Abstract:
An optical distributor for deflecting a light beam in different directions comprises a single semi-reflecting mirror 30 carried by a motor-driven turntable 31. The mirror is capable of pivoting about an axis 33 when a stop 46 is withdrawn (position Z of the notch and of the stud 38) and of taking up a position 52 in which it does not intercept the light beam 14. in the other positions (X and Y), the mirror intercepts the beam 14 and deflects it in the desired directions.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to devices for orienting a light beam in a number of different directions. The invention is more particularly concerned with devices of this type which produce a distribution of the beam in three channels by means of a rotating mirror. 
     2. Description of the Prior Art 
     Three-channel optical distributors are already known and are employed, for example, in certain x-ray devices for orienting the light beam produced by the x-radiation/light-radiation converter towards various devices for processing light images. By way of example, these devices consist of a video camera alone, a photographic camera or else a movie camera. Thus it is a usual practice to obtain simultaneously an image on the video camera and the photographic camera or on the video camera and the movie camera, or else an image on the video camera alone. 
     The schematic FIGS. 1a-1c and 2a-2b of the accompanying drawings show two known ways of constructing three-channel optical devices of this type. 
     In FIG. 1a-1c, the optical distributor comprises two semi-reflecting mirrors 10 and 11 which pivot respectively about two axes 12 and 13 perpendicular to the plane of the drawing. These two axes 12 and 13 are located on each side of the path of a light beam 14 to be deflected. 
     In the position of the mirrors of FIG. 1a, the mirror 11 is in a position parallel to the beam 14 and does not intercept this latter whilst the mirror 12 is inclined at 45° with respect to the beam. This mirror deflects a portion of the beam 14 in the direction B which is at 90° with respect to that of the incident beam 14. The other portion passes through the mirror 10 in the direction A. 
     In the position of the mirrors of FIG. 1b, the mirror 10 is in a position parallel to the beam 14 and does not intercept this latter whilst the mirror 11 is inclined at 45° with respect to the beam. In this case, one portion of the beam 14 is deflected in the direction C which is at 90° with respect to that of the incident beam 14 and at 180° with respect to the direction B. The other portion of the beam passes through the mirror 11 in the direction A. 
     Finally, in the position of the mirrors of FIG. 1c, the two mirrors 10 and 11 are both parallel to the beam 14 and do not intercept it. In this case, the incident beam 14 is not reflected by a mirror and is therefore not deflected. 
     The optical distributor which has just been described offers the advantage of being compact but calls for two mirrors, two rotation mechanisms and two rotation motors with accurate positioning in order to reproduce the same angle of slope of the mirrors. 
     Another three-channel distributor in accordance with the prior art will be described with reference to FIG. 2a and 2b. This distributor has a semireflecting mirror 20 which is inclined at 45° with respect to an incident beam 21. This mirror is fixed on a rotary turret 22 which is rigidly fixed to an arm 23. Said arm pivots about a shaft 24 which is parallel to the beam 21. In regard to the turret 22, this latter is capable of rotating about the axis of the beam 21. 
     In the position of FIG. 2a, part of the incident beam 21 is transmitted in the direction A and the remainder is deflected in the direction B at right angles to the direction of the incident beam. 
     If the turret 22 rotates through an angle of 90° in the direction of the arrow 25, part of the incident beam is transmitted in the direction A and the remainder is deflected in the direction C at right angles to the direction of the incident beam and to the direction B. 
     On the other hand, if the turret rotates through an angle of 90° in the direction opposite to the arrow 25, part of the incident beam is transmitted in the direction A and the remainder is deflected in the direction D at right angles to the direction of the incident beam and to the direction B. 
     Finally, the pivotal displacement of the arm 23 about the shaft 24 in the direction of the arrow 26 withdraws the turret 22 from the path of the incident beam 21 and this latter is therefore transmitted directly towards A without attenuation. 
     The optical distributor of FIG. 2 makes it possible to obtain four different optical channels, which is not necessary in the case of an x-ray apparatus but the distributor requires two rotation motors, namely one for the turret 22 and the other for the arm 23 as well as their associated mechanism. Furthermore, the movement of withdrawal of the turret results in substantial overall size. 
