THz spectroscopy: High resolution

10 Mar 2015

At the recent Photonics West show, Laser Quantum launched new capabilities for its high resolution HASSP-THz time domain spectroscopy system. The new modular format allows the system to be used in transmission, reflectance and ATR modes.

THz spectroscopy is becoming an increasingly popular topic of research due its potential in many applications such as particles research, biochemistry, pharmaceuticals and security.

The HASSP-THz spectrometer has always offered high resolution up to 1GHz and a wide spectral coverage of 6.5THz. At the recent Photonics West exhibition, Laser Quantum launched the next generation HASSP that benefits from a modular design allowing easy removal of moisture from the sample compartment, sample testing in transmission (focal point or collimated), reflectance, attenuated total reflectance (ATR) modes and in addition, it can be used with a cell for gaseous samples. These modes are interchangeable to ensure the maximum flexibility of the system.

The high resolution of the HASSP-THz system comes from the method it uses to create the time lag between pump and probe pulses. Instead of using a mechanical delay line, the HASSP-THz uses a taccor laser operating at 1GHz with a second operating at a slightly offset repetition frequency. This technique, ASynchronous OPtical Sampling (ASOPS) was pioneered by Laser Quantum and the frequency offset automatically ramps the time delay between pump and probe, an order of magnitude faster than is capable by conventional mechanical stage setups.

The ASOPS technique can also be used for other time domain applications such as thin layer film measurements. By using the ultra-high resolution provided by the ASOPS technique, film thicknesses have been measured by a team at the University of Konstanz in the order of sub-nm. To find out more, download our whitepaper “Sub-nm layer measurements using ASOPS and laser induced ultrasound”.

You can download the white paper from here