Abstract:
An improved lateral transfer retroreflector assembly is provided. The lateral transfer retroreflector assembly of the invention comprises a first segment comprising a mirror panel housing, a second segment comprising a roof mirror housing, and a third segment comprising an off-the-shelf connecting member between the two housings. The mirror panel housing will have mounted thereto a mirror panel. The roof mirror housing will have mounted thereto a roof mirror assembly, and the connecting member will be mounted between the mirror panel housing and the roof mirror housing. The off-the-shelf aspect of assembling the connecting allows the assembly to be built to customer specifications, thereby allowing for customized creation of lateral transfer retroreflectors, but at a time and cost savings to the customer.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This invention relates to the field of retroreflectors, and more particularly, to lateral transfer retroreflectors.  
           [0002]    Retroreflectors generally have the property of causing incident and reflected light rays to travel along parallel paths. To achieve this parallelism, a retroreflector normally consists of three optically flat reflecting surfaces, each reflecting surface positioned at a right angle to each of the other reflecting surfaces. Any departure of the reflecting surfaces from their perpendicular orientation will cause the incident and reflected light rays to depart from parallel.  
           [0003]    Retroreflectors lose accuracy when they are exposed to external stresses. Examples of such external stresses are mass, thermal expansion or contraction of the substrate material from which the retroreflector is made, or deflection caused by curing of the adhesives which join members of the retroreflector.  
           [0004]    Retroreflectors, and lateral transfer retroreflectors (which translate the reflected beam some calculated distance from the incident light beam), are old in the art. Examples of prior art retroreflectors and lateral transfer retroreflectors are:  
           [0005]    U.S. Pat. No. 3,977,765 to Morton S. Lipkins, which disclosed a retroreflector mounted to a support structure through means of applying an adhesive into the joints formed between joined members of the retroreflector and to a flat surface of the support structure.  
           [0006]    U.S. Pat. No. 4,065,204, also to Morton S. Lipkins, which disclosed a lateral transfer retroreflector consisting of a base, a roof reflector having two reflecting plates and a third reflector. The base acts as an extension of the third reflector by attaching the third reflector to the roof reflector in the manner known to retroreflectors to produce the lateral transfer retroreflector construction.  
           [0007]    U.S. Pat. No. 5,024,514 to Zvi Bleier and Morton S. Lipkins, which discloses a lateral transfer retroreflector having a tubular member, a roof mirror and a mirror panel. Both the roof mirror and mirror panel are attached to the tubular member by use of three coplanar mounting pads.  
           [0008]    U.S. Pat. No. 5,361,171, also to Zvi Bleier, which discloses a lateral transfer retroreflector having a fixed-length tubular member, a roof mirror secured within a channel portion extending from an end of the tubular member and a mirror panel attached to the tubular member at the opposite end from the roof mirror and roof mirror panel.  
           [0009]    It would be desirable to provide a high-accuracy lateral transfer retroreflector that is off-the-shelf adjustable as to the displaced length between the mirror panel and the roof mirror and also having a less temperature-deviant assembly and mounting of the roof mirror and mirror panel.  
         SUMMARY OF THE INVENTION  
         [0010]    In accordance with the invention, an improved lateral transfer retroreflector assembly is provided. The lateral transfer retroreflector assembly of the invention is comprised of three separate, attached segments. A first segment comprising a mirror panel housing, a second segment comprising a roof mirror housing, and a third segment comprising a connecting member between the two housings.  
           [0011]    The mirror panel housing will have mounted thereto a mirror panel. The roof mirror housing will have mounted thereto a roof mirror assembly, and the connecting member will be mounted between the mirror panel housing and the roof mirror housing. In addition, based upon the mounting together of the three separate segments, the connecting member will have the ability of being an off-the-shelf member that is selectively able to be cut to a particular length dimension based upon customer specifications, thereby allowing for customized creation of lateral transfer retroreflectors, but at a time and cost savings to the customer.  
