Size Of Light Source Research Articles

Interactions among Light Source Luminance, Illuminance and Size on Discomfort Glare

Discomfort glare from vehicle lighting is more difficult to measure precisely than disability glare, but may have important implications for driver behavior, and in turn on driving safety. Many studies of discomfort glare have found that, as with disability glare, the illuminance at the eyes from a bright light is the primary determinant of the sensation of glare. Nonetheless, the luminance of a light source also can influence discomfort glare, especially when the source is close enough to subtend a relatively large visual angle on the order of a third of a degree or larger. In addition, interactions with the absolute illuminance from a light source are not well understood. The results of an experimental investigation of discomfort glare in terms of light source illuminance, luminance and size are presented and discussed along with implications for automotive lighting applications. Language: en

Effects of speckle in Makyoh topography for the studies of extended defects

The effects of the speckle phenomenon on Makyoh-topography imaging is analysed. The speckle manifests itself as a quasiperiodic pattern in the Makyoh image which is easily mistaken for an image of a periodic surface morphology. The characteristic signature of speckles in Makyoh images is determined, thus allowing for its recognition. The effects of speckle on the Makyoh imaging is analysed as a function of surface roughness, illumination coherency and wavelength, light source size and instrumental parameters. It is shown that speckle effects are present even for incoherent illumination because of the coherency enhancement due to the limited source size. The findings are illustrated with experimental images of various semiconductor samples.

Mueller matrix imaging of targets under an air-sea interface

The Mueller matrix imaging method is a powerful tool for target detection. In this study, the effect of the air-sea interface on the detection of underwater objects is studied. A backward Monte Carlo code has been developed to study this effect. The main result is that the reflection of the diffuse sky light by the interface reduces the Mueller image contrast. If the air-sea interface is ruffled by wind, the distinction between different regions of the underwater target is smoothed out. The effect of the finite size of an active light source is also studied. The image contrast is found to be relatively insensitive to the size of the light source. The volume scattering function plays an important role on the underwater object detection. Generally, a smaller asymmetry parameter decreases the contrast of the polarimetry images.

Near-Field Scanning Nanophotonic Microscopy—Breaking the Diffraction Limit Using Integrated Nano Light-Emitting Probe Tip

We introduce a novel scanning ldquonanophotonicrdquo microscope through monolithic integration of a nanoscale LED (Nano-LED) on a silicon cantilever. We review two recent trends of incorporating miniature light sources on the scanning probes for near-field scanning optical microscopy: one is to attach fluorephores at the tip to define a small light source, while the other is to integrate an LED and a nanometer aperture into scanning probes, based on silicon microfabrication techniques. The creation of Nano-LED combines the advantages of previous two approaches: no external sources are required and the reduction of the light source size directly leads to resolution improvement. Two types of Nano-LEDs have been successfully demonstrated utilizing nanofabrication and microelectromechanical systems technologies: 1) formation of thin silicon dioxide light-emitting layer between heavily doped p + and n+ silicon layers created by a focused ion beam and 2) electrostatic trapping and excitation of CdSe/ZnS core-shell nanoparticles in a nanogap. We employed these probes into a standard near-field scanning and excitation setup. The probe successfully measured optical as well as topographic images of chromium test patterns with imaging resolutions of 400 and 50 nm, respectively. In addition, the directional resolution dependence of the acquired images suggests the size and shape of the light source. To our knowledge, these results are probably the first successful near-field images directly measured by such tip-embedded light sources. With the potential emission capability from near UV to IR and additional mass producibility, the nanophotonic microscope presents exciting opportunities in near-field optics, integrated circuit technology, nanomanufacturing and molecular imaging, and sensing in biomedicine.

Photographic methods to detect colourants in archaeological textiles

Protocols for photography of archaeological textiles to detect components of differing chemistry that are indicative of colourants were developed. Parameters of light source, camera distance, filter type, film type, film speed, and aperture size were evaluated for visible, UV-reflectance, UV-fluorescence, and infrared photography. Using these techniques facilitates selective sampling for further analysis that maximizes critical data acquisition while minimizing destruction of the artefact. Hence, forensic photography of archaeological perishable materials should be regarded as a precursor to destructive analytical methods.