     The aim of the present invention is therefore to provide a rotating-mirror optical distributor which is not subject to the above-mentioned disadvantages of distributors of the prior art and which is of simple and rugged construction. 
     SUMMARY OF THE INVENTION 
     The invention relates to a device for deflecting a light beam, essentially comprising a motor-driven turntable rotatably mounted on a shaft which is rigidly fixed to a frame and placed at right angles to the light beam, a semi-reflecting mirror which is carried by the turntable and the reflecting face of which is parallel to the axis of rotation of the turntable, said mirror being normally in position for intercepting the light beam when the turntable rotates so as to deflect said beam in the desired directions, said device being provided with means for causing the mirror to pivot on one side about an axis parallel to the axis of rotation of the turntable so as to withdraw said mirror from the path of the light beam over a predetermined angular range of the turntable with respect to the light beam. 
     The means for causing the mirror to pivot about its axis of pivotal displacement comprise a stud which is rigidly fixed to the mirror and located on the side opposite to said axis of pivotal displacement, a stop which serves to maintain the mirror in fixed relation to the turntable and withdraws from the start of said angular range and a mechanical part rigidly fixed to the frame and provided with a groove in which said stud is engaged for sliding displacement in respect of said angular range, with the result that the mirror is capable of pivoting about its axis as the turntable rotates within said angular range and is no longer capable of intercepting the light beam. 
     In the case of three angular positions of the mirror with respect to the beam, the turntable is provided on its periphery with three notches which correspond to said angular positions, said notches being adapted to cooperate with a resilient stud fixed to the frame in order to stop the movement of the turntable when the stud engages within a notch. 
     When the turntable is caused to rotate by an electric motor, a switch in series with the motor supply circuit is associated with the stud in order to cut-off the supply when the stud is engaged in a notch. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1a, 1b and 1c are schematic views showing the arrangement and operation of a three-channel optical distributor having two rotating mirrors in accordance with the prior art. 
     FIGS. 2a and 2b are schematic views showing the arrangement and operation of a four-channel optical distributor in accordance with the prior art. 
     FIGS. 3a, 3b and 3c are schematic views showing the arrangement and operation of a three-channel optical distributor in accordance with the present invention. 
     FIG. 4 is a diagram showing one embodiment of the three-channel automatic distributor in accordance with the invention as well as the various positions of the mirror in order to obtain the three channels. 
     FIG. 4a is a diagram showing one embodiment of the three-channel automatic distributor in accordance with the invention as well as one position of the mirror. 
     FIG. 4b is a diagram showing one embodiment of the three-channel automatic distributor in accordance with the invention as well a one position of the mirror. 
     FIG. 4c is a diagram showing one embodiment of the three-channel automatic distributor in accordance with the invention as well as one position of the mirror. 
     FIG. 5 is a top view, partly broken away, showing a second embodiment of the optical distributor in accordance with the invention. 
     FIG. 6 is a view in perspective, partly broken away, showing the second embodiment corresponding to FIG. 5. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In FIG. 3a, 3b and 3c, there is shown diagrammatically a semi-reflecting mirror 30 mounted on a turntable 31 which rotates about a central axis 32 extending at right angles to the plane of the drawing. The mirror 30 is capable of pivoting about a pin 33 which is rigidly fixed to the turntable 31. Moreover, that side of the mirror 30 which is opposite to the pin 33 has a stud 47 which, in respect of a predetermined angular range of rotation of the turntable 31, is adapted to cooperate with a linear guide (not shown in FIG. 3). 
     In the position of FIG. 3a, part of the incident beam 14 is transmitted by the mirror 30 in the direction A to a video camera 34 and the remainder of the beam is reflected in the direction B to a photographic camera 35. 
     In the position of FIG. 3b, that is to say after a rotation of the turntable 31 through an angle of 90° in the direction of the arrow 36, the incident beam 14 is also partly transmitted by the mirror 30 in the direction A to the video camera 34, the remainder of the beam being reflected in the direction C to a movie camera 37. 
