Fresnel Technologies offers an extensive array of tooling facilities. These can be divided into four general areas.
The first area, and our most recent addition, is diamond machining for the manufacture of molds and prototype plastics optics. We can also offer small-volume production of directly machined plastics optics, as well as production of diamond-machined optics from other materials such as germanium.
We have recently added three significant new diamond machines to the companys collection of optical surface generating equipment: two two-axis ultraprecision lathes and a four-axis ultraprecision freeform surface generating machine, all fitted with on-machine measuring and compensation devices. The largest diameter that can be turned on our new machines is approximately 24 (600mm), or almost 28" (710mm) with special fixturing. One of the two-axis lathes is fitted with a fast tool servo for the generation of non-rotationally symmetric surfaces, such as phase plates and anamorphic lenses. These machines complement the existing Fresnel lens generating machine, a machine for cutting large linear structures, and a machine for cutting arrays of conventional aspheres, as well as Fresnel Technologies famed capabilities in making parqueted arrays of lenses. In addition, two of the worlds leaders in the field of ultraprecision machining, Donald Combs and Dr. John Mader, have recently joined our technical staff.
The picture below shows the diamond machining of an electroless nickel mold insert. This insert was measured to have a surface finish of 2nm Ra. The insert was measured to have a form error of 44nm peak to valley, excluding a 100nm feature in the center due to tool centering. This accuracy was achieved, over a 50mm workpiece diameter, without making use of the on-machine error compensation.
We also offer diamond machining facilities for the generation of molds for unusual items. These include items with linear symmetry such as lenticular arrays, arrays of prisms (also known as Fresnel prisms), and cylindrical (in fact, usually acylindrical) Fresnel lenses. They also include ordinary (conical-grooved) Fresnel lenses with diameters up to 24" (61 cm), toroidal Fresnel lenses, and curved acylindrical Fresnel lenses. We have made arrays of very fast continuous-surface (non-Fresnel) aspheric lenses, such as that shown in the picture below, as well as microlens arrays in large sizes, up to about 16" by 30" (41 cm by 76 cm), or even larger if small seams from parqueting are acceptable. The pictured array of 64 aspheres is used as part of a system to couple the output of 64 light emitting diodes (LEDs) into a single light pipe. Each asphere is over 7mm in diameter, with a 4.25mm focal length (~f/0.6). Each asphere is located, on the molded piece, to an accuracy of better than 25 micrometers.
We can offer design, modeling, and ray tracing facilities for all these types of items. We also maintain mechanical design facilities which can exchange surface and solids data with most CAD systems. Our design facilities are seamlessly networked with our diamond and conventional machining facilities.
The second area, and that in which we have the longest experience, is oriented toward the building of molds for lenses and arrays of lenses. An example is the mold for Fresnel Technologies' CM 0.77 GI V3 ceiling mount PIR lens array:
These lens arrays are used, for instance, in passive infrared (PIR) motion detection in the security and lighting control industries. Fresnel Technologies was the first to manufacture such arrays, in 1979, and our techniques for design, moldmaking, and molding are unparalleled. We have also made such "parqueted" arrangements of lenses for use in illumination, displays, and many other areas.
The third area is a world-class all-CNC machine shop. The primary focus of this facility is in the building of injection and other molds for our own and our customers' products. To that end, we have and use:
- high-precision (few-micron) 3-axis milling
- high-precision (few-micron) turning
- form EDM
- wire EDM
- small hole EDM
- surface grinding
The fourth area is in the texturing of mold surfaces to produce desired optical effects. These facilities are commonly used for projects in lighting; they have also been used in the production of Fresnel Technologies' Scratchgard® surface finishes. These finishes provide significant protection against scratching for passive infrared lens arrays, without much effect on the transmittance in the 8-14 µm region of the infrared.