A 945nm longpass filter is an optical component that allows only light with wavelengths greater than 945nm to pass through, while effectively blocking or reflecting near-infrared and visible light with wavelengths shorter than 945nm. Typical applications of 945nm longpass filters:
- Intelligent Identification & Security: Used in facial and iris recognition with IR LED illumination to capture high-quality infrared images for better accuracy.
- Machine Vision & Industrial Inspection: Remove visible stray light to boost IR-band contrast, ensuring clearer and more reliable inspections.
- Scientific Research & Optical Instruments: Applied in fluorescence spectroscopy and Raman analysis to separate excitation light from signal light.
4.What is key parameter when choose for suitable 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.
Related products:
LP900, 900nm Longpass Filter, OD2, AR coating, dielectric coating, NIR Filter for machine vision
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Remark：Because the interference type filter varies its performance at different angles, the spectral parameters usually determine its appearance color; moreover, the pictures in this link may originate from various shooting angles, so the actual color should therefore rely on the final spectral parameters required as the standard.
