WO2023275502A1

WO2023275502A1 - Direct optical path

Info

Publication number: WO2023275502A1
Application number: PCT/FR2022/051331
Authority: WO
Inventors: Françoise CAU; Frédéric DUVAL; Philippe Patry; Vincent Marie
Original assignee: Safran Electronics & Defense
Priority date: 2021-07-02
Filing date: 2022-07-04
Publication date: 2023-01-05
Also published as: FR3124863A1

Abstract

The present invention relates to a direct optical path (1) comprising: - an optical lens system (2), - an ocular path separation system (3), - a system for injecting a video pathway (4), - a first observation optical path (5), and - a second observation optical path (6). - characterised in that the direct optical path (1) comprises: means for rotating the first observation optical path (5), in particular for interpupillary adjustment, and a first optical rectification system (8) and a second optical rectification system (10) for each of the first observation optical path (5) and the second observation optical path (6), respectively.

Description

OPTICAL DIRECT PATH

FIELD OF THE INVENTION

The present invention relates to the field of optical devices, in particular optical observation devices, and more particularly to the field of objective mono-optical devices for binocular observation.

STATE OF THE ART

In a known manner, a simple direct optical path, also called by the acronym VDO, consists of an objective E and one or two eyepieces C. The magnification of such a direct optical path is equal to the ratio between the focal length of the objective and the focal length of the eyepiece.

However, this type of direct optical pathway has the disadvantage of presenting an inverted image in the eyepieces. In order to straighten the image, it is known to add a conveying system, in particular in the case of riflescopes, or a straightening prism system, such as a Schmidt-Pechan or Péchan roof prism, a Porro prism, a roof pentaprism, an Abbe-Porro prism or an Abbe-Konig prism...

The addition of a conveying system nevertheless has the disadvantage of significantly lengthening the optical formula by disfavoring the quality in the field, in particular because of the strong presence of the so-called field curvature aberration.

The addition of a rectifying prism system is generally used in binoculars or reflex cameras. Such a straightening prism system guarantees good image quality in a reduced size.

In addition, to produce a direct optical channel, of the simple type without carrier, binocular, it is known to straighten the image for each eyepiece by: introducing a straightening prism A before the binocular separation, or introducing a straightening prism for each eyepiece.

Binocular systems require the ability to adjust a distance between the eyepieces corresponding to the inter-pupillary space of a user.

As shown in Figures 1 and 2, the inter-pupillary adjustment is most often achieved by the rotation of rhombohedrons B, one on each eye, which are rotated with the corresponding eyepiece C around their axis of input (they are rotation invariant). As represented in FIGS. 3 and 4, it can also be made by a straightening prism system, for example a Porro prism D, by the same principle of rotation when the straightening of the image is carried out in each eyepiece.

In addition, binocular separation necessarily implies that the lengths of the optical paths (air and glass) are the same up to the plane containing the two image planes of the objective. Typically, for an inter-pupillary adjustment with rhombohedrons, it is necessary to compensate for the crossing of the separation cube for one of the eyepieces by a glass slide on the other eyepiece.

Nevertheless, the known solutions for straightening the image and allowing adjustment of the inter-pupillary distance have major drawbacks.

In particular, they may comprise a splitter cube which has the dual function of splitting the single entry channel into two ocular channels and of injecting into the eyepieces a video image and/or overlays, such as symbols or text.

Thus, on the one hand, the separating cube, which is made up, in the first case, of part of one of the rhombohedrons and, in the second case, of part of one of the Porro prisms, must rotate with the corresponding eyepiece arm.

When the direct optical channel incorporates a restitution optical channel, such as a video optical channel superimposed on the direct optical channel, it is therefore also necessary for the restitution optical channel to rotate with the eyepiece arm. As a result, it is excessively constraining and complicated to ensure rotation of the complete optical pathway.

On the other hand, if the optical path presents a glass displaying, for example, a reticle located in the image plane of the objective in one or the other of the ocular arms, it will also have a rotational movement (cant) . This is very inconvenient or even prohibitive for a stadia reticle. Moreover, the movement of the reticle is very unfavorable to a conservation of the harmonization with other optical paths.

These two disadvantages are intrinsically linked to the constraint of having a reticle serving as a line of sight reference and to that of having a restitution channel.

