Abstract:
A polygonal prism receives at least one incident light and generates at least one outward light. The prism includes a plurality of planes, with the prism made from one piece of material.

Description:
RELATED CASES  
       [0001]     This is a continuation-in-part of co-pending Ser. No. 10/850,181, filed May 20, 2004, whose disclosure is incorporated by this reference as though fully set forth herein. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     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.  
         [0004]     2. Description of the Prior Art  
         [0005]     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.  
         [0006]     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.  
         [0007]     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  
       [0008]     It is an object of the present invention to provide a polygonal prism that is made in a single piece.  
         [0009]     It is another object of the present invention to provide a polygonal prism which is provided at lower costs.  
         [0010]     It is yet another object of the present invention to provide a polygonal prism which accurately receives and emits light.  
         [0011]     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 plurality of planes, with the prism made from one piece of material. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1A  is a perspective view of a pentagonal prism according to one embodiment of the present invention.  
         [0013]      FIG. 1B  illustrates one set of possible light trajectories for the prism of  FIG. 1A .  
         [0014]      FIG. 2  illustrates another set of possible light trajectories for the prism of  FIG. 1A .  
         [0015]      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 .  
         [0016]      FIG. 3B  illustrates one set of possible light trajectories for the prism of  FIG. 3A .  
         [0017]      FIG. 4  illustrates the prism of  FIG. 1A  supported by a carriage.  
         [0018]      FIG. 5A  is a perspective view of a polygonal prism according to another embodiment of the present invention.  
         [0019]      FIG. 5B  illustrates one set of possible light trajectories for the prism of  FIG. 5A . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]     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.  
         [0021]      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 .  
         [0022]     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.  
         [0023]     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.  
         [0024]      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 .  
         [0025]     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.  
         [0026]     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.  
         [0027]      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 .  
         [0028]      FIGS. 5A and 5B  illustrate a polygonal prism  600  according to another embodiment of the present invention. The prism  600  can be made of glass or plastic, and has a first plane  601 , a second plane  602 , a third plane  603 , a fourth plane  604 , a fifth plane  605  and a sixth plane  606 . The first plane  601  and the second plane  602  are parallel and opposite to each other. The fourth and sixth planes  604 ,  606  are connected to the first plane  601 , and are also perpendicular to the first plane  601  and opposite to each other. The second plane  602  is perpendicular to the fourth plane  604 . The third plane  603  extends at an angle from the second plane  602 . The first plane  601  and the third plane  603  are not connected to each other, but the first plane  601  and the third plane  603  extend at lines that intersect at an angle C. Angle C can be any angle less than 90 degrees, and in one embodiment of the present invention, angle C is 45 degrees. The fifth plane  605  is connected to the third plane  603  and the sixth plane  606 , and extends at an angle from the sixth plane  606 . The first plane  601  and the fifth plane  605  are not connected to each other, but the first plane  601  and the fifth plane  605  extend at lines that intersect at an angle D. Angle D can also be any angle less than 90 degrees, and in one embodiment of the present invention, angle D is 45 degrees. Thus, in the embodiment where the angle C is 45 degrees and the angle D is 45 degrees, the angle between the third plane  603  and the fifth plane  605  would be ninety degrees.  
         [0029]     In the embodiment of  FIGS. 5A and 5B , the first plane  601  is coated with a partially reflective film, and the third plane  603  and the fifth plane  605  are coated with a fully reflective film. When incident light  612  is introduced into the prism  600  from the second plane  602  at an inclined angle (see  FIG. 5B ), the incident light  612  is refracted by the second plane  602  and travels to the first plane  601 . Since the first plane  601  is coated with a partially reflective film, part of the incident light  612  reaching the first plane  601  will be refracted outside the prism  600  as a first outward light  616 , and part of the incident light  612  reaching the first plane  601  will be reflected towards the third plane  603  and the fifth plane  605 . Since the third plane  603  and the fifth plane  605  are each coated with a fully reflective film, the incident light  612  reaching the third plane  603  will be reflected towards the fourth plane  604  where it is refracted outside the prism  600  as a second outward light  618 . Similarly, the incident light  612  reaching the fifth plane  605  will be reflected towards the sixth plane  606 , where it is refracted outside the prism  600  as a third outward light  620 . Here, as mentioned above, the angle between the first outward light  616  and the second outward light  618  is two times angle C (i.e., 2×C), and the angle between the first outward light  616  and the third outward light  620  is two times angle D (i.e., 2×D). Thus, if angle C and D are each 45 degrees, then the first outward light  616  would be perpendicular (i.e., 90 degrees) to the second outward light  618  and the third outward light  620 .  
         [0030]     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 ,  601 ,  602 ,  603 ,  605  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.  
         [0031]     Thus, the polygonal prisms  300 ,  600  of the present invention may be made in one piece using a simple process, rather than by bonding two separate prism pieces. As a result, the prisms  300 ,  600  can be made using less time and work, thereby reducing their cost.  
         [0032]     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.