Long-pass filters

With long-pass filters, long wavelengths are transmitted and short wavelengths are blocked

A long-pass filter is an edge filter that separates spectral ranges into transmitted and blocked regions. It works by selectively transmitting longer wavelengths while blocking shorter wavelengths. In this way, long-pass filters separate short-wavelength radiation from long-wavelength radiation, reducing unwanted extraneous light.

The position of the transition (or "edge") can be adjusted, and long-pass filters are designed with steep transitions and high transmission above the defined cut-on wavelength. They are optimized to transmit light with wavelengths longer than the cut-on wavelength, while reflecting or absorbing light with shorter wavelengths.

• Long wavelengths are transmitted
• Short wavelengths are reflected
• Optimum light throughput
• Position of the edge is adjustable
• Stable cut-off wavelengths
• Minimization of reflections in optical systems
• Reduction of interfering wavelengths due to strong blocking and high optical density
• Spectral range: UV to IR
• Substrates: Borofloat, B270, float glass, selected plastics, etc.