Longpass Lens Filter 640 nm, Select your size, passes all light above 626 nm

The Longpass Lens Filter 640 nm is an optical lens filter designed to transmit wavelengths above 640 nm, providing a useful spectral range from approximately 626–1100 nm while effectively blocking shorter wavelengths. It mounts directly onto a machine vision lens via standard filter threading. By suppressing unwanted lower-wavelength content—including blue, green, and most visible spectrum light—the LP640 improves contrast, stabilizes illumination response, and enhances feature visibility in demanding inspection environments.

Multiple filter thread sizes are available so you can match the filter to virtually any industrial lens.

Longpass Lens Filter 640 nm Specification

A longpass filter blocks light below a defined cutoff wavelength and allows light above that point to pass. 

For the LP640, wavelengths above 640 nm are transmitted efficiently, while wavelengths below ~626 nm are strongly suppressed.

Because it supports both visible-red and NIR imaging, the LP640 is well suited to systems using broadband, red, or infrared illumination.

Specification
Filter type	Longpass
Useful wavelength range	626-1100 nm

LP640 Longpass Filter Applications

The LP640 efficiently transmits light above its 640 nm cutoff, offering a stable passband through 1100 nm. By removing blue, green, and most mid-visible wavelengths, the filter improves contrast and reduces chromatic noise when used with:

• Red LED illumination

• Broad-spectrum lighting where short-wavelength removal is beneficial

This makes the LP640 valuable in machine vision, inspection tasks, laboratory instruments, and imaging systems that depend on controlled spectral separation.

Typical Applications

• Suppressing blue, green, and mid-visible wavelengths
• Enhancing images under red or NIR illumination
• Print, surface, and material inspection
• Imaging in dusty, hazy, or backlit environments where shorter wavelengths scatter heavily

Key Benefits

• High transmission above 640 nm
• Strong blocking below 626 nm for superior contrast
• Improved detail visibility and cleaner signal capture
• Consistent performance under both fixed and variable lighting
• Enables repeatable, accurate measurements in machine-vision systems

Longpass Lens Filter 640 nm Lens & Camera Compatibility

Most machine vision lenses include a front filter thread, allowing the LP640 to be mounted directly in front of the optics.

For systems using a C-mount lens on a USB3 camera or GigE camera, the filter can also be fitted within the C-mount interface. 

This option is especially helpful when the lens has no front filter thread.

Positioning the filter between the lens and camera ensures proper optical alignment and maintains consistent imaging performance without requiring mechanical changes to the system.

The LP640 is versatile and integrates easily with a wide range of optical configurations.

Available Thread Sizes and Mechanical Options

To support a wide range of lens models, the LP640 is offered in numerous industry standard thread sizes:

- C-mount filter

- 0.5 thread (pitch): M22.5×0.5, M25.5×0.5, M27×0.5, M30.5×0.5, M34×0.5, M35.5×0.5, M37×0.5, M37.5×0.5, M40.5×0.5

- 0.75 thread (pitch): M37×0.75, M43×0.75, M46×0.75, M49×0.75, M52×0.75, M55×0.75, M58×0.75, M60×0.75, M62×0.75, M67×0.75, M72×0.75 

If you plan to use a C-mount (CMT) filter thread, complete the form below to receive instant access to the installation guide and lens compatibility information.

Questions about LP640 Longpass Filters?

Select the Longpass Lens Filter 640 nm in the thread size you need. If you need help choosing the correct cutoff wavelength or mechanical size, our team can assist.