Sapphire single crystal is widely used in weapons, aerospace and other fields because of its high hardness, high temperature resistance and excellent optical properties. The surface topography of sapphire grinding has an important influence on its subsequent processing and service performance. Aiming at giving consideration to machining efficiency and surface quality, this paper puts forward a high-efficiency ultra precision machining scheme of sapphire by using ultra precision five axis machining center machine tool and diamond grinding wheels with different particle sizes to realize efficient removal of crystal materials and obtain high machining surface quality. Through experiments, the effects of different grinding process parameters on machined surface roughness and material removal rate are studied. The surface roughness and surface morphology of sapphire ground by diamond grinding wheel are detected by metallographic microscope and touched optical measuring instrument. The test results show that the feed speed of grinding wheel has the greatest influence on the surface quality and roughness and material remove rate, the rotation speed of grinding wheel takes the second place, and the rotation speed of substrate has little influence; Reducing the grinding particle diameter of grinding wheel is helpful to improve the machined surface quality.
With the science technology development, Electro-optical devices requires higher demands for optical lens. Less than 10mm small-sized cylindrical lens were fabricated and inspected. With conventional methods, custom designed fixture, cylindrical lens satisfies the designed demands were fabricated on classical polishing machine. A reliable processing procedure was acquired, which can guide the operator successfully fabricate the lens, and also be reference to the fabrication of similar optical lens.
According to the requirements of the military optoelectronic system for the application of the reflector, optical processing experiments were carried out on the SiCp/Al coating nickel phosphorus alloy plane mirror; The optical properties of the SiCp/Al and several commonly used optical materials were compared; The turning test and polishing test of uncoated nickel-phosphorus and nickel-phosphorus-coated aluminum-based silicon carbide were carried out, the optical processing of φ150mm SiCp/Al coating nickel-phosphorus alloy plane mirror was realized, and the high quality and high precision optical surface was obtained. The RMS value of surface accuracy was 1/27λ(λ=632.8nm), The surface roughness Ra was better than 3.3nm, which confirmed the feasibility of using SiCp/Al composites in military optoelectronic systems and met the requirements of precision of the reflector.
Aiming at the processing of infrared optical parts and the adjustment of infrared optical system, key links, such as surface shape change, optical axis deviation, etc and influencing factors were analyzed in detail caused by internal defects and stress of Infrared optical parts, differences in material properties and adjusting tightening force from the aspects of optical processing and opto-mechanical adjustment, whose influence on the final performance and quality of the infrared system was pointed out. On this basis, the problems existing in the current manufacturing process of the infrared optical system were sorted out, and the related technology which was needed to be carried out and the content of continuous attention were put forward to realize the refinement and parameterization of infrared system process control, and improve the manufacturing performance and quality of infrared optical system.
Most of the spherical shell of the photoelectric multifunctional instrument was designed as multi optical channel mode to adapt to the different band of the sensor, there were mainly TV, laser and infrared channels. Without affecting the optical diameter, wind resistance and pneumatic performance of the optical system, the overall layout of the spherical shell was optimized to save space and reduce weight. Most of the shape of the optical windows were special-shaped, each optical window directly participated in the high resolution imaging of the corresponding sensor system, and the optical axis parallelism of each sensor needed to meet the accuracy requirement of 0.05mrad.Therefore precision machining of optical window parts quality will directly affect the photoelectric system's pointing accuracy and interchangeability. Processing and testing of the TV and laser window had been very mature, while because of the special nature of the material, transparent and high refractive rate, infrared window parts had the problems of imaging quality and the control of the minimum focal length and second level parallel in the processing. Based on years of practical experience, this paper was focused on how to control the shape and parallel difference precision of infrared window parts in the processing. Single pass rate was increased from 40% to more than 95%, the processing efficiency was significantly enhanced, an effective solution to the bottleneck problem in the actual processing, which effectively solve the bottlenecks in research and production.
With the process test for the choice of materials, the test materials and the molds, the abrasives, the temperature and the different machining process monitoring parameters of the polishing machine, the process method and the quality control technology were figured out for the Φ130 sapphire window element with long distance and high resolution (hereinafter referred to as window element), meantime, the optimum process condition was determined to machine the element. The results were that the high resolution imaging window was processed with the surface roughness Ra of 0.639nm, the transmission distortion of λ/10 (λ=632.8nm), the parallel error of 5″, the resolution of 1.47″ and the focal length of 5 km, which can satisfy the imaging requirements better for the military photoelectric device for sapphire window with long distance and high resolution.
The optical parallelism is an important indicators of isosceles prism. However, it cannot be directly measured in the processing process, and it is measured when the small surface is coated with silver film, which results in low processing rate. By analyzing the principles of the first optical parallelism and the second optical parallelism, this paper provides a new processing and detection method for isosceles prism. The good verticality between the three working face for isosceles prism and a side face can ensure the second optical parallelism. The small difference of 67.5°can ensure the first optical parallelism. By changing the position of the incident light when testing, the number of reflections can be reduced from seven to three. The reflection principle deduces the formula: θII(7)=2.4θII(3),which to improve the machining accuracy and avoid the surface imperfections in detection. By using this process, precision and productivity can be effectively improved, the complexity of the process is reduced, and the qualification of isosceles prism has been improved.
With the development of infrared optical systems in military and civil areas, chalcogenide glass aspherical lens possess some advantages, such as large infrared transmission, good thermal stability performance and image quality. Aspherical lens using chalcogenide glass can satisfy the requirements of modern infrared optical systems. Therefore, precision manufacturing of chalcogenide glass aspheric has received more and more attention. The molding technology of chalcogenide glass aspheric has become a research hotspot, because it can achieve mass and low cost manufacturing. The article of molding technology is focusing on a kind of chalcogenide glass aspherical lens. We report on design and fabrication of the mold that through simulation analysis of molding. Finally, through molding test, the fabrication of mold’s surface and parameters of molding has been optimized, ensuring the indicators of chalcogenide glass aspherical lens meet the requirements.
Large angle wedge parts were widely used in the optical system that was used for achieving a wide range of scanning. Due to the parts having the characteristic of large difference in the thickness of both ends and high density, the accuracy of the wedge angle was hard to ensure to reach second level in optical processing. Generally, wedge mirror angle was measured by contact comparison method which was easy to damage the surface. In view of the existence of two practical problems, in this paper, based on theoretical analysis, by taking three key measures that were the accurate positioning for the central position of the large angle wedge part, the accuracy control of angle precision machined of wedge mirror and fast and non destructive laser assisted absolute measurement of large angle wedge, the qualified rate of parts were increased to 100%, a feasible, controllable and efficient process route for large angle infrared wedge parts was found out.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.