Processing technology of Aspheric Lens
An aspheric lens can be designed to minimize aberration by adjusting the conic constant and aspheric coefficients of the curved surface of the lens. The most notable benefit of aspheric lenses is their ability to correct for spherical aberration, an optical effect which causes incident light rays to focus at different points when forming an image, creating a blur. Spherical aberration is commonly seen in spherical lenses, such as plano-convex or double-convex lens shapes, but aspheric lenses focus light to a small point, creating comparatively no blur and improving image quality.
Now we'd like to introduce roughly one way to manufacture a aspheric lens.
● Firstly, use aspherical milling equipment to grind the aspherical surface. The circular grinding wheel is installed on the above axis and rotates at high speed. The workpiece is installed on the below axis and rotates slowly at the same time. The feeding track of this axis is controlled by the computer, grinding wheel is milled on the surface of workpiece to produce outline of aspheric lens.
● Then install the milled workpiece together with the base on the polishing workpiece shaft, and polish the surface of aspheric lens by the elastic polishing mould. After polishing, to measure the surface error by Taylor Hobson contour apparatus, and to read the error curve and calculate the opposite compensation path through our design software. Then to install the workpiece again on the milling equipment and grind it according to the compensation path. At this time, there has a certian surface error on the aspherical lens, after polishing and grinding. The surface error curve is exactly opposite to the curve talked above, which surface is polished.
● For the third, the polished aspheric lens need to be polished again on the machine, all the setting of polishing parameters are completely the same with last time. Since the current surface error is complementary to the surface error after last polishing, the error after polishing gets certain compensation. However, the change of surface shape will also affect the polishing result, so the polished surface is just close to the designed surface accuracy, but there is still a certain amount of residual error.
● Finally, in order to remove the residual error after polishing and further improve the surface precision, it is necessary to use small polishing tools to correct and reach final requirement. Because the surface has been very smooth at this time, it's just removed slightly, sothe millstone can be ignored during the polishing process, which has little influence on the polishing precision, and can also greatly shorten the polishing time.
Aspheric lenses allow optical designers to correct aberrations using fewer elements than conventional spherical optics because the former gives them more aberration correction than multiple surfaces of the latter. For example, in zoom lenses where ten or more lens elements are typically used, two aspheric lenses can be substituted for a handful of spherical lenses in order to achieve similar or better optical results, while reducing system size and potentially reducing the overall cost of production. So it's the better choices for your application sometimes.
Besides, there have many different processing technology for aspheric lens,Precision Polishing,Diamond Turning,Molded Polymer Aspheres, Injection Molding. To choose suitable processing technology will be cost-effective and high price performance. Hopefully our introduction will give you more choices.
|Precision Glass Molded||Ideal for high volume production requirements because rapid production of many lenses allows for amortization of large up-front tooling charges.|
|Precision Polished||Ideal for prototypes or low to mid-volume requirements because of short lead times and low tooling costs. Also ideal for the highest performance requirements.|
|Polymer Molded||An ideal alternative to Glass Molding for mild aspheric departures or mid-volume production.|
|Injection Molded||Ideal for volume production as a weight-sensitive, low cost alternative to glass aspheric lenses.|