For example, for civilian binoculars, there is neither reticle nor restitution. For a binocular microscope, there may optionally be a reticle, but it is not used as a line-of-sight reference and there is no return path. The interpupillary adjustment by rotation of the two ocular arms therefore poses no problem in these cases. A solution to avoid these drawbacks is to rotate only one of the eyepiece arms, for example the right eyepiece arm of Figure 2 or Figure 4, so that the splitter cube no longer rotates, the restitution path is fixed and the reticle, which can be placed on the left ocular arm, will also be fixed.

Such a solution solves the two aforementioned major drawbacks, but a new one is introduced. Indeed, when adjusting the inter-pupillary distance, the axis of the two eyepieces tilts strongly, as seen in Figures 5 to 8, which forces the user to tilt his head, and therefore which, ergonomically not acceptable

The problem of the strong inclination of the axis of the eyepieces comes from the fact that the eyepiece moves on a portion of a circle whose center is located on the axis of entry of the rhombohedron or the Porro prisms. An angle Q between the axis of the eyepieces in the middle position and the axis connecting the entry and exit of the eyepiece arm determines the portion of the circle useful for inter-pupillary adjustment.

Such a portion of a circle induces a horizontal movement, which is necessary for the inter-pupillary adjustment, but also a parasitic vertical movement. The smaller the angle Q, the greater the vertical parasitic motion.

Ideally, there should be an angle Q of 90° allowing the bottom of the circle to be used during the rotation to have a very small vertical displacement.

This vertical movement is weaker in the Porro version because the Q angle is greater.

The angle Q is itself dependent on a length "l" between the entry and the exit of the eyepiece arm. Increasing the length "l" increases the angle Q.

However, such an increase would come at the expense of the bulk, mass, and focal lengths of the objective and eyepiece given the increased travel in the eyepiece arms.

Moreover, such an increase in length has limits and does not allow to reach an angle Q close to 90°

The inclination of the axis of the eyepieces depends on several factors related to the dimensioning of the direct optical path. In a typical case, it is of the order of ±15° for the rhombohedron solution, and of the order of ±8° for the Porro prism solution. In this context, it is necessary to provide a direct optical path making it possible to carry out an inter-pupillary adjustment without the separator cube rotating, and without the axis of the eyepieces tilting significantly.

DISCLOSURE OF THE INVENTION

According to a first aspect, the invention proposes a direct optical path comprising an objective optical system, an ocular path separation system, a system for injecting a video path, a first optical observation path, and a second optical path of observation.

In addition, the direct optical path comprises means for rotating the first optical observation path, in particular with a view to interpupillary adjustment, and a first rectifying optical system and a second rectifying optical system, respectively for each of the first optical observation path and the second optical observation path.

The means for rotating the first optical observation path and/or the second optical system for rectifying an image in the first optical observation path may comprise an Abbe-Porro prism.

The means of rotation can comprise a half-rhombohedron.

The means of rotation can comprise a mirror half-rhombohedron.

The first optical observation channel may comprise, successively following an optical path from the separation means: the second rectifier optical system, in particular the Abbe-Porro prism, the half-rhombohedron, and the half-rhombohedron mirror.

The first rectifier optical system may include a Porro prism.

The optical direct path may comprise, successively following an optical path from the objective optical system: the system for separating the ocular paths, the system for injecting a video path, the first rectifying optical system, in particular the prism of Porro, and in parallel, the first optical observation path and the second optical observation path.

The second optical observation path can comprise a glass allowing the display of a reticle and/or a distance scale.

Of course, the different characteristics, variants and/or embodiments of the present invention can be associated with each other in various combinations insofar as they are not incompatible or exclusive of each other.

DESCRIPTION OF FIGURES

The invention will be better understood and other characteristics and advantages will become apparent on reading the following detailed description comprising embodiments given by way of illustration with reference to the appended figures, presented by way of non-limiting examples, which may be used to complete the understanding of the invention and the presentation of its realization and, where appropriate, contribute to its definition, on which:

FIG. 1 is a schematic representation, in perspective, of a direct optical channel of the prior art;

Figure 2 is a schematic representation of the direct optical path of Figure 1;

FIG. 3 is a schematic representation, in perspective, of a direct optical channel of the prior art;

Figure 4 is a schematic representation of the direct optical path of Figure 3;

Figure 5 is a schematic representation of the direct optical pathway of Figure 1 during maximum inter-pupillary distance;

Figure 6 is a schematic representation of the direct optical path of Figure 1 during a minimum inter-pupillary distance;

Figure 7 is a schematic representation of the direct optical pathway of Figure 3 during maximum inter-pupillary distance;

Figure 8 is a schematic representation of the direct optical path of Figure 3 during a minimum inter-pupillary distance;

Figure 9 is a schematic representation, in perspective, of a Porro prism; FIG. 10 is a schematic representation, in perspective, of an Abbe-Porro prism;

FIG. 11 is a schematic representation, in perspective, of a direct optical channel according to the invention;

FIG. 12 is a representation of the rotation of the first optical channel for observation of the direct optical channel according to the invention during maximum inter-pupillary separation; and

FIG. 13 is a representation of the rotation of the first optical channel for observation of the direct optical channel according to the invention during a minimum inter-pupillary distance.

