamic infrared scene projection is a technology for converting infrared (IR) digital image sequences into IR radiating image sequences. One of the most promising technologies is light down-conversion technology based on photoinduced opaque (PIO) effect. A parametric end-to-end steady-state model was proposed to describe the PIO mechanism. It consisted of three submodels such as the silicon parameter model, the photoinduced free carrier model, and the constitutive relation model. Furthermore, the parametric full-link from pump photons’ power density, photoinduced free carrier concentration, complex dielectric constant, and complex refractive index to the emissivity was constructed and mathematically analyzed by the above model. In order to verify the model, an intrinsic silicon wafer was pumped by a continuous-wave running Nd:YAG laser when the wafer was heated up to 321, 423, 459, and 498 K, respectively. Correspondingly, the emissivity integrated from 3 to 5 μm, with the increase of the pump power density measured by an IR camera. The measurement result agreed well with the theoretical result computed by the parametric end-to-end steady-state model. The maximum apparent temperature of the region illuminated by the laser with a pump power density of 407 W cm − 2 is up to 453 K when the silicon wafer was kept at 498 K. At the same time, the background temperature was elevated to 330 K owing to the initial free-carrier absorption enhancement.
An infrared scene projector is described in this paper which based on light down conversion. The film transducer is the key device of the projector which is a free standing substrate and coated on one side with an absorbing optical black. The optical black coating absorbs the visible light and emits the infrared light. The emission spectrum is similar with the blackbody. The single pixel which is 25×25μm in sizes and 35um at intervals in a film transducer is realized by MEMS technology. The array size of the film transducer is more than 1024×1024 in a transducer of 76.2mm (3 inch) diameter. Illuminated by a visible light projector with different intensities, the gray scale is more than 200 and the equivalent black body temperature of the transducer could be varied in the range of 293K to 573K.
The Hardware-in-the-loop simulation can establish the target/interference physical radiation and interception of product flight process in the testing room. In particular, the simulation of environment is more difficult for high radiation energy and complicated interference model. Here the development in IR scene generation produced by a fiber array imaging transducer with circumferential lamp spot sources is introduced. The IR simulation capability includes effective simulation of aircraft signatures and point-source IR countermeasures. Two point-sources as interference can move in two-dimension random directions. For simulation the process of interference release, the radiation and motion characteristic is tested. Through the zero calibration for optical axis of simulator, the radiation can be well projected to the product detector. The test and calibration results show the new type compound simulator can be used in the hardware-in-the-loop simulation trial.
Microchannel plate (MCP) is a photoelectron multiplier as the core component of low-level light (LLL) image intensifier. MCP has two-dimensional space, time, and energy resolution, fast response time, low background noise, wide dynamic range and high gain characteristics, as well as electrons, ions, UV and soft X-ray photon detection capability directly. In recent years, with the publication of foreign advanced technology and Chinese research staff in-depth understanding of MCP’s unique characteristics, the applications of MCP have extended into many new fields accordingly in China. In addition to the image intensifier, the MCP can be used in deep space exploration and scientific experiments, detecting kinds of trace rays and particles, such as pulsars navigation, nuclear simulation diagnostics, UV, EUV, neutron, neutrino detection and imaging. North Night Vision Technology Co. Ltd (NVT) as the only unit possessing MCP production capacity in China is constantly working on improving, innovation and application research on MCP technology. In this paper, based on the researches on MCP in some new fields the NVT Company has undertaken and ongoing, the technological breakthroughs and application research progresses achieved are described.
According to the aero-thermal effects and aero-thermal radiation effects of the optical window, the thermo-optic effect, the elasto-optical effect and the thermal deformation of the optical window are analyzed using finite element analysis method. Also, the peak value and its location of the point spread function, which is caused by the thermo-optic effect and the dome thermal deformation, are calculated with the variance of time. Furthermore, the temperature gradient influence to the transmission of optical window, the variation trend of transmission as well as optical window radiation with time are studied based on temperature distribution analysis. The simulations results show that: When the incident light is perpendicular to the optical window, image shift is mainly caused by its thermal deformation, and the value of image shift is very small. Image shift is determined only by the angle of the incident light. With a certain incident angle, image shift is not affected by the gradient refractive index change. The optical window transmission is mainly affected by temperature gradient and thus not neglectable to image quality. Therefore, the selection of window cooling methods, needs not only consider the window temperature but try to eliminate the temperature gradient. When calculating the thermal radiation, the optical window should be regarded as volume radiation source instead of surface radiator. The results provide the basis for the optical window design, material selection and the later image processing.
An infrared scene projector with high spatial resolution using the visible to infrared transducer is described in this paper. The film transducer is fabricated by MEMS technology. The single pixel with 25×25μm in sizes and 35um at intervals in a transducer which is 76.2mm (3 inch) diameter is realized. So, the array size of the film transducer is more than 1024×1024. Illuminated by a visible light projector with different intensities, the equivalent black body temperature of the transducer could be varied in the range of 293K to 573K. The emission spectrum is similar with the blackbody and the gray scale is more than 200.
