Band pass filter plate are divided into short-pass and long-pass filters according to whether they transmit below or above the transition wavelength. The transition wavelength or cut-on/off wavelength is the wavelength at which the transmission is 50% of its peak value.

General Specifications:

Material:     N-BK7, UV Fused silica
Dimension tolerance:  +/- 0,1 mm
Parallelism:     3 arcmin
Flatness:       λ/4 @633nm
Surface quality:     60-40 S/D

Coating

One surface(S1):      HR @ wavelength-1 + HT @ wavelength-2
The other surface(S2):     depends
Angle of incident:       0° or 45°

How to Order Bandpass Filters? Example:

Substrate:  N-BK7, Φ>20x2.0mm

Coating:   T>80% @400--500nm  AOI= 0-8°
                T=50% @590+/-15nm
                T<1%   @640--740nm