BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a polygonal prism, and in particular, to a polygonal prism that can be used to convert an incoming ray of light into separate light rays.
2. Description of the Prior Art
The advancements in technology have made laser appliances useful for a wide variety of applications. Examples include laser levelers for use in marking lines in engineering work, and optical instruments or lenses for survey instruments. A polygonal prism is a basic part of these laser devices.
Conventional polygonal prisms are typically provided in the form of two pieces (e.g., a triangular three-dimensional piece and a pentagonal three-dimensional piece) that are glued together to form the polygonal prism. Selected planes or surfaces of the two pieces are coated with semi-reflective film or fully reflective film to alter the path of a light beam that is directed at selected planes or surfaces of the polygonal prism. Specifically, the incident (i.e., incoming) light is refracted or reflected to change the directions of the light, so that the polygonal prism outputs a plurality of light beams that are emitted at desired and precise angles with respect to each other.
Unfortunately, precision in the bonding of the two prism pieces is critical. Specifically, the two prism pieces must be bonded precisely before undergoing precision polishing. In addition, for the emitted light outputs to be accurate, certain surfaces or planes of the two prism pieces must be precisely parallel to each other after the two prism pieces are bonded together. Unfortunately, this precise bonding can be difficult and expensive to accomplish.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a polygonal prism that is made in a single piece.
It is another object of the present invention to provide a polygonal prism which is provided at lower costs.
It is yet another object of the present invention to provide a polygonal prism which accurately receives and emits light.
In order to achieve the objectives of the present invention, there is provided a polygonal prism that receives at least one incident light and generates at least one outward light. The prism includes a first plane, a second plane parallel with the first plane, a third plane that crosses the first and second planes at an angle, and a fourth plane that is perpendicular to the first and second planes, with the prism made from one piece of material.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is a perspective view of a pentagonal prism according to one embodiment of the present invention.
FIG. 1B illustrates one set of possible light trajectories for the prism of FIG. 1A.
FIG. 2 illustrates another set of possible light trajectories for the prism of FIG. 1A.
FIG. 3A is a perspective view of the pentagonal prism of FIG. 1A with the incident light being introduced at a different angle than in FIG. 1A.
FIG. 3B illustrates one set of possible light trajectories for the prism of FIG. 3A.
FIG. 4 illustrates the prism of FIG. 1A supported by a carriage.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following detailed description is of the best presently contemplated modes of carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating general principles of embodiments of the invention. The scope of the invention is best defined by the appended claims.
FIG. 1 illustrates a polygonal prism 300 according to one embodiment of the present invention. The prism 300 can be made of glass or plastic, and has a first plane 302, a second plane 304, a third plane 306, a fourth plane 308 and a fifth plane 310. The first plane 302 and the second plane 304 are parallel and opposite to each other. The fourth plane 308 is connected, and perpendicular, to the first plane 302. The third plane 306 is connected to the second plane 304. The second and third planes 304, 306 extend at lines that intersect at an angle A, which can be any angle less than 90 degrees. The first and third planes 302, 306 are not connected to each other, but the first and third planes 302, 306 also extend at lines that intersect at the same angle A. Angle A can be any angle, and in one embodiment of the present invention, angle A is 45 degrees. The fifth plane 310 connects the first and third planes 302, 306, and essentially crosses the first and third planes 302, 306.
When viewed from the side (e.g., see FIGS. 1B and 2), the prism 300 has a pentagonal shape. The prism 300 can be a piece of optical plastic or glass that is made in one piece by plastic injection.
