Holographic Laser Bandpass Filters

Our Holographic Laser Bandpass Filters are fabricated by recording interference patterns formed between two mutually coherent laser beams, unlike conventional interference filters, which are made by vacuum evaporation techniques. These filters represent a major technical breakthrough in the optical filtering of unwanted plasma lines or fluorescence from laser sources. By using the unexpanded laser beam and combining high laser throughput with narrow spectral bandwidth, the Holographic Bandpass Filter provides the user with a previously unattainable level of performance.

Laser Throughput >90% of S-polarized laser line
Spectral Bandwidth <2 nm at O.D. 0.3 or 50% points with user supplied spatial filter (aperture)
Laser Damage Threshold >5 watts C.W. unexpanded at 514 nm and 1064 nm
Wavelength Range Standard Wavelengths (nm):
442, 457, 476, 488, 514, 532, 568, 633, 647, 752, 785, 1064
Custom Wavelengths: Between 457.9 nm and 1064 nm
Environmental Stability No detectable performance change after cycling between -50ºC to +80ºC and returned to room temperature.
Size 24.2 x 24.2 mm footprint, 20 mm high
Warranty 3 Years


Theory of Operation


The Holographic Bandpass Filter consists of a volume transmission grating located between two prisms. A collimated S-polarized laser beam is directed perpendicularly into the cube. The internal transmission grating diffracts the laser line through 90 degrees so that the output beam is nominally perpendicular to the exit face of the cube. The grating is spectrally selective so only the light which is very close to the design wavelength of the filter is diffracted. The undiffracted light passes through the back face of the cube. Unwanted light with wavelengths near the laser line is diffracted by the transmission grating but at a different angle than the laser line. This unwanted diffracted light can be removed by a spatial filter (slit or aperture) located beyond the exit face of the cube.

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