High Refractive Index
Low Abbe V_d Number for Maximum Dispersion
Material: F2, N-F2, N-SF11, CaF₂, or ZnSe

Our Dispersive Equilateral Prisms, which are fabricated from F2, N-F2, N-SF11, CaF2, or ZnSe are available in sizes ranging from 10 mm to 50 mm. These prisms create less stray light than diffraction gratings, thereby eliminating the higher order problems typically associated with gratings.

N-SF11, F2, and N-F2

Both N-SF11 and F2 offer excellent performance in the visible range. When compared to each other, F2, which is a flint glass, has superior chemical resistance and better transmission than N-SF11. For instance, at 420 nm the theoretical internal transmittance of a 10 mm thick piece of F2 is 0.995, whereas for the same thickness of N-SF11, the internal transmittance is 0.910. If the glass is increased to a thickness of 25 mm, these internal transmission values decrease to 0.987 and 0.790, respectively. With high indices of refraction and low Abbe Numbers Vd, N-SF11 and F2 provide maximum dispersive power.

N-F2 is a RoHS compliant material that has been engineered to have nearly identical optical properties as F2. At 633 nm, both N-F2 and F2 have an index of refraction of 1.617, and they have nearly identical Abbe numbers of 36.43 and 36.37, respectively.

Calcium Fluoride

CaF2 is commonly used for applications requiring high transmission in the infrared and ultraviolet spectral ranges. The material exhibits a low refractive index, varying from 1.35 to 1.51 within its usage range of 180 nm to 8.0 µm, as well as an extremely high laser damage threshold. Calcium fluoride is also fairly chemically inert and offers superior hardness compared to its barium fluoride, magnesium fluoride, and lithium fluoride cousins.

Zine Selenide

Zinc Selenide is ideal for use in the 600 nm to 16 µm wavelength range. It features low absorption (including in the red visible wavelength range) and high resistance to thermal shock. ZnSe is ideal for use in CO2 laser systems operating at 10.6 µm, including those with HeNe alignment lasers. Please note that, due to its low hardness, care should be taken when handling ZnSe optics.