The TCF is a temperature stabilised etalon device, designed to reduce the intensity of spurious secondary laser modes found on many modern commercial solid state laser light sources.
These secondary modes are very weak with an intensity typically 10^-8 to 10^-11 of the laser intensity, but unfortunately they lie in the region of interest for Brillouin spectroscopy measurements.
A Brillouin spectrum measured in the presence of a strong elastic peak will inevitably show these secondary peaks in the background, making interpretation of the spectrum difficult.
The TCF filter will strongly attenuates these modes, in many cases reducing them below the detection threshold.

The active component of a TCF is a small and thin etalon plate, mounted in a sealed holder. Etalons are already available for the red (613-653 nm),  green (512-552 nm) and blue (440-480 nm) regions of the spectrum. Etalons for different colors can be purchased separately and used on the same device. The ordinary TCFs etalons are suitable for laser beam power up to 300 mW; an high power version of the green etalon (512-552 nm) is available on request. 

The TCF-2 is an improved version of the filter, including an additional stabiliser:
 

The stabiliser constantly samples the output beam and applies small corrections to the temperature setpoint in order to maintain an optimal tuning and the maximum power output. It efficiently compensates long-time drifts of room temperature and laser wavelength, which could otherwise worsen the performance.

The stabiliser is also sold separately and can be used to upgrade pre-existing TCF-1 devices to TCF-2.

TCF units can be mounted on both imperial or metric standard optical tables. 

External dimensions (including stabiliser): 105 x 180 x 170 mm (W x L x H) 

Weight (without power supply):                      895 g 

TCF manual

TCF Brochure