An achromatic lens is a lens consisting of two optical components, a positive low refractive index (coronet) and a negative high refractive index (flint), glued together. Compared to monolithic lenses that contain only a single piece of glass, the doublet design of a two-piece lens provides the user with additional design freedom and further optimizes the lens performance. As a result, achromatic lenses offer significant advantages over monolithic lenses of equal diameter and focal length.

An achromatic lens is available in various types of configurations, the common ones being positive achromatic lenses, negative achromatic lenses, triple achromatic lenses, and aspheric achromatic lenses. It is important to note that achromatic lenses can be doublet (two elements) or triplet (three elements) and the number of elements is independent of the amount of light corrected by the lens. In other words, an achromatic lens in either a doublet or triplet configuration can correct for both red and blue light in the visible range.

An achromatic double bonded lens is an achromatic lens made by bonding a positive lens of low dispersion coronet glass and a negative lens of high dispersion flint glass. The design optimizes the different values of dispersion and lens shape at three wavelengths, blue (486.1 nm), green (546.1 nm), and red (656.3 nm), to achieve minimum chromatic aberration. As a result, these lenses can be used in the entire visible light region. The spherical aberration has also been optimized in the design and is much smaller in achromatic doublet lenses compared to single lenses. The spherical aberration is minimized when used in the infinite conjugate state.achromatic lens technology can be used in a wide range of optical systems to improve and customize specific optical properties, such as improving image quality, adjusting focal length, reducing dispersion, etc.