CM-845 Cold Mirror & Longpass Filter

The CM-845 is engineered for deep-infrared and shortwave-thermal applications, with a 50 % cut-on point at 844 nm that blocks virtually all visible and much of the near-infrared spectrum. Peak transmission reaches 100.0 % at 1542 nm, deep in the thermal-infrared region. Visible extinction is comprehensive (UV 1.5 %, blue 0.1 %, green 0.0 %, yellow 0.1 %, red 0.2 %), while the critical NIR (700-850 nm) is heavily attenuated at just 21.2 %. The transition steepens in NIR (850-1000 nm) at 87.2 %, then climbs to near-perfect SWIR (1000-1200 nm) transmission at 99.0 %. This aggressive blocking profile isolates the deepest infrared signals from all shorter-wavelength noise.

Key Advantages

• Extended Visible-NIR Rejection - Blocks 700-844 nm almost completely, eliminating visible, red, and early-NIR contamination in systems requiring pure deep-IR thermal data
• Near-Perfect SWIR Pass - 99.0 % transmission from 1000-1200 nm supports ultra-sensitive long-wavelength thermal and spectroscopic measurements with minimal system loss
• Sharp Transmission Edge - Steep transition from blocking to pass enables clean multi-wavelength separation, ideal for dual-band thermal camera designs
• Durable Hard-Oxide Ion-Assisted Design - Engineered for extended service life under thermal stress, mechanical handling, and field contamination without degradation
• Full-Range Custom Substrates & Apertures - Available as round, square, free-form blanks from 5 mm to 450 mm with thickness 0.21-3.8 mm on Borofloat, soda-lime, Schott D263 T, or Corning Eagle XG

Typical Applications

• Long-Wavelength Thermal Imaging - Isolates 1000-1200 nm thermal signatures from visible-light backgrounds, ideal for temperature mapping in industrial, scientific, and medical applications
• Mid-Wave & Long-Wave Thermal Cameras - Removes NIR and visible solar radiation to enable daylight-blind thermal imaging for surveillance and security
• Thermal Spectroscopy & Gas Analysis - Passes deep-IR absorption features while blocking shorter-wavelength interference, improving chemical identification and concentration measurement
• Materials Science & Combustion Research - Enables isolated measurement of blackbody radiation and thermal emission from high-temperature processes without visible-light artifacts
• Space & Astronomical Infrared Observation - Provides clean deep-IR detection windows for satellite-based and ground-based thermal observation of distant objects

The CM-845 is purpose-engineered for deep-IR research and imaging. Our team supports rapid prototyping of custom apertures and can scale production to support both low-volume research and high-volume commercial deployment.