Posted in | Optical Filters

IR Longpass Filters from Lake Shore Cryogenics

Lake Shore’s product line of mid- and far-infrared (IR) long-pass filters is based on porous silicon technology. The unique patent pending all-silicon design has superior thermal and mechanical properties, even at elevated and cryogenic temperatures, and delamination will not occur under difficult conditions. Short wavelength radiation is blocked by long-pass IR filters in order to enhance signal-to-noise in mid- and far-IR applications, including FTIR spectroscopy, astronomy, IR detector research, and terahertz imaging.

IR filters from Lake Shore have a flat and wide spectral response to 200 µm and above with rejection edge wavelengths from 1 to 50 µm. The innovative electrochemical etching of silicon forms the basis of these scattering-type IR filters. The short waves are scattered by the random macroporous silicon within the blocking range of the filter. The filter rejection edge is controlled by the innovative design and fabrication processes. Rejection band blocking extends to 100 nm with optical densities greater than 2. Standard and custom designs ranging in diameter from 0.5 to 4 inches are offered. Furthermore, spectral measurements can be performed at 4.2 K and 77 K. Spectral measurements at room temperature are also included.

Key Features

The key features of the IR longpass filters are:

  • Superior thermal and mechanical properties even at cryogenic and elevated temperatures (survivable up to 600 K)
  • Will not delaminate under harsh conditions
  • Wide and flat spectral response to terahertz (0.3 THz)
  • Rejection edge wavelengths from 1 to 50 µm
  • Diameters from 0.5 to 4 in
  • Long Wave Pass Filters
  • Has a Scattering Design
  • Cleaning and Handling of Filters is simple
  • Spectral Scans are possible
  • THz & IR Band Pass Filters

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