Equilateral Dispersing Prisms

Equilateral prisms are normally used for the dispersion of light into its different colors. Light incident at an oblique angle to the first face is dispersed according to its wavelength and emerges as a spectrum from the opposite face. We offer these prisms made from BK7, Synthetic Fused Silica adn S-TIH11 optical glass.

The roof angle of 60 degrees causes the best combination of wide dispersion and low reflection losses. A glass with large dispersive power or small Abbe’s number leads to large angular dispersion.
We offer both BK7 and fused silica for wavelengths from UV to near IR. We recommend a prism of BK7 if the light is not UV, because the angular dispersion of BK7 is larger than that of fused silica.
The DPTIH11 uses high index glass resulting in superior dispersion.

Common Specifications

Part Number	DPB	DPSQ	DPTIH11
Material	BK7	Synthetic fused silica	S-TIH11 equivalent
Refractive Index n_d	1.517	1.458	1.785
Minimum Deviation	68.7°	63.6°	96.4°
Abbe number ν_d^*	64.1	67.8	25.7
Angle	60 °±3′	60 °±3′	60 °±3′
Surface Flatness of Substrate	λ/10	λ/10	λ/4
Surface Quality (Scratch-Dig)	20 ₋ 10	20 ₋ 10	40 ₋ 20
Clear Aperture	Circle or ellipse inscribed in a rectangular of 90% of the dimensions A and B