DE2753781A1 - OPTICAL SYSTEM - Google Patents

Description

The invention relates to an optical system with devices for aligning the system to a specific point and with a measuring device for determining the deviation
a radiation source from the line of sight to that point.

The invention is intended in particular for weapon systems
Guiding a moving object, e.g. a projectile, to a target can be used. In such cases it will
optical system is aimed at a point on the target, and the operator continuously directs the line of sight on the target. If now the moving object with means

809823/0828

is provided for emitting radiation, the deviation of the radiation means from the line of sight can be determined by means of the measuring device which is responsive to the emitted radiation. The radiation can be generated by a radiation source located within the housing of the moving Object is attached, or it can be generated by the drive motor of the moving object, in which case the Radiation takes the form of infrared radiation. However, the radiation can also emanate from reflectors on the moving object are arranged. In this case the radiation is generated by a radiation source, e.g. is arranged at the location of the optical system. The radiation is then transmitted to the moving object and then reflected back to the optical system by the reflectors.

In a particularly important and advantageous embodiment, the invention features an optical sight of the type combined, which has a tracking telescope having crossed hairs or other reference symbols for the sight to make it easier for the operator to the sight aiming at the goal and following it. The measuring device for determining the deviation of the radiation source from the line of sight comprises a movable measuring mask which is arranged in an image plane of the optical system, so that the radiation emitted by the radiation source alternately passes through or is retained by the mask

809823/0828
- 2 -

will. The movable mask can, for example, consist of a glass plate with an opaque, modulating pattern applied thereon, the pattern having a shape such that information via the location of the radiation source from the fluctuations in radiation intensity and the current angular position the measurement mask can be obtained.

Already known tracking telescopes are primarily with an objective lens, an eyepiece and a visible one Visor reference symbol or reference symbol for the sight, generally of the cross-haired type, wherein thin lines are provided on a glass surface which is arranged in the image plane of the objective. The operator can see the target and its background by means of the eyepiece and with the help of aiming buttons or the like Point the reference symbol of the sight at the target and point the symbol at the target during the tracking process keep. Due to the fact that two different main functions, namely aiming and measuring the location, are effected it has heretofore been necessary to use two different optical systems, one optical system for aiming or an optical system for measuring the location. In order to obtain acceptable accuracy when measuring, it is essential that that the relative position of the measuring device and the target device is not caused by mechanical deformations or temperature changes etc. is influenced. An influence on an optj.

809823/0828
- 3 -

see or mechanical element may change the lead relative position of the optical systems of the visor. The measuring systems are therefore generally equipped with devices in order that sufficient measuring accuracy can be obtained for checking and adjusting the line of sight of the telescope and the axes of the measuring unit.

It is therefore an object of the invention to create an optical system in which the above-mentioned disadvantages can be avoided in a technically simple manner.

This object is achieved in that the optics of the optical system share optics for both alignment as well as measuring the place.

This means that any change in the optical system is also increased same changes will result in both bodies while the relative setting of the two devices to each other remains unchanged. Any means of control or adjustment are not required.

The radiation emitted by the radiation source is received in the measuring device by a photodetector, the should be provided with a small detector surface to achieve a low noise level and a correspondingly high sensitivity. The image plane in which the measuring device

809823/0828
- 4 -

device is arranged, should therefore expediently on the photodetector with the greatest possible reduction on such Be imaged in a manner that all of the light that passes through the measuring device also reaches the detector. One In this case, a certain size of the detector surface corresponds to the largest value of the deviation angle that can be measured. In different systems for measuring the location is however, the radiation emitted from the radiation source is generally strong when the angle of deviation is large.

This is the case, for example, when the radiation source is away from the

Position measuring system at a constant distance from the line of sight. If measurements are taken over short distances, the measuring device must be provided with a large field of view, while at the same time the de- The signal size provided by the detector must be sufficiently large. When measuring at great distances, that is However, the field of view is small and the signal size made available by the detector is often not large enough.

Therefore, another object of the invention is to provide a photodetector in a measuring device of the above Type in which an acceptable signal magnitude is passed through the detector at both short and long distances Distances is provided. To achieve this, in a preferred embodiment of the invention is still a photodetector is provided, which is located in or near a picture

809823/0828
- 5 -

plane of the optical system is arranged and provided with a surface which is sensitive to the radiation emitted by the radiation source, the surface in two or several sub-surfaces, each of which corresponds to a particular range of angles at which the Location of the radiation source can be determined.

