Optical Engineering / Apps / Glass Catalog

Glass selection plots can be tuned using several options including dispersion computation method, minimum and maximum wavelengths, and thermal options.

Dispersion, noted here V, is frequently used to discriminate glass, such as in the traditional glass chart (n-V), partial dispersion chart (ρ-V), thermal power chart (G, 1/V) and (V, θ) chart.

Dispersion can be computed differently for monochromatic and polychromatic systems.

In polychromatic systems, the extended Abbe number is used. Polychromatic dispersion will require a design wavelength and two auxiliary wavelengths. Conventional thin-doublet achromat formula will yield lenses with equal focal lengths at the two auxiliary wavelengths. The residual difference in focus between the auxiliary wavelengths and the design wavelength is known as the secondary spectrum and can be optimized through the partial dispersion chart.

In monochromatic system, an instantaneous version of the Abbe number is used. When using the thin-doublet achromat formula, a lens with minimum wavelength sensitivity is obtained.

Finaly, it is possible to use quick presets for common optical design scenarios, such as designing for the visible, uv, infrared, or for some typical laser wavelengths.

Minimum and maximum wavelengths for refractive index plots, dispersion plots, and transmission plots can be changed using the minimum plot wavelength and maximum plot wavelength fields.

It is possible to tune the thermal (V, θ) chart by providing a thermal target.

When designing an athermal achromatic doublets, (V, θ) chart allows to reach a specific thermal power for the lens. Once the correct thermal target has been set in the options, glasses with similar θ but dissimilar V will yield glass combinations capable of reaching the given thermal power.