Double lens element

glassachromatic

Doublet lenses or best known as acrhomat are rectified for chromatic and sperical peculiarity. The achromatic lens comprises of 2 or more parts, typically of crown and flint glass, so that the complex element is rectified for chromatic peculiarity as against 2 picked wavelengths. The achromatic lenses minimize the chromatic, spherical and coma peculiarities. These parts are manufactured as against 3 wavelengths - 480nm, 546.1nm and 643.8nm. You could prefer achromats to change singlets in the areas where efficiency needs to be developed. It has to be kept in mind that the cemented achromats will not be able to resist high laser power levels. In situations like these you may use air - spaced achromats. The positve acrhomatic lenses have a diameter resistence of + 0 / - 0.1, center density resistence of ±0.2mm, focal length resistance of ±0.2mm, centering resistance of 3 ~ 5 arc minutes, surface quality of 60 - 40 scratch and dig and clear vent of 90 % .