The invention is described below, for example, with reference to the accompanying drawings. Show it:

Fig. 1 in a schematic representation of an inventive optical system;

FIG. 2 shows an alternative embodiment of the system according to FIG Fig. 1;

Fig. 3 means by which the alignment of the system is facilitated;

4 shows the measuring device;

Fig. 5 shows a further embodiment of the invention with a photodetector, the sensitive surface in two divided into separate areas;

809823/0828
- 6 -

6 shows the sensitive surface of the detector;

7 shows an alternative embodiment of the detector surface;

8 is an enlarged view of the measuring device;

FIG. 9 is an enlarged sectional view of the area between the permeable and impermeable areas of FIG Measuring device; and

10 shows an alternative and improved embodiment in a view according to FIG. 9.

In Fig. 1, the optical system according to the invention is shown schematically. As mentioned earlier, this is optical System particularly suitable for being built into an optical sight. For this reason it will be used in the following in connection with an optical sight which has the two main functions that the Target looked at and the line of sight can be kept on the target and that the path of a projectile with the line of sight compared and the deviation between the projectile and the line of sight can be determined. The type of measurement process and the way in which the deviation determined by the measuring process is converted into an electrical signal

809823 / Ü828
- 7 -

and how this signal is processed and evaluated does not form part of the invention and is therefore not discussed here described in more detail.

The optical system essentially comprises a single optical input port with an objective lens 1, a glass plate 2 and a prism 3 to receive the visible light from the target and from its background and the radiation emitted by the radiation source of the projectile. The radiation source can for example consist of a laser source, preferably a laser diode which is attached to the projectile in such a way that the laser light is emitted towards the sight. the Objective lens 1 collects both visible light and laser light and is designed so that the focal length for visible light and laser light is different. It follows from this that an image of the target and its background is _{projected into the image plane F 1} for visible light, while an image of the radiation source is projected into another image plane F ₂ for laser light. In Fig. 1, the beam path of visible light is indicated by dashed lines, while the Laser light is indicated by solid lines. The beam paths are divided in the prism 3 in a manner known per se, so that visible light passes through the prism and falls out of this through an eyepiece 4 into the eyes of an operator, while the laser light through the prism reflected and out of this through a lens system 6

809823/0828
- 8th -

2703781

arrives at a detector 7.

In order to facilitate the tracking process, the optical system is provided with a reference symbol for the sight sight, which consists of thin lines on a glass surface which is _{arranged in the image plane F 1} , so that the operator can see the target and its background together with the reference symbol of the Sight in the eyepiece 4 can see. The symbol can consist of a circle 8 or arc 9 or several concentric circles or arcs (see FIG. 3) which have the line of sight 10 as their common center.

The latter embodiment is preferred over conventional crossed hair when the measuring device, as described below, rotated around the line of sight as the axis of rotation. The lines of the reference symbol of the sient visor must be so thin that they do not hinder the operation of the measuring device by the fact that the light rays to be interrupted.

In order to determine the deviation of the projectile from the line of sight, the optical system is provided with a measuring device which has the form of a measuring mask 11 (see FIG. 4) and is arranged in the image plane F ₂ . The measuring mask can consist of a glass plate with a dichroic plate arranged on it

809823 / Ü828
- 9 -

/ S

exist geometric pattern that is permeable to visible light, but impermeable to the laser light emitted by the radiation source. Because this pattern is for visible light is permeable, it does not interfere with the optical image and the reference symbol of the sight even when the mask is is moved away.

The distance between the two image planes F ₁ and F ₂ is so great that the masking effects caused by the lines of the reference symbol of the sighting device are small, while at the same time the measurement mask and the reference symbol des Sight visors are arranged on the same optical element, for example on each side of the glass plate 2, the side surfaces of which coincide with the planes F ₁ and F ₂ . As the glass plate common element for the functions of both aiming and aiming of location measurement, any change in the optical system results to the same changes in both institutions, while the relative attitude of these two institutions remains unchanged. Any means of controlling and adjusting the line of sight and the axes of the measuring device are not necessary.

Instead of a common glass plate, two glass plates 13 »14 can be used (see FIG. 2). In this case, the image plane F ₁ 'for the visible light preferably coincides with the surface of the glass plate 13, which is used for loading

809823/0828
- 10 -

2 7 b 3 7 8 Ί / ffe

supervisor executed 1st. The image plane P ^ 'for the Analogously, laser light should coincide with the surface of the glass plate 14 which is directed towards the detector 7. Others too Embodiments with two glass plates are possible; however, the only condition that must be observed is that the glass surfaces on which the reference symbol for the sight and the measuring mask are attached coincide with the corresponding image plane and that both glass plates so are connected that they are not moved relative to each other can. For the visler to work, it is necessary for the glass plate 14 to rotate. The glass plate 13 can with the Glass plate 14 be rigidly connected and rotate at the same rotational speed. However, it can also be fixed; in in this case, the reference symbol can be made of crossed hairs stand.

