Diffractive Design of Lens
Customers engage Syntec Optics to conduct diffractive lens design. Once the suitable material is determined, the first step of the design investigation is to design a single precision diffractive element. The diffractive lens design is optimized at a single wavelength and aspheric terms are added to both surfaces. The correction with up to 6th order aspheres is quite good as long as the field of view is small and there is a single wavelength. Often with the use of ZnS material, once the wavelength range of 8-12 μm is introduced, then the performance is degraded by chromatic error. A diffractive surface can be added, which achromatized the solution. The total number of zones can be over 9, which means the solution is good. One of the most common applications of diffractive surfaces is in IR imaging systems to provide the chromatic correction. Below is a quick summary of the singlet ZnS design.