           [0012]    In addition, the roof mirror assembly and the mirror panel mounting are kinematic structures that are also improvements over earlier constructions. In particular, the roof mirror assembly of the subject invention has at least a pair of mounting members that act also as back supports and are located substantially at opposite ends of the roof mirror. The manner of attachment of the mounting members to the back portions of the mirror panels making up the roof mirror assembly, is such that expansion and contraction of the reflective surfaces of the mirror panels of the roof mirror assembly will only be in a direction substantially perpendicular to the direction of the roof angle axis. Deflection in this direction does not cause displacement (error), of the transmitted light beam traveling through the lateral transfer retroreflector, and therefore such a mounting system is advantageous. Similarly, the mounting of the mirror panel to the mirror panel housing by means of substantially 45° chamfered edges, insures that the forces exerted by thermal expansion or contraction of the bonding material situated along those chamfered edges, will have a canceling effect, and not deflect the reflective surface of the mirror panel.  
           [0013]    Accordingly, it is an object of the present invention to provide an improved lateral transfer retroreflector assembly.  
           [0014]    Still another object of the invention is to provide a lateral transfer retroreflector assembly having a component construction capable of, allowing for off-the-shelf customization for different customer needs based upon differing customer specifications.  
           [0015]    Yet a further object of the invention is to provide a lateral transfer retroreflector assembly having a roof mirror assembly construction and mounting such that deformations in the reflective surfaces of the mirror panels of the roof mirror assembly due to thermal expansion/contraction are minimized in the direction of the roof angle axis.  
           [0016]    A still further object of the invention is to provide a lateral transfer retroreflector assembly, wherein the deflective forces exerted on the mirror panel by thermal expansion or contraction of the joint bonding the mirror panel to the mirror panel housing, are minimized.  
           [0017]    Other objects of the invention will in part be obvious and will in part be apparent from the following description taken in association with the figures.  
           [0018]    The invention accordingly comprises an assembly possessing the features, properties and relation of components which will be exemplified in the products hereinafter described, and the scope of the invention will be indicated in the claims. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    For a fuller understanding of the invention, reference is made to the following description taken in connection with the accompanying drawings, in which:  
         [0020]    [0020]FIG. 1 is a perspective view of a lateral transfer retroreflector assembly made in accordance with the invention;  
         [0021]    [0021]FIG. 2 is a cross-sectional view taken along line  2 - 2  of FIG. 1;  
         [0022]    [0022]FIG. 3 is a perspective view of the mirror panel of the invention;  
         [0023]    [0023]FIG. 4 is a left side elevational view of the mirror panel housing of the invention;  
         [0024]    [0024]FIG. 4A is a partial prespective view of the mounting pad of member  26  of the mirror panel housing;  
         [0025]    [0025]FIG. 4B is a partial perspective view of the mounting pad of member  24  of the mirror panel housing;  
         [0026]    [0026]FIG. 5 is a right side elevational view of the mirror panel housing;  
         [0027]    [0027]FIG. 6 is a cross-sectional view taken along line  6 - 6  of FIG. 5;  
         [0028]    [0028]FIG. 7 is a left side elevational view of the mirror panel housing;  
         [0029]    [0029]FIG. 8 is a cross-sectional view taken along line  8 - 8  of FIG. 7;  
         [0030]    [0030]FIG. 9 is a perspective view of the roof mirror assembly of the subject invention;  
         [0031]    [0031]FIG. 10 is an elevational view of one end of the roof mirror assembly of FIG. 9;  
         [0032]    [0032]FIG. 11 is an elevational view of the other end of the roof mirror assembly of FIG. 9;  
         [0033]    [0033]FIG. 12 is a bottom plan view of the roof mirror assembly of FIG. 9; and  
         [0034]    [0034]FIG. 13 is a perspective view of a second embodiment of the roof mirror assembly of the subject invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0035]    Referring to FIG. 1, a lateral transfer retroreflector assembly made in accordance with the invention and generally designated at  10 , is illustrated. Lateral Transfer Retroreflector (“LTR”)  10  comprises three components; those being a mirror panel housing  20 , a roof mirror assembly housing  60  and a connecting member  90 .  
