Patent Publication Number: US-2022214518-A1

Title: Device for mounting spherical optical components

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of international patent application PCT/EP2020/075664, filed Sep. 14, 2020 designating the United States and claiming priority from German application 10 2019 006 980.3, filed Sep. 30, 2019, and the entire content of both applications is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The disclosure relates to a device for mounting two spherical optical components. 
     BACKGROUND 
     It is known to align optical components to be joined in all three spatial directions independently of one another. For example, when producing a cemented group of two lens elements, a melting cement is distributed on one of the surfaces to be joined. The two lens elements are joined together and trapped air bubbles are squeezed out by moving the lens elements relative to one another. The optical axes of the lens elements are then aligned with one another. However, the thickness of the cementing gap between the surfaces of the lens elements cannot be accurately reproduced. Furthermore, highly accurate positioning of the lens elements in the direction of the course of the optical axis is very difficult: a lateral displacement can simultaneously result in a change in distance due to the curvature of the surfaces. 
     Document RU 2 599 598 C1 discloses a device for setting a spherical holder for an optical element. The device is used for setting the optical element in an optical resonator. In the device, the optical element is held in a spherical, convex holder. The spherical convex holder lies in a spherical-concave mount. The holder is connected to the mount via four adjusting screws, which are offset from one another by 90° on the outer edge. By setting the adjusting screws, the holder can be moved on the spherical surfaces in the mount and a desired state of adjustment can thus be set. The set state of adjustment is permanently secured via a non-shrinking adhesive, which is inserted into an annular groove of the mount. 
     SUMMARY 
     It is an object of the disclosure to provide a device for mounting spherical components in order to adjust two spherical optical components geometrically accurately and at a defined distance from one another and to mount them. The distance should be reproducible and optionally settable. 
     The aforementioned object can, for example, be achieved by a device for mounting spherical optical components. The device includes a first holder, with a mount/receptacle for a first optical element having a first spherical convex surface with a radius R 1  and a second holder with a mount/receptacle for a second optical element having a second spherical optical concave surface with a radius R 2 . At least one of the holders has a bearing surface with a radius R 3  and the first holder can be borne on the second holder in such a way that the radii R 1 , R 2 , R 3  have a common center point when the first optical element has been received in the first holder and the second optical element has been received in the second holder. 
     The radii R 1 , R 2 , R 3  are preferably dimensioned such that a gap establishes a defined distance between the optical surface of the first element and the optical surface of the second element. 
     It goes without saying that, while maintaining the effects according to the disclosure, the radius R 1  may be concave and the radius R 2  may be convex. 
     Due to the fact that the spherical surfaces and the bearing surface(s) are arranged concentrically, displacement around the common center point of these surfaces is impeded and only relative displacements of the elements around this center point are possible. 
     With this type of bearing arrangement, the optical elements or their optical axes can be positioned in relation to one another (within the limits of the relative adjustability of the holders in relation to one another), without the risk that such a positioning movement could adversely affect the amount of the distance between the spherical surfaces of the optical elements determined by the radii R 1 , R 2 , R 3 . The device according to the disclosure thus allows optical elements to be positioned in relation to one another very much more easily and accurately than has hitherto been customary in the prior art. 
     The positioning can take place in particular for the purpose of aligning two optical elements with one another and then adhesively bonding them to form a substrate composite. 
     The bearing surfaces of the holders are preferably arranged outside a central area of the holders in which the optical elements are placed. 
     In a first embodiment, the bearing surface is in the form of a spherical cap. 
     In a second embodiment, the bearing surface is produced by a three-point support. 
     The optical elements can be received in the holder via a generated vacuum. 
     Alternatively, the optical elements can be fixed to the holder via a spring clamp. 
     Advantageously, the distance between the optical surface of the first element and the optical surface of the second element can be set. 
     In a first embodiment, adjusting screws in one of the holders are arranged at the periphery outside the central area in which the optical element is placed and act on the bearing surface of the other holder. 
     In a second embodiment, the adjusting screws in one of the holders are located at the periphery inside the central area in which the optical element is placed and act on the optical element. 
     Preferably provided for determining a defined distance between the optical elements is a measuring system, which is set up for determining a central thickness and thus for determining the distance between the optical surfaces of the optical elements. In this way, the process of joining and positioning the optical elements can be checked, controlled on an open-loop basis and, if necessary, controlled on a closed-loop basis. 
     With the setup according to the disclosure, it is possible to position and join two optical elements in a series-like process. With the aid of the device according to the disclosure, an advantageous spherical bearing arrangement of the components in relation to one another can be realized, with very much more accurate and easy mounting of the optical elements being possible. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described with reference to the drawings wherein: 
         FIG. 1  shows a setup of a device according to the disclosure for the mounting of spherical components; 
         FIG. 2  shows a further setup of a device according to the disclosure for the mounting of spherical components; 
         FIG. 3  shows a first detail of a device according to the disclosure (spring holder of an optical element); 
         FIG. 4  shows a second detail of a device according to the disclosure (adjusting screws which act on an optical element); and 
         FIG. 5  shows a third detail of a device according to the disclosure (adjusting screws which act on a holder). 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows the setup of the device for mounting spherical components  1 . A first holder  2  receives a first optical element  3  in such a way that a spherical optical surface of the optical element  3  with the radius R 1  is freely accessible. In the example, this optical surface is convex. A second holder  4  receives a second optical element  5  in such a way that a spherical optical surface of the second optical element  5  with a radius R 2  is freely accessible. In the example, this optical surface is concave. 