In the embodiment of FIGS. 1A and 1B, the first plane 302 and the second plane 304 are coated with a partially reflective film, and the third plane 306 is coated with a fully reflective film. When incident light 312 is introduced into the prism 300 from the second plane 304 at an inclined angle (see FIG. 1B), the partially reflective film on the second plane 304 will reflect part of the incident light 312 as a first outward light 314. The remainder of the incident light 312 is refracted by the second plane 304 and travels to the first plane 302. Since the first plane 302 is coated with a partially reflective film, part of the incident light 312 reaching the first plane 302 will be refracted outside the prism 300 as a second outward light 316, and part of the incident light 312 reaching the first plane 302 will be reflected towards the third plane 306. Since the third plane 306 is coated with a fully reflective film, all of the incident light 312 reaching the third plane 306 will be reflected towards the fourth plane 308, where it is refracted outside the prism 300 as a third outward light 318. Here, since (i) the first plane 302 is parallel to the second plane 304, (ii) the fourth plane 308 is perpendicular to the first plane 302 and the second plane 304, and (iii) the first and third planes 302, 306 extend at lines that intersect at an angle of A, the introduction of the incident light 312 would generate two outward lights 316 and 318 that are spaced apart at an angle of two times angle A (i.e., 2×A). If angle A is 45 degrees, then the outward lights 316, 318 would be perpendicular (i.e., 90 degrees, see angle B) to each other.
FIG. 2 illustrates the introduction of three incident lights 402, 404 and 406 into the same prism 300. The three incident lights 402, 404 and 406 are introduced at the same angles as the outward lights 314, 316 and 318, respectively, into the second plane 304, the first plane 302, and the fourth plane 308, respectively. The three incident lights 402, 404 and 406 generate an outgoing light 408 that exits the second plane 304 along the same direction as the incident light 312 in FIG. 1B.
In one embodiment of the present invention, the first plane 302 may be coated with red light for passing and green light for reflection, the second plane 304 may be coated with red light and green light for passing and blue light for reflection. If a white light is introduced into the prism 300 in the same direction as the incident light 312, the first outward light 314 would then be blue, the second outward light 316 would be red, and the third outward light 318 would then be green. Similarly, if the three incident lights 402, 404 and 406 are blue, red and green, respectively, then the combined outward light 408 would be white light.
Referring to FIGS. 3A and 3B, when incident light 312 is introduced into the prism 300 from the second plane 304 at an angle of 45 degrees with respect to the second plane 304 (see FIG. 3B), the partially reflective film on the second plane 304 will reflect part of the incident light 312 as a first outward light 314. The remainder of the incident light 312 is refracted by the second plane 304 and travels to the first plane 302. Since the first plane 302 is coated with a partially reflective film, part of the incident light 312 reaching the first plane 302 will be refracted outside the prism 300 as a second outward light 316, and part of the incident light 312 reaching the first plane 302 will be reflected towards the third plane 306. Since the third plane 306 is coated with a fully reflective film, all of the incident light 312 reaching the third plane 306 will be reflected towards the fourth plane 308, where it is refracted outside the prism 300 as a third outward light 318. Here, the introduction of the incident light 312 at an angle of 45 degrees with respect to the second plane 304 would generate three outward lights 314, 316 and 318 that are perpendicular to each other.
FIG. 4 illustrates the prism 300 supported by a carriage 500 which has a first surface 512 and a second surface 514 that are bonded to opposite surfaces (e.g., first plane 302 and second plane 304, respectively) of the prism 300.
Although the description hereinabove has described coating certain planes with partially-reflective or fully reflective films, it is possible to coat any of the planes 302, 304, 306, 308, 310 with no film, a partially reflective film, or a fully reflective film, depending on the desired light outputs. It is also possible to provide coatings in other patterns to decompose the white incident light into any desired set of outgoing lights having different colors. It is further possible to combine a plurality of incident lights of any set of different colors to produce a single outward light of any desired colors. The implementation of these alternatives would be well-known to a person of ordinary skill in the art given the disclosures made hereinabove.
Thus, the polygonal prism 300 of the present invention is made in one piece using a simple process, rather than by bonding two separate prism pieces. As a result, the prism 300 can be made using less time and work, thereby reducing its cost.
While the description above refers to particular embodiments of the present invention, it will be understood that many modifications may be made without departing from the spirit thereof. The accompanying claims are intended to cover such modifications as would fall within the true scope and spirit of the present invention.
Patent Application
20050134978
