Laser-assisted diamond turning has been shown to reduce tool wear, improve productivity, and achieve better surface specifications (including roughness and form) for traditionally diamond turnable materials for infrared optics. Amorphous glass being typically harder than IR materials, thus, diamond turning is less effective compared to traditional grinding and polishing methods. However, traditional grinding and polishing come with drawbacks, such as introducing significant subsurface damage ranging from 20-60 μm, necessitating removal during the polishing process, known as grey out. During grey out polishing, the optical axis can wander, leading to errors between the mechanical axis and optical axis when polishing aspheres. Moreover, sub-aperture polishing steps add mid-spatial frequency errors with each subsequent iteration before form convergence to a low irregularity. Laser-assisted diamond turning for amorphous glass shows promise as a method for rapidly producing near-net optics with minimal sub-surface damage.. This enables two critical gains for optics manufacturing: 1) glass optics can be polished to finished specifications much more quickly than with traditional grinding and polishing; and 2) mechanical tolerances such as wedge and sag can be maintained with precision, reducing manufacturing errors in aspheric optics. In this work, we present data showing that subsurface damage can be reduced to <3 μm for glass optics. Additionally, we demonstrate that form accuracy remains better than 500 nm for even after 10 or more diamond turning passes, indicating extended tool life and high level of conformity to near-net shape.
There is an ever-increasing demand for small optical systems, applications such as cell phone camera lenses, Infrared night vision sensors, and medical devices continue to grow. For these applications, a new compact ultra-precision diamond turning machine offering the highest precision for making both lenses and mold inserts has been developed. A small footprint ideally suited for limited lab space combined with the ability to add a Fast Tool system, optical metrology and automated loading and unloading makes for a versatile yet highly capable machine for precise freeform manufacturing. Unique hardware and software designs yield the highest accuracy on the market.
The need for increasingly complex optics and the demand for freeform optics with ultra-high precision specifications is growing rapidly for numerous applications. Achieving the required accuracies in freeform manufacturing still demands very long machining times, high production costs, a need for experienced, highly skilled operators as well as numerous manual interventions, tying up valuable resources while machining a small number of parts. By utilizing fully integrated optical measurement features, high accuracy long stroke fast tool, an advanced software package with built in tool path calculation and analysis as well as corrective machining functions the UPC 300 eliminates these burdens.
Increasingly freeform prototypes and molds for high volume replication are being manufactured using diamond machining. Nevertheless, stroke limits of established fast tools require using time consuming slow tool processes reducing productivity. Further, freeform measurements require high efforts. The UPC 400 overcomes these limitations. Utilizing a fast tool with an industry leading stroke length permits machining a wide range of freeform optics in the shortest time while increasing productivity and accuracy. Machine integrated, optical metrology allows for comfortable freeform measurements without having to remove the optic. Besides precise measurements, this enables corrective machining to create surfaces of the highest quality.
Innovative freeform optical systems such as head-up displays or LED headlights often require high quality and high volume optics. Injection molded polymer optics offer a cost effective solution. However, mold manufacturing for this process is extremely challenging as the machining of freeform surfaces is currently characterized by several independent production steps which can limit surface accuracy. By integrating diamond turning, milling, and metrology onto a single platform, the UPC 400 improves surface accuracy. Advanced software for machining and measurement data further reduces surface inaccuracies. This combination makes the UPC 400 efficient for prototyping free-form optics and manufacturing high precision molds.
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