HM-635 Visible-pass / infrared-attenuating filter

Visible-pass / infrared-attenuating filter (HM-635)

HM-635 is a visible-pass / infrared-attenuating filter. The main high-transmission region is approximately 399-627 nm. It can be considered when visible light is required and part of the longer-wavelength spectrum needs attenuation.

Optical performance

• Measured wavelength range: 300-1200 nm. Performance outside this measured interval is not established by this curve.
• Selected regions at or above 80% transmission: 399-627 nm; 1193-1200 nm. Approximate measured intervals.
• Selected regions at or below 5% transmission: 300-365 nm; 650-1023 nm. Measured sample intervals; confirm the required blocking for your order.
• Peak transmission: Approximately 94.4% at 559 nm. Peak wavelength is not the same as a defined centre wavelength.
• Average measured transmission, 450-600 nm: 93.511%. Calculated from the factory sample data.
• Average measured transmission, 710-900 nm: 0.050%. Calculated from the factory sample data.
• Measured edge at 50% transmission: Approximately 635.3 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

• Visible-light camera systems: Evaluate attenuation of unwanted longer-wavelength light while retaining the visible signal. Check the entire detector sensitivity range, including any transmission recovery.
• Illumination optics: Consider spectral conditioning between a source and the illuminated object. Confirm the source-weighted transmitted power and how reflected or absorbed power is managed.
• Color-imaging development: Compare the visible response with the required camera color balance. Account for differences at the blue and red edges before choosing the optic.

Choosing this filter

• Additional regions reach at least 50% transmission at approximately 1046-1068 nm; 1082-1120 nm; 1173-1200 nm. Include these in the detector and blocking assessment.
• 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.