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Short wave pass filters

LONG WAVE PASS EDGE FILTERS

Short wave pass filters

Often referred to as long wave pass (LWP) and short wave pass (SWP) filters, these sharp-cut edge filters are distinguished by their high rate of transition between their region of reflection and transmission. This high rate of transition makes them an excellent choice as emission filters in fluorescence applications, and as order sorting filters in photometry. They are also very useful as stray light or trim filters, to eliminate any unwanted near band radiation. All Andover LWP/SWP filters are constructed of hard, durable first-surface dielectric coatings, and will withstand the normal cleaning and handling associated with any high-quality optical component. Their film construction is essentially a modified quarter-wave stack, using interference effects rather than absorption to isolate their spectral bands. Unlike filter glass, which is not sensitive to wavelength shift with angle, these filters will shift shorter in wavelength with an increase in their angle of incidence. This feature can be useful in applications where it may be desirable to fine tune the 50% cut-on, or cut-off wavelength. All standard edge filters are available in 50nm increments from 400nm to 1000nm. Custom edge filters are available and will be quoted upon request. Please contact one of our technical sales representatives for more specific information.

General Specifications  
   
Thickness: 4.0mm maximum 
Size Tolerance: +0.0mm/-0.5mm
Min. Clear Aperture: 85% of outside dimension
Substrate Material: Glass (Note: BK-7 or Borofloat available as an option for higher Tx.)
Flatness: 3-5 waves per 25 TWF
Surface Quality: 80-50 per MIL-C-48497A
Humidity and Abrasion: Per MIL-C-675A
Operating Temperature: -50°C to +200°C
Cut-on Slope: 6% maximum (11% for 300nm filter)
Cut-on Tolerance: ±10nm from 400nm-1100nm
±5nm from 300nm - 375nm
Mechanical: Unmounted

 

Transmission  
Long Wave Pass: 85% average from the 50% cut-on point to 2000nm
Short Wave Pass:

400-450nm: 85% avererage from the 50% cut-on point to 0.75 x the 50% cut-off point

500-1000nm: 85% avererage from the 50% cut-on point to 0.75 x the 50% cut-off point

Note: with the exception of the 400nm filter, all SWP filters will drop off in transmission at wavelengths under 400nm.)

Rejection  
Long Wave Pass: 99% or greater from 0.9 x the 50% point to the UV
Short Wave Pass: 99% or greater from 1.07 x the 50% point to 1.25 x the 50% point
Effective index of refraction (n*) 1.7 (approximately)

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