Optical measurements


» Low Energy Optics
During the past few years, we have developed various techniques to investigate the frequency dependent conductivity and dielectric constant of (mainly) highly conducting materials over broad frequency range. The focus of our technique development effort is on the low frequency response, at frequencies below what conventional optical methods cover. Various resonant cavities enclosed, and composite resonators with high quality factors have been designed and built in the microwave and millimeter wave spectral range, operating at various frequencies between 2.5 and 150 GHz, where resonant techniques are necessary to investigate the perturbation due to the specimens. Various configurations are employed and these depend on the sample geometry and measurement frequency among other factors. A so-called coherent source spectrometer, based on semiconductor and on Backward Wave Oscillator (BWO) sources and on a quasioptical arrangement has recently been constructed. We have acquired a range of Impatt oscillators in the 2 - 7 cm-1 range, while external magnetic field driven BWO sources cover the entire submillimeter wave range up to 25 cm-1. A few years ago, we have also acquired a Bruker IFS 113v Fourier Transform spectrometer which operates from 15 to 5500 cm-1.

» Conventional optics
In the UV and visible, a Beckman Coulter DU 640 Spectrophotometer is used. This is complemented by a Perkin Elmer IR spectrometer. A Bruker IFS 113v Fourier Transform spectrometer operates from 15 to 5500 cm-1 spectral range.



Fig 1. Optical measurement facilities


UV-Vis spectrometer Infrared spectrometer