     After an additional rotation of 90° in the direction of the arrow 36, the turntable 31 and the mirror 30 are in the position of FIG. 3c. In other words, the mirror no longer intercepts the incident beam 14 and is located in a so-called &#34;parked&#34; position in which the stud 47 has moved within the linear guide (not shown) progressively as the rotation of the 15 turntable has taken place from the position of FIG. 3b. In this case, the incident beam is transmitted directly and solely in the direction A to the video camera 34. 
     FIG. 4 illustrates a first mode of construction of the three-channel optical distributor in accordance with the invention. The three positions of FIGS. 3a, 3b and 3c are obtained by means of V-shaped notches X, Y and Z formed at the periphery of the turntable 31 and disposed at 90° with respect to each other. The notches are adapted to cooperate with a locking-stud 38 and this latter is rigidly fixed to the frame (not shown) which supports the shaft 32 of the turntable 31. The stud 38 is maintained against the periphery of the turntable 31 by a spring 39. The spring 39 presses against the frame 49a on which frame 49a the stud 38 is fixed to. The turntable 31 is driven in rotation by a motor 40 which is rigidly fixed to the frame, by means of a driving belt 41 which is wound around pulleys 42 and 43, said pulleys being rigidly fixed respectively to the motor 40 and to the turntable 31. The supply of electric current to the motor 40 is controlled in particular by a switch 44 which is associated with the stud 38 so as to ensure that the power supply to the motor 40 is cut-off when the stud is located within any one of the notches X, Y or Z. 
     As mentioned earlier, the turntable 31 serves as a support for the mirror 30 which is maintained within a rigid frame 45. The mirror 30 is capable of pivoting by means of its frame 45 about an axis 33 which is located at the periphery of the turntable 31 and is perpendicular to the plane of the drawing. In order to prevent pivotal displacement of the mirror, that side of the frame 45 which is opposite to the axis 33 is held in position by means of a locking stop 46 which is rigidly fixed to the turntable 31. Said stop 46 withdraws in respect of certain positions of the turntable, which permits pivotal displacement of the mirror about the axis 33. On the same side as the stop 46, the frame 45 is provided with a stud 47 which, in respect of a predetermined position of the turntable 31, is adapted to engage within a guiding groove 48 formed in a part 49 which is fixed on the frame 49a (not shown in its entirety in the drawings but only partially). 
     When the stud 38 has engaged in the notch X, the mirror 30 has the position shown in a full line in FIG. 4, which corresponds to the schematic view of FIG. 3a. When, starting from this position, the turntable 31 is driven in rotation by the motor 40 in the direction of the arrow 36, the stud 38 disengages from the notch X but remains in contact with the periphery of the turntable, with the result that it engages in the notch Y when this latter comes into position. As soon as the stud 38 is within a notch X, Y or Z, it interrupts the supply of current to the motor 40. In this position of the notch Y in which the stud 38 has engaged, the mirror 30 has the position 50 shown in chain-dotted lines in FIG. 4, which corresponds to the schematic view of FIG. 3b. 
     As soon as the turntable leaves the position Y, the stop 46 is withdrawn by making use of means which are not shown in FIG. 4, with the result that the mirror 30 is capable of pivoting about the axis 33 in the direction of the arrow 51 progressively as rotation of the turntable 31 takes place in the direction of the arrow 36. Moreover, the stud 47 engages in the groove 48, with the result that the corresponding side of the mirror moves away from the turntable 31 as this latter rotates. When the notch Z comes into position opposite to the stud 38, the mirror 30 has the position 52 shown in chain-dotted lines, which corresponds to the schematic view of FIG. 3c. 
     Position Z corresponds to the end position of rotation of the turntable 31 in the direction of the arrow 36. In order to return to position Y and then to position X, the turntable must rotate in the direction opposite to the arrow 36. In this reverse movement, the stud 47 slides within the groove 48 and disengages from this latter in position Y. 
     At the same time, the retractable stop 46 comes into position so as to lock the mirror on the turntable (position 50). If the reverse movement of rotation continues, there is then a return to the starting position X which is also an end position of the turntable 31. In other words, the turntable 31 can only carry out a movement of rotation through an angle of 180° in one direction or in the other. 