Resolution of a reflection hologram recorded with a slit

Resolution of the reconstructed image is evaluated for the reflection hologram recorded by use of a slit. Sharp and deep images are obtained because the resolution in the vertical direction is higher than that of the conventional reflection holograms and is independent of the size of the illuminating light source. In contrast, the resolution in the horizontal direction depends on the light-source size in this direction. The optimum source size is discussed in connection with the balance in the resolutions for both directions. A method for obtaining the vertical parallax by use of multiple slits is proposed, and application of the proposed hologram to the heads-up display is also demonstrated.

Dimensional control of metallic objects by artificial vision: contribution to lighting condition studies

We present an original method that enables real time automatic dimensional control of defects on metallic objects. The method is based on the theoretical and experimental study of light reflection mechanisms that can be seen as a function of the surface roughness and of the light source size. We show that it is possible to reconstruct the profile of an object from a single gray level image. An industrial application enables us to validate our results. Finally, an error computation fixes the limits of our method and enables us to better understand illumination problems.

Fabrication and testing of hard x-ray sputtered-sliced zone plate

A sputtered-sliced hard x-ray zone plate has been made by the physical vapor deposition of alternating transparent and opaque layers onto a fine gold wire core of 50 μm diameter. The zone plate is designed to operate with a focal length of 124 mm at 8.05 eV and consists of 25 pairs of alternating Ag and C layers with a thickness of ∼40 μm along the wire axis. Using monochromized synchrotron x ray with an energy of 8.05 keV the minimum focal spot size attained for the first order focal beam was 2.3 μm in the vertical and horizontal directions, respectively. The light-collecting efficiency was determined to be ∼4%. The focal spot size obtained was substantially larger than the 1.2 μm φ spatial resolution predicted from the contradiction of the light source size.

Equivalent Veiling Luminance Caused by Small Glare Light Source near the Visual Line.

An experiment was conducted on the degradation of visibility when affected by glare light sources near the visual line, to examine the effects of glare light source size and eccentricity, and background luminance on the equivalent veiling luminance. In this experiment, a circular glare light source of diameter 3 to 27 minutes was presented near the visual line of an observer. Landolt rings were employed as test objects on a screen panel. When the size of the glare light source was relatively small, the rate of degradation in visibility depended on not only the luminous intensity of the light but also its size.

Minimal angle of resolution in monocular, single-colour vision and the TAIS model.

The mathematical model TAIS simulates visual perception of single-colour or black-and-white, non-moving objects. It makes an analysis of the luminance spatial distribution in an optional direction and describes it in linguistic terms. The model comprises three modules that successively convolve the luminance distribution with a spatial filter (a normalized Gaussian function), calculate the second derivative of the convolution and, with use of context-free and context-sensitive grammars, generate a string of symbols. The string of symbols contains the information, simplified in form and rectified from visual noise, about perceived spatial changes of brightness. The model simulates various visual phenomena, e.g. edge detection and spatial resolution, and it predicts the resolving power dependence on the light source size. The model-generated dependence of minimal angle of resolution on the light source width fits the experimental data with linear correlation coefficients in the range 0.70-0.94. The diagram consists of decreasing and constant parts, its shape adjusted to experimental data through selection of the Gaussian filter parameter and second derivative threshold.

画像解析による輝度データからの光源の位置、輝度、立体角の測定

画像解析による輝度データからの光源の位置、輝度、立体角の測定

Lighting Quality and Light Source Size

Lighting Quality and Light Source Size

Stellar occultation of polarized light from circumstellar electrons. I - Flat envelopes viewed edge on

The depolarizing and occultation effects of a finite spherical light source on the polarization of light Thomson-scattered from a flat circumstellar envelope seen edge-on are analyzed. The analysis shows that neglect of the finite size of the light source leads to a gross overestimate of the polarization for a given disk geometry. By including occultation and depolarization, it is found that B-star envelopes are necessarily highly flattened disk-type structures. For a disk viewed edge-on, the effect of occultation reduces the polarization more than the inclusion of the depolarization factor alone. Analysis of a one-dimensional plume leads to a powerful technique that permits the electron density distribution to be explicitly obtained from the polarimetric data.

