Automated optical measurement system and method for near eye display
An automated optical measurement system and method for a near eye display are provided. A controller first controls the near eye display to display a specific pattern, then controls a displacement generation module to drive an image sensing module toward or away from an imaging module, and controls the image sensing module to capture the specific pattern to obtain focus images; and the controller performs focusing according to the focus images. Finally, the controller measures an optical characteristic of the near eye display. Accordingly, the focusing method used is to capture the specific pattern displayed by the near eye display while moving the image sensing module, and perform automatic focusing by comparing the capture results.
1 . An automated optical measurement system for a near eye display, comprising:
an imaging module, configured to face the near eye display;
an image sensing module, connected to the imaging module;
a displacement generation module, adapted to displace the image sensing module in at least one dimension; and
a controller, electrically connected to the near eye display, the image sensing module, and the displacement generation module,
wherein the controller is configured to:
control the near eye display to display a specific pattern comprising a high-contrast slanted edge pattern;
control the displacement generation module to drive the image sensing module to a plurality of positions relative to the imaging module; and
control the image sensing module to capture the specific pattern at each of the plurality of positions to obtain a plurality of focus image; and
perform a focusing process by:
obtaining a line spread function from the plurality of focus images based on edge information of the high-contrast slanted edge pattern via differential processing;
calculating Modulation Transfer Function (MTF) values by performing a Fast Fourier Transform (FFT) on the line spread function, thereby generating a curve waveform representing the Modulation Transfer Function values versus spatial frequency;
transforming the curve waveform into a focus curve; and
determining a peak of the focus curve and controlling the displacement generation module to drive the image sensing module to a position corresponding to the peak.
2 . The automated optical measurement system according to claim 1 , wherein the controller further controls the image sensing module to measure at least one of imaging quality, color brightness, accommodation distance (AID), virtual image distance (VID), and binocular refractive power of the near eye display.
3 . An automated optical measurement method for a near eye display, comprising the following steps:
(A) controlling, by a controller, the near eye display to display a specific pattern comprising a high-contrast slanted edge pattern;
(B) performing, by the controller, a focusing process, the focusing process comprising:
controlling a displacement generation module to drive an image sensing module to a plurality of positions relative to an imaging module;
controlling the image sensing module to capture the specific pattern at the plurality of positions to obtain a plurality of focus images, wherein the imaging module is between the near eye display and the image sensing module;
obtaining a line spread function from the plurality of focus images based on edge information of the high-contrast slanted edge pattern via differential processing;
calculating Modulation Transfer Function (MTF) values by performing a Fast Fourier Transform (FFT) on the line spread function, thereby generating a curve waveform representing the Modulation Transfer Function values versus spatial frequency;
transforming the curve waveform into a focus curve; and
determining a peak of the focus curve and controlling the displacement generation module to drive the image sensing module to a position corresponding to the peak; and
(C) measuring, by the controller, an optical characteristic of the near eye display using the image sensing module positioned at the position corresponding to the determined peak.
4 . The automated optical measurement method according to claim 3 , wherein in step (C), the optical characteristic comprises at least one of imaging quality, color brightness, accommodation distance (AID), virtual image distance (VID), and binocular refractive power of the near eye display.