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Microdisplays are usually extremely small displays with very small pixels. They serve, for example, as a built-in image source in many modern AR/VR/XR applications. Since other optical components usually magnify them, they require a very high pixel density. There are already models with a resolution of several thousand pixels per inch. 
Since microdisplays can base on LCD, µLED or OLED technology, the same measurement applications become relevant. In particular uniformity and DeMURA, i.e., the assignment of luminance and/or chromaticity to specific pixels and resolution measurements — to check the resolution capability of the display and the possible crosstalk between the small subpixels — are relevant measurement applications. But effects such as image sticking or conoscopic luminance, contrast, and color can also be relevant measurement points. While the evaluations and methods are identical to those of standard displays regarding software, the imaging conditions are exceptional.

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Single pixel line of a microdisplay. One display pixel is 11 μm.

Our solution

TechnoTeam offers a wide range of high-magnification macroscopic and microscopic lenses that characterize this demanding display type to meet the unique requirements of microdisplay metrology. Our standard lenses cover optical magnification from 0.5 to 50, which, combined with our LMK6, corresponds to an optical resolution of 7.5 micrometer/camera pixel to theoretically up to 0.075 micrometer/camera pixel. If a luminance image exists, you can use the standard software add-ons to evaluate the measurands.

RELEVANT PRODUCTS

RELEVANT PUBLICATIONS

International Conference on Display Technology (ICDT 2024)

In this contribution, we present typical practical implications of high magnification lenses required for camera-based microdisplay measurements and analyze their impact on existing measurement methods for DeMURA, resolution and contrast. Furthermore, we show hardware and software-based methods to improve or handle the shortcomings of these high-magnification lenses.
Authors: Ingo Rotscholl, Kilian Kirchhoff, Stefan Schramm, Bob Liu, Udo Krüger

International Display Workshop (IDW 2023)

In this contribution we research calibration related impacts on MTF measurements using the Slanted Line approach in oversampling conditions. Based on this we propose a simplified workflow of the Slanted Line MTF method and conclude benefits and limitations of these setup conditions.
Authors: I. Rotscholl, U. Krüger

International Conference on Display Technology (ICDT 2023)

This paper provides an overview of image stitching and its general advantages and challenges. Further, we introduce a novel stitching concept based on our advanced pixel registration (APR) procedure. It allows easy and comparable flexible stitching setups for DeMURA and uniformity measurements in laboratory and production environments.
Authors: Ingo Rotscholl, Bob Liu, Udo Krüger