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Broadband TOFS

Streak camera system

Our research group has developed and used a system based on continuum generation in a non-linear photonic crystal fiber and a streak camera or a time-correlated single photon counting system for detection. The first system covers the 500 nm to 1100 nm spectral range, while the other 600 - 1400 nm, and has been used mainly in pharmaceutical applications.

Time-resolved spectroscopy for pharmaceutical applications
C. Abrahamsson, PhD Thesis (2005)

Scatter correction of transmission near-infrared spectra by photon migration data: Quantitative analysis of solids
C. Abrahamsson, A. Lowgren, B. Stromdahl, T. Svensson, S. Andersson-Engels, J. Johansson, and S. Folestad
Appl. Spectrosc.59, 1381-1387 (2005)

Time-resolved NIR spectroscopy for quantitative analysis of intact pharmaceutical tablets
C. Abrahamsson, J. Johansson, S. Andersson-Engels, S. Svanberg, and S. Folestad
Anal. Chem.77, 1055-1059 (2005)

The new system

We have recently developed a broadband system based on a supercontinuum fiber laser, acousto optical tunable filtering and time-correlated single photon counting (TCSPC). The goal was to extend operation well into the near-infrared spectral range, reaching diagnostically important overtone and combination bands of fundamental vibrations found in the infrared. While earlier work on TOFS have been limited to the spectral range below 1100 nm, we recently managed to perform experiments up to 1400 nm. An article presenting our progress has been published in Rev. Sci. Instrum. The capability of working above 1100 nm dramatically increase the applicability of TOFS for analysis of turbid materials. We are currently implementing practical improvements. At the same time we are also using it for characterisation of various turbid materials and investigations of light propagation.

Near infrared photon time-of-flight spectroscopy of turbid materials
up to 1400 nm
 
T. Svensson, E. Alerstam, D. Khoptyar, J. Johansson,
S. Folestad, and S. Andersson-Engels
Review of Scientific Instruments80, 063105 (2009)