Apparent transfer function for partially coherent optical information processing

In this paper, the general formulations of the apparent transfer function for the partially coherent optical processor will be derived. Although these formulas show that the apparent transfer function is dependent upon the degree of spatial and temporal coherence, there is actually more variability in the spatial coherence. We note that the obtained formulas may also be used as a criterion in the selection of source size and spectral bandwidth of an incoherent light source. Thus a specific optical information processing operation can be carried out with an incoherent source.

A fundamental study on the quantity of veiling light caused by a highly luminant light source

The results of the study on the threshold value of visual perception of Landolt’s Ring visual targets within the visual field in a visual environment having uniform background luminance has already been reported. In the present paper are described the results of an experiment concerning the effect of a highly luminant object such as a light source or window existing in the visual field on the threshold value of visual perception. In the experiment, an apparatus as shown in Fig. 1 and a target consisting of a sheet of unglossed printing paper with its one half printed in black were used, and the observers were told to adjust the position at which the boundary of the white and black parts of the target become imperceptible as the target was brought near to the light source. Considering that at that point the contrast of the target and the background luminance were changed to the threshould value of visual perception by the veiling light produced by the highly luminant light source, the quantity of the veiling light was calculated. The results of the calculation obtained are summarized as follows:(1) The veiling light radically decreases in the inverse proportion to the light source deflection angle from the position at which the glare light source does not enter directly into the fovea centralis of the eye.(2) The quantity of the veiling light occurring in the human visual system increases approximately in direct proportion to the increase of the luminance of the glare light source.(3) When the size of the glare light source is increased, the quantity of the equivalent veiling luminance increases approximately in the direct proportion to the increased size.(4) For the quantity of the equivalent veiling light when the size of a light source is large, the large glare light source should be divided by the solid angle of 1° visual angle and the quantities of the equivalent veiling light generated by the respective units of the divided light source should be summed up, and thus the background luminance and the contrast can be obtained.

Hologram Reconstruction by Incoherent Light. I. Theoretical Foundation

Theoretical considerations are presented on characteristics of holograms reconstructed by incoherent light after recorded by coherent light. The following problems are discussed: (1) The generalized formula for the reconstructed image by incoherent light, (2) image blur from color dispersion (the lack of temporal coherence) and by the reconstructing light source size (the lack of spatial coherence), (3) the distortion of the reconstructed images depending on the wavelength ratio of reconstructing to recording light, (4) the degree of the improvement for the achromatized reconstructed images with the diffraction grating (or hologram) for compensating color dispersion.

Influence of Light Source Size on Diffraction by an Opaque Strip

In this paper the effect of the extension of the light source on the interference fringes in the geometrical shadow of an opaque strip is examined. A relation between the width of the light source, the distance of the light source to the opaque strip, and the wavelength on which the interference fringes may be seen is established.

Influence of Light Source Size on Interference

In this paper the effect of the extension of two coherent light sources on interference fringes is examined. The change in the aspect of the fringes when the coherent sources are widened in the same direction is discussed. A relation between the width of the coherent sources, the distance of the screen, and the wavelength for which the interference fringes may be seen, is established. This relation is discussed in connection with some special cases.

Control of Fluorescent Screen Dot Size for Color TV

Methods of fabricating dot fluorescent screens for color television mask-type tubes are summarized, and the dot size control factors associated with the different methods are explored. Special emphasis is given to screening factors for focus mask-type tubes which have high-transmission masks. The tube and mask geometry is studied, and the effect of light-intensity gradients across the dot image as a function of light source size is considered. From these studies, and a knowledge of the physical characteristics of the binder and phosphor materials, an optical method of dot-size control is developed using photographic exposure time and light source size as the parameters. Lastly, annulus-shaped light exposure sources are considered and are shown to produce images having improved size control characteristics.

Physical Optic Analysis of Image Quality in Schlieren Photography

This paper will consider the schlieren system as a problem in physical optics. On the basis of such considerations the effect of aperture, focal length, light-source size, and knife-edge position on the quality of schlieren photographs will be discussed. First, the mathematical analysis of the subject will be briefly presented. On the basis of this analysis the schlieren system will be considered using a point source. The case of finite- source size then will be discussed. A brief discussion of the effect of astigmatism on the focal length of the system also will be presented.