Ondax’s NoiseBlock™ 90/10 Beamsplitter Filters are designed to diffract 90% of the incoming light that matches the designed Bragg wavelength (λ0) and incident angle. All other wavelengths will be transmitted through the filter, making them excellent for boosting the effective signal of a Raman spectrometer.

Adding a NoiseBlock™ 90/10 beamsplitter filter to a Raman spectrometer with a wavelength stabilized laser source can increase the recovered Raman signal by almost a factor of 4 relative to a broadband 50/50 beamsplitter. The filter’s narrow spectral profile (HWHM <10cm-1) is designed to match the SureBlock™ Ultra Narrow-band Notch Filter and NoiseBlock™ ASE Suppression Filter , making it ideal for enabling Ultra-low Frequency (Low Wavenumber) Raman Spectroscopy with high signal-to-noise.


  • High transmittance at design wavelength
  • Narrow spectral bandwidth
  • Customizable slant angle for angular separation of beams
  • No degradation under high power illumination conditions:
  • 90/10 Beamsplitter
  • Removal of Broadband ASE, Fluorescence, and unwanted laser line emission in Raman Spectroscopy

Table 1: NoiseBlock™ Specifications
Parameter Minimum Typ Unit
Center Wavelength 405 488,514.5,532,633,785,987 nm
Bandwidth (FWHM)1 0.03 <0.15<10
nm (FWHM)cm-1
Diffraction Efficiency >90
Temperature Dependence 0.01 nm/°C
Total Deflection Angle (2θ) 8-12 Degrees
InterbeamAngle (γ) 2 Degrees
Clear Aperture Diameter 9mm in 1″ mount.Custom sizes available mm

1Grating bandwidth is a function of wavelength and thickness