Luminance measurement for curved surface sources with an imaging luminance measurement device

Abstract

Due to the advantages of fast measurement speed, imaging luminance measurement devices (ILMDs) have become more and more popular in the recent years. However, even though an ILMD is corrected by flat field calibration, the measured results deviate from the real values when measuring curved surface sources. The deviation is larger in particular when the curvature of the source is smaller or when the source is unlike a Lambertian source. This paper shows how to obtain correction factors to increase the measurement accuracy of the ILMD when measuring different types of curved surface sources. The issue of how the measurement conditions affect the level of image blur is also discussed in this paper.

28.5: Metrological Challenges of non‐planar Displays

“…Some recent publications have addressed a selection of specific problems that are related to the measurement of the electro-optical properties of non-planar displays and light sources. Yu et al [4] analyze the effect of defocusing (in the case of imaging LMDs) on measurement results and conclude that it is rather the directional variation of emission (or transmission) of the display under test and the geometry of the measurement setup that are causing increased uncertainties. The case that conoscopic instruments measure cylindrical displays behind a cover glass with the front focal plane being above the display is analyzed by Boher et al, [5] with respect to angular distortions.…”

“…Since imaging LMDs have been calibrated for the case of planar objects of measurement, the measurement of non-planar samples may introduce errors due to de-focusing. Analyses of this effect by Yu [4] identify the main sources of measurement uncertainty to be the directional variation of light emission and the geometrical details of the measurement setup.…”

“…In order to control Moiré-effects, measurements can be done defocused [7]. Thus one has to be aware of the focus plane / depth of focus [4].…”

33‐1: Invited Paper: Metrological Challenges of Curved Displays

“…Some recent publications have addressed a selection of specific problems that are related to the measurement of the electrooptical properties of non-planar displays and light sources. Yu et al [1] analyze the effect of defocusing of imaging LMDs on the measurement results and conclude that it is rather the directional variation of emission (or transmission) of the display under test and the geometry of the measurement setup that are causing increased uncertainties. The case that conoscopic instruments measure cylindrical displays behind a cover glass with the front focal plane being above the display is analyzed by Boher et al, [2] with respect to angular distortions.…”

“…Since imaging LMDs have been calibrated for the case of planar objects of measurement, the measurement of non-planar samples may introduce errors due to de-focusing. Analysis of this effect by Yu [1] identify the main sources of measurement uncertainty to be the directional variation of light emission and the geometrical details of the measurement setup.…”