CM-845 Near-infrared longpass / cold-mirror filter

Near-infrared longpass / cold-mirror filter (CM-845)

CM-845 is a near-infrared longpass / cold-mirror filter. A high-transmission region is shown at approximately 898-1600 nm. Consider it when you need to pass longer wavelengths and reduce shorter-wavelength light within the measured range.

Optical performance

• Measured wavelength range: 300-1600 nm. Performance outside this measured interval is not established by this curve.
• Selected regions at or above 80% transmission: 898-1600 nm. Approximate measured intervals.
• Selected regions at or below 5% transmission: 300-372 nm; 386-744 nm. Measured sample intervals; confirm the required blocking for your order.
• Peak transmission: Approximately 100% at 1542 nm. Peak wavelength is not the same as a defined centre wavelength.
• Average measured transmission, 1000-1600 nm: 99.291%. Calculated from the factory sample data.
• Measured edge at 50% transmission: Approximately 843.8 nm. Interpolated absolute-transmission crossing, checked against the factory summary.
• Customization: We can customize stock and sample-book designs. Tell us the wavelength response, size and operating conditions you need.

These values come from the measured samples and help you choose a starting design. We will agree the final specification for your order. Custom versions have their own specifications and measured curves.

Applications to consider

• Near-infrared illuminated inspection: Consider receiving light in 898-1600 nm while reducing shorter-wavelength background. Match the source band and detector sensitivity to the full curve.
• Illumination-path development: Evaluate wavelength separation in a light source. For a reflected visible path, confirm reflection and working angle rather than inferring them from transmission.
• Infrared sensing prototypes: Consider a longer-wavelength transmission window for an instrument whose detector band is covered by the measured curve. Specify any additional required wavelength coverage.

Choosing this filter

• Check the full wavelength range of your light source, the wavelengths your detector responds to, and how much unwanted light you need to block. Use the full curve when choosing a filter; the product code and peak do not tell the whole story.
• Tell us the angle at which light reaches the filter and whether the beam is parallel or converging. For demanding rejection or high-power use, confirm the required blocking and power-handling specifications.

Custom options

Start with this stock or sample-book design, then tell us what you need to change. We can discuss the wavelength bands, transmission, blocking, angle, glass material, size and operating conditions with you, and agree a specification for your custom filter.