DE1297351B - Device used to depict an object in infinity - Google Patents

Description

The invention relates to a device for imaging an object or several optically superimposed objects, preferably at or almost at infinity, the device has a large exit pupil and a wide angle of field of view and also has a compact structure and light weight.

It is particularly useful when building simulators for pilot training already known to generate an image of a nearby object located in infinity use a cocave mirror (U.S. Patent 2,482,115). Such a device however, requires a partially transparent plane mirror that is inclined to the axis of the curved mirror is arranged in front of its concave side.

The invention is based on the object of a device of The aforementioned type to be built in such a way that the observer can look at the Konkav mirror at will can approach far.

According to the invention, this object is achieved in that the device has the following features: a first planar polarizer, one for this polarizer towards convex partially transparent curved mirror, a first quarter-wave plate on the concave side of the curved mirror, a partially transparent plane mirror on the side of the first quarter-wave plate remote from the curved mirror, a second quarter-wave plate on top of that of the first quarter-wave plate remote side of the partially transparent plane mirror and a second plane polarizer on the side of the second quarter-wave plate remote from the partially transparent plane mirror.

The device is advantageously constructed in such a way that the quarter-wave plates, the partially transparent plane mirror and the plane polarizer made of flat, in one package assembled panes are formed and the curved mirror is spherical Mirror is.

Around the observer towards the object, not at the concave mirror To shield reflected light, the polarization elements are advantageous arranged so that the fast and slow axes of the first quarter wave plate are at essentially 45 ° to the plane of polarization of the first polarizer, and that the fast and slow axes of the second quarter-wave plate to aligned with the corresponding axes of the first quarter wave plate at angles are equal to a first, substantially whole multiple of 90 °, where the plane of polarization of the second plane polarizer to the plane of polarization of the first Planar polarizer under a second, essentially whole multiple of 90 ° is aligned at the same angle, with one multiple straight, and the other is odd.

In the drawing, some exemplary embodiments of the invention are shown in FIG shown schematically. It shows F i g. 1 is an exploded perspective view the individual parts of the device, F i g. Figure 2 is a side view of the assembled device according to FIG. 1, Fig. 3 shows an embodiment of the subject matter of the invention which the object to be imaged is a diffuse radiator, F i g. 4 the representation of a further embodiment of the subject matter of the invention, in which the Object consists of superimposed images, FIG. 5 shows a device similar to that in FIG. 4 shown, in which, however, one of the objects shown is an objective sphere simulated on the surface of the celestial sphere, F i g. 6 shows a diagram of a further exemplary embodiment, in which, however, the depicted The object contains a real aerial image generated by a projection system in the room, F i g. 7 is a diagram of one of the types shown in FIG. 6 shown embodiment similar Embodiment with a spherical concave mirror as a projection system.

In Fig. 1 denotes 2 an unpolarized light source, which generally has a certain spatial extent. In the embodiment according to FIG. 3, the source 2 is visible on the diffusion screen 32, while in the exemplary embodiment according to FIG. 6 the source is formed by a real aerial image indicated by the dashed line 62.

In Fig. 1 also shows a first polarizer 4 which linearly polarizes the light from source 2 passing through it. The direction of polarization of the polarizer 4 is shown in FIG. 1 indicated by a vertical arrow 4 ', although any direction can of course be used. The resulting polarization of the light passing through the element 4 is indicated by the vertical arrow 1 . Part of the linearly polarized light goes from the polarizer 4 through a partially transparent curved mirror 6 that is convex towards the source 2. The mirror 6 is, for example, spherical. Behind the mirror 6, ie on its right-hand side in FIG. 1, the linearly polarized light passing through this mirror hits a quarter-wave plate B. The mutually perpendicular fast and slow axes F and S of the plate 8 are at 45 ° to the plane of polarization aligned around the direction of propagation indicated by 5. The linearly polarized light emerging at the polarizer 4, which emerges from the quarter-wave plate 8, is circularly polarized either to the right or to the left, depending on whether the angle between the plane of polarization and the axis F is -h45 ° or -45 °. Let it be assumed that the light emerging from the quarter-wave plate 8 is circularly polarized, as indicated by the spiral line 3. This right circularly polarized light then hits a partially transparent and partially reflective plane mirror 10. The part of the right circularly polarized light passing through the mirror 10 hits a second quarter-wave plate 12, the fast and slow axes F 'and S' of which are perpendicular to the corresponding axes of the plate 8 are. Consequently, the light emerging from the plate 12 in the direction of propagation 5 is returned to linearly polarized light with a polarization plane below 90 ° to that of the polarizer 4. This is shown in FIG. 1 indicated by the arrow 7. This horizontally polarized light is blocked at a second plane polarizer 14, the polarization plane of which is parallel to that of the polarizer 4 , as indicated by the arrow 14 ' therein.