3 shows a view of the glass surface, which is arranged in the image plane F ₁ , with the reference symbol of the sight sight, which comprises concentric circles 8 and arcs 9 around a center point which lies on the sight line 10. The middle point is preferably indicated by a small point 15. The blurred spot 16 is related to the image of the radiation source, which _{is blurred in the image plane F 1} , but has sharp boundaries in the image plane Fp. In this case, it is assumed that the wavelength of the beam radiation source emitted radiation in the visible range of the

809823/0828
- 11 -

Spectrum lies. However, it can also be advantageous to choose the wavelength of the emitted radiation outside the visible range of the spectrum, in which case no blurred image appears in the image plane F ₁ .

4 shows a view of the glass surface, which is arranged in the image plane F ₂ , with the measuring mask 11, which consists of a glass plate which bears a dichroic geometric pattern. The entire surface of the glass plate is permeable to visible light. The pattern arranged on it However, is for radiation emitted by the radiation source is emitted, impermeable. The boundary line 17 of the opaque pattern can have such a shape that information relating to the position of the radiation source from the Relationship between the occurring fluctuations of the strah lung intensity and the angular position of the mask can be. This is in the simultaneously filed patent application No. ..., that of the Swedish patent application No. 76 13514-4, described more clearly.

In order to obtain a low noise level and a correspondingly high sensitivity of the detector 7 ¹ , the detector is arranged in an image plane F (see FIG. 5) in such a way that the image plane F ₂ with the position measuring device is as reduced as possible to the detector surface is mapped. All radiation emitted by the

809823/0828
- 12 -

In this case, the detector 7 ' reach. The sensitive surface of the detector is divided into two or more separate areas, each of these separate areas corresponding to a certain range of angles in which the location of the radiation source is determined can. Preferably, the surface of the detector consists of an inner central surface 19 and an outer annular surface 20 (see Fig. 6).

The inner surface 19 corresponds to the range of angles or the measuring range in which the deviation of the radiation source is small, i.e. a narrow field of view of the optical system. The outer surface 20, on the other hand, corresponds to the range of angles or the measuring range in which the deviation the radiation source is large, i.e. a wide field of view of the optical system. The electrical connection to the outside Surface 20 can be interrupted when the deviation angle is small and great sensitivity is required. In this case, the possibility is eliminated that the measuring device by other radiation sources within the Measuring range of the outer detector could be disturbed. Also the electrical connection to the inner detector surface 19 can be interrupted, e.g. in cases where

isjfc. the angle of deviation of the radiation source is quite large / and the incident light has a great intensity.

809823/0828
- 13 -

In Fig. 7 an alternative embodiment of the detector surface is shown. Corresponding bits of the embodiment according to FIG. 2 is the detector surface in a central one Surface 21 and an outer surface 22 divided. In this case the inner surface is rectangular, and the outer surface does not completely enclose the inner surface. Such a form of detector surfaces is preferred when different measuring ranges are required in the vertical plane and the horizontal plane. If the measuring range is in the vertical direction is not fully used, the corresponding area of the sensitive detector surface can be omitted, which means that the surface area can be reduced and a corresponding increase in sensitivity can be obtained.

It is important, in order to obtain an accurate measurement of the location of the projectile, that the boundary line 17, i.e. the transition between the permeable part 12 and the opaque part 18 the mask is clearly delimited. In practice, however, this is the case difficult to achieve because the dichroic pattern consists of several thin dielectric layers, which are arranged on top of one another. This results in a transition zone between the permeable and opaque areas of the mask in which the permeability gradually increases from a high value to a low value changes.

809823/0828
- 14 -

2/53781

XO

From Flg. 9, which is an enlarged cross-sectional view of the Area between the transparent and opaque areas of the mask shows, it can be seen that the dlchrolsche pattern 12 consists of a number of layers 23, usually made of dielectric material, which are deposited on the glass plate are arranged and together form a layer which interrupts the radiation in question. Due to the large number of Layers included in the pattern, a transition zone d occurs. As already mentioned, such an over- transition zone is not satisfactory if the location of the property is to be precisely determined. As an example of the level of accuracy that is required, it can be mentioned that for a change in the transmitted radiation intensity of 90 %, a change in location of the projectile of a maximum of 0.05 mrad allowed is.

