Virtual image display having a high efficiency grid beamsplitter
First Claim
1. A virtual image display system comprising:
- an image source for providing polarized light disposed at one end an optical path;
a relay lens disposed along the optical path for transmitting the polarized light provided by the image source;
a concave mirror disposed at an opposite end of the optical path;
a quarter-wave plate disposed along the optical path between the relay lens and the concave mirror, anda grid beamsplitter disposed along the optical path between the relay lens and the quarter-wave plate;
and wherein the concave mirror produces a virtual magnified image of the image source at the location of a user.
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Abstract
A focusable virtual image display system employing a focusable image source such as a cathode ray tube and imaging optics to provide a virtual image. The virtual image is viewable by a user and its effective range may be changed without changing the apparent field of view or resolution. By placing the focus point of the imaging optics at the design eye, the image source is moved backwards and forwards, thus effectively changing the range of the virtual image observed by the user without changing the apparent field of view or resolution. The present invention allows the user to adjust the focus position of the virtual image of the image source by moving it relative to the imaging optics, while maintaining the size and resolution of the image. If the user wants to move the image further away, when the image source is moved, the imaging optics moves the virtual image further away and magnifies the image such that the angular field of view stays the same. The user cannot distinguish between the sizes, although the focus will be more comfortable for a particular accommodation range. The relative cost of the virtual image display system is relatively less expensive than large screen monitors due to the nature and complexity of the smaller components. By including a focus adjustment mechanism, the focusable virtual image display monitor has an added feature that a conventional large screen monitor does not provide.
152 Citations
20 Claims
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1. A virtual image display system comprising:
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an image source for providing polarized light disposed at one end an optical path; a relay lens disposed along the optical path for transmitting the polarized light provided by the image source; a concave mirror disposed at an opposite end of the optical path; a quarter-wave plate disposed along the optical path between the relay lens and the concave mirror, and a grid beamsplitter disposed along the optical path between the relay lens and the quarter-wave plate; and wherein the concave mirror produces a virtual magnified image of the image source at the location of a user. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. In a virtual image display system comprising an image source for providing polarized light, a relay lens for transmitting the polarized light, a concave mirror reflecting the polarized light, and a quarter-wave plate disposed between the relay lens and the concave mirror, wherein the improvement comprises:
a grid beamsplitter disposed between the relay lens and the quarter-wave plate. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A grid beamsplitter for use in a virtual image display system including an image source for providing polarized light, a relay lens for transmitting the polarized light, a concave mirror reflecting the polarized light, and a quarter-wave plate disposed between the relay lens and the concave mirror, and wherein the beamsplitter is disposed between the relay lens and the quarter-wave plate, said grid beamsplitter comprising:
a relatively flat optically transparent substrate having metal grid lines with spacing much less than the wavelength of visible light projected by the image source formed on its surface. - View Dependent Claims (17, 18, 19, 20)
Specification