Extend the range of Raman spectroscopy with THz-Raman®

Ondax’sLow Frequency THz-Raman Spectroscopy Systems patented THz-Raman® Spectroscopy Systems extend the range of traditional Raman spectroscopy into the terahertz/low-frequency regime, exploring the same range of energy transitions as terahertz spectroscopy – without limiting the ability to measure the fingerprint region. The THz-Raman spectral region covers both Stokes and anti-Stokes signals from ±5 cm-1 to 200 cm-1, (or 150 GHz to 6 THz), which contain important structural information about the molecule or crystal lattice. This region reveals a new “Structural Fingerprint” to complement the traditional “Chemical Fingerprint” of Raman, enabling simultaneous analysis of both molecular structure and chemical composition in one instrument for advanced materials characterization.

See What You’ve Been Missing – More Data, Better Sensitivity and Reliability

THz-Raman spectra show clear differentiation of structural attributes of the material, ideal for identification and analysis of polymorphs, raw material sources, defects & contamination, crystal formation and orientation, phase monitoring and synthesis methods. Applications include pharmaceuticals, explosives, narcotics, nano- and bio-materials, semiconductors, photovoltaics, and petrochemicals.

By adding both low-frequency and anti-Stokes signals to the traditional fingerprint, THz-Raman systems boost overall Raman intensity and improve SNR.. And the symmetrical nature of the anti-Stokes signals act as a confirmation of Stokes peaks, while providing an inherent calibration reference that improves overall confidence and reliability.

One Sample, One System, One Answer

Low Frequency Raman Spectrum of Carbamazepine

Full Raman spectrum of the pharmaceutical Carbamazepine showing both the THz-Raman “Structural Fingerprint” and traditional “Chemical Fingerprint” regions. Note higher intensity, stronger differentiation, and inherent symmetry of THz-Raman signals.

Combining both composition and structural analysis eliminates the need for multiple samples and instruments, lowering capital, training and maintenance costs. These compact plug-and-play platforms can be integrated with virtually any lab-grade microscope or Raman system. With excitation wavelengths ranging from 488nm to 976nm, and a wide range of options and compatible spectrometers to choose from, an Ondax THz-Raman® system can be optimized to match any application.

Plug-and-Play upgrade to your existing microscope or Raman system, or configurable as a complete custom system
All THz-Raman® Series platforms are ultra-compact and simple to connect via fiber to almost any spectrometer or Raman system. Our patented SureBlock™
ultra-narrow-band Volume Holographic Grating (VHG) filters precisely block only the Rayleigh excitation with >OD8 attenuation, enabling simultaneous capture of both Stokes and anti-Stokes signals. A high-power, wavelength-stabilized, ASE-free single-frequency laser source is precisely matched to the filters to assure maximum throughput and exceptional attenuation of the excitation source.

Low Frequency THz-Raman Microscope

TR-MICRO THz-Raman® Microscope Platform mounted on Leica DM2700 Microscope

The TR-MICRO mounts directly to a broad range of popular microscope platforms and micro-Raman systems, and can be easily switched in and out of the optical path. The system includes an Ondax SureLock™ 785nm, 850nm, 976nm or 1064nm laser source, notch filters, and optional circular polarization (linear polarization is standard). A 532nm excitation source or a sample imaging camera are also available upon request.

The new TR-PROBE is a compact, robust THz-Raman probe that enables in-situ reaction or process monitoring. The TR-PROBE can be configured with a variety of immersion or contact probe tips, a convenient vial holder, or a steerable collimated beam.

The XLF-CLM is configured for Benchtop use and offers an optional vial/cuvette sample holder for fast, easy measurements. The system also comes with a standard cage mounting plate (centered on the collimated output beam) to allow for customized collection optics or easy integration into a customized system. The XLF-CLM includes a SureLock™ 785nm, 850nm, 976nm or 1064nm laser source, notch filters, and optional circular polarization.

Low Frequency THz-Raman Probe

TR-PROBE In-situ THz-Raman® Probe with optional Ballprobe tip

Low Frequency/THz-Raman Spectroscopy Modules

TR-BENCH Benchtop THz-Raman® Module with optional vial/cuvette/tablet sample holder



  • Polymorphic structure identification and monitoring
  • Amorphous-to-crystalline transformation
  • Structural studies of nano-and bio-materials
  • In-situ Crystallization and Reaction Monitoring
  • Trace detection and source attribution of explosives/hazmat/drugs
  • Forensics studies
  • Geological specimen analysis and gemology
  • Fast collection of THz-Raman/Low frequency spectra
  • Simultaneous Stokes and anti-Stokes signals improve SNR while providing inherent calibration reference
  • High Optical Density (>OD8) with extremely high throughput
  • Ultra-compact footprint, plug-and-play operation, fiber coupled output
  • Compatible with most commercial spectrometers, microscopes and Raman systems
  • Integrated ASE filtering with high-throughput 90/10 dichroic beamsplitter
  • Available at 532, 633, 785, 850, 976nm, and 1064nm.


Parameter Units Specification
Wavelength nm 532 785/850 976
Power at sample port (min) mW 50 to 250* 100 300
* Specify power level at time of order
Fixed Grating Spectrometer Tunable Grating Spectrometer
Spectral Range (typical) -200cm-1 to +2200cm-1 0-1100 nm (w/Si Detector)
Spectral Resolution 2.5cm-1 to 4cm-1 1.25cm-1 or greater
Computer Interface  USB USB
Polymorph ID

For more information on Polymorph Identification click here

Low frequency/THz-Raman Spectra of CBZ

Low Frequency/THz-Raman spectra of CBZ Polymorphs Forms 2 and 3, plus Hydrate

Low frequency THz-Raman spectra of common APIs

Complete Raman spectra of common APIs. Note stronger intensity in THz-Raman region

Explosives Detection

For more information on Explosives Detection and Source Attribution click here

HMTD Low Frequency THz-Raman Spectra

HMTD, a common homemade explosive (HME), showing strong THz-Raman signals that improve detection sensitivity and reliability. (Sample courtesy Dr. Brian Leigh, UCSD).

HMTD Low Frequency THz-Raman Spectra
TATP Low Frequency/THz-Raman Spectra

TATP, another well known HME. (Sample courtesy Dr. Brian Leigh, UCSD).

Ammonium Nitrate Low Frequency/THz-Raman Spectra

Ammonium Nitrate

Crystallization and Reaction Monitoring

For more information on Crystallization and Reaction Monitoring click here

Theophylline transformation low frequency waterfall spectra

Low frequency Raman spectra of Theophylline amorphous-crystalline transition

Transformation profile of Theophylline based on Low frequency Raman spectra

Transformation profile of Theophylline based on Low frequency Raman spectra