266nm Bandpass Filters

266nm bandpass filters are designed to transmit a selected deep-UV band centered near 266nm while reducing unwanted out-of-band light.

Applications:
- 266nm fourth-harmonic Nd:YAG or Nd:YVO₄ laser line cleanup
- Deep-UV laser excitation for spectroscopy or optical measurement
- Harmonic separation in systems involving 1064nm, 532nm, 355nm, and 266nm light
- Detector-side 266nm signal isolation before UV-sensitive photodiodes, PMTs, or spectrometers
- Broadband DUV source filtering for UV optical testing or measurement setups

Bandwidth options:
- 10nm FWHM for 266nm laser-line selection and detector-side signal isolation
- 40nm FWHM for broader DUV signal collection, broadband source filtering, or systems that need more transmitted UV signal

Select the bandwidth based on the laser source, blocking requirement, detector sensitivity, DUV transmission requirement, and optical power level.

Fourth-harmonic Nd:YAG / Nd:YVO₄ laser at 266nm

Use CWL 266nm with 10nm FWHM for 266nm fourth-harmonic laser line selection, source cleanup, or detector-side isolation.

266nm is commonly generated as the fourth harmonic of 1064nm Nd:YAG or Nd:YVO₄ lasers. For this source, the key specs are CWL match near 266nm, FWHM, transmission at 266nm, OD blocking over the unwanted wavelength range, and suitable DUV coating performance for the beam condition.

Broadband DUV source filtering

Use CWL 266nm with 40nm FWHM for broadband DUV source filtering when the setup needs more transmitted UV signal around 266nm.

For deuterium lamps, xenon lamps, or broadband UV sources, the filter extracts a DUV band from a wider spectrum. A 40nm FWHM option is more practical when the system needs usable UV signal for illumination, testing, or detector-side measurement.

US20030219252A1 - Molecular Optical Air Data Systems (MOADS)

Context: An airborne LIDAR system that replaces physical pitot tubes with optical sensors to measure air data parameters.

Usage of Filter: Integrated within a Fabry-Pérot interferometer receiver assembly.

Function: It acts as a spectral sieve to strictly isolate the 266nm backscattered laser light, rejecting background solar radiation (which is naturally low in this "solar blind" UV region) and other stray light.

Result: Achieves precise measurement of wind velocity, air density, and temperature by analyzing the Doppler shift of the filtered light.

US20200163553 - Label-Free Single and Multi-Photon Fluorescence Spectroscopy

Context: A diagnostic medical device that analyzes brain tissue to detect neurodegenerative diseases without using chemical dyes.

Usage of Filter: Placed in the excitation path to clean the laser source and/or in the emission path to block the 266nm excitation light while passing the auto-fluorescence signal.

Function: Purifies the 266nm excitation beam to ensure it specifically excites the amino acid Tryptophan (which has a peak absorption/emission distinct to 266nm excitation).

Result: Achieves the detection of biomarker anomalies (Tryptophan levels) associated with Alzheimer’s and Parkinson’s disease.

US9061083B2 - Ultraviolet Laser Sterilization System

Context: A robotic sterilization system using directed UV lasers to disinfect surfaces in hospitals or laboratories.

Usage of Filter: Used within the laser output module (often a harmonic separator).

Function: Isolates the 266nm (4th harmonic) UV-C beam by blocking the residual fundamental (1064nm) and second-harmonic (532nm) wavelengths generated by the Nd:YAG laser source.

Result: Achieves rapid, non-contact sterilization of target areas (1-4 mm²) by delivering high-intensity germicidal UV radiation without heating the surface.

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