DETAILED DESCRIPTION OF THE INVENTION

General principle

It should be noted that, in the figures, the structural and/or functional elements common to the different embodiments may have the same references. Thus, unless otherwise stated, such elements have identical structural, dimensional and material properties.

FIG. 11 is a schematic representation, in perspective, of a direct optical channel 1 according to the invention. According to a first aspect, the direct optical channel 1 comprises in particular: an optical lens system 2, a system for separating the ocular channels, 3 and a system for injecting a video channel 4.

Advantageously, the direct optical path 1 can also comprise: a first optical observation path 5, and a second optical observation path 6.

In addition, the direct optical channel 1 comprises means for rotating the first optical observation channel 5 in order to provide inter-pupillary adjustment.

Furthermore, the direct optical channel 1 comprises a first rectifier optical system 8 and a second rectifier optical system 10 of an image in the first optical observation channel 5.

FIGS. 12 and 13 are representations of the rotation of the first optical channel for observation of the direct optical channel according to the invention, respectively during a maximum inter-pupillary distance and a minimum inter-pupillary distance. The synergy of the rotation of one of the optical observation paths and the straightening in this same optical observation path is a particularly advantageous technical arrangement which makes it possible, as shown in FIGS. 12 and 13, to adjust a spacing inter-pupillary, while having a very low inclination of an axis O connecting the centers of the eyepieces 7.

Such an arrangement makes it possible to maintain identical optical paths in the two ocular paths, such as the first optical observation path 5 and the second optical observation path 6.

In other words, this arrangement makes it possible to keep the axis O connecting the centers of the eyepieces 7 substantially fixed so that a user is not constrained in its use. Thus, it is no longer necessary to tilt the head to compensate for a strong inclination of the axis O connecting the centers of the eyepieces 7.

In addition, the rotation of a single optical observation path makes it possible to introduce, for example, a reticle into the second optical observation path 6. Due to its total immobility, the reticle will not be disoriented.

In other words, and as will be detailed below, the direct optical path 1 according to the invention makes it possible to solve the drawbacks of the devices of the prior art and therefore makes it possible to carry out an inter-pupillary adjustment without movement of the video channel and without significant inclination of the axis of the eyepieces. In addition, it allows the use of a stadia reticle regardless of the chosen ocular distance.

Means of rotation and second rectifying optical system

According to an advantageous arrangement, the rectifying means of the first optical observation path 5 can comprise an Abbe-Porro prism 10, as a rectifying optical system.

Indeed, with particular reference to FIG. 10 which is a schematic representation, in perspective, of an Abbe-Porro prism, the structure of the Abbe-Porro prism 10 enables it to combine the functions of rectifying the image and, due to its architecture where the input and output face are axially offset, to gain in length on the horizontal path compared to a conventional Porro system.

It is specified that, by optical rectifier system, it is understood an optical system of zero power.

More particularly, the gain in horizontal path allowed by the Abbe-Porro prism 10 advantageously makes it possible to add a vertical path for a rhombohedron 12. Advantageously, according to a particular example of embodiment, the rhombohedron 12 is composed: on the one hand, in particular for half, of a glass prism, in particular bent at 90°, having the double function of half- rhombohedron 121 and compensation plate; and on the other hand, in particular for the other half, of a mirror half-rhombohedron 122, in particular with a 90° bend.

In other words, the means of rotation can comprise the half-rhombohedron 121 and a half-mirror rhombohedron 122, together forming the rhombohedron 12.

This arrangement makes it possible to balance the paths of the first optical observation path 5 and of the second optical observation path 6 and the inter-pupillary adjustment is made by rotation of the rhombohedron 12 with the corresponding eyepiece 7.

In addition, the first optical rectifier system 8 is a Porro prism 8 that can be positioned after the separation of the first optical observation path 5 and the second optical observation path 6.

