Microstructure optical components in the form of Fresnel, TIR, microgroove, micro lens array provide a lot design
freedom for high compact optical systems. It is a key factor which enables the cutting edge technology for
telecommunication, surveillance and high-definition display system. Therefore, the demand of manufacturing such
element is rapidly increasing. These elements usually contain high precision, tiny structure and complex form, which
have posed many new challenges for tooling, programming as well as ultra-precision machining. To cope with the fast
development of the technology and meet the increasing demand of the market, we have developed our own
manufacturing process to fabricate microstructure optical components by way of Diamond tuning, Shaping, Raster
cutting, Slow Slide Servo (SSS), Diamond milling and Post polishing. This paper is to focus on how we employed these
methods to produce complex prototype of microstructure optical components and precision mold inserts which either
contains aspheric lens array or freeform V grooves. The high quality finish of these surfaces meets application
requirements. Measurement results are presented. Advantages and disadvantages of these methods are compared and
discussed in the paper.
Nowadays ultra precision machining of single-point diamond turning has played an important role in manufacturing high-precision optical components where surface finish is critical. This paper describes how diamond turning technology was applied to fabricate two tight-tolerance, high accuracy aspheric mirrors for a big-screen high-resolution television projection system. The system consists of two mirrors, a primary and a secondary mirror. Both mirrors have off axis rotational aspheric form. In order to get a good finish, the mirror surface was nickel plated and then diamond turned. Post polish was applied to remove diamond turning grooves and to improve the surface quality. As the off-axis aspheric surface could not be measured by conventional profile meter, a white interferometer was used to measure the off axis aspheric form. The measurement results were compared with that of the design CAD model. The form deviation was less than 3 um. The optical performance of the mirrors was tested in an optical lab. The result was very satisfactory. As the diamond turned prototype mirrors worked so wonderfully with the system, mass production of the mirrors by plastic injection is on the way to bring the new products to the market.
LPI Precision Optics Ltd. in Hong Kong has successfully produced some very complex prototype freeform optics and
mold inserts by using Nanotech 350- FG five axis diamond turning machine. One of such typical optics is an LED car
head lamp, which consists of several non-symmetrical freeform surfaces. In order to make these surfaces, we have
developed in-house special software which can combine 3D freeform surface with DT parameters to generate slow tool
servo program for diamond turning. The software can generate program not only for single freeform surface or multiple
freeform surfaces but also for freeform lens arrays. The produced freeform surfaces were measured by 3D interferometer
and compared with the designed CAD models. The form deviation was around 5 um and the surface roughness was
within 10 nm. Diamond milling was employed to fabricate more complicated multifaceted freeform surfaces. The
milling program was optimized by means of UG software. Processing parameters and details are to be discussed in the
paper.
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