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- Cheng, Haynes P. H., et al.
(författare)
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Autofluorescence of pigmented skin lesions using a pulsed UV laser
- 2010
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Ingår i: Proceedings of SPIE. - : SPIE. ; 7715, s. 1-77151
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Konferensbidrag (refereegranskat)abstract
- We report preliminary clinical results of autofluorescence imaging of malignant and benign skin lesions, using pulsed 355 nm laser excitation with synchronized detection. The novel synchronized detection system allows high signal-tonoise ratio to be achieved in the resulting autofluorescence signal, which may in turn produce high contrast images that improve diagnosis, even in the presence of ambient room light. The synchronized set-up utilizes a compact, diode pumped, pulsed UV laser at 355 nm which is coupled to a CCD camera and a liquid crystal tunable filter. The excitation and image capture is sampled at 5 kHz and the resulting autofluorescence is captured with the liquid crystal filter cycling through seven wavelengths between 420 nm and 580 nm. The clinical study targets pigmented skin lesions and evaluates the prospects of using autofluorescence as a possible means in differentiating malignant and benign skin tumors. Up to now, sixteen patients have participated in the clinical study. The autofluorescence images, averaged over the exposure time of one second, will be presented along with histopathological results. Initial survey of the images show good contrast and diagnostic results show promising agreement based on the histopathological results.
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| 8. |
- Holm, Jesper, et al.
(författare)
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High power 404 nm source based on second harmonic generation in PPKTP of a tapered external feedback diode laser
- 2008
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Ingår i: Optics Express. - 1094-4087. ; 16:4, s. 2486-2493
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Tidskriftsartikel (refereegranskat)abstract
- We present results on a 404 nm laser system based on second harmonic generation in a new compact external cavity configuration. We obtain a stable 318 mW cw diffraction limited output from the system with a mode-matched pump power of 630 mW. We observe up to 620 mW SHG, when the cavity is operating in scanning mode. The pump source is an external cavity grating feedback tapered diode laser operating at 808 nm. We find that thermal effects in the nonlinear crystal severely limit the efficiency of the setup with high input powers.
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| 9. |
- Holm, Jesper, et al.
(författare)
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Novel low-loss 3-element ring resonator for second-harmonic generation of 808nm into 404nm using periodically poled KTP
- 2007
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Ingår i: Nonlinear Frequency Generation and Conversion: Materials, Devices, and Applications VI. - : SPIE. - 1996-756X .- 0277-786X. - 9780819465689 ; 6455
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Konferensbidrag (refereegranskat)abstract
- We present a novel ring resonator for second harmonic generation consisting of only two spherical mirrors and a refractive element. In our work we use periodically poled KTP as a nonlinear material for generating the second harmonic using an 808nm tapered grating stabilized external cavity laser as pump source. With 286mW of fundamental 808nm radiation coupled into the resonator, we generate 130mW blue light at 404nm, resulting in a power conversion efficiency of 45\%.
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| 10. |
- Kamran, Faisal, et al.
(författare)
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Computationally effective solution of the inverse problem in time-of-flight spectroscopy
- 2015
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Ingår i: Optics Express. - 1094-4087. ; 23:5, s. 6937-6945
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Tidskriftsartikel (refereegranskat)abstract
- Photon time-of-flight (PTOF) spectroscopy enables the estimation of absorption and reduced scattering coefficients of turbid media by measuring the propagation time of short light pulses through turbid medium. The present investigation provides a comparison of the assessed absorption and reduced scattering coefficients from PTOF measurements of intralipid 20% and India ink-based optical phantoms covering a wide range of optical properties relevant for biological tissues and dairy products. Three different models are used to obtain the optical properties by fitting to measured temporal profiles: the Liemert-Kienle model (LKM), the diffusion model (DM) and a white Monte-Carlo (WMC) simulation-based algorithm. For the infinite space geometry, a very good agreement is found between the LKM and WMC, while the results obtained by the DM differ, indicating that the LKM can provide accurate estimation of the optical parameters beyond the limits of the diffusion approximation in a computational effective and accurate manner. This result increases the potential range of applications for PTOF spectroscopy within industrial and biomedical applications. (C) 2015 Optical Society of America
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