| 1. |
- Andersson, Angelica, et al.
(författare)
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TV shearography : quantitative measurement of shear-magnitude fields by use of digital speckle photography
- 2000
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 39:16, s. 2565-2568
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Tidskriftsartikel (refereegranskat)abstract
- Digital speckle photography combined with TV shearography is developed for precise measurement of the magnitude of the shear field in a linear shear configuration. As an application the method is implemented to determine the slope-change variations of a three-dimensional object with TV shearography in which the shear magnitude is obtained with the digital speckle photography technique
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| 2. |
- Baxter, G. W., et al.
(författare)
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Single-mode near-infrared optical parametric oscillator amplifier based on periodically poled KTiOPO4
- 2001
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 40:36, s. 6659-6662
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Tidskriftsartikel (refereegranskat)abstract
- A singly resonant, single-axial-mode, optical parametric oscillator (OPO) based on periodically poled KTiOPO4 (PPKTP) is reported. Signal (1.68 mum) and idler (2.90 mum) optical bandwidths have been narrowed to < 400 MHz by use of a diffraction grating at grazing incidence. The OPO generates 370 muJ of signal radiation when pumped by 3.1 mJ of 1.064-mum radiation. We implemented a single-pass PPKTP amplifier to yield 2.15-mJ signal and 1.17-mJ idler radiation without broadening the spectral bandwidths.
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| 3. |
- Bjurshagen, Stefan, et al.
(författare)
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Modeling of energy-transfer upconversion and thermal effects in end-pumped quasi-three-level lasers
- 2004
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 43:24, s. 4735-4767
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Tidskriftsartikel (refereegranskat)abstract
- An analytical model of cw quasi-three-level lasers that includes the influence of energy-transfer upconversion (ETU) has been developed. The results of the general output modeling were applied to a laser with Gaussian beams, and rigorous numerical calculations have been made to study the influence of ETU on threshold, output power, spatial distribution of population-inversion density, and fractional thermal loading. The model was applied to a laser operating at 946 nm in Nd:YAG, where the dependence of laser-beam size on laser performance was investigated in particular. A simple model for the degradation of laser-beam quality from a transversally varying saturated gain is proposed that is in good agreement with measurements of the laser in a plane-plane cavity.
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| 4. |
- Blom, Hans, et al.
(författare)
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Parallel Flow Measurements in Microstructures by Use of a Multifocal 4 x 1 Diffractive Optical Fan-Out Element
- 2002
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 41:31, s. 6614-6620
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Tidskriftsartikel (refereegranskat)abstract
- We have developed a multifocal optical fluorescence correlation spectroscopy system for parallel flow analyses. Multifocal excitation was made possible through a 4 x 1 diffractive optical fan-out element, which produces uniform intensity in all four foci. Autocorrelation flow analyses inside a 20 μm x 20 μm square microchannel, with the 4 x 1 fan-out foci perpendicular to the flow direction, made it possible to monitor different flows in all four foci simultaneously. We were able to perform cross-correlation flow analyses by turning the microstructure, thereby having all four foci parallel to the direction of flow. Transport effects of the diffusion as a function of flow and distance could then also be studied.
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| 5. |
- Blom, Hans, et al.
(författare)
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Parallel Fluorescence Detection of Single Biomolecules in Microarrays by a Diffractive-Optical-Designed 2 x 2 Fan-Out Element
- 2002
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 41:16, s. 3336-3342
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Tidskriftsartikel (refereegranskat)abstract
- We have developed a multifocal diffractive-optical fluorescence correlation spectroscopy system for parallel excitation and detection of single tetramethylrhodamine biomolecules in microarrays. Multifocal excitation was made possible through the use of a 2 × 2 fan-out diffractive-optical element with uniform intensity in all foci. Characterization of the 2 × 2 fan-out diffractive-optical element shows formation of almost perfect Gaussian foci of submicrometer lateral diameter, as analyzed by thermal motion of tetramethylrhodamine dye molecules in solution. Results of parallel excitation and detection in a high-density microarray of circular wells show single-biomolecule sensitivity in all four foci simultaneously.
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| 6. |
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| 7. |
- Burvall, Anna, et al.
(författare)
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Simple lens axicon
- 2004
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 43:25, s. 4838-4844
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Tidskriftsartikel (refereegranskat)abstract
- We present the design of a cemented doublet-lens axicon made from spherical surfaces only. Compared with diffractive axicons, refractive cone axicons, and earlier lens axicons with aspheric surfaces, this element is inexpensive and easy to manufacture even with large apertures. The lens axicon is based on the deliberate use of the spherical aberration of the surfaces. The design principles of the element and its characterization, numerically and experimentally, are presented in detail. Although performance was traded for simplicity and robustness, the results show that the lens axicon has the main axicon properties: a narrow, extended line focus of relatively constant width.
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| 8. |
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| 9. |
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| 10. |
- Cronhjort, Andreas, et al.
(författare)
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Segmentation Algorithm for Diesel Spray Image Analysis
- 2004
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 43:32, s. 5971-5980
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Tidskriftsartikel (refereegranskat)abstract
- An algorithm for segmentation of diesel spray images has been developed. Its most important feature is robustness against experimental setups that fail to guarantee images whose histograms show two distinct peaks. According to the approach presented, only the peak from the background is used, and it is assumed that the background peak is narrow enough not to include too much of the spray. The algorithm has proved successful for evaluation of images from a pressurized vessel as well as from an engine with optical access, with no need for adjusting the tuning parameters. By adjusting them, one may tune the noise sensitivity.
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