NBP400-20nm Narrow Bandpass Filter, 400nm CWL, 20nm FWHM, Optical Filter for medical devices, microscopy, machine vision & laser systems

1.Product Descriptions:

2.Measured Spectral Graph – 400nm narrow bandpass filters:

Picture 1: BP400-20nm Spectral Graph

3.What is typical application for 400nm narrow bandpass filter?

A 400nm narrow bandpass filter is an interference-type optical device that allows transmission of light only within an extremely narrow wavelength range centered at 400nm, while effectively blocking all light outside this passband.

Typical applications of 400nm narrow bandpass filters include:

• Biomedicine & Clinical Diagnostics: used in fluorescence analyzers, biochemical analyzers, microplate readers, and flow cytometers to precisely separate and detect fluorescence signals or specific reaction spectra.
• Optical Measurement & Spectral Analysis: used in spectrometers and colorimetric devices for selecting specific wavelengths of light for quantitative chemical analysis or environmental testing. Also applicable to laser Raman spectroscopy, flame photometry, and fluorescence immunoassays, which require precise optical signal analysis.
• Laser Technology & Light Source Purification: used to isolate specific spectral lines from lasers or gas discharge lamps for beam purification. Also commonly integrated with laser diode modules and LEDs to obtain a pure 400nm light source.
• Machine Vision & Industrial Inspection: in machine vision systems, it helps cameras accurately capture specific wavelengths of light for quality inspection or feature recognition.
• Biometrics & Security: applied in biometric systems such as iris recognition to improve recognition accuracy by filtering out ambient light interference.

4.What are key parameters when choose for a suitable Bandpass Filters?

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

• Central Wavelength (CWL)：CWL is one of key parameter to designate first, it refer to the central wavelength at stable high transmission rate passband.
• Peak or Average Transmittance: typically ≥90%, Higher transmittance might need Anti-reflective(AR) coating.
• Full width at half maximum (FWHM): FWHM refer to the interval between the two wavelength points where the transmittance rate reaches 50%.
• Blocking rate: usually 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 considered 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:

555nm Narrow Bandpass Filter, 555nm CWL, 20nm FWHM,Support Customized

Shenzhen Hengda Liyuan Optoelectronics introduced advanced optical vacuum technology that apply depositing nano-materials through ion-assisted evaporation onto a multilayer hard film in a high vacuum environment which coating layer is firm and has good tightness, and small bandwidth drift. Besides, Liyuan optoelectronics have been focus on optical coating for more than 17 years ,and the company offer one-stop optical filters solution including Narrow Bandpass Filters, IR cut-off Filters, Longpass Filters, Shortpass Filters, Notch Filters, ND filters, Star filters and Optical sapphire block.

Remark: The appearance color of the optical filter is usually determined by the spectral parameters, the interference type filter varies at different angles, and the pictures in this link may have been taken from different angles, so the actual color should be based on the final spectral parameters required！