Time-resolved detection technique employs pulsed radiation perform imaging and to study optical properties of an object. Light pulses undergo absorption and scattering in the object and are finally registered in transmission or reflection mode (in regard to the direction of the incident light). Interaction with the medium results in change of the pulses characteristics, namely peak intensity (pulse amplitude) and energy and width and arrival time (in time domain). Detection of light is performed by a time-gating device, e.g. by a streak camera.
In our research, we use light from femtosecond Ti: sapphire laser and a streak camera with temporal resolution of 2 ps. We show that changes of optical properties (mainly scattering) introduced by administration of glucose into tissue-mimicking liquid phantom (2% Intralipid) or blood can be detected by time-of-flight method.
Scheme of the TOF experimental setup: (1) fs laser; (2) beam splitter; (3) attenuator; (4) multilayer biological tissue model; (5) metal holder fixing the ends of optical fibres; (6) optical fibre; (7) streak camera; (8) imaging system; (9) CCD camera; (10) computer.
Backscattered pulses from the 5-mm-thick layer of 2% Intralipid solution. Duration of the pulse detected at the 1st fiber (right-most) is 90 ps, at 2nd fiber (middle) – about 100 ps, at 3rd fiber (left-most) – about 110 ps.
(a) time profiles for 3 detecting fibers at glucose concentration of 500 mg/dl, (b) pulse intensity vs. glucose concentration for three detecting fibers.is 90 ps, at 2nd fiber (middle) – about 100 ps, at 3rd fiber (left-most) – about 110 ps.
A.. Popov, A. Bykov, S. Toppari, M. Kinnunen, A. Priezzhev, R. Myllylä, "Glucose sensing in flowing blood and Intralipid by laser pulse time-of-flight and optical coherence tomography techiques", IEEE J. Select. Topics Quant Electron. 18 (4), 1335-1342 (2012). [PDF]
A.V. Bykov, A.K. Indukaev, A.V. Priezzhev, R. Myllylä, "Study of the influence of glucose on diffuse reflection of ultrashort laser pulses from a medium simulating a biological tissue", Quantum Electron. 38(5), 491-496 (2008). [PDF]
M.Yu. Kirillin, A. V. Bykov, A. V. Priezzhev, R. Myllylä, “Application of time gating in the measurement of glucose level in a three-layer biotissue model by using ultrashort laser pulses”, Quantum Electron. 38(5), 486-490 (2008). [PDF]
M. Kinnunen, R. Myllylä, ”Application of optical coherence tomography, pulsed photoacoustic technique and time-of-flight technique to detect changes in the scattering properties of a tissue-simulating phantom”, J. Biomed. Opt. 13(2), 024005 (2008). [PDF]
A.P. Popov, A.V. Priezzhev, R. Myllylä, "Effect of glucose concentration in a model light-scattering suspension on propagation of ultrashort laser pulses", Quantum Electron. 35(11), 1075-1078 (2005). [PDF]
M. Kinnunen, A.P. Popov, J. Pluciński, R. Myllylä, A.V. Priezzhev, “Measurements of glucose content in scattering media with time of flight technique; comparison with Monte Carlo simulations”, Proc. SPIE 5474, 181-191 (2004). [PDF]
Last updated: 9.9.2016