ALMA Newsletter N°5
... Only longer waves can escape from such regions, since visible light is absorbed and scattered by dust. ALMA can operate at a wavelength as short as 0.3 mm. However, to resolve features in a planet-forming disk around a star like the Sun, one finds that ALMA must have a total extent, D, of 16 km. The ...
... Only longer waves can escape from such regions, since visible light is absorbed and scattered by dust. ALMA can operate at a wavelength as short as 0.3 mm. However, to resolve features in a planet-forming disk around a star like the Sun, one finds that ALMA must have a total extent, D, of 16 km. The ...
Shaped ultrafast laser pulses in the deep ultraviolet
... There is substantial interest in using ultraviolet light for probing molecular chemistry on a femtosecond timescale. Optical pulse shaping (for example see [1, 2, 3]) has been used extensively in applications that require control over broadband laser pulses. By combining pulse shapers and feedback a ...
... There is substantial interest in using ultraviolet light for probing molecular chemistry on a femtosecond timescale. Optical pulse shaping (for example see [1, 2, 3]) has been used extensively in applications that require control over broadband laser pulses. By combining pulse shapers and feedback a ...
Impact of Liquid Crystals in Active and Adaptive Optics
... shown the possibility of increasing the switching speed of LC valves by at least one order of magnitude with the use of biaxial LCs. This increase is obtained by rotating the LC along the molecules’ small axes instead of the longest ones [24,27]. Nonlinear optics has also benefited from liquid cryst ...
... shown the possibility of increasing the switching speed of LC valves by at least one order of magnitude with the use of biaxial LCs. This increase is obtained by rotating the LC along the molecules’ small axes instead of the longest ones [24,27]. Nonlinear optics has also benefited from liquid cryst ...
Clutter elimination for deep clinical optoacoustic imaging using
... E-mail address: [email protected] (M. Frenz). URL: http://www.iapbp.unibe.ch ...
... E-mail address: [email protected] (M. Frenz). URL: http://www.iapbp.unibe.ch ...
CHAPTER 1 Wave Nature of Light
... The minimum spot size to which a Gaussian beam can be focused • Suppose that we reflect the Gaussian beam back on itself so that the beam is traveling in the –z direction and converging towards O. • The beam would still have the same diameter 2w0 (waist) at O. • From then on, the beam again diverge ...
... The minimum spot size to which a Gaussian beam can be focused • Suppose that we reflect the Gaussian beam back on itself so that the beam is traveling in the –z direction and converging towards O. • The beam would still have the same diameter 2w0 (waist) at O. • From then on, the beam again diverge ...
Experimental demonstration of near-infrared
... [39] (Method 2). Note that another graphical retrieval method with phase unwrapping techniques can also be used to accurately predict the effective parameters of bulk metamaterials from a single layer of unit cells [40]. In addition, the values of n and k calculated from the nonlocal dispersion rela ...
... [39] (Method 2). Note that another graphical retrieval method with phase unwrapping techniques can also be used to accurately predict the effective parameters of bulk metamaterials from a single layer of unit cells [40]. In addition, the values of n and k calculated from the nonlocal dispersion rela ...
4Pi Microscopy
... properties of the dye to break the diffraction barrier. Using two lenses for STED, the axial resolution was improved down to 30 to 50 nm (Dyba and Hell, 2002; Dyba et al., 2003). However, as STED is still in its infancy and, unlike I5M and 4Pi microscopy, relies on the specific properties of the dye ...
... properties of the dye to break the diffraction barrier. Using two lenses for STED, the axial resolution was improved down to 30 to 50 nm (Dyba and Hell, 2002; Dyba et al., 2003). However, as STED is still in its infancy and, unlike I5M and 4Pi microscopy, relies on the specific properties of the dye ...
Absolute length measurement of prismatic bodies with PTB´s new
... Traceability of length measurements to the international system of units (SI) can be realized by using optical interferometry. This paper describes PTB´s new double-ended interferometer, which is used to determine the absolute length of prismatic bodies (e.g. gauge blocks) from the analysis of two s ...
... Traceability of length measurements to the international system of units (SI) can be realized by using optical interferometry. This paper describes PTB´s new double-ended interferometer, which is used to determine the absolute length of prismatic bodies (e.g. gauge blocks) from the analysis of two s ...
