Sighting arrangement comprising a prism system with a flat top surface

Abstract

A sighting arrangement, comprising an illuminated mark and a prism system consisting of a first prism and a second prism which are connected to each other via a dichroic reflector surface, the prism system comprising a sight axis and a superimposition axis for imaging the illuminated mark onto a sighted target. The bottom surface, via which the imaging beam path emanating from the illuminated mark is coupled into the prism system, and the convexly curved mirror surface, which is absolutely necessary for collimating the imaging beam path, are located on the same side of the prism system, namely on the mounting side facing a device on which the prism system is mounted as intended. As a result, the prism system has a flat top surface which does not limit the field of view section determined by the visible edges of the prism system.

Claims

1. A sighting arrangement, comprising: an illuminated mark, and a prism system consisting of a first prism and a second prism which are connected to one another via a dichroic reflector surface which encloses an angle with a sight axis which is orthogonal to an entrance surface present on the first prism and to an exit surface parallel thereto and present on the second prism, wherein a convexly curved mirror surface is present on the second prism, which convexly curved mirror surface has a vertex and a focal point, said focal point defining a superimposition axis together with the vertex and being located on a bottom surface formed on the first prism, where the illuminated mark is also positioned, and wherein the superimposition axis and the sight axis coincide between the exit surface and the dichroic reflector surface, and wherein the angle is greater than 45°, less than 90° and the first prism has a planar mirror surface arranged opposite the convexly curved mirror surface, which is arranged on a mounting side of the prism system, said planar mirror surface also being arranged orthogonally to the entrance surface and to the exit surface, at which planar mirror surface the superimposition axis is folded once between the bottom surface and the dichroic reflector surface.

2. The sighting arrangement according to claim 1, wherein two or a multiple of two further planar mirror surfaces are present between the planar mirror surface and the convexly curved mirror surface.

3. The sighting arrangement according to claim 1, wherein the bottom surface is parallel to the planar mirror surface.

4. The sighting arrangement according to claim 2, wherein the bottom surface is parallel to the planar mirror surface.

5. A sighting arrangement, comprising: an illuminated mark, and a prism system consisting of a first prism and a second prism which are connected to one another via a dichroic reflector surface which encloses an angle with a sight axis which is orthogonal to an entrance surface present on the first prism and to an exit surface parallel thereto and present on the second prism, wherein a convexly curved mirror surface is present on the second prism, which convexly curved mirror surface has a vertex and a focal point, said focal point defining a superimposition axis together with the vertex and being located a distance from a bottom surface formed on the first prism, outside the prism system, where the illuminated mark is also positioned, and wherein the superimposition axis and the sight axis coincide between the exit surface and the dichroic reflector surface, and wherein the angle is greater than 45°, less than 90° and the first prism has a planar mirror surface arranged opposite the convexly curved mirror surface, which is arranged on a mounting side of the prism system, said planar mirror surface also being arranged orthogonally to the entrance surface and to the exit surface, at which planar mirror surface the superimposition axis is folded once between the bottom surface and the dichroic reflector surface.

6. The sighting arrangement according to claim 5, wherein two or a multiple of two further planar mirror surfaces are present between the planar mirror surface and the convexly curved mirror surface.

7. The sighting arrangement according to claim 5, wherein the bottom surface is parallel to the planar mirror surface.

8. The sighting arrangement according to claim 7, wherein the bottom surface is parallel to the planar mirror surface.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be explained in more detail below with reference to an exemplary embodiments and with the help of drawings, wherein:

(2) FIG. 1 shows a three-dimensional view of a sighting arrangement according to the invention;

(3) FIG. 2 shows a lateral view of the sighting arrangement according to FIG. 1 including the imaging beam path of the illuminated mark,

(4) FIG. 3 shows a rear view of the sighting arrangement according to FIG. 1, and

(5) FIG. 4 shows a lateral view of another sighting arrangement, including the imaging beam path of the illuminated mark.

DETAILED DESCRIPTION

(6) A sighting arrangement according to the invention, shown in FIGS. 1 to 3, includes an illuminated mark 7 and a prism system formed by a first prism 1 and a second prism 2. The prisms 1, 2 are connected to each other via a dichroic reflector surface 3, which is inclined at an angle α to the optical axis, hereafter referred to as the sight axis 4, between an entrance surface 1.1 present on the first prism 1 and an exit surface 2.1 present on the second prism 2 and arranged parallel to the entrance surface 1.1.

(7) The sight axis 4 is orthogonal to the entrance surface 1.1 and to the exit surface 2.1, so that the prism system acts as a plane-parallel plate for the imaging of a target sighted on the sight axis 4 in the eye of an observer and is thus non-refractive.

