Introduction of Aspherical Achromatic Lens

Ⅰ. Introduction of achromatic lens

Ordinary achromatic lens refers to a lens group that corrects the color difference of light of three wavelengths such as blue, green, and red. Because the focus of the blue image of the light converged by the convergent lens is close, while the concave lens has a high divergence rate for the blue light, and the positive and negative color differences of the two mirrors are opposite, the red and blue images can coincide into one, basically eliminating the color difference. Crescent surface can limit spherical aberration and coma aberration. But there are astigmatism and distortion. The achromatic lens was mostly used to shoot scenery in the early stage, so it is called a landscape lens.

More and more laser cutting engraving and marking systems use the visual system to observe the working effect of the laser synchronously. The previous laser cutting lens does not have the function of achromatic, so the light used for observation is inconsistent with the working wavelength of the laser, and the focus of the two does not coincide, which brings great inconvenience to the vision system. The achromatic lens can make the focus of the two beams coincide, making the observation effect direct and clear. Achromatic lenses are suitable for various applications such as detection or spectroscopy.

Ⅱ. The difference between the aspheric achromatic lens and achromatic lens

The achromatic lens is a kind of lens composed of two optical components, including positive low refractive index (crown plate) and negative high refractive index (Flint). Compared with a single lens containing only a single glass, the double combination design of the double lens can provide users with additional design freedom and further optimize the lens performance. Therefore, the advantages of an achromatic lens are more significant than a single-chip lens with an equal diameter and focal length. Compared with a single lens, it can form smaller light spots.

Aspheric achromatic lens is made of glass optical lens glued with photosensitive polymer. The photosensitive polymer is only applied to one side of the double lens and is very easy to replicate in a short time. At the same time, it can provide the same flexibility as a specific multi-element assembly. Different from the glass element, the aspheric achromatic lens has a small operating temperature range, ranging from 20 ℃ to 80 ℃. This temperature range limits the possibility of using antireflective coatings on aspheric achromatic lens surfaces. In addition, the material of the aspheric achromatic lens blocks the transmission of deep UV, so the lens is not suitable for some applications. Although this lens does not have scratch resistance, it is cost-effective and easy to replace.