         [0036]    As seen in FIGS. 1 and 4, mirror panel housing  20  is comprised of first and second side members  24  and  26 , as well as receiving member  28 , for receiving connecting member  90 . Housing  20  can also include member  30 , to lend extra stability to the structure, as well as aperture receiving member  22 , having aperture  32  extending therethrough. Aperture  32  can be of any geometric configuration, the preferred configurations being in the circle and square families. Aperture  32  has a first end  33  and a second end  35 , the distance between which will help dictate the inside diameter of connecting member  90 . It is to be understood herein that member  90  does not have to be circular in cross section, but could be of other shapes; particularly square. However, since light beams to be passed through LTR  10  are normally themselves circular in cross section, the preferred embodiment shown in the figures and discussed herein, will regard a circular aperture  32  and a circular tubular member  90 .  
         [0037]    Continuing with the above discussion, the dimensional congruity between the size of aperture  32  and the cross sectional diameter of member  90  will insure that a light beam passing through LTR  10  will propagate through member  90  very close to the inside surface of member  90  as the beam approaches either of ends  33  or  35  of aperture  32 .  
         [0038]    Turning now to FIG. 3, mirror panel  34  to be used with LTR  10  is shown. Mirror panel  34  has a reflective surface  40 , and two chamfered edges  36  and  38 . As seen in FIG. 1, mirror panel  34  is adhered to mirror panel housing  20  in such a manner as to be oriented with its reflective surface  40  below, and in reflective relation with, aperture  32  and member  90 . In practice, and as will be discussed in more detail below, the light beam, if it is entering LTR  10  through aperture  32 , will then reflect off of reflective surface  40  of mirror panel  34 , and propagate through member  90  into roof mirror assembly housing  60 , where it will reflect off of reflective surfaces  104  and  114  of roof mirror assembly  100  to propagate back toward the source of the beam, in a direction substantially parallel to the beam&#39;s incident direction, but at a displaced distance, substantially based upon the length of member  90 .  
         [0039]    Continuing with FIGS.  3 - 8 , it is seen that mirror panel  34  is adhered at three contact surfaces to corresponding mounting pads  21 ,  23 , and  25  of edge portions  27  and  29  of first and second side members  24  and  26 , respectively. In particular, edge portions of  27  and  29 , and their corresponding mounting pads  21 ,  23  and  25 , onto which mirror panel  34  is adhered, are themselves chamfered, as is best seen in FIGS. 4A and 4B. The construction and mounting of mirror panel  34  of the subject invention is different to that of the prior art in U.S. Patent Nos. 5,024,514 and 5,361,171 (discussed earlier herein), in that the subject connection between mirror panel  34  and mirror panel housing  20  is chamfered surface to chamfered surface, as opposed to the prior art disclosure of mounting pads oriented perpendicularly to the reflective surface. What is similar, however, between the subject connection of mirror panel  34 , and the prior art connections, is the adhesion of mirror panel  34  to mirror panel housing  20  at only three distinct areas; two areas along chamfered surface  38  and only one area along chamfered surface  36 . The use of the matching chamfered surfaces  36 / 38  and  21 / 23  and  25  helps to reduce the distortional effect of the connection of mirror panel  34  to mirror panel housing  20 , as well as to help reduce stresses caused by thermal expansion/contraction, as the substantially 45° of the chamfers insures that such distortional forces do not distort rereflective surface  40  in a way to effect the orientation of the beam passing through LTR  10 .  
         [0040]    Specifically, LTR  10  of the present invention is a highly accurate instrument which can be used in such precise fields as surveying, military and aerospace applications, to name a few. It is usually necessary that instruments used in these areas meet very specific stress and dimensional specifications, and therefore the manner of construction of LTR  10  with respect to joining parts thereof together, and the length and depth dimensions of LTR  10 , are important. Accordingly, as will be discussed in more detail below, although lateral transfer retroreflectors are old in the art, the particular manners in which mirror panel  34  and roof mirror assembly  100  are made and mounted to their respective housings, will impact the durability and dimensional integrity of LTR  10 .  