The part of the circularly polarized light from the quarter-wave plate 8 which is reflected on the partially transparent plane mirror 10 is converted into circularly polarized light of opposite rotation, ie into left circularly polarized light in the assumed case, during such reflection. That is in Fig. 1 indicated by means of the left-handed spiral 9. When it returns to the direction of propagation 5, but towards the source 2 , this left-hand circularly polarized light hits the quarter-wave plate 8 again, from which it emerges as linearly polarized light with a polarization plane below 90 ° to that of the light initially polarized at this element 4. This is in FIG. 1 indicated by the horizontal arrow 11. This horizontally linearly polarized light is partly reflected on the partially transparent concave mirror 6 without changing the orientation of its plane of polarization. The light reflected in this way is circularly polarized to the left as it passes through the quarter-wave plate 8, as indicated by the left-handed spiral 13. The part of this left-hand circularly polarized light passing through the beam splitter 10 is converted by the second quarter-wave plate 12 into linearly polarized light in a vertical plane of polarization, as indicated by the vertical arrow 15. This light is consequently transmitted through the second plane polarizer 14 and forms the only part of unpolarized light from the source 2 which is suitable for a on the right-hand side of the in the arrangement of FIG. 1 is visible to the standing observer.

The in connection with F i g. 1 described combination of plane polarizer 4, partially transparent curved mirror 6, quarter wave plate 8, partially transparent plane mirror 10, second quarter wave plate 12 and second plane polaristor 14 is used in the invention to enable the generation of a virtual image in or near the main focal point of the concave mirror 6 . This virtual image is then in turn reproduced at infinity by this curved mirror. Elements 8, 10, 12 and 14 of FIG. 1 can be assembled in a compact flat package which, for the purposes of the observer, takes up negligible space on the right-hand side of the concave mirror 6 and leaves this space completely free of any kind of obstruction. Neither the object to be finally depicted in infinity nor any oblique, partially transparent mirror are arranged in this space. The linear and angular dimensions of this object are therefore not limited by considerations of the distance between the concave mirror and any such oblique, partially transparent mirror, nor by the freedom of movement that the observer needs to be able to move freely.

Such a package is shown in FIG. 2 located generally at 16 and includes planar polarizer 14, quarter wave plates 8 and 12, and partially transparent plane mirror 10. In FIG. 2 are also a diffusing screen 20 which, when illuminated, serves as the object to be imaged and the source 2 of FIG. 1, the first polarizer 4 and the partially transparent concave mirror 6 are shown. The screen 20 is shown curved convexly towards the other elements, as it can advantageously be designed so that its virtual image generated by the plane mirror 10 can coincide with the curved focal surface of the spherical mirror 6 .

The combined thickness of the elements 8, 10, 12 and 14 forming the package 16 may be less than the sagitta s of the mirror 6, ie its depth. The focal surface of the mirror 6 is indicated by the dashed line f and is away from the mirror 6 by half its radius R. If one normally considers the combined thicknesses of elements 8, 10, 12 and 14 to be negligible with respect to the distance R / 2 and particularly takes into account that the mirror 10 is from the. Edge of the mirror 6 does not have any significant distance: is from FIG. 2 it can be seen that at a distance x of the unpolarized light source 20 to the left of the vertex of the mirror 6 such that x -I- s = R / 2 - s, then the object 20 from the plane mirror 10 on or in the vicinity of the focal surface f . is mapped virtually so that the spherical mirror 6 on the right side at infinity creates an image of the object provided by this upright image.

This is explained in more detail with reference to FIG. 3, which shows an exemplary embodiment of the invention, in which an object, for example a transparent object carrier 30 , is imaged by a projection lens 31 on a translucent diffusing screen 32. On the right side of the screen 32, the polarizer 4, the spherical partially transparent mirror 6 and the arrangement of the elements 8, 10, 12 and 14 indicated overall at 16 are arranged with a distance x between the screen 32 and the apex of the mirror 6 the result is an image of the object 30 on the right-hand side at infinity.