... This thesis presents the development and assessment of imaging techniques in the millimeterwave (mmW) and terahertz frequency bands. In the first part of the thesis, the development of a 94 GHz passive screener based on a total-power radiometer (TPR) with mechanical beamscanning is presented. Severa ...
Enhanced 3D spatial resolution in quantitative phase
... samples using quadri-wave interferometry,” Proc. SPIE 8587, 85871D (2013). ...
... samples using quadri-wave interferometry,” Proc. SPIE 8587, 85871D (2013). ...
Comprehensive and reliable diagnostics for the corona of laser
... plasma. Assume that the plasma density profile is given as, n e ( z ) = n e 0 exp(− z / l s ) . Then the error σ induced by the deflection of the rays can be approximated as σ = L • θ . For L ~ 300 µm, in order to control the total error under 20 µm, the error of refraction should be less than < 15 ...
... plasma. Assume that the plasma density profile is given as, n e ( z ) = n e 0 exp(− z / l s ) . Then the error σ induced by the deflection of the rays can be approximated as σ = L • θ . For L ~ 300 µm, in order to control the total error under 20 µm, the error of refraction should be less than < 15 ...
Opto acoustic
... characterized by its scattering cross section [m2] and phase function p(), using Mie theory the scattering may be determined knowing; the size parameter (perimeter compared to wavelength), refractive index ratio between particle and media. ...
... characterized by its scattering cross section [m2] and phase function p(), using Mie theory the scattering may be determined knowing; the size parameter (perimeter compared to wavelength), refractive index ratio between particle and media. ...
Optical interference component irradiances."
... Note that this is for the case of maxima in reflected light, but also minima in the transmitted light. The case for minima in reflected light and maxima in transmitted light is as follows: ...
... Note that this is for the case of maxima in reflected light, but also minima in the transmitted light. The case for minima in reflected light and maxima in transmitted light is as follows: ...
26 - Journal of Optoelectronics and Advanced Materials
... Assuming that the charge carriers generated in the p- and n-layer do not contribute to the photocurrent, the i-layer represents the absorber layer. It was prepared using a gas mixture of silane, methane and hydrogen. Thus, it is composed of amorphous silicon carbide (a-SiC:H) and has an optical band ...
... Assuming that the charge carriers generated in the p- and n-layer do not contribute to the photocurrent, the i-layer represents the absorber layer. It was prepared using a gas mixture of silane, methane and hydrogen. Thus, it is composed of amorphous silicon carbide (a-SiC:H) and has an optical band ...
incoherent
... simple object: two point sources narrowband, mutually incoherent (input field is spatially incoherent) MIT 2.71/2.710 Optics 11/10/04 wk10-b-11 ...
... simple object: two point sources narrowband, mutually incoherent (input field is spatially incoherent) MIT 2.71/2.710 Optics 11/10/04 wk10-b-11 ...
Optics of Anisotropic Media
... and we identify it as the direction of the ray of familiar geometric optics. Whereas in isotropic media the ray is always parallel to the wave vector, and is therefore perpendicular to the wavefront, this is no longer so in anisotropic media, except for propagation along one of the principal axes. T ...
... and we identify it as the direction of the ray of familiar geometric optics. Whereas in isotropic media the ray is always parallel to the wave vector, and is therefore perpendicular to the wavefront, this is no longer so in anisotropic media, except for propagation along one of the principal axes. T ...
Thermal Lensing in a Nd:YAG Laser Rod
... within the accuracy of these two methods which we believe is in the order of 20%. In order to check the degree of physical distortion in the flatness of the rod ends under pump light an experiment as shown in Fig. 5 was performed. The collimated beam of a He-Ne gas laser reflected off the first surf ...
... within the accuracy of these two methods which we believe is in the order of 20%. In order to check the degree of physical distortion in the flatness of the rod ends under pump light an experiment as shown in Fig. 5 was performed. The collimated beam of a He-Ne gas laser reflected off the first surf ...
Review and Comparison of High
... noise, the conventional intensity-based pixel saturation identification method is sometimes susceptible, which determines the brightest intensity reaching the highest quantization level, for example, 255 for an 8-bit camera. Thus, the brightest intensity recorded in a pixel can be unstable and devia ...