(8) For the superimposition of an illuminated mark 7 onto the sight axis 4, a bottom surface 1.2 for the entry of the imaging beam path into the prism system, a planar mirror surface 1.3 for a first reflection, a convexly curved mirror surface 2.2 for a second reflection as well as collimation, and the dichroic reflector surface 3 for a third reflection in the direction of the sight axis 4 are provided on the first prism 1 along a further optical axis, hereinafter referred to as the superimposition axis 5, in the direction of the imaging of the illuminated mark 7. In the case of the convexly curved mirror surface 2.2 present on the second prism 2, it is assumed in a simplified manner for an easily understandable description of the invention that this is a spherical mirror surface with a vertex S and a focal point F. The optical distance between the focal point F and the vertex S represents the back focal length of the convexly curved mirror surface 2.2. The prism system is dimensioned such that the focal point F is either on the bottom surface 1.2 or at a distance from the bottom surface 1.2 outside the prism system (see FIG. 2).

(9) For the intended use of the prism system, it is placed on a device to be aligned with a target, in particular on a hand-held firearm, in such a way that the sight axis 4 extends parallel to a shooting axis of the device. The bottom surface 1.2 and the convexly curved mirror surface 2.2 are arranged facing the device on a mounting side of the prism system. Accordingly, the planar mirror surface 1.3 on the first prism 1 is part of the top surface of the prism system connecting the entrance surface 1.1 and the exit surface 2.1. The bottom surface 1.2 can be arranged inclined to the planar mirror surface 1.3 so that the superimposition axis 5 is orthogonal to it.

(10) Referring also to FIG. 4, advantageously, however, since this is easier to produce, bottom surface 1.2 can alternatively be arranged parallel to the planar mirror surface 2.1, which is negligible for the quality of the image of the illuminated mark 7 due to the narrow-band wavelength spectrum with which the illuminated mark 7 is illuminated or with which it glows.

(11) It is common for prism systems of sighting arrangements to be inserted in a prism holder when connected to the weapon. A prism system according to the invention is connected to a prism holder or the device itself for mounting on a device as intended in such a way that the bottom surface 1.2 and the convexly curved mirror surface 2.2 are enclosed by the prism holder or the housing of the device below a mounting plane, but the entrance surface 1.1 and the exit surface 1.2 lie above the mounting plane and are not limited by the prism holder or the housing.

(12) If the illuminated mark 7 is arranged outside the prism system, the illuminated mark 7 is advantageously attached to the prism holder or to the housing of the device. The attachment is advantageously adjustable in order to align the illuminated mark 7 exactly in the focal point of the convexly curved mirror surface 2.2.

(13) The prism system of a sighting arrangement according to the invention differs from that of the aforementioned U.S. Pat. No. 5,901,452 A essentially in that, in addition to the aforementioned five functional surfaces, namely the dichroic reflector surface 3, the entrance surface 1.1, the exit surface 2.1, the convexly curved mirror surface 2.2 and the bottom surface 1.2, there is exactly one further functional surface which is formed by the planar mirror surface 1.3.

(14) The planar mirror surface 1.3 is arranged orthogonally to the entrance surface 1.1, bounding the first prism 1, between the entrance surface 1.1 and the exit surface 2.1. The projection of the planar mirror surface 1.3 in the direction of the sight axis 4 thus only represents a line that coincides with an upper edge of the entrance surface 1.1, which is why the top surface of the prism system is flat. In contrast to the sighting arrangements according to the aforementioned U.S. Pat. No. 5,901,452 A and also the aforementioned DE 10 2016 105 751 A1, the convexly curved mirror surface 2.2 does not create an edge region limiting the field of view section, since the convexly curved mirror surface 2.2 is arranged below the mounting plane of a device which limits the field of view section towards the device.

(15) Like known sighting arrangements, the beam reflected and collimated via the convexly curved mirror surface 2.2 is deflected via the dichroic reflector surface 3 in the direction of the sight axis 4, and the superimposition axis 5 and the sight axis 4 coincide. The radius of curvature of the convexly curved mirror surface 2.2 is selected such that its back focal length is equal to or slightly longer than the path of the axial ray of the beam which the latter travels between the bottom surface 1.2 and the convexly curved mirror surface 2.2.

(16) As shown in FIG. 2, a beam emanating from the illuminated mark 7 is reflected at the planar mirror surface 1.3 before it impinges on the dichroic mirror surface 2.2, so that, in comparison with the aforementioned U.S. Pat. No. 5,901,452 A, the focal length, determined by the radius of curvature and the refractive index of the material of the prism system, and thus also the back focal length is longer. Practically, the focal length F could be further increased by providing two or even a multiple of two more planar mirror surfaces between the planar mirror surface 1.3 and the convexly curved mirror surface 2.2. This would have the advantage that for a given width b of the prism system and thus the width of the field of view section, the construction height h.sub.b can be reduced. The construction height h.sub.b is greater than a height h.sub.s of the field of view section, at least by the projection height b.sub.p, which results from the projection of the convexly curved mirror surface 2.2 in the direction of the sight axis 4. As already explained, when the prism system is mounted on a device in the intended manner, the convexly curved mirror surface 2.2 does not lie within the field of view section which is limited by the visible edges of the sighting system which the eye perceives when sighting. A mounting plane on the device is perceived as the lower edge. Regardless of its radius of curvature, the convexly curved mirror surface 2.2 lies below said mounting plane, which is why the projection of the convexly curved mirror surface 2.2 in the direction of the sight axis does not form an edge region limiting the field of view section. However, it influences the distance of the sight axis 4 to the axis of a firearm on which the prism system is mounted as intended, which is why a large radius of curvature, i.e. a small curvature, is advantageous.