In Fig. 3, two points of the object formed by the luminescent screen are shown at o1 and 02. Your virtual images in the partially transparent plane mirror 10 of the unit 16 are shown on or in the vicinity of the focal surface of the mirror 6 indicated by the dashed line f at oi and 02 '. The path of two rays selected at the edge of the mirror 6 is indicated from each of these points. These are designated for the point o1 with 01 "and ol"'and for the point o2 with a2' and 02 "' . It can be seen that an observer at every point between the rays o1"' and o2 "in the collimated light can observe an image of the complete object running from o1 to o2.

In the embodiment of FIG. 3, the exit pupil of the system is formed at the edge of the mirror 6 itself. While the screen 32 in FIG. 3 is shown flat, it can advantageously be convexly curved towards the mirror 6 , as in connection with FIG. 2 is shown and explained. The radius of curvature of the screen 32 should as precisely as possible be equal to R / 2, ie the radius of curvature of the focal surface of the mirror 6, which serves as a collimator eyepiece. By choosing such a curvature for the screen 32 , a flat field is achieved.

In the embodiment of FIG. 3, the projection lens 30 and the screen 32 could be replaced by a cathode ray tube, the fluorescent screen of this tube replacing the screen 32 .

F i g. 4 shows an embodiment of the invention similar to that in FIG. 3, in which, however, a partially transparent plane mirror 41 is arranged obliquely through the optical axis of the system between the diffusion screen 33 and the first linear polarizer 4 . A second object, for example the pane of a television tube 43, is arranged in such a way that its image is generated in front of the mirror 41 in superimposition with the screen 33. In this way, the viewer or viewers on the right side of the package 16 in FIG. 4 an image of two object fields are presented in superposition. As desired, the embodiment of FIG. 4 the dimensional feature explained above in the form of the relationship x -I- s = r / 2 -s, according to which the distance x of the object 33 from the apex of the concave mirror 6 plus the depth s of this mirror is equal to or substantially equal to half the radius of curvature of this mirror minus this depth is.

F i g. 5 shows another embodiment of the invention similarly as in Fig. 4, only here is in place of the permeable slide 30, the Projection lens 31 and the diffusion screen 32 or 33 described above are, a sphere 52 is used, on which a counter image of the celestial sphere is applied can be. In Fig. 5 are also those of two points o. And o4 on the ball 42 and from the corresponding object points o and o8 on the screen 43 of the television tube outgoing rays and bundles of rays are shown. Cone of these points As you can see, diverging rays of light are produced by the partially transparent plane mirror reflected in the packet 16. Since in this embodiment as in that of F i g. 2 the optical distance from these object points to the plane mirror in the package 16 is approximately the same as the distance from this plane mirror to the focal surface of the mirror 6, these light cones hit after reflection by the plane mirror in the package 16 on the mirror 6 and are there in two parallel bundles converted, one of which in the figure with o4, o5 and the other with o4 ', 0e is designated.

In the device of the invention, the exit pupil of the partially transparent curved mirror or it can be shaped like a true exit pupil an image of the aperture stop of the system can be provided in the imaging space. A Such an image is then seen in the imaging space, specifically optically, behind it Mirror arranged. Optical positions behind this mirror are due to light, that originates from the object or objects and has been reflected on this mirror.

In the embodiments described so far, the spherical partially transparent mirror 6 itself mainly determines the angular range of the light bundles or light cones emanating from a point in the actual object (ie a point on the screens 32 or 33 of FIGS System. The spherical mirror thus forms the aperture diaphragm in these systems. Since, in relation to rays reflected on this mirror, there are, moreover, no optical elements which have a reflecting or refractive effect on these rays and consequently can produce an image of the edge of this mirror in the imaging space, there is no image of the edge or the edge of the Mirror 6 in the imaging space and consequently no exit pupil different from the edge or the edge of the mirror 6 itself. The embodiment of FIG. 5 has this characteristic feature, although the intersection of the boundary rays shown for the collimated bundles 041, os and o3 ', o. On the right-hand side of the mirror 6 gives the opposite appearance. This appearance is due to the fact that the boundary rays are shown well inside the edge of the mirror 6 in order to display the reflection from the mirror 10 in the package 16 of this figure back onto the mirror 6. In reality, the cones emanating from points o3, 04, o5 and o. And passing through the system have a common base determined by the edge of the mirror 6, and the parallel beams o4 0e and o3, 0s also in reality have by the edge of the mirror 6 limited cross-sections. These bundles consequently intersect at the mirror 6 and not to the right of it.

