Ondax’s patented1 SureBlock™ XLF Notch Filter Systems enable fast, clear capture of Raman spectra in the Low-Frequency (Low Wavenumber/THz regime (~5 cm-1 to 200 cm-1, or 150 GHz to 6 THz), using only a standard single-stage spectrometer. THz-Raman is powerful new technique for molecular and intermolecular structural analysis that is both simple and compact when compared to multi-stage or THz spectrometers, and represents a dramatic shift in the economics, efficiency, and ease of use of Raman spectroscopy.

The unique ultra-narrow band design of our patented2 SureBlock™ Notch Filters also delivers exceptionally high throughput of both Stokes and anti-Stokes shifts up to >5000cm-1 (>150 THz). This allows observation of low-frequency vibrational/phonon modes, differentiation of polymorphs and other structural characteristics of pharmaceuticals, nano- and bio-materials; trace detection and forensics analysis of explosives and chemical/biological threat agents; and characterization of industrial, polymers, petroleum, heavy metals, and geological samples.

The XLF is an integrated, pre-aligned, light-tight, double-notch system with selectable fiber- or free-space input and outputs, adaptable for use with any single-stage spectrometer. All XLF systems provide > OD 8 Rayleigh suppression, and are engineered for fast, flexible integration with a wide variety of existing commercial spectrometers microscopes, and Raman systems. Available at standard Raman wavelengths including: 488nm, 514nm, 532nm, 633nm, and 785nm, and 830nm, these compact, robust plug-and-play systems deliver incredible speed, resolution and ease of use, all at an extremely affordable price!

  • Polymorphic structure identification
  • Structural studies of nano-and bio-materials
  • Trace detection and source attribution of explosives/hazmat/drugs
  • Forensics studies
  • Geological specimen analysis and gemology
    • Fast collection of ultra-low-frequencey/THz-Raman spectra
    • High Optical Density (.OD8) with extremely high thoughput*
    • Ultra-compact footprint, plug-and-play operation, configurable input & output ports (free space or fiber coupled)
    • Compatible with most commercial spectrometers, microscopes and Raman systems
    • Available at 488, 514, 532, 633, 785 and 830nm. Custom wavelengths by request

*Throughput varies with wavelength

Table 1: SureBlock™ XLF Specifications
Parameter 488nm 514nm 532nm 633nm 78Xnm
Spectral Transition Width
(center to 50% transmission)
<10cm-1 <10cm-1 <10cm-1 <10cm-1 <10cm-1
Optical Density at Laser Line
(each filter)
>4 >4 >4 >4 >4
Expected System Optical Density >8 >8 >8 >8 >8
Free Space Aperture Diameter Standard: 9mm, Custom sizes available
Fiber Input/Output Connector Type Recommended: FC/PC, Others available upon request
Technical Data
Ultra narrow notch transition to 50% transmission

Captured Raman Spectra of L-Cystine
High throughput Stokes and anti-Stokes

Ultra-low frequency measurements1 <10cm-1

1Data taken using an Ondax SureLock™ 785nm wavelength stabilized laser, SureBlock™ 785nm ultra narrow-band notch filter, and a single-stage Princeton Instruments SpectraPro 2300i

Mechanical Drawings
Fiber Input to Fiber Output Configuration

All dimensions in mm

Free Space Input to Fiber Output Configuration

All dimensions in mm

Ordering Information
Fiber In, Fiber Out

Free Space In, Fiber Out

Output via multimode fiber is recommended
*Throughput varies with wavelength