Plenoptic camera measurement and calibration of head-mounted displays
A method for measuring performance of a head-mounted display module, the method including arranging the head-mounted display module relative to a plenoptic camera assembly so that an exit pupil of the head-mounted display module coincides with a pupil of the plenoptic camera assembly; emitting light from the head-mounted display module while the head-mounted display module is arranged relative to the plenoptic camera assembly; filtering the light at the exit pupil of the head-mounted display module; acquiring, with the plenoptic camera assembly, one or more light field images projected from the head-mounted display module with the filtered light; and determining information about the performance of the head-mounted display module based on acquired light field image.
1 . A method for measuring performance of a head-mounted display module, the method comprising:
emitting light from the head-mounted display module while the head-mounted display module is arranged relative to a plenoptic camera assembly;
filtering the light at an exit pupil of the head-mounted display module;
acquiring, with the plenoptic camera assembly, one or more light field images projected from the head-mounted display module with the filtered light; and
determining information about the performance of the head-mounted display module based on acquired light field image.
2 . The method of claim 1 , comprising arranging the head-mounted display module relative to the plenoptic camera assembly so that the exit pupil of the head-mounted display module coincides with a pupil of the plenoptic camera assembly.
3 . The method of claim 1 , wherein the light is filtered by a plurality of spatially discrete filters positioned at a pupil of the plenoptic camera assembly.
4 . The method of claim 3 , wherein the spatially discrete filters comprise color filters.
5 . The method of claim 4 , wherein the color filters comprise X, Y, Z color matching function color filters.
6 . The method of claim 4 , wherein the spatially discrete filters comprise polarization filters, or neutral density filters.
7 . The method of claim 1 , wherein the light is filtered by a first set of spatially discrete filters and a second set of spatially discrete filters overlapping with the first set, the first and second sets of spatially discrete filters filtering different properties of the light.
8 . The method of claim 7 , wherein the properties of the light are selected from a group consisting of color, polarization, and intensity.
9 . The method of claim 1 , wherein acquiring the one or more light field images comprises reimaging a real image from the head-mounted display module to a multi-element sensor using a microlens array.
10 . The method of claim 9 , wherein the microlens array samples portions of an exit pupil of a lens of the plenoptic camera assembly to provide different angular views of the real image from the head-mounted display module.
11 . The method of claim 1 , wherein the plenoptic camera assembly defines a light path from a pupil of the plenoptic camera assembly to a sensor array, the plenoptic camera assembly comprising a camera lens assembly in the light path defining the pupil of the plenoptic camera assembly and defining an image plane, the plenoptic camera assembly further comprising an array of focusing elements in the light path between the image plane and the sensor array.
12 . The method of claim 1 , wherein the information about the performance of the head-mounted display module comprises information about at least one of a performance parameter selected from the group consisting of radiance, luminance, color, geometric distortion, virtual image distance, and field curvature.
13 . The method of claim 1 , wherein determining the information about the performance of the head-mounted display module comprises calculating two-dimensional images at multiple different depths over a three-dimensional volume of interest of the head-mounted display module.
14 . The method of claim 13 , wherein determining the information further comprises determining information about one or more properties of each of the two-dimensional images.
15 . The method of claim 1 , further comprising combining emitted light from multiple different locations of the exit pupil of the head-mounted display module to form multiple overlapping images at a sensor of the plenoptic camera assembly, each of the multiple overlapping images corresponding to a different user view for the head-mounted display module.
16 . The method of claim 1 , wherein acquiring, with the plenoptic camera assembly, one or more light field images comprises acquiring, with a multiplexing assembly and the plenoptic camera assembly, one or more light field images across multiple user pupil positions.
17 . The method of claim 16 , comprising arranging the multiplexing assembly relative to the plenoptic camera assembly so that an exit pupil of the multiplexing assembly coincides with a pupil of the plenoptic camera assembly.
18 . A method for calibrating a head-mounted display, comprising:
measuring a performance of the head-mounted display using the method of claim 1 ; and
adjusting an operation of the head-mounted display based on the measured performance.