Development of Aspheric Optical Processing Technology at Home and Abroad
May 25, 2018
A: The role of aspherical optical components
Aspherical optical components are a very important optical component. Commonly used are parabolic mirrors, hyperbolic mirrors, ellipsoidal mirrors, and the like. Aspherical optical components can achieve unparalleled imaging quality for spherical optics. They can well correct many aberrations in optical systems, improve image quality, and improve system identification capabilities. It can be used with one or several non- Spherical parts replace multiple spherical parts, simplifying the instrument structure, reducing costs and effectively reducing the weight of the instrument.
The application of aspherical optical components in military and civilian optoelectronic products is also extensive, such as in camera lenses and viewfinders, television camera tubes, zoom lenses, movie playback lenses, satellite infrared telescopes, video recorder lenses, video and audio recording discs. Reading head, barcode reading head, optical fiber communication fiber connector, medical equipment, etc.
II: Status Quo of Ultra-precision Machining Technology for Foreign Non-spherical Parts
Since the 1980s, there have been a variety of new aspheric ultra-precision machining technologies, mainly including: computer numerical control single-point diamond turning technology, computer numerical control grinding technology, computer numerical control ion beam forming technology, computer numerical control ultra-precision polishing technology and aspherical surface Copying technology, etc., these processing methods basically solved the problems that exist in the processing of various aspherical mirrors. The first four methods use numerical control technology. They all have high machining accuracy and high efficiency, and are suitable for mass production.
When aspherical parts are machined, factors such as material, shape, accuracy, and bore diameter of the parts to be machined are taken into account. For soft materials such as copper and aluminum, superfinishing can be performed using single point diamond cutting (SPDT). Or plastics, etc., currently use the first ultra-precision processing of its mold, and then use the forming method to produce aspherical parts. For other high-hardness brittle materials, it is mainly through ultra-precision grinding and ultra-precision grinding, polishing and other methods. Processed, additional. There are also special processing techniques for aspherical parts such as ion beam polishing.
Many foreign companies have integrated ultra-precision turning, grinding, grinding and polishing processes, and developed ultra-precision composite processing systems, such as Nanoform300, Nanoform250 manufactured by RankPneumo, Nanocentre developed by CUPE, AHN60-3D, ULP of Japan. A 100A (H) has a composite processing function, so that the processing of aspherical parts can be more flexible.
III: Status Quo of Ultra-precision Machining Technology for Non-spherical Parts in China
China began to research on ultra-precision machining technology since the early 1980s, which lags behind that of foreign countries for 20 years. In recent years, the units that have performed well in this work include the Beijing Institute of Machine Tools, the China Aviation Precision Machinery Research Institute, Harbin Institute of Technology, and the Changchun Institute of Optics, Applied Optics Laboratory of the Chinese Academy of Sciences.
In order to better carry out research on this ultra-precision machining technology, the National Commission for Science, Technology and Industry for Defence first established China's first key laboratory for ultra-precision machining technology research in China Aviation Precision Machinery Research Institute in 1995.
Four: Aspherical Parts Ultra-precision Machining Technology
In 1972, UnionCarbide Corporation of the United States successfully developed the R-θ method of aspherical creation and processing machine. This is a two-axis CNC lathe with position feedback, which can change the rotation angle θ and radius R of the tool holder guide in real time to realize aspherical mirror processing. The processing diameter is φ380mm, the precision of the processing workpiece is ±0.63μm, and the surface roughness is Ra0.025μm.
In 1980, Moore first developed an M-18AG aspherical machine tool that uses three coordinate controls. This machine can machine a variety of aspherical metal mirrors with a diameter of 356mm.
In 1980, RankPneumo of the United Kingdom introduced to the market a two-axis linkage machining machine (MSG-325) using laser feedback control. The machine can process aspherical metal mirrors with a diameter of 350mm, and the precision of machined workpieces reaches 0.25-0.5μm. The surface roughness Ra is between 0.01 and 0.025 μm. Subsequently, the ASG2500, ASG2500T, and Nanoform300 machines were introduced. In addition, the company developed the Nanoform 600 on the basis of the machine tools described above. This machine can machine aspherical mirrors with a diameter of 600mm, and the accuracy of the machined workpiece is better than zero. .1μm, the surface roughness is better than 0.01μm.
On behalf of today's high-level ultra-precision diamond lathe is the United States Lawrence. Developed in 1984 by the LLNL laboratory, it can process workpieces up to 2,100 mm in diameter and weighing up to 4,500 kg with a machining accuracy of 0.25 μm and a surface roughness Ra of 0.0076 μm. The machine can machine flat surfaces, Spherical and aspherical surfaces are mainly used to process parts required for laser fusion engineering, parts for infrared devices, and large astronomical reflectors.
Large-scale ultra-precision diamond right mirror-cutting machine tool developed by the Institute of Precision Engineering (CUPE), Cranfield University, UK, capable of processing aspherical mirrors for large-scale X-ray celestial bodies and telescopes (up to 1400mm in diameter and 600mm in length) ). The Institute has also successfully developed a diamond cutting machine that can be machined for X-ray viewing of the far side mirror inner revolution paraboloid and the outer turning hyperboloid mirror.
The ultra-precision machining tools developed in Japan are mainly used for the processing of lenses and reflectors required for civilian products. At present, the Japanese-manufactured machining tools include: ULG-l00A(H) developed by Toshiba Machines, ASP-L15 and Toyota Works. AHN10, AHN30×25, AHN60―3D aspherical processing machine tools, etc.