However, the invention can also be embodied in arrangements in which a true exit pupil is formed which determines the position within which the observer or observers must stand if they are to see the entire object. In this figure, the object presented to the combination of elements consisting of the polarizer 4, the mirror 6 and the package 16 is generated on a surface in space by means of a refractive and / or reflective object arranged to the left of it and shown schematically at 64, at 62 indicated real aerial view. These optics can be similar or essentially identical to that at 31 in FIG. 4 projection lens shown. The task of the optics 64 is to generate a real image at the point 62 which shows the image shown in FIG. 1 is intended to depict the device of the invention shown schematically at infinity on the right-hand side. In the embodiment of FIG. 6, the cone of the rays diverging to the right from each point in the real image at 62 is bounded by some element in the system 64, and according to the usual pupil theory all the collimated bundles corresponding to these cones pass through a common cross section called the exit pupil of the system, shown at 66 and defined as the image of the aperture stop created by all elements of the system optically behind the aperture stop in the direction of passage of light from the original object 31 to the final image at infinity on the right.

As in Fig. 6, the real aerial image at 62 can be composed of a combination of several real aerial images. In this figure, the slide 31 forms a first entrance. A second input is provided on a transparent or opaque further object carrier or image shown at 65, of which a virtual image is superimposed on the object 31 by means of a partially transparent plane mirror 67. Another input is indicated at 69 for connection to the inputs 31 and 65 by means of the semitransparent plane mirror or "connecting glass" 41 at the position 62. A projection system (not shown) which may be similar to the projection system 64 can be used to project from a diffusely luminous actual Object to generate a real image arranged through the glass 41 at the point 62. FIG. 7 shows yet another embodiment of the invention, which is similar to the example of FIG. 6, when the combination of spherical mirror 6 and package 16 is presented with a real aerial image 72 as an object, and furthermore FIG. 6, when an exit pupil is formed on the right side (in FIG. 7) of the package 16. In the embodiment of FIG. 7 takes the lens 64 from FIG. 6, however, the shape of a concave mirror 74 and associated semitransparent plane mirror 76 . The mirror 74 works with conjugates lying in the finite, the objective position for this being indicated at 78. Any individual image or a superimposition of several images can be generated at the point 78 by means not shown. For example, an illuminated transmissive slide can be disposed at location 78. In order to determine the nature of the passage of light through the system of FIG. 7, two points in the object are shown at 78 at o1 and o2, and parts of the light cone are shown at C1 and C2 which diverge from these points and pass through the system.

In Fig. 1 it was assumed that the planes of polarization of the planar polarizers 4 and 14 are parallel to one another and that the quarter-wave plates 8 and 12 are crossed with one another. However, the invention is not limited to this arrangement. When the respective axes of the plates 8 and 12 are parallel and when instead the polarizers 4 and 14 are crossed, the operation is essentially the same.

The polarizer 4 will, as before, linearly polarize the light from the source 2 , and the plate 8 will, as before, circularly polarize the linearly polarized light that has passed through the polarizer 4 and the concave mirror 6, with the mutually perpendicular fast and slow axes of the plate 8 again lie essentially at 45 ° to the plane of polarization imposed by the polarizer 4. If the fast and slow axes of the plate 12 are now parallel to those of the plate 8 , the plate 12 effects a return of this circularly polarized light into plane polarized light with a polarization plane shifted by 90 ° compared to the plane to which the light is returned, when the axes of the plate 12 with respect to the axes of the plate 8 are crossed. Assuming that the plane of polarization of the element 4 is perpendicular and that the respective axes of the plates 8 and 12 are parallel to each other, then that which passes from the source 2 through the polarizer 4 and arrives at the plate 12 without being subjected to reflection Light returned from plate 12 to perpendicular plane polarization. If, however, as is now assumed, the axes of the polarizers 4 and 14 are crossed, then the light emerging from the plate 12 at the polarizer 14 is blocked.