     In FIG. 4, the position of the mirror 30 which corresponds to the position of the mirror 30 of FIG. 3a is shown in solid lines and denoted by the reference numeral 3a. The position of the mirror 30 which corresponds to the position of the mirror 30 of FIG. 3b is shown in shortened dashed line segments with dots between each of the shortened dashed line segments and denoted by the reference nemeral 3b. The position of mirror 30 which corresponds to the position of the mirror 30 of FIG. 3c is shown in short dashed lines interspersed with long dashed lines and is denoted by the reference numeral 3c. 
     Analogous to FIG. 3a the incident beam 14 shown in FIG. 4 is transmitted by the mirror 30 in the direction A and the remainder of the beam 14 is reflected in the direction B when the mirror is in the position denoted by 3a. 
     Analogous to FIG. 3b the incident beam 14 is transmitted by the mirror 30 in the direction A and the remainder of the beam 14 is reflected in the direction C when the mirror 30 is in the position denoted by 3b. 
     Analogous to FIG. 3c the incident beam 14 is transmitted through the mirror 30 or reflected thereby when the mirror 30 is in the position denoted by 3c. 
     In FIG. 4a, the incident light beam 14 is shown transmitted by the mirror 30 in the direction A and the remainder of the beam 14 is reflected in the direction B. 
     In FIG. 4b, the incident light beam 14 is shown transmitted by the mirror 30 in the direction A and the remainder of the beam 14 is reflected in the direction C. 
     In FIG. 4c, the incident light beam 14 is neither transmitted through the mirror 30 or reflected thereby. 
     FIGS. 5 and 6 show in detail another example of construction of the optical distributor in accordance with the invention. In these figures, elements which are identical or similar to those of the preceding figures are designated by the same references. Moreover, the position of the mirror 30 which has been illustrated is that of the notch Y in which the stud 38 has engaged. In this embodiment, the stud is designed in the form of a roller mounted on an oscillating arm 53 which maintains the roller within the notch by means of the spring 39. By cooperating with the switch 44, the arm 53 interrupts the power supply to the motor 40. It will be noted that the different notches X, Y and Z are located on the internal peripheral flange 68 of the turntable 31. 
     The turntable 31 which is rigidly fixed to a toothed wheel 63 rotates about the shaft 32 carried by a frame 54 (as shown in FIG. 6). The toothed wheel 63 directly engages a toothed pinion 62 carried by the shaft of the motor 40. The mirror 30 is maintained in position on the turntable 31 by two stops, one stop being retractable and designated by the reference 46 and the other stop being stationary and adjustable and designated by the reference 59. 
     The stop 59 is constituted by a device having a threaded rod 55 which is screwed on a shouldered element 56 of the turntable 31 and one end of which comes into contact with the lower portion of the frame 45. Screwing or unscrewing of the rod 55 permits accurate adjustment of the angular position of the mirror 30. Locking of the rod is obtained by means of nuts 57 and 58. 
     The retractable stop 46 has an arm 60 which oscillates about a shaft 61 carried by the turntable 31 within an opening 64 of this latter. One end of the arm 60 is adapted to cooperate with the frame 45 of the mirror whilst the other end is adapted to cooperate with a circular cam 65 carried by the frame 54. Thus, when said second end is engaged with the cam 65, the first end is no longer in contact with the frame 45, with the result that the mirror is capable of pivoting about the pin 33. On the other hand, when the cam 65 is not engaged, a spring (not shown) maintains the first end against the mirror which is in any case locked by the stationary stop 59. 
     The mechanical part 49, which is preferably made of teflon and in which the stud 47 is capable of sliding, is so arranged that the groove 48 is directed along a diameter of the turntable. In order that the stud 47 should engage within the groove 48 from the position of the mirror shown in FIG. 6, the lower portion of the part 49 is provided on the sides corresponding to the turntable 31 and the stop 59 with an extension 66 which prevents the mirror from moving beyond this angular position. Moreover, the turntable has a peripheral notch 67 over an angular sector which is sufficient to permit progressive disengagement of the stud 47. 
     The operation of the optical distributor of FIGS. 5 and 6 is identical with that described in connection with FIGS. 3 and 4. In this case, however, the direction of rotation of the turntable is reversed in regard to the foregoing explanation. In other words, the turntable passes from position X to position Y and to position Z as it rotates in the direction of the arrow 69.