The sudden interference of highlighted objects in the field of view of infrared imagers causes the overall gray distribution of the image to shift to the highlighted region, leading to the decline of target recognition effect. In this paper, an infrared image processing algorithm which runs by FPGA is introduced. Through histogram statistics and gray value conversion, the infrared image is compressed and the image details are enhanced. Through the recognition and processing of the high gray value region in the histogram, the interference of highlighting can be suppressed, and a good effect has been achieved.
Silicon aspherical optics are of widely used these years with the development of the improvement of optical manufacturing and testing technologies. Single point diamond turning for silicon aspherical optics can obtain high surface precision. However, the surface microscopic quality is difficult to reach the ideal specification, caused by the limitation of material characteristics. An experimental study on the combined manufacturing technology of single point diamond turning and polishing has been carried out and proposed in this paper. The optimum turning parameters of the main factors affecting the micro-nano quality of silicon diamond turning surface, such as cutting depth, spindle speed and feeding speed, were obtained by orthogonal experiments. After polishing, the surface roughness was reduced from 5.35 nm to 1.16 nm. Meanwhile, the PSD was improved obviously. The combined manufacturing technology can be applied for high precision silicon aspherical optics.
In some optical systems, high requirements are put forward for the roughness of the thin-walled side of infrared materials, and ultra-precision grinding is needed. In this paper, the removal of residual tool marks in the side forming process of such parts is studied, and the influence of two different grinding methods of fixed abrasive on the side roughness is analyzed, and polycrystalline magnesium fluoride (MgF2) is taken as the research object. Firstly, the comparative experiment of peripheral grinding on the side of MgF2 is carried out by using diamond grinding wheel with different particle sizes, and then the end grinding is carried out by using different particle sizes of pellets. It is proved that the tool marks can be removed by end face grinding, and the surface roughness Ra decreases from 1.4241μm to 0.0458μm.
A fundamental issue in spherical optical manufacturing process is how to measure the radius of curvature accurately. Due to the high precision requirement for some advanced optics applications, the accuracy of the measurement is usually crucial. In this paper, kinds of spherical curvature radius methods that use spherometer, laser interferometer and profilometer are introduced, the error sources of these methods are analyzed. A series of measurement experiences with radius rang from R 7.65mm to R790.5mm are carried out and the results are analyzed according to measurement error theory. Consequently the advantages of the three kinds of instruments in radius measurement are obtained.
Different from the abrasive grinding process, diamond particles are solidified in matrix materials and the fixed motion between abrasives and workpieces which good for precision machining, so we take this method to grind glass-ceramic reflector and a good surface quality was obtained by using diamond W14 pellets. Through the grinding process experiment, the material removal rate on the glass-ceramic reflector are measured at the given rotation speed, the pendulum frequency and pressure by W28, W14, W5 pellets. In addition, the surface roughness measurement results show that the surface roughness of 181.6nm can be obtained by using W28 diamond pellets. The experiment also demonstrates that the surface roughness of the glass-ceramic reflector is decrease with changing pellets in a smaller diamond size. After ultra fine grinding processing by using W5 diamond pellets, finally, the optical surface with a roughness of 20.8nm is obtained. The experimental results show that the method of using diamond pellets to process glass-ceramic reflector can replace the traditional abrasive finishing process in rough grinding, fine grinding and superfine grinding.
Traverse oscillating cutting is one of the cutoff process with low cutting forces, low contact zone, favorable cooling, long cutting time which is suitable for hard and brittle materials. The cutting process will generate residual stress, which affects the surface profile and mechanical properties. In this paper, the fused silica glass is selected to carry out the cutting experiment. The effect of the two cutting modes, horizontal cutting and longitudinal cutting on the residual stress was studied experimentally. And the parameters such as rotating speed, feed speed and cutting depth were optimized. The results show that both cutting modes produce large residual stress at the edge, while the horizontal cutting in the middle region produces smaller residual stress. There is no significant linear relationship between the parameters and residual stress, which has an optimal range. And an optimal traverse oscillating cutting technique is obtained.
In shape processing of the ultra-thin mirror, deformation will be produced under cutting forces, which is a major cause of quality deterioration. An ultra-thin mirror with diameter-thickness ratio more than 10 is studied in this paper. Rigidity characteristic of the grinding process by diamond wheel is analyzed by FEM. A receptance model of the micro-cutting process and the surface accuracy is established by a self-adaptive multi-scale method according the first strength method. And the effectiveness of the mathematical model is verified by experience. And the dynamic stiffness caused by grinding is optimized. As a result, deformation of the optical surface is reduced to 0.004λ and the acceptable surface accuracy can be achieved.
In the last few years, synchrospeed polishing has been widely employed in the mass spherical optical surface manufacturing process with the development of the optical polishing technology and equipment. However, the edge collapse appears easily in the synchrospeed polishing process because of the high edge pressure. The principle of the spherical surface synchrospeed polishing process is introduced, and the motion mathematical model is developed. A new multi-mode polishing method which utilizes a big polishing tool combined with a small one to correction on the edge collapse is proposed. A sphere that aperture is 110mm and radiuses is 238mm is polished via the mew method. The collapse radio is decease from 20% to 10%, and the D-value of collapse is deceased from 459.29nm to 68.74nm before and after the correct polishing process. The surface figure accuracy RMS is improved from 90.97nm to 15.97nm accordingly. The experiment proved that the correction method is very useful to correct the edge collapse.
Sphere ultra-precision NC grinding process with diamond cup wheel is widely used as an indispensable working procedure for manufacturing spherical, most aspherical, and some freeform surfaces. This paper presents a mathematic model of sphere grinding with cup diamond wheel based on homogeneous transformation method to simulate grinding marks. Different kinds of grinding marks are obtained by changing the geometrical parameters including the shift in axis X and Y axis and inclination angle deviation. Form accuracy and dimensional errors caused by geometrical parameters are also analyzed, and hence a three-step method utilizing grinding marks is proposed to correct these errors. A series of experiments are conducted and the results show that the proposed method is very efficient and effective in actual spherical surface generating process.
The properties of optical system will be decreased by the centering errors of the lens. But the centering errors are
inescapability during the manufacturing process. Different from the sphere surface, the aspheric surface is a center axis
only, the centering error has been fixed once the two surfaces are polished or turned et al. For high precision optical
system assembly, the centering error of the aspheric lens must be measured accurately. The principle of centering error
measurement for aspheric lens is introduced in the paper. The device for the centering error testing has been developed.
For a high accurate measurement, the factors include axis the tilt and shift of axis of Z, F, T and the coincidence error e
of symmetry axis of aspheric surface and reference axis are analyzed. Finally, a double aspheric surface lens is tested by
device self developed and TRIOPTICS AMT100 with the same method and the results are almost agreement.
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