660nm Longpass Filter,LP660nm Long-wavelength pass Filter, Support customized

660nm longpass filters are widely used in biomedical imaging such as fluorescence microscopy, flow cytometry, and in-vivo imaging to isolate red/near-infrared emission signals and improve contrast and signal-to-noise ratio; in machine vision applications such as agricultural sorting, food detection, and traffic sensing to filter out blue/green ambient light and enhance red feature clarity; and as a core component in atmospheric monitoring, astronomy, night vision, skin therapy, plant research, and laser protection to block short-wavelength noise, enabling stable, accurate, and high-performance system operation.

5.What is key parameter when choose for right Longpass Filter?

When selecting a Longpass Filter, normally the following factors need to be taken into consideration：

• Cut-Off Wavelength: it is one of the most important parameters, typically defined as the wavelength transmittance at 50% .
• Average or Peak transmittance: usually average transmittance ≥90%, higher transmittance e.g. 92% or 95% on average or specific single point need to definite and communicate with manufacturer, higher transmittance need to additional AR coating.
• Blocking rate: usually expressed in terms of optical density(OD), OD2-OD3 for standard and higher will be OD4-OD6 per requirement
• Angle of Incidence (AOI): AOI need to be consider as Interference Filter is angle sensitive, 0° AOI  by default, other AOI e.g. 30/45° need to be specified.
• Physical and environmental requirement: Substrate type, dimensions and thickness, surface quality, and environmental durability.