(17) The function of the planar mirror surface 1.3 is basically not the folding of the imaging beam path for the purpose of extending the focal length, but the fact that the bottom surface 1.2, via which the imaging beam path emanating from the illuminated mark 7 is coupled into the prism system, and the convexly curved mirror surface 2.2, which is absolutely necessary for collimating the imaging beam path, are located on the same side of the prism system, namely on the mounting side facing a device on which the prism system is mounted as intended.

(18) The edges of the prism system which limit the field of view section are only limited by the visible edges of the entrance surface 1.1 or the exit surface 2.1 in addition to the mounting plane. However, these can have a certain width due to structurally necessary means such as chamfers, which are formed in glass components to prevent and eliminate cracks. When aiming, the user sees a prismatic body with planar entrance and exit surfaces and a top surface that is planar with respect to the housing of the device. The side surfaces along the sighting line can be designed to be inclined with respect to the top surface to allow impact without damage. Advantageously, the entrance surface 1.1 and the exit surface are identical in shape and size.

(19) With the extension of the first prism 1, when arranging several planar mirror surfaces, the viewing window height h.sub.s can be reduced while maintaining the radius of curvature and thus the focal length, whereby the viewing window height h.sub.s of the prism system can be realised in a manner optimally adapted to the required circumstances, independent of the focal length. If there is only a slight curvature, the width b, determined by the distance between the lateral surfaces 6 of the prism system, can also be chosen comparatively large in relation to the height h.sub.s, namely more than twice as large. For a great number of sighting situations, a field of view section with a large width is desired, although its height can be comparatively small. Accordingly, the prism system has a comparatively large width b, which corresponds, in this case, to the construction width and the viewing window width, and a comparatively low viewing window height h.sub.s is sufficient.

(20) As in the prior art, the illuminated mark 7 can be an illuminated mark or advantageously a light source, for example in the form of an LED, in particular a light-emitting diode in the red spectrum. The wavelength range here is relatively narrow-band, which is why the reflective coatings only have to be designed for this wavelength range. As the focal length can be comparatively long, the need for the smallest possible illuminated mark, which can only be realised by masking the light exit surface of a light source, i.e. an illuminated mark, is alleviated.

(21) The use of a spherical surface has the disadvantage that not all rays of the beam emanating from the illuminated mark 7 are imaged to infinity. This image error is due to the spherical aberration of a spherical lens surface. Since this type of sight is intended to provide a large, clear field of view section, the curved mirror surface, which acts like a lens segment, is made larger than directly necessary. This also increases the system-related image errors. In particular, it is unfavourable if the pupil of the eye is not arranged on the sight axis 4 but displaced towards an edge of the exit surface 2.1, which is referred to as an off-axis gaze. Due to the spherical aberration, the effect is that the image of the illuminated mark 7 is created at a different distance than that at which the target object is located. In conjunction with the off-axis gaze through the sight, there is a sighting error known as parallax error, caused by the different distances of the target object and the image of the illuminated mark 7. The parallax is expressed in the sense that a different position of the target object is perceived depending on the distance of the eye from the sight axis 4, although the position of the sight as such is not changed. Also, this error cannot be prevented by adjustment measures, since the coincidence of the image and object planes has already been established on the sight axis 4.

(22) To avoid a possible parallax error, the convexly curved mirror surface 2.2 can advantageously be designed not as a spherical mirror surface, but as an aspherical mirror surface in the form of a paraboloid of rotation. As is generally known, all rays emanating from the focal point of a parabola are reflected in an ideal manner as a parallel light beam. Spherical aberration and distortion are also completely eliminated by such a parabolic mirror surface.

(23) Advantageously, the first and second prisms 1, 2 may be made of a plastic material if the operating temperature of the sight permits the use of a plastic material. The plastic parts can be produced in a moulding process, e.g. by injection moulding, or in a shaping process.

(24) However, plastics also have disadvantages compared to glass in robust use, such as lower scratch resistance and only low resistance to solvents and cleaning agents.

(25) In a straight view along the sight axis 4, the magnification remains completely unchanged. Dispersion also does not occur when the same materials are chosen for the individual prisms. Only through the dichroic reflector surface 3 are there partial transmission losses.

LIST OF REFERENCE NUMERALS

(26) 1 first prism

(27) 1.1 entrance surface

(28) 1.2 bottom surface

(29) 1.3 planar mirror surface

(30) 2 second prism

(31) 2.1 exit surface

(32) 2.2 convexly curved mirror surface

(33) 3 dichroic reflector surface

(34) 4 sight axis (shown as a dashed line)

(35) 5 superimposition axis (shown as a dashed/dotted line)

(36) 6 lateral surface

(37) 7 illuminated mark

(38) F focal point

(39) S vertex

(40) h.sub.s viewing window height

(41) b width

(42) α angle

(43) h.sub.b construction height

(44) h.sub.p projection height