Intensity Distributions Of Light Sources Research Articles

Direct near-field phase measurement of laser diodes employing a single-mode fiber interferometer

A method of direct measurement of near-field phase and intensity distribution of laser diodes employing a single-mode fiber interferometer is proposed and demonstrated. The phase and intensity of the output beam of the laser in the vicinity of the output facet are measured directly via interferometry. Using a 980 nm laser diode as an example, we obtained a beam width of 0.9 and 3.6 μm at the output facet in the vertical and horizontal axes, respectively. In addition, the phase information of the output beam was also obtained by using interferometry. This technique is particularly useful for laser diodes whose near-field phases are difficult to measure directly. The measured vertical and horizontal wavefront radius of curvatures of a laser diode are in good agreement with the calculation from Gaussian beam theory. Detailed understanding and measurement of the near-field phase and intensity distributions of light sources and optical components are essential for micro-optic designs with better mode matching to minimize the insertion loss.

Measuring and modeling intensity distributions of light sources in waveguide illumination systems

We discuss our experimental measurement and theoretical modeling of flux distributions from light sources used in waveguide illumination systems. We have constructed a computer-controlled goniometric detection system to map the intensity distributions of these light sources. As an example, we measure the intensity distribution of an incandescent light bulb. This light bulb is used in the waveguide illumination system of an automobile dashboard. The intensity distribution of this light bulb is not uniform. We present a model for this intensity distribution based on radiometric principles and the shape of the light bulb filament. This model describes the light bulb's intensity distribution as a function of the filament's projected area as seen from the detector.

Lighting Design in Interreflective Environments Using Hopfield Neural Networks

This paper proposes a method for calculating luminous intensity distributions of multiple light sources taking into account both direct and interreflected light when a desired luminance distribution in a space is given. This inverse lighting problem is useful for designing rooms and tunnels. In our approach, a luminance distribution is specified instead of an illuminance distribution, because it is closely connected to the appearance of rooms and is used for lighting design in a tunnel. To calculate the intensity distributions of light sources quickly and robustly, the property of Hopfield neural networks that their energy converges to a minimum is exploited. The proposed method should greatly facilitate lighting design when used with rendering techniques such as the radiosity method. Several examples including lighting design in a tunnel are shown to demonstrate the usefulness of the proposed method.

球形光束計の測光誤差の検討

球形光束計の測光誤差の検討

Simultaneous acquisition of spectral image information

A technique for the simultaneous acquisition of spectral image information, which implies spectral and spatial intensity distributions of light sources, is described. With this technique projections of an intensity distribution of the source o(x, y, lambda) onto the xy plane are detected simultaneously, and the original distribution is numerically reconstructed from them by using an algorithm of computed tomography. Five projections are obtained experimentally as shared images by means of an imaging system equipped with a transmission grating and detected by a monochromatic television camera. The spatial and spectral distributions of the objects are reconstructed with the multiplicative algebraic reconstruction technique.

A shading model for atmospheric scattering considering luminous intensity distribution of light sources

Studio spotlights produce dazzling shafts of light, while light scattered from fog illuminated by automobile headlights renders driving difficult. This is because the particles in the illuminated volume become visible by scattering light. A shading model for scattering and absorption of light caused by particles in the atmosphere is proposed in this paper. The method takes into account luminous intensity distribution of light sources, shadows due to obstacles, and density of particles. The intensity at a viewpoint is calculated by integration of light scattered by particles between the viewpoint and a given point on an object. The regions to be treated in this manner are localized by considering illumination volumes and shadow volumes caused by obstacles in the illumination volumes.

Instrument for Measuring Angular Intensity Distributions of Light Sources Within a Few Milliseconds

An instrument is described that allows measuring within a few milliseconds the angular intensity distributions of light sources, particularly light scattering objects. The basic idea is to achieve a rapid rotation of the direction of observation by means of a rotating prism and two conical reflecting surfaces. The photosensitive detector as well as the light source remain fixed. Light scattering experiments done with a suspension of polystyrene latex spheres demonstrate the operation of the instrument. The short measuring period is of special importance for the investigation of small particles in time-dependent processes or for serial analyses.