The optical wave wavefront measurement system can perform non-contact real-time quantitative monitoring of the gas flow rate according to the gas density changes in the wind tunnel test. Since the quality of the optical surface of the wind tunnel window directly affects the acquisition accuracy of wavefront information, it is necessary to evaluate the adaptability of the opto-mechanical structure to fluid load in the development stage. To solve this problem, this paper proposes a gas flow field change model based on Finite Element Analysis (FEA). By calculating the fluid-structure coupling response of the wind tunnel window, the displacement field of the wind tunnel window and the maximum displacement of the node are obtained. It is 0.00018mm, and the result shows that the window glass has good environmental adaptability at a flow rate of 885m/s.
In order to evaluate the ability of a space-based optical system to suppress off-axis stray light, a large-field, multispectrum space-based stray light test method based on point source transmittance (PST) is proposed in this paper. A stray light test facility is constructed using multiple laser sources, large aperture off-axis reflective parallel light tubes and a high-precision positioning mechanism to evaluate the PST index of stray light in the visible and near infrared bands for a space-based optical system. Based on theoretical analysis, experimental measurements of standard lenses in various wavelength bands have proven that the dynamic range of the facility in the visible light band is 10-6 and in the infrared band is 10-3. The facility has the advantages of wide range of detectable wavelengths, high automation, and large dynamic range. The test results can be used for correction of the hood, which provides a reliable traceability basis for the stray light suppression of a space-based optical system.
Mid-wave infrared(MWIR) and long-wave infrared(LWIR) two-band scene simulation system is a kind of testing equipment that used for infrared two-band imaging seeker. Not only it would be qualified for working waveband, but also realize the essence requests that infrared radiation characteristics should correspond to the real scene. Past single-digital micromirror device (DMD) based infrared scene simulation system does not take the huge difference between targets and background radiation into account, and it cannot realize the separated modulation to two-band light beam. Consequently, single-DMD based infrared scene simulation system cannot accurately express the thermal scene model that upper-computer built, and it is not that practical. To solve the problem, we design a dual-DMD based, dual-channel, co-aperture, compact-structure infrared two-band scene simulation system. The operating principle of the system is introduced in detail, and energy transfer process of the hardware-in-the-loop simulation experiment is analyzed as well. Also, it builds the equation about the signal-to-noise ratio of infrared detector in the seeker, directing the system overall design. The general design scheme of system is given, including the creation of infrared scene model, overall control, optical-mechanical structure design and image registration. By analyzing and comparing the past designs, we discuss the arrangement of optical engine framework in the system. According to the main content of working principle and overall design, we summarize each key techniques in the system.
Infrared scene projector is essential and standard equipment for training and testing IR threat detection systems including missile warning systems and hostile fire indicators. DMD as one of the scene generator used in IRSP has performed several attractive features including high spatial resolution, high framerates, no dead pixel and excellent uniformity. In this paper we proposed a new structure of DMD based IRSP. We use a field lens and a mirror as separator to achieve a wide field-of-view optical system design. Since the field lens is a part of the illumination path as well as projection path, it brings several challenges to the optical system design. In this approach we detailed analyze the design method and perform test equipment and facilities we developed.
With the development of photoelectric detection technology, machine vision has a wider use in the field of industry. The paper mainly introduces auto lamps tester calibrator measuring system, of which CCD image sampling system is the core. Also, it shows the measuring principle of optical axial angle and light intensity, and proves the linear relationship between calibrator’s facula illumination and image plane illumination. The paper provides an important specification of CCD imaging system. Image processing by MATLAB can get flare’s geometric midpoint and average gray level. By fitting the statistics via the method of the least square, we can get regression equation of illumination and gray level. It analyzes the error of experimental result of measurement system, and gives the standard uncertainty of synthesis and the resource of optical axial angle. Optical axial angle’s average measuring accuracy is controlled within 40′′. The whole testing process uses digital means instead of artificial factors, which has higher accuracy, more repeatability and better mentality than any other measuring systems.
In order to avoid the phenomenon of some image information were lost, which is due to the jamming signals, such as incident laser, make the pixels dot on CCD saturated. In this article a device of optical-mechanical structure was designed, which utilized the DMD (Digital Micro mirror Device) to modulate the image. The DMD reflection imaging optical system adopts the telecentric light path. However, because the design is not only required to guarantee a 66° angle between the optical axis of the relay optics and the DMD, but also to ensure that the optical axis of the projection system keeps parallel with the perpendicular bisector of the micro-mirror which is in the "flat" state, so the TIR prism is introduced,and making the relay optics and the DMD satisfy the optical institution’s requirements. In this paper, a mechanical structure of the imaging optical system was designed and at the meanwhile the lens assembly has been well connected and fixed and fine-tuned by detailed structural design, which included the tilt decentered lens, wedge flanges, prisms. By optimizing the design, the issues of mutual restraint between the inverting optical system and the projecting system were well resolved, and prevented the blocking of the two systems. In addition, the structure size of the whole DMD reflection imaging optical system was minimized; it reduced the energy loss and ensured the image quality.
With the development of science and technology, CCD(Charge-coupled Device) has been widely applied in various fields and plays an important role in the modern sensing system, therefore researching a real-time image acquisition and display plan based on CCD device has great significance. This paper introduces an image data acquisition and display system of area array CCD based on FPGA. Several key technical challenges and problems of the system have also been analyzed and followed solutions put forward .The FPGA works as the core processing unit in the system that controls the integral time sequence .The ICX285AL area array CCD image sensor produced by SONY Corporation has been used in the system. The FPGA works to complete the driver of the area array CCD, then analog front end (AFE) processes the signal of the CCD image, including amplification, filtering, noise elimination, CDS correlation double sampling, etc. AD9945 produced by ADI Corporation to convert analog signal to digital signal. Developed Camera Link high-speed data transmission circuit, and completed the PC-end software design of the image acquisition, and realized the real-time display of images. The result through practical testing indicates that the system in the image acquisition and control is stable and reliable, and the indicators meet the actual project requirements.
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