Optical Direct Path Architecture

Referring again to FIG. 11, following an optical path from the objective optical system 2, the direct optical path 1 comprises successively: the objective optical system 2, the ocular path separation system 3, and the system for injecting a video channel 4, then, in parallel, the first optical observation channel 5 and the second optical observation channel 6.

The first optical observation channel 5 comprises, successively, the Abbe-Porro prism 10, the half-rhombohedron 121 and the mirror half-rhombohedron 122 then the ocular optical system 7.

The second optical observation path 6 comprises, successively, the Porro prism 8 then the ocular optical system 7.

In addition, in a particularly advantageous manner, the second optical observation channel 6 may comprise a reticle and/or a distance scale (stadimetry).

Advantageously, according to an alternative embodiment, the first optical observation path 5 and the second optical observation path 6 have the same optical length. Thus, in such an arrangement, the association of the optical rectifier system 10, in particular the Abbe-Porro prism 10, and of the rhombohedron 12 of the first optical observation path 5 makes it possible to have an optical path equal to the prism of Porro 8 of the second optical path of observation 6.

Thus, in use, a user can move the first optical observation path 5 in rotation to adjust an ocular distance corresponding to the interpupillary distance of the user.

As explained previously, the structure of the direct optical path 1 according to the invention makes it possible to adjust the eye gap by tilting the axis O connecting the centers of the eyepieces 7 to a minimum and simultaneously to preserve the orientation of a possible reticle stadimetric.

Indeed, such a reticle is preferably integrated into the second optical observation path 6, it is therefore immobile since the second optical observation path 6 does not pivot to adjust the spacing.

Furthermore, the relative immobility of the axis O connecting the centers of the eyepieces 7 guarantees that the rotation of the first optical observation path 5 does not induce any inclination of the whole of the direct optical path 1.

In an observation situation, the light enters the objective optical system, schematically along an axis L, then crosses the injection system of a video channel. The video channel is schematized by an axis V. The luminous flux of the video channel can be added to the luminous flux coming from the lens optical system 2 and/or replace it, in particular by action of a shutter located in the channel optical direct 1.

Furthermore, the system for separating the ocular pathways 3 is also capable of serving as an injection for the video pathway, the first rectifying optical system 8 being located after the separation.

Then, in parallel, two luminous fluxes L1 and L2 travel simultaneously through the first optical observation path 5 and the second optical observation path 6, as represented in FIG. 11. The identical optical length of the first optical observation path 5 and the second optical observation path 6 allows the two light fluxes L1 and L2 to arrive simultaneously each in their respective eyepiece.

Obviously, the invention is not limited to the embodiments described above and provided solely by way of non-limiting examples. It also encompasses various modifications, alternate forms and other variations that may consider the skilled person in the context of the present invention and in particular all combinations of the different modes of operation described above, which can be taken separately or in combination.

Claims

1. Direct optical path (1) comprising: an optical lens system (2), an ocular path separation system (3), a video path injection system (4), a first optical path of observation (5), and a second optical observation path (6); characterized in that the direct optical channel (1) comprises: means for rotating the first optical observation channel (5), in particular with a view to inter-pupillary adjustment, and a first rectifying optical system (8) and a second optical rectifier system (10), respectively for the first optical observation path (5) and the second optical observation path (6).

2. direct optical path (1) according to claim 1, characterized in that the means for rotating the first optical observation path and / or the second rectifying optical system (10) of an image in the first optical path d observation (5) include an Abbe-Porro prism.

3. direct optical path (1) according to any one of the preceding claims, characterized in that the means of rotation comprise a half-rhombohedron (121).

4. direct optical path (1) according to any one of the preceding claims, characterized in that the means of rotation comprise a mirror half-rhombohedron (122).

5. direct optical path (1) according to claims 1 to 4 in combination, characterized in that the first optical observation path (5) comprises, successively following an optical path from the separation means: the second optical system rectifier (10), in particular the Abbe-Porro prism, the half-rhombohedron (121), and the half-rhombohedron mirror (122).

6. direct optical channel (1) according to any one of the preceding claims, characterized in that the first optical rectifier system (8) comprises a Porro prism.

7. direct optical path (1) according to claim 6, characterized in that the direct optical path (1) comprises, successively following an optical path from the objective optical system (2): the channel separation system eyepieces (3), - the system for injecting a video channel (4), the first optical rectifier system (8), in particular the Porro prism, and in parallel, the first optical observation channel (5) and the second optical observation path (6).

8. Direct optical path (1) according to any one of the preceding claims, characterized in that the second optical observation path (6) comprises a glass allowing the display of a reticle and / or a scale of distance.