... noise, the conventional intensity-based pixel saturation identification method is sometimes susceptible, which determines the brightest intensity reaching the highest quantization level, for example, 255 for an 8-bit camera. Thus, the brightest intensity recorded in a pixel can be unstable and devia ...
Biomedical Imaging and Applied Optics Laboratory
... changes have been found to be diagnostically useful in scattering spectroscopy in the visible range. Cellular organelles in epithelial tissue can be modelled as spheroidal scatterers whose interactions with light are governed by Mie theory. Mie theory provides an analytical closed-form description o ...
... changes have been found to be diagnostically useful in scattering spectroscopy in the visible range. Cellular organelles in epithelial tissue can be modelled as spheroidal scatterers whose interactions with light are governed by Mie theory. Mie theory provides an analytical closed-form description o ...
Get PDF - OSA Publishing
... where s = (s x , sy , sz ) is a unit vector normal to the spherical wavefront and k = 2π/λ is the wavenumber of the incident illumination and f is the focal length of the lens. It can be shown [12] that in order for this to be valid one requires z p ≪ f and that the Fresnel number of the lens must b ...
... where s = (s x , sy , sz ) is a unit vector normal to the spherical wavefront and k = 2π/λ is the wavenumber of the incident illumination and f is the focal length of the lens. It can be shown [12] that in order for this to be valid one requires z p ≪ f and that the Fresnel number of the lens must b ...
Yu Chen
... Diffuse optical spectroscopy (DOS) and tomography (DOT) using NearInfrared (NIR) light provide promising tools for non-invasive imaging and clinical diagnosis of deep tissue. These techniques are capable of quantitative reconstructions of tissue absorption and scattering properties, thus can map in ...
... Diffuse optical spectroscopy (DOS) and tomography (DOT) using NearInfrared (NIR) light provide promising tools for non-invasive imaging and clinical diagnosis of deep tissue. These techniques are capable of quantitative reconstructions of tissue absorption and scattering properties, thus can map in ...
Motion of hot spots in smoothed beams
... and plasma. Smoothing techniques are relevant here in that they create inside the focal spot many hot spots that disappear rapidly within a few picoseconds. Although a low optical contrast is not required for indirect drive, it is necessary to turn off the hot spots in a short time. The use of one-d ...
... and plasma. Smoothing techniques are relevant here in that they create inside the focal spot many hot spots that disappear rapidly within a few picoseconds. Although a low optical contrast is not required for indirect drive, it is necessary to turn off the hot spots in a short time. The use of one-d ...
Performance of synchronous optical receivers using atmospheric
... received signal matches that of the local oscillator. Any mismatch of the amplitudes and phases of the two fields will result in a loss in downconverted power. Adaptive compensation of atmospheric wave-front phase distortion to improve the performance of atmospheric systems has been an important fie ...
... received signal matches that of the local oscillator. Any mismatch of the amplitudes and phases of the two fields will result in a loss in downconverted power. Adaptive compensation of atmospheric wave-front phase distortion to improve the performance of atmospheric systems has been an important fie ...
Phase-contrast X-ray imaging
Phase-contrast X-ray imaging (PCI) or phase-sensitive X-ray imaging is a general term for different technical methods that use information concerning changes in the phase of an X-ray beam that passes through an object in order to create its images. Standard X-ray imaging techniques like radiography or computed tomography (CT) rely on a decrease of the X-ray beam's intensity (attenuation) when traversing the sample, which can be measured directly with the assistance of an X-ray detector. In PCI however, the beam's phase shift caused by the sample is not measured directly, but is transformed into variations in intensity, which then can be recorded by the detector.In addition to producing projection images, PCI, like conventional transmission, can be combined with tomographic techniques to obtain the 3D distribution of the real part of the refractive index of the sample. When applied to samples that consist of atoms with low atomic number Z, PCI is more sensitive to density variations in the sample than conventional transmission-based X-ray imaging. This leads to images with improved soft tissue contrast.In the last several years, a variety of phase-contrast X-ray imaging techniques have been developed, all of which are based on the observation of interference patterns between diffracted and undiffracted waves. The most common techniques are crystal interferometry, propagation-based imaging, analyzer-based imaging, edge-illumination and grating-based imaging (see below).