| It has long been known that lenses with spherical  surfaces are less than ideal for creating optical images, however, the ease of  making them has made them ubiquitous. With advances in technology however,  aspheres are beginning to see a widespread use. As the name suggests, aspherics  have non-spherical surfaces and a single one can replace a multi-lens design.  This reduces both the size as well as the back reflections so common in lens  systems. The complex surface of an asphere eliminates spherical aberration and  reduces other optical aberrations. While smaller aspheres are created from  molds, larger ones are made by grinding and polishing. Aspherics that require  higher precision are made by single point diamond-turning; a technique that  utilizes a CNC lathe with a diamond point to carve the glass to the precise  contour of a CAD drawing. Molded aspherics are usually used in less  expensive consumer products.  So, while  the initial cost of a mold can be high the large quantities are used to  amortize it. Applications for plastic (PMMA, Acrylics) or glass molded lenses  come in laser diode collimators, automotive cameras and other consumer areas. Diamond-turned  lenses are much more precise and expensive, so they find their application in  more expensive product lines, such as night vision systems and other specialty  optics. Standard MgF2 AR coatings or metal coatings are often applied. AgniRoth OPTIK supplies both Molded and  Diamond-turned aspherics.   
                          
                            | Material | Typical Materials: Optical Glass,    BK7, Schott, Ohara, Hoya, CDGM IR Materials: FS, Ge, Si, CaF2, ZnS, ZnSe
 |  
                            | Diameter | 2mm – 350mm |  
                            | Dimensional    Tolerance | ±0.1mm  |  
                            | Aperture Angle | Up to 180º |  
                            | Form Precision | Up to 0.2 nm p-v |  
                            | Tangential Error  | 0.2    mrad |  
                            | Surface Roughness | < 1nm Rq  |  |