| 1. |
- Abramson, Nils H.
(författare)
-
Elliptic visualizing optical resolution and kinetic energy
- 2017
-
Ingår i: Applied Optics. - : Optical Society of America. - 1559-128X .- 2155-3165. ; 56:5, s. 1413-1416
-
Tidskriftsartikel (refereegranskat)abstract
- Diffraction limited resolution as introduced by Abbe is well established, but interference limited resolution was not well known until holographic interferometry was introduced. The holodiagram is used to simplify holography and in a new way visualize the distribution, ratio, and relation among resolutions of different optical techniques, including relativistic phenomena. Resolution, when measured by optical methods based on the number of wavelengths of light, is defined in the following as the minimum distance between resolvable points, or the largest object needed to be resolved. Everywhere in the diagram this resolution is represented by two orthogonal diagonals of rhombs.
|
|
| 2. |
- Abramson, Nils H.
(författare)
-
Holodiagram : elliptic visualizing interferometry, relativity, and light-in-flight
- 2014
-
Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 53:11, s. 2398-2404
-
Tidskriftsartikel (refereegranskat)abstract
- In holographic interferometry, there is usually a static distance separating the point of illumination and the point of observation. In Special Relativity, this separation is dynamic and is caused by the velocity of the observer. The corrections needed to compensate for these separations are similar in the two fields. We use the ellipsoids of the holodiagram for measurement and in a graphic way to explain and evaluate optical resolution, gated viewing, radar, holography, three-dimensional interferometry, Special Relativity, and light-in-flight recordings. Lorentz contraction together with time dilation is explained as the result of the eccentricity of the measuring ellipsoid, caused by its velocity. The extremely thin ellipsoid of the very first light appears as a beam aimed directly at the observer, which might explain the wave or ray duality of light and entanglement. Finally, we introduce the concept of ellipsoids of observation.
|
|
| 3. |
- Abramson, Nils H.
(författare)
-
Optical resolution and the duality of light
- 2008
-
Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 47:19, s. D1-D5
-
Tidskriftsartikel (refereegranskat)abstract
- For 15 years, lensless microscopes have been constructed based on the use of holography, a digital CCD detector, and a computer for image reconstruction by use of, e.g., Fourier transformation. Thus, no lens is involved and therefore the conventional resolution limit of half the wavelength no longer applies. Instead of being limited by the wavelength, the resolution is in this case limited by how exact one can measure the phases of the light. It is remarkable that the interference-limited resolution is approximately 0.01X, whereas the diffraction-limited resolution is only of the order of 0.5X. It is my hope that by combining these two techniques it will be possible to increase the magnification in optical systems by at least an order of magnitude. The calculations at so indicate that information does not necessarily decrease with distance.
|
|
| 4. |
- Abramson, N, et al.
(författare)
-
Light-in-flight recording. 5: Theory of slowing down the faster-than-light motion of the light shutter
- 1989
-
Ingår i: Applied Optics. - 2155-3165. ; 28:4, s. 759-765
-
Tidskriftsartikel (refereegranskat)abstract
- Light-in-flight recording by holography uses a picosecond pulse for the reference beam, which like a sheet of light intersects the hologram plate and produces a sensitivity area that with a speed faster than light moves over the plate like a light shutter. If, however, the front of the reference pulse by diffraction in a grating is tilted relative to its direction of motion, the velocity of the light shutter can be slowed down resulting in increased recording time. The practical result using a reflection grating was a true recording that corresponded to a time compression of two to one. To minimize distortions of the recorded pulse shape we studied intersections that are identical for apparent (ellipsoidal) and true (spheroidal) wavefronts.
|
|
| 5. |
- af Klinteberg, C, et al.
(författare)
-
In vivo absorption spectroscopy of tumor sensitizers with femtosecond white light
- 2005
-
Ingår i: Applied Optics. - 2155-3165. ; 44:11, s. 2213-2220
-
Tidskriftsartikel (refereegranskat)abstract
- A system based on a femtosecond white-light continuum and a streak camera was used for recordings of the in vivo absorption spectra of the tumor-seeking agent disulphonated aluminum phthalocyanine. Measurements for different drug doses were performed on tumor tissue (muscle-implanted adenocarcinoma) and normal muscle tissue in rats. It was found that the shape of the spectrum is tissue dependent. The peak of the absorption spectrum is blueshifted in tumor tissue as compared with the muscle. Thus the contrast in the drug-related absorption can be altered by up to a factor of 2 from the primary drug molecular-concentration contrast between normal muscle and tumor by the proper selection of the illumination wavelength.
|
|
| 6. |
- Afzelius, Mikael, et al.
(författare)
-
Development of multipoint vibrational coherent anti-Stokes Raman spectroscopy for flame applications
- 2006
-
Ingår i: Applied Optics. - 2155-3165. ; 45:6, s. 1177-1186
-
Tidskriftsartikel (refereegranskat)abstract
- A novel technique for coherent anti-Stokes Raman spectroscopy (CARS) measurements in multiple points is presented. In a multipass cavity the pump and Stokes laser beams are multiply reflected and refocused into a measurement volume with an adjustable number of separated points along a line. This optical arrangement was used in a vibrational CARS setup with planar BOXCARS phase-matching configuration. The CARS spectra from spatially separated points were recorded at different heights on a CCD camera. Measurements of temperature profiles were carried out in the burned gas zone of a premixed one-dimensional flame to demonstrate the applicability of this method for temperature measurements in high-temperature regions. The ability to measure in flames with strong density gradients was demonstrated by simultaneous measurements of Q-branch spectra of N-2 and CO in a Wolfhard-Parker burner flame. Interference phenomena found in multipoint spectra are discussed, and possible solutions are proposed. Merits and limitations of the technique are discussed. (c) 2006 Optical Society of America.
|
|
| 7. |
- Afzelius, Mikael, et al.
(författare)
-
Pure rotational coherent anti-Stokes Raman spectroscopy in mixtures of CO and N-2
- 2004
-
Ingår i: Applied Optics. - 2155-3165. ; 43:36, s. 6664-6672
-
Tidskriftsartikel (refereegranskat)abstract
- We present a model for quantitative measurements in binary mixtures of nitrogen and carbon monoxide by the use of dual-broadband rotational coherent anti-Stokes Raman spectroscopy. The model has been compared with experimental rotational coherent anti-Stokes Raman scattering spectra recorded within the temperature range of 294-702 K. Temperatures and concentrations were evaluated by spectral fits using libraries of theoretically calculated spectra. The relative error of the temperature measurements was 1-2%, and the absolute error of the CO concentration measurements was <0.5% for temperatures less than or equal to600 K. For higher temperatures, the gas composition was not chemically stable, and we observed a conversion of CO to CO2. The influence of important spectroscopic parameters such as the anisotropic polarizability and Raman line-broadening coefficients are discussed in terms of concentration measurements. In particular, it is shown that the CO concentration measurement was more accurate if N-2-CO and CO-N-2 line-broadening coefficients were included in the calculation. The applicability of the model for quantitative flame measurements is demonstrated by measuring CO concentrations in ethylene/air flames. (C) 2004 Optical Society of America.
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
|
|
