365nm UV bandpass filters

365 nm bandpass filters are designed to transmit a selected UVA band centered near 365 nm while reducing unwanted out-of-band light.

Applications:
- 365 nm UV LED source cleanup
- Mercury i-line and mercury-xenon lamp filtering
- DAPI/Hoechst-type fluorescence excitation
- UV inspection and detector-side UVA signal isolation
- UV curing, resin exposure, adhesive curing, coating exposure, and i-line photoresist exposure

Bandwidth options:
- 3 nm and 10 nm FWHM for tighter 365 nm selection
- 20 nm and 30 nm FWHM for balanced UVA signal and wavelength control
- 40 nm or wider FWHM for higher UVA output in illumination or exposure systems

Select the bandwidth based on the light source, target material or sample, detector sensitivity, blocking range, and required signal level.

365 nm UV LED or LED array

Use CWL 365 nm with 10–30 nm FWHM for most 365 nm UV LED systems that need a practical balance between LED output cleanup and usable UVA signal.

365 nm UV LEDs have broader emission than laser lines, so medium bandwidths such as 10 nm, 20 nm, or 30 nm are usually practical for source cleanup, UV inspection, fluorescence excitation, and exposure systems. Use 40 nm FWHM or wider when the setup needs more UVA output and can accept broader wavelength selection.

Mercury i-line source at 365 nm

Use CWL 365 nm with 3–10 nm FWHM when isolating the mercury i-line from a mercury or mercury-xenon lamp source.

For mercury lamp systems, 365 nm is a real spectral line. A 3 nm or 10 nm FWHM filter is appropriate when the system needs stronger i-line selection. Use 20–40 nm FWHM when the setup can accept a wider UVA band and needs more transmitted signal.

Broadband UV source

Use CWL 365 nm with 10–30 nm FWHM to select a practical UVA band from xenon, deuterium, mercury-xenon, or other broadband UV sources.

For broadband UV illumination, the filter extracts a 365 nm-centered band from a wider spectrum. Use 10–20 nm FWHM for more defined wavelength selection. Use 30–40 nm FWHM or wider when the setup needs higher transmitted UVA signal for illumination, inspection, or detection.

DAPI / Hoechst-type fluorescence excitation

Use CWL 365 nm with 20–50 nm FWHM for DAPI/Hoechst-type near-UV excitation channels when the fluorescence system is designed around 365 nm excitation.

For fluorescence microscopes or fluorescence detection systems, the 365 nm filter is usually placed on the excitation side before the sample. The emission-side filter should be centered at the actual blue emission band, not at 365 nm. Match the excitation filter with the light source, dichroic mirror, and emission filter set.

UV curing, resin, adhesive, and photoresist exposure

Use CWL 365 nm with 20–40 nm FWHM or wider for 365 nm curing, resin exposure, UV adhesive, coating, or i-line photoresist exposure systems.

For exposure applications, the filter defines the UVA irradiation band delivered to the material. Select the FWHM according to the lamp or LED spectrum, required irradiance, material sensitivity near 365 nm, and out-of-band blocking requirement.

Detector-side 365 nm signal isolation

Use CWL 365 nm with 3–20 nm FWHM before a UV-enhanced silicon photodiode, PMT, UV-sensitive spectrometer, or UV-capable camera when the target signal is near 365 nm.

For detector-side filtering, the filter should pass the 365 nm signal while reducing unwanted background outside the target band. Use 3–10 nm FWHM when stronger wavelength isolation is needed. Use 20 nm FWHM or wider when signal throughput is more important.

365nm Filter + US Patent 7,098,469 - Forensic Light Source Kit

Context: This patent describes a portable forensic light source used by crime scene investigators to detect evidence that is invisible under normal light, such as bodily fluids, hair, and fibers.

The Bandpass Filter is used as: A Source Clean-Up / Excitation Filter.

Function: Standard UV bulbs and LEDs often "leak" a significant amount of visible violet/purple light. This filter is placed over the 365nm light source to block that visible purple leakage while transmitting the invisible UV energy.

Result: It achieves High Contrast Fluorescence. By eliminating the visible purple "background noise," faint fluorescent evidence (like a fingerprint treated with dye or a trace of saliva) glows brightly against a totally dark background, making it visible to the investigator.

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