In order to improve the sharpness of the edge of the dichroic pattern and thus to reduce this transition zone, is the edge of the pattern, which is adjacent to the transmissive part of the mask, provided with a layer 24 suitable for the Radiation is opaque (see Fig. 8). This edge layer extends along the borderline of the pattern and is so narrow that when the mask rotates the device is still see-through. The edge layer is preferably made of a metal that can be shaped very precisely,

809823/0828
- 15 -

2 7 5 3 7 8 i

ZA

e.g. aluminum. From Flg. It can be seen that the metal layer is placed on top of the dielectric layers. However, it is also possible to place the edge layer under the dielectric layers along your boundary lines.

809823/0828
- 16 -

Claims (16)

Claims 1. Optical system with devices for aligning the System to a certain point and with a measuring device for determining the deviation of a radiation source from the Direction to this point, characterized in that for aligning the system and measuring a common optical system is provided for the deviation. 2. Optical system according to claim 1, characterized in that the optics are an objective lens (1) to collect both visible light and radiation emitted from the radiation source 809823/0828
- 1 - Optical element (2), which both means in the form of reference symbols (8, 9, 15) of a sight to align the optical system to the point, as well as includes the measuring device (11) and a prism (3) for separating the visible light and the radiation emitted by the radiation source. 3. Optical system according to claim 1 or 2, characterized in that the objective lens (1) is designed so that the focal lengths for visible light and the radiation emitted by the radiation source are different, so that a visible image in a first image plane (F ₁ , F ₁ ') and an image representing the radiation source is projected _{in a second image plane (F 2} , F ₂ ^1). 4. Optical system according to claim 3, characterized in that the optical element (2) is arranged so that the reference symbol (8, 9, 15) for the sight in the first image plane (F ₁ , F ₁ ·) and the Measuring device (11) is located in the second image plane (F ₂ , F ₂ ¹ ). 5. Optical system according to claim 4, characterized in that the distance between the first (F ₁ , F ₁ ¹ ) and the second (F ₂ , F ₂ ¹ ) image plane is so large that the influence of the measuring device (11) on the sight is small. 809823/0828
- 2 - 6. Optical system according to one of claims 3 to 5, characterized in that the optical element consists of a glass plate (2) which carries the reference symbol (β, 9, 15) of the sight and the heating device on each of the two opposite side surfaces of the glass plate, which in the two image planes (F ^ or . F ₂ ) are arranged. 7. Optical system according to one of claims 3 to 5, characterized in that the optical system (2) includes two parallel glass plates (13, 14), of which one glass plate (13) has a side surface which extends in the first image plane (F ₁ ¹ ) is arranged, in which the reference symbol (8, 9, 13) of the sight is located, and of which the other glass plate (14) has a side surface which is arranged in the other image plane (F ₂ ') in which the measuring device (11) is located. 8. Optical system according to claim 7, characterized in that the reference symbol (8, 9, 13) of the Sight sight and the measuring device (11) are arranged on two side surfaces which are directed towards one another. 9. Optical system according to one of claims 1 to 8, characterized by a photodetector (7 ¹ ) »in or near an image plane (F 1) of the optical 809823/0828
- 3 - System is arranged and provided with a surface that is sensitive to the radiation emitted by the radiation source is, this surface being divided into two or more separate sections (19, 20), each of which is one corresponds to a certain range of angles representing the deviation of the radiation source. 10. Optical system according to claim 9, characterized in that the sensitive surface of the Photodetector (7 ') from an inner central surface (19), which corresponds to a range of angles at which the deviation of the radiation source is small, and from an outer one Surface (20) which includes the inner surface (19) and corresponds to a range of angles at which the deviation of the radiation source is large. 11. Optical system according to claim 10, characterized in that the detector surfaces (19, 20) can be electrically switched off independently of one another. 12. Optical system according to one of claims 9 to 11, characterized in that the shape of the detector surfaces (21, 22) corresponds to a specific measuring range for the deviation of the radiation source. 809823/0828
- 4 - ir 13. Optical system according to one of claims 4 to 12, characterized in that the measuring device consists of a rotating measuring mask (11) which has a surface on which a dichroic pattern is applied and is arranged so that the entire surface of the mask is transparent and partially opaque to visible light is for the radiation emitted by the radiation source. 14. Optical system according to one of claims 4 to 13 »characterized in that the dichroic Pattern (12) on its boundary line (17), which adjoins the part of the mask surface which is for by the radiation source emitted radiation is transparent, is provided with a narrow layer (18) to improve the sharpness of the edge of the dichroic layer (12). 15. Optical system according to one of claims 4 to 14, characterized in that the reference symbol for the sight of a circle or several circles (8) or arcs (9), which are the axes of rotation of the measuring mask (11) as the center. 16. Optical system according to one of claims 1 to 15, characterized in that the radiation source emits laser light. 809823/0828 - 5 -