Long/Short Wave Pass Filters

Service Detail from Deposition Sciences, Inc.

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Edge filters, also sometimes called dichroic filters, are coatings that include long wave pass and short wave pass filters.  Specifically, these coatings transmit one range of wavelengths while blocking others.  However, they are distinct from bandpass and notch filters in that they either pass wavelengths above (long wave pass) or below (short wave pass) a given single wavelength value, rather than a limited band of wavelengths within a range.

DSI custom manufactures a wide selection of edge filters for use at wavelengths ranging from the ultraviolet through the long-wave infrared. The designs can be optimized for various performance characteristics, including high in-band transmission, strong out-of-band blocking, polarization insensitivity, and sharp transitions between the passband and blocking region. DSI edge filters are distinguished by excellent durability with no wet/dry shift.

Technical Information:

DSI utilizes both evaporative and MicroDyn sputtering methods for the fabrication of edge filters.  That enables us to tailor coating performance, cost and durability to meet your particular performance specifications and budget.

MicroDyn: DSI employs this technology to deliver environmentally stable and exceptionally durable coatings from the UV to the midwave IR, making it ideal for many aerospace applications.  Because MicroDyn deposition can be performed at relatively low temperatures, these edge filter coatings can be applied to a wide range of substrate types, including plastics and temperature-sensitive active devices.

Evaporation: DSI produces evaporated edge filter coatings from the midwave infrared through the longwave infrared.  Ion assisted deposition (IAD) technology is utilized to improve coating adhesion to the substrate, and can also be used to lower film stress for greater environmental durability.

DSI Long/Short Wave Pass Advantages:

  • High in-band transmission
  • Sharp cut-on and cut-off slopes
  • Excellent out-of-band blocking
  • No wet/dry wavelength shift
DSI Long/Short Wave Pass Applications:
  • Laser systems
  • Projection systems
  • Spectroscopy and fluorescence imaging
  • Military imaging, target designation and countermeasures