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- Samsöe Andersen, Eva, et al.
(författare)
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A novel diode laser system for photodynamic therapy
- 2001
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Ingår i: LASER-TISSUE INTERACTIONS, THERAPEUTIC APPLICATIONS, AND PHOTODYNAMIC THERAPY. - : SPIE. - 0277-786X .- 1996-756X. - 0819441473 ; 4433:33, s. 134-139
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Konferensbidrag (refereegranskat)abstract
- In this paper a novel diode laser system for photodynamic therapy is demonstrated. The system is based on linear spatial filtering and optical phase conjugate feedback from a photorefractive BaTiO3 crystal. The spatial coherence properties of the diode laser are significantly improved. The system provides an almost diffraction limited output which is efficiently coupled into a 50 mum core diameter fiber. The optical power transmitted through the fiber is increased by a factor of six when the feedback is applied to the diode laser. 85 percent of the power from the freely running laser diode is extracted in a high-quality beam and 80 percent of the output power is extracted through the fiber. The power transmitted through tile fiber scales linearly with the power of the laser diode. which means that a laser diode emitting 1.7 W multi-mode radiation would provide 1 W of optical power through a 50 mum core diameter fiber. The system is compact, portable, stable, and easy to operate.
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| 2. |
- Samsöe Andersen, Eva, et al.
(författare)
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Improvement of brightness and output power of high-power laser diodes in the visible spectral region
- 2003
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Ingår i: Optics Communications. - 0030-4018. ; 219:1-6, s. 369-375
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports on a novel design for a high-brightness quantum-well AlGaInP laser-diode system operating at 635 nm. The spatial coherence of two broad area laser diodes is improved using spatial filtering and optical feedback from a narrow mirror stripe on each laser. To increase power, the outputs from the two systems are passively combined using a polarizing beam splitter. The result is a compact system providing a high-brightness beam. The beam-quality parameter is improved in one direction from M-2 = 12 and M-2 = 16 for the two lasers, to M-2 = 2.1 for the combined beam. The other direction of the beam is left unchanged due to its natural high quality with an M-2 value around 1.5. A procedure for efficient coupling of the two lasers into a small core-diameter optical fiber is given. This capability facilitates a wide range of applications including interstitial medical therapies, where delivery of the treatment light through thin optical fibers is essential. (C) 2003 Elsevier Science B.V. All rights reserved.
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| 3. |
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| 4. |
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| 5. |
- Samsoe, E, et al.
(författare)
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Improvement of spatial and temporal coherence of a broad area laser diode using an external-cavity design with double grating feedback
- 2004
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Ingår i: Optics Express. - 1094-4087. ; 12:4, s. 609-616
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a novel technique for narrow bandwidth and highly improved lateral mode operation of a high-power broad area laser diode. The system uses simultaneous feedback from the first diffracted order and the zeroth reflected order of a diffraction grating. The two feedback paths lead to simultaneously improvement of the spectral and spatial properties of the laser diode. The laser system operates in the well-known asymmetric double-lobed far field pattern with the larger lobe being extracted as the output. The bandwidth of the output beam is measured to 0.07 nm, which corresponds to an improvement of a factor of 17 compared to the bandwidth of the freely running laser. The output from the system contains 54% of the energy reaching the grating, or 75% of the power reflected into the zeroth order. The improvements in both the spatial and temporal coherence opens the possibility of using this laser system in applications such as frequency doubling and pumping of optical parametric oscillators. (C) 2004 Optical Society of America.
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| 6. |
- Weber, M., et al.
(författare)
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Preserved slow conducting corticomotoneuronal projections in ALS patients with autosomal recessive D90A CuZn-SOD mutation.
- 2000
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Ingår i: Brain. - : Oxford University Press (OUP). - 0006-8950 .- 1460-2156. ; 123:7, s. 1505-1515
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Tidskriftsartikel (refereegranskat)abstract
- Recently, a subgroup of the amyotrophic lateral sclerosis (ALS) syndrome associated with mutations in the gene encoding the free radical scavenging enzyme CuZn-superoxide dismutase (CuZn-SOD, SOD1) has been identified. Some 67 different mutations have been reported worldwide to date, comprising about one-fifth of familial ALS cases in the populations studied. The autosomal recessively inherited D90A CuZn-SOD mutation has been associated with a very slowly progressive, clinically distinct phenotype, and is neurophysiologically characterized by very slow central motor conduction. It is not known which physiological and/or biochemical mechanisms are responsible for the different clinical course. To delineate ALS associated with this particular CuZn-SOD mutation from ALS without mutations, we performed a detailed neurophysiological study of the corticomotoneuronal function using peristimulus time histograms (PSTHs) in eight ALS patients homozygous for the D90A CuZn-SOD mutation. The results were compared with those obtained in 12 non-hereditary ALS patients and 11 healthy subjects. PSTHs were constructed from three to seven different, voluntarily recruited motor units of the extensor digitorum communis muscle (EDC) in each patient. The onset latency, number of excess bins, duration and synchrony of the primary peak were analysed. All measurements differed significantly between healthy controls and the D90A patients (P < 0.0007). The mean onset latency of the primary peak in D90A patients was 35.3 ms, compared with 24.2 ms for non-hereditary ALS patients and 19.3 ms for normal subjects (P < 0.0000). Delayed primary peaks in the D90A patients were desynchronized and characteristically preceded by a marked suppression phase. This suppression phase was not seen in non-hereditary ALS patients. We conclude that the mainly slow conducting and/or polysynaptic corticomotoneuronal connections are preserved in the D90A homozygous cases, and that the cortical and possibly spinal inhibitory circuitry is preserved. These events may partially protect the motor neurons, slowing down the degenerative process.
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| 7. |
- Weber, M., et al.
(författare)
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The physiological basis of conduction slowing in ALS patients homozygous for the autosomal recessive D90A CuZn-SOD mutation
- 2001
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Ingår i: Muscle and Nerve. - 0148-639X .- 1097-4598. ; 24:1, s. 89-97
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Tidskriftsartikel (refereegranskat)abstract
- Familial amyotrophic lateral sclerosis (ALS) with the autosomal-recessively inherited D90A CuZn-superoxide dismutase (CuZn-SOD) mutation is characterized by a stereotypic slowly progressive, distinctive phenotype and very slow central motor conduction. To determine the basis of this slowing, we assessed corticomotoneuronal function using peristimulus time histograms (PSTHs) in 8 ALS patients homozygous for the D90A CuZn-SOD mutation. The results were compared with findings in 10 patients with multiple sclerosis (MS), in which slowing of central motor conduction is common, and 11 healthy subjects. PSTHs were constructed from 3-7 different, voluntarily recruited motor units recorded in each patient from the extensor digitorum communis muscle (EDC). In D90A and MS patients, the stimulus threshold, onset latency, number of excess bins, duration, amplitude, and synchrony of the primary peak differed significantly from controls (P < 0.0004). The mean onset latency of the primary peak in D90A patients was 35.3 ms, compared to 23.6 ms for MS patients and 19.3 ms for normal subjects (P < 0.0001). In the D90A patients, the onset latencies of the primary peak had a bimodal distribution, whereas in MS the distribution showed a continuum. Loss of synchrony was similar in D90A and MS patients, but the threshold, number of excess bins, and duration differed significantly (P < 0.0057), which suggests that either axonal loss or demyelination can result in delayed and desynchronized primary peaks. We propose that conduction slowing in the D90A homozygotes results from selective loss of fast-conducting large pyramidal cells with preservation of slow-conducting mono- or polysynaptic corticomotoneuronal connections. Copyright 2001 John Wiley & Sons, Inc.
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