The alignment of the second quarter-wave plate 12 with parallel axes to those of the plate 8 has no influence on the effect of the elements 10, 8 and 6 on the part of the circularly polarized light generated on the plate 8 which is reflected on the plane beam splitter 10. Therefore, the light obtained from the latter by reflection on the concave mirror 6 and indicated at 13 has parallel light as in the case of the one actually shown in FIG. 1, when it arrives at the second plate 12 , a circular polarization that corresponds to that at 3 in FIG. 1 for the light first subjected to circular polarization by the quarter-wave plate 8 is opposite. It is therefore returned by the plate 12 in plane-polarized light which is polarized in a plane which is perpendicular to the plane into which the plate 12 returns the circularly polarized light indicated at 3. That is, assuming that the plane of polarization of the element 4 is perpendicular, the collimated light from the mirror 6 is returned through the plate 12 into horizontally polarized light. This light therefore passes through the planar polarizer 14 with a polarization plane now assumed to be perpendicular to the polarization plane of the polarizer 4.

In general, therefore, it can be said that the mutually perpendicular fast and slow axes of the two quarter-wave or "lambda / four" plates 8 and 12 should be oriented at substantially ± 45 ° to the plane of polarization of each of the plane polarizers that the corresponding axes (i.e. their fast axes) of the two quarter-wave plates should be aligned to each other at an angle that is a first, essentially whole multiple of 90 °, and that the planes of polarization of the two planar polarizers should be aligned to each other at an angle that is a second, essentially whole multiple of 90 °, one multiple being even and the other being odd. So if the first multiple is even, with the value zero, the corresponding axes of the quarter-wave plates are parallel and the second multiple is odd with the value one, so that the plane polarizers are crossed. If the first multiple is odd, ie, has the value one, the quarter-wave plates are crossed and the second multiple is even, ie, has the value zero, so that the plane polarizers become parallel. That is actually the one in FIG. 1 case. It is not necessary to consider even multiples other than zero or odd multiples than one.

Planar polarizers 4 and 14 and quarter wave plates 8 and 12 can all be formed as flat disks, which are well known in the art today. These devices are described, for example, in the article on polarized light in Vol. 10 of McGraw Hills "Encyclopedia of Science and Technology", 1960, pp. 448-454.

The invention is of course not restricted to the use of spherical mirrors. Other shapes of curved mirrors can be used. For such curved mirrors other than the spherical mirrors discussed, the object from which the system of the invention is to image at or near infinity (ie element 20, 32, 33, 43 and 52 in Figs , 4 and 5 or the real aerial image 62 or 72 from FIGS. 6 and 7) be arranged at such a distance from the beam-splitting mirror 10 that the virtual image of this object generated by this plane mirror is on or near the focal surface of the curved mirror occurs.

While in FIG. 2 the first polarizer is shown from the vertex of the mirror 6 by the distance x = R / 2 - 2 s, it can of course be arranged closer to the mirror 6 and it can be further than this distance x from the mirror 6, at least in embodiments of the invention which use a real aerial image, for example that of FIG. 6, use. In its simplest form, the invention therefore does not need to contain more than the curved mirror 6, the first quarter-wave plate 8, the partially transparent plane mirror 10, the second quarter-wave plate 12 and the plane polarizer 14. In general, although the invention has only been described on the basis of a number of exemplary embodiments which are currently preferred, it is not restricted to these.

Claims (3)

Claims: 1. For imaging an object at infinity, in particular as an eyepiece of a telescopic or microscopic system, having a concave mirror device, characterized by a first plane polarizer (4), a partially transparent curved mirror (6) convex towards this polarizer, a first quarter-wave plate (8) on the concave side of the curved mirror (6), a partially transparent plane mirror (10) on the side of the first quarter-wave plate (8) remote from the curved mirror (6), a second quarter-wave plate (12) on that of the first quarter-wave plate (8) remote side of the partially transparent plane mirror (10), and a second plane polarizer (14) on the side of the second quarter-wave plate (12) which is remote from the partly transparent plane mirror (10). 2. Apparatus according to claim 1, characterized in that the quarter-wave plates (8, 12), the partially transparent plane mirror (10) and the plane polarizer (14) are formed from flat disks assembled into a package and the curved mirror (6) is a spherical one Mirror is. 3. Apparatus according to claims 1 and 2, characterized in that the fast and slow axis of the first quarter-wave plate (8) are at substantially 45 ° to the plane of polarization of the first polarizer (4) and that the fast and slow axis of the second quarter-wave plate ( 12) are aligned to the corresponding axes of the first quarter-wave plate (8) at angles which are equal to a first substantially whole multiple of 90 °, the polarization plane of the second planar polarizer (14) to the polarization plane of the first planar polarizer (4) at one second, substantially whole multiples of 90 ° is aligned the same angle, one multiple being even and the other odd.