IR Long Pass Filters improve signal-to-noise ratio in FTIR, spectroscopy, astronomy, IR detector research, THz imaging, and other mid to far IR applications by blocking short wavelength radiation. Lake Shore’s line of IR Long Pass Filters are available in diameters of 0.5 to 4 inches and feature rejection edge wavelengths from 1 µm to 50 µm, a wide and flat spectral response to terahertz (0.3 THz), and excellent thermal and mechanical properties.
IR filters from Lake Shore are based on porous silicon technology. This results in IR Long Pass Filters with excellent thermal and mechanical properties, even at cryogenic and elevated temperatures (survivable up to 600 k). These scattering-type IR filters are based on novel electrochemical etching of silicon. The random macroporous silicon scatters the short waves within the blocking range of the filter. Unique design and fabrication processes control the filter rejection edge. Rejection band blocking extends to 100 nm with optical densities greater than 2. Additionally, these IR Long Pass Filters will not delaminate under harsh conditions.