- Scanning of large biological objects with pulsed NIR Lasers
- Recording by bh's Multidimensional TCSPC Technique
- Fast Multiplexing of Several Laser Wavelenths
- Detection of diffusely backscattered or transmitted light
- Detection of distribution of time of flight of the photons (DTOF)
- Buildup of time-resolved images by bh FLIM Technique
For details please see The bh TCSPC Handbook, 8th edition, chapter 'Diffuse Optical Tomography: DOT, NIRS and fNIRS
The measurement object is scanned by a laser beam via a fast galvanometer scanner. The scanner is driven by a bh GVD 120 scan controller the same way as in the bh confocal FLIM systems. The light returning from the sample (diffusely scattered lightor fluorescence) is separated from the excitation beam by a beam splitter. The light passes a filter and a pinhole, and is detected by an HPM 100-50 hybrid detector. The single-photon pulses from the detector are recorded by an SPC 150N TCSPC FLIM module. The pixel, line, and frame clock pulses for synchronisation with the scan are delivered by a GVD-120 scan controller.
A supercontinuum laser delivers the pulsed excitation light. The wavelength is selected by an AOTF. The AOTF is able to select between eight programmable wavelengths by signals applied to the ‘MOD’ inputs of the AOTF controller. These signals are provided by a counter that is driven by the frame clock pulses of the scan controller. The result is that the AOTF cycles through the 8 wavelengths for subsequent frames of the scans. Simultaneously, the routing inputs of the SPC-150N module are driven by signals from the counter outputs. Thus, the SPC module builds up separate images for the individual laser wavelengths.
The bh TCSPC Handbook, 8th edition, chapter 'Diffuse Optical Tomography: DOT, NIRS and fNIRS
H. Wabnitz, M. Mazurenka, L. Di Sieno, G. Boso, W. Becker, K. Fuchs, D. Contini, A. Dalla Mora, A. Tosi, R. Macdonald, A. Pifferi, Time-domain diffuse optical imaging of tissue by non-contact scanning. In: W. Becker (ed.) Advanced time-correlated single photon counting applications. Springer, Berlin, Heidelberg, New York (2015)
M. Mazurenka, L. Di Sieno, G. Boso, D. Contini, A. Pifferi, A. Dalla Mora, A. Tosi, H. Wabnitz, R. Macdonald, Non-contact in vivo diffuse optical imaging using a time-gated scanning system, Biomed. Opt. Express 4(10), 2257–2268 (2013)
The bh TCSPC Handbook
8th edition, corrected and updated September 2019