         [0041]    Turning now to a discussion of roof mirror assembly  100 , this assembly is best seen in FIGS.  9 - 12 . Roof mirror assembly  100  comprises a pair of mirror panels  102  and  112 , and a pair of mounting blocks  140  and  160 .  
         [0042]    Mirror panels  102  and  112  have reflective surfaces  104  and  114 , respectively, which reflective surfaces are in reflective relation with reflective surface  40  of mirror panel  34 , as well as member  90  and aperture  32 . In particular, reflective surface  104  is substantially perpendicularly oriented to reflective surface  114 , and reflective surface  40  is itself oriented substantially perpendicularly to both reflective surfaces  104  and  114 . This mutually perpendicular orientation of the three reflective surfaces of LTR  10  essentially duplicates the construction of a standard Hollow™ retroreflector as is known in the art. Referring to FIGS.  9 - 11 , mirror panels  102  and  112  are seen to be adhered together at miter joint  110 . In order to create miter joint  110 , the attachment surfaces of mirror panels  102  and  112  which are joined together to create miter joint  110 , are at substantially 45 degree angles to reflective surfaces  104  and  114 , so as to create the perpendicularity between the reflective surfaces upon creation of miter joint  110 , and the associated reduction of distortive forces, as earlier discussed.  
         [0043]    Continuing with a discussion of FIGS.  9 - 11 , it is seen that connected together panels  102  and  112  are finally formed into a secure roof mirror assembly through the mounting of back surfaces of panels  102  and  104  to portions of surfaces  142  and  162  of mounting blocks  140  and  160 . In so mounting panels  102  and  104  to blocks  140  and  160 , air gaps  150 ,  152 ,  154  and  156  are created between surfaces of mounting blocks  140  and  160  and surfaces  106  and  126  of panel  102 , and surfaces  116  and  136  of panel  112  (see FIGS. 10 and 11).  
         [0044]    As is further seen in FIGS. 10 and 11, the back surfaces of panels  102  and  112  that are adhered to mounting blocks  140  and  160  as discussed above, are surfaces  108  and  128  for panel  102 , and surfaces  118  and  138  for panel  112 . In construction, surfaces  108 / 128  and  118 / 138  are all substantially perpendicular in orientation to miter joint  110 . Such a construction ensures that any substantial distortional effects due to thermal expansion/contraction of panels  102  and  112  and/or block  140  and  160  will be in a direction substantially perpendicular to a longitudal axis for roof mirror assembly  100 ; i.e., perpendicular to the planes of reflective surfaces  104  and  114 .  
         [0045]    Turning again to FIG. 1, it is seen that roof mirror assembly  100  is secured to roof mirror assembly housing  60  by way of connection between bottom surfaces  141  and  161  of blocks  140  and  160  to member  70  of housing  60 . Such a secure connection of roof mirror assembly  100  to housing  60  assists and strengthens the durability of LTR  10 .  
         [0046]    Regarding connecting member  90 , as has been stated, this member can be cut from an off-the-shelf member of standard construction and length. Such an off-the-shelf retro-fit of connecting member  90  allows one to stock separate quantities of housings  20  and  60 , and member  90 , for construction of an LTR  10  to meet any customer specifications, in a quick and cost affective manner.  
         [0047]    Turning now to a discussion of FIG. 13, a second embodiment of the inventive roof mirror assembly  100  is shown at  300 . Assembly  300  is constructed identically to that of assembly  100 , accept for the addition of back plate member  302 , adhered below mounting blocks  340  and  360 , to surfaces  341  and  361  (not shown).  
         [0048]    It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained, and, since certain changes may be made in the above constructions without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.  
         [0049]    It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which, as a matter of language might be said to fall therebetween.