     The first holder  2  has at the periphery outside its central area in which the optical element  3  is placed a bearing surface  6 , which is formed convexly with a radius R 3 . Furthermore, the second holder  4  likewise has at the periphery outside the central area in which the optical element  5  is placed a bearing surface  6 , which however is formed concavely, likewise with the radius R 3 . 
     The second holder  4  is arranged at the bottom in such a way that the optical surface of the second optical element  5  is exposed in the upward direction. The first holder  2  with the received optical element  3  is positioned with its exposed optical surface over the exposed optical surface of the second optical element  5 . The position of the optical surfaces of the two optical elements  3  and  5  is set to a predetermined distance by the bearing surfaces  6  of the holders  2  and  4 , so that a defined gap  7  (for example of 1 μm or 5 μm or 20 μm or 50 μm or 100 μm) between the optical surfaces is realized. 
     It is essential that the radii R 1  and R 2  of the optical surfaces of the optical elements  3  and  5  and the radius R 3  of the bearing surfaces  6  of the holders  2  and  4  have a common center point MP. If the holders  2  and  4  are placed one on top of the other, as described, the optical surfaces of the optical elements  3  and  5  and the bearing surface  6  assume a coaxial position in relation to one another. A movement of the optical elements  3  and  5  in the radial direction is thus impeded and the distance between the optical surfaces is defined by the gap  7 . Therefore, only a rotational movement or a displacement of the optical elements  3  and  5  in relation to one another on the radius R 3  of the bearing surfaces  6  is possible. 
       FIG. 1  also shows by way of example the possibility of using a measuring system  11  to determine the size of the gap  7 , which corresponds to the distance between the optical surfaces. Provided for this purpose in the center of the first holder  2  is a hole  10 , by which the distance of the optical elements  3  and  5  from one another, which is also referred to as the central thickness, can be determined with the measuring system  11 . With the measuring system  11  for determining the central thickness, the process of joining and positioning two optical elements  3  and  5  can be checked, controlled on an open-loop basis and, if necessary, controlled on a closed-loop basis. Such a joining process is helpful in particular when positioning a film on a spectacle lens of data glasses. The gap  7  between the first optical element  3 , in the example the spectacle lens, and the second optical element  5 , in the example of the film, can be produced with an accuracy of less than 5 μm. 
       FIG. 2  shows the concentric setup of the device according to  FIG. 1  in a clearer way. The radius R 1  of the optical surface of the first optical element  3 , the radius R 2  of the optical surface of the second optical element  5  and the radius R 3  of the bearing surfaces  6  of the first and second holders  2  and  4  have the common center point MP. In the example, the first optical element is the lens of data glasses and the second optical element  5  is a thin film that rests on the second holder  4 . Furthermore, another way of holding the first optical element  3  in the first holder  2  is shown in  FIG. 2 . 
       FIG. 3  illustrates the holding shown in  FIG. 2  of the first optical element  3  in the first holder  2 . The first optical element  3  is pressed with a spring clamp  8 , which acts on an edge of a concave optical surface of the first optical element  3 , against contact points  12 , which act on the convex optical surface of the first optical element  3 . For example, the contact points  12  are three V-grooves, which are arranged at an angle of 120 degrees and in each of which a ball is fixed. The spherical surfaces form the bearing surface  6 . 
       FIG. 4  shows the device for mounting spherical components  1  according to  FIGS. 1 and 2  with a possibility for adjusting the size of the gap  7  via adjusting screws  9 . The adjusting screws  9  act on the edge of the concave optical surface of the first optical element  3  via balls  14 . Compression springs  13 , which are arranged at the edge of the convex optical surface of the first optical element  3 , press the first optical element  3  against the adjusting screws  9 . 
     The size of the gap  7  can be set by an adjustment of the adjusting screws  9 . 
       FIG. 5  shows a second variant for setting the size of the gap  7 . In this example, the adjusting screws  9  act on the bearing surface  6  of the second holder  4  via balls. Here, too, the size of the gap  7  is set by an adjustment of the adjusting screws  9 . A further variant for holding the first optical element  3  is also shown in  FIG. 5 . In this example, the concave optical surface is pressed by a spring clamp  8 , which acts on the convex optical surface, against contact points  12  of the first holder  2 .  FIG. 5  shows that the first optical element is fixed by compression springs  13 , which are arranged at the edge of the convex optical surface. The compression springs  13  press the first optical element  3  against contact points  13 , which are arranged on the edge of the concave optical surface of the optical element  3 . 
     It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims. 
     LIST OF REFERENCE SIGNS 
       1  Mounting device 
       2  First holder 
       3  First optical element 
       4  Second holder 
       5  Second optical element 
       6  Bearing surface 
       7  Gap 
       8  Spring clamp 
       9  Adjusting screws 
       10  Hole 
       11  Measuring system 
       12  Contact points 
       13  Compression spring 
       14  Ball 
     R 1  Radius of a convex optical surface 
     R 2  Radius of a concave optical surface 
     R 3  Radius of bearing surfaces 
     MP Center point