Microwave (MW)/Infrared(IR) dual-mode compound guidance technology has greatly developed
recent years for enhancing guidance precision effectively. Here a new micro-mirror array structure is
introduced as upright display for MW/IR beam combiner in HWIL simulation. The beam combiner is used in the
IR/MW compound HWIL system for transmitting the MW signal while reflecting the IR signal. The spatial
resolution and spatial uniformity are two important performance indicators for beam combiner in the application
of HWIL simulation system. In this paper, the definitions, measurement methods, and results of spatial
resolution and spatial uniformity are given. Through the measurement by multiple groups of black and white
stripes, the spatial resolution and the spatial uniformity can be got. It shows the micro-mirror array beam
combiner can be applied for MW/IR dual-mode common-aperture HWIL simulation system.
The Microchannel plate (MCP) is the main noise source of low-level light (LLL) image intensifier. Material and
the whole manufacturing process of MCP have great impact on the noises of MCP. In this paper, based on the physical
mechanisms of MCP, noises of MCP are classified scientifically. By using the data obtained from the actual production
and the process test, the regression equation of the noise figure of MCP is derived, and the theoretical model of MCP
noise figure is established, including the background noise figure model caused by the dark current of the MCP primarily
about the time of the alkali corrosion technic, the ion feedback induced noise figure model caused by the patterns of the
MCP channel wall primarily about the time and temperature of the hydrogen reduction technic, and the electronic
scattering noise figure model caused by the open area ratio of the MCP primarily about the time of the alkali corrosion
technic. Guided by the theoretical model of noise figure, the methods of suppressing noises of MCP are obtained and the
technics are optimized. Taking advantage of the new techniques, the noise figure of the third generation MCP has been
reduced to below 1.8.
Modern infrared focal plane arrays (IR FPA) with high dynamic range, and multiband versions are being deployed in fielded systems. It needs to develop advanced scene projection technology to operate both in laboratory testing for hardware-in-the-loop simulation and validation of fielded units immediately prior to mission use. One of the fiber array visible to infrared imaging transducer is introduced. Different from the fiber bundle, the fiber array is etched on the substrate material. The property of transducer is determined by the substrate material. Polyimide (PI) film has the property of high dynamic range for temperature resistant, electric insulating, radiation resistant, good thermosetting and thermomechanical effect. The heat diffusion property of PI film is analyzed by experimental study. For experimental study, samples of with sputtered graphite on surface and different thickness of PI film were made. Using the visible light irradiate on the film and a high speed infrared camera capture the temperature information. The time of raising temperature process and the max temperature were recorded. The different energy of visible light was tried for the max temperature for samples. The result show the PI film can be achieved to 600K and has high thermal efficiency. And the surface film with good absorptivity is also important for heat transforming. PI film can be used as one of the material in the Infrared imaging transducer for high dynamic range and multiband radiation.
A technique of fiber array structure of visible to infrared image transducer for infrared imaging control and guide was
discussed. Be different from the normal fiber array, the structure here is micro-fabricated on quartz glass covered with
visible absorb member in front of the fiber. The fiber array structure works in vacuum and cooling chamber. The 3D
model of fiber array structure for finite element analysis based on the secondary radiation was established. The material
parameter, including density, specific heat and thermal conductivity, and the structure size including section size, length
of fiber array transducer for temperature and time character were studied. The simulation results show that the thermal
conductivity and length of fiber array are key parameters for transducer's property, and the optimized parameters for
fiber array structure transducer were given. The fiber array structure of visible to infrared image transducer has the
advantage of higher spatial and temperature resolution, and less manufacture cost. The optimized parameter for fiber
array visible to infrared image transducer can reach the frequency of 100Hz and higher temperature of 250°C in case of
increasing impulse power which can be used as infrared scene projector in hardware-in-the-loop simulation experiment.
Dichroic beam combiner is the kernel technology of the dual mode guiding simulation system. Based on the photonic
band gap structure of one-dimensional Photonic crystals, a new method of designing a diachronic beam combiner is
proposed in this paper, through which mid-IR region high reflection mirror coating is designed and calculated by using
plane-wave expansion method. Simple construction, combination of broad wave band beams in 2D and wide-angle is
realized, and polarization of off-axis incident beams is prevented. The analysis of infrared reflectivity and radio
frequency transmission rate demonstrates that this new method can perfectly satisfy the demand of design.
Pulsed infrared thermal wave nondestructive evaluation has been widely used in various materials' R&D,
quality supervise, detection and evaluation. Furthermore, based on pulse infrared thermal wave thermography
experiment, a new signal analyze method called pulse phase thermography was introduced by changing the temporal
signal to frequency field through Fourier transform. The pulse signal consists of various frequencies information and
different thermal wave frequency reaches corresponding depth in the material. According to the relation of thermal
wave's frequency to conduction depth, pulse phase thermography method can detect the depth of defects. The
intuitionistic thermograph result is the phase information of each pixel in frequency field, through that the defect's size,
location can be well distinguished. In order to solve the depth detection, two standard flat bottom holes samples made of
aluminum and steel were studied. By analyzing the experimental results, it showed the theoretical depth value and actual
depth relations, which can provide an assistant way for subsurface defects detection of material and structure. In that case,
given a standard sample with artificial defects, the products made of the same material can be well detected and
evaluated. At the same time, corresponding to the pulse infrared thermal wave thermography, phase thermographs with
the phase information have higher sensitivity to the defects, and do not influence with the ununiformity of the light