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Search Publications by: Yoshi Ohno (Fed)

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Displaying 126 - 150 of 198

Luminous Intensity of LEDs at NIST

October 1, 2001
Author(s)
Carl C. Miller, Yoshihiro Ohno
Calibration facilities and procedures for measurement of Averaged LED intensity using the detector-based method have been developed at the National Institute of Standards and Technology (NIST). The scale has been established on two standard photometers

Photometry: Sensing Light Color

September 1, 2001
Author(s)
Yoshihiro Ohno, Steven W. Brown
This article first addresses the need and importance of photometry and colorimetry for many products in our daily life- light bulbs in homes and offices; TV sets, computer monitors, headlights of cars, traffic lights, etc. Then the concepts of photometry

The Art and Science of Lamp Photometry

August 1, 2001
Author(s)
R S. Bergman, Yoshi Ohno
This paper first overviews photometric quantities of lamps - luminous flux, luminous intensity, illuminance, and luminance - and general techniques for measurement of these quantities to characterize lamps. The total luminous flux of lamps (in lumens) is

Total Luminous Flux Calibrations of LEDs at NIST

August 1, 2001
Author(s)
Carl C. Miller, Yoshihiro Ohno
The total luminous flux (lumen) is one of the most important characteristics of Light Emitting Diodes (LEDs), and is commonly measured using integrating sphere photometers. Large variations of measurement results are reported among different manufacturers

Luminous Intensity Calibrations and Colorimetry of LEDs at NIST

July 1, 2001
Author(s)
Carl C. Miller, Yoshihiro Ohno
Light Emitting Diodes (LEDs) are unique light sources differing greatly from traditional lamps in terms of physical size, flux level, spectrum and spatial distribution. The transfer of photometric scales from luminous intensity standard lamps to LEDs is

NIST Colorimetric Calibration Facility for Displays - Part 2

June 1, 2001
Author(s)
F Manoocheri, Steven W. Brown, Yoshi Ohno
velopment of a calibration facility for spectroradiometric, colorimetric, and goniometric measurements of displays, display colorimeters, and spectroradiometers has been completed at the National Institute of Standards and Technology (NIST). An overview of

Luminous Flux Calibrations of LEDs at NIST

May 1, 2001
Author(s)
Carl C. Miller, Yoshihiro Ohno
The total luminous flux (lumen) is one of the most important characteristics of Light Emitting Diodes (LEDs), and is commonly measured using integrating sphere photometers. Large variations of measurement results are reported among different manufacturers

Spectroradiometer Characterization for Colorimetry of LEDs

May 1, 2001
Author(s)
Yoshihiro Ohno, B Kranicz
The uncertainties in color measurements of LEDs by spectroradiometers can be much larger than those for traditional broadband sources due to the quasi-monochromatic nature of LED spectra. In this paper, the uncertainties in chromaticity of LEDS due to

A Numerical Method for Color Uncertainty

January 1, 2001
Author(s)
Yoshihiro Ohno
A method for calculating uncertainties of color quantities has been developed using a numerical approach based on the ISO Guide to the Expression of Uncertainty in Measurement. The uncertainties of any color quantities such as chromaticity coordinates

An Assessment Standard for the Evaluation of Display Measurement Capabilities

November 1, 2000
Author(s)
John M. Libert, Paul A. Boynton, Edward F. Kelley, Steven W. Brown, Yoshi Ohno
A prototype display measurement assessment transfer standard (DMATS) is being developed by NIST to assist the display industry in standardizing measurement methods used to quantify the performance of electronic displays. Designed as an idealized electronic

An AC/DC Technique for the Absolute Integrating-Sphere Method

October 1, 2000
Author(s)
Yoshihiro Ohno, R Kohler, M F. Stock
The Bureau International des Poids et Mesures (BIPM) has historically maintained the results of international intercomparisons of luminous intensity and luminous flux as so-called world-mean values in the form of groups of lamps for more than 60 years. It

CIE Fundamentals for Color Measurements

October 1, 2000
Author(s)
Yoshihiro Ohno
The paper first overviews the CIE system of colorimetry, covering CIE 1931 color matching functions, XYZ tristimulus values, the x, y diagram, the 1976 u', v' diagram, and the evolvement of CIELUV and CIELAB color spaces and color difference formulae. The

Color Issues of White LEDs

October 1, 2000
Author(s)
Yoshihiro Ohno
For white LEDs to be used for general lighting, they should have appropriate white color and good color rendering performance for illuminated objects. Color rendering, as well as energy efficiency (efficacy), have been the two most important criteria for