CN221595400U

CN221595400U - Catadioptric lens and artificial vision device

Info

Publication number: CN221595400U
Application number: CN202420144159.XU
Authority: CN
Inventors: 安德烈亚·贝尔托卢奇; 卢卡·里佐托
Original assignee: Opto Engineering Ag
Current assignee: Opto Engineering Ag
Priority date: 2023-12-14
Filing date: 2024-01-19
Publication date: 2024-08-23
Anticipated expiration: 2034-01-19

Abstract

The application discloses a catadioptric lens and an artificial vision device, the catadioptric lens comprises: a main mirror (10); a sub-mirror (20); an adaptive lens (30) arranged at the rear with respect to the primary mirror (10) so as to receive the light reflected by the secondary mirror (20); and at least one rear optical unit (40) comprising a diaphragm aperture and adapted to transmit light from the secondary mirror (20) towards an imaging plane (50) of the sensor. According to the catadioptric lens of the present application, the adaptive lens (30) may be controlled to adjust the focal point of the lens.

Description

Catadioptric lens and artificial vision device

Technical Field

The present utility model relates to a catadioptric lens, in particular for use in an artificial vision device.

Background

Lenses for inspection and measurement applications are known which ensure high optical performance over the entire operating range.

In these applications, it is sometimes desirable to inspect the outer wall of a three-dimensional object from above using a single camera. With lenses according to the prior art in order to inspect different diameters of the outer walls of objects or to inspect objects of different sizes, the aperture of the lens must be significantly closed, thereby losing light and resolution, or the focal area is changed using a manual lens focusing system operated by a user, thereby increasing the structural complexity and working time of the lens.

Disclosure of utility model

It is an object of the present utility model to provide a catadioptric lens which is capable of inspecting different diameters of the outer wall of an object while overcoming the limitations of the lenses of the known art.

This object is achieved by a catadioptric lens and an artificial vision device according to the application.

According to an embodiment of the present application, there is provided a catadioptric lens including: a primary mirror having a concave reflective surface extending around an optical axis and facing forward to receive light from an object under observation, the primary mirror having a primary mirror central aperture therein coaxial with the optical axis; a secondary mirror coaxial with the optical axis and having a convex reflective surface facing the concave reflective surface of the primary mirror, the secondary mirror being arranged such that the convex reflective surface receives light reflected by the concave reflective surface and directs the light through the primary mirror central aperture to a rear portion relative to the primary mirror; an adaptive lens disposed at a rear of the primary mirror so as to receive light reflected by the secondary mirror, the adaptive lens being controllable to adjust a focus of the catadioptric lens; and at least one rear optical unit comprising a diaphragm aperture and adapted to transmit light from the secondary mirror towards the imaging plane of the sensor.

Further, the concave reflective surface is a spherical surface.

Further, the concave reflective surface is an aspheric surface.

Further, the convex reflective surface is a spherical surface.

Further, the convex reflective surface is an aspheric surface.

Further, a sub-mirror center hole coaxial with the optical axis is provided in the sub-mirror.

Further, a lens having negative optical power is arranged in or near the sub-mirror central aperture, the lens having negative optical power being adapted to cause light rays from a central portion of the viewing object to converge towards a main mirror central aperture so as to magnify a viewing angle of the central portion of the viewing object.

Further, the adaptive lens is arranged at the rear with respect to the rear optical unit.

Further, the adaptive lens is arranged inside the rear optical unit.

Further, the rear optical unit is a fixed focus with a proper focal length, has a fixed or variable aperture, and has a focus adjustment mechanism.

Further, the rear optical unit is a zoom objective with a fixed or variable aperture and a variable focal length allowing to vary the size of the image circle produced by the objective.

Further, the secondary mirror is attached to a window that is located in a plane orthogonal to the optical axis and is transparent to visible light and near infrared light.

Further, the window is mechanically integral with the primary mirror.

Further, the concave reflective surface is a tapered surface.

Further, the convex reflective surface is a tapered surface.

Further, the central portion of the viewing object includes a bottom wall or a top wall.

Further, the adaptive lens is arranged between lenses constituting the rear optical unit.

According to another embodiment of the present application, there is provided an artificial vision apparatus including the catadioptric lens described above and a sensor forming an imaging plane, the sensor being adapted to receive light from the rear optical unit of the catadioptric lens.

Further, the artificial vision apparatus further includes: a controller is operatively connected to the adaptive lens and configured to control the optical power of the adaptive lens in accordance with a desired focus of the adaptive lens.

The catadioptric lens and artificial vision device according to the present application are capable of inspecting different diameters of the outer wall of an object while overcoming the limitations of the lenses of the known art.

Drawings

Other features and advantages of the catadioptric lens according to the utility model will become apparent from the description of a preferred exemplary embodiment provided below, provided by way of non-limiting example only, with reference to the accompanying drawings, in which:

Fig. 1 is an optical schematic diagram of a catadioptric lens according to a first embodiment of the present utility model;

FIG. 2 is an optical schematic of a catadioptric lens according to a second embodiment of the utility model;

Fig. 3 is an optical schematic diagram of a catadioptric lens according to a third embodiment of the present utility model;

Fig. 4 is an optical schematic diagram of a catadioptric lens according to a fourth embodiment of the present utility model;

FIG. 5 is an optical schematic of the catadioptric lens of FIG. 1 in which the viewing object is disposed beyond the entrance pupil of the lens;

FIG. 6 shows an example of a practical implementation of a catadioptric lens according to the utility model;

fig. 7 shows an example of an object to be inspected using the catadioptric lens in fig. 6;

FIG. 8 depicts an image of the outer wall of the object of FIG. 7 taken by the catadioptric lens of FIG. 6, wherein a first focus has been set, and an enlarged view of the detail is depicted; and

Fig. 9 depicts an image of the outer wall of the object of fig. 7 taken by the catadioptric lens of fig. 6, wherein a second focus has been set, and an enlarged view of the detail is depicted.

Detailed Description

In the following description, elements common to the various embodiments of the present utility model should be denoted by the same reference numerals.

Furthermore, the terms "front" and "rear" will be used with reference to an observation object arranged in front of the lens and a sensor arranged behind the lens.

In the drawings, 1 denotes as a whole a catadioptric lens according to the utility model.

The catadioptric lens extends along an optical axis X, which is shown horizontally in the drawing.

According to a general embodiment, catadioptric lens 1 comprises a primary mirror 10, a secondary mirror 20, an adaptive lens 30, and at least one rear optical unit 40.

The main mirror 10 has a concave reflecting surface 12 extending around the optical axis X and facing forward to receive light from the observation object 2.

A main mirror center hole 14 coaxial with the optical axis X is obtained in the main mirror 10.

The secondary mirror 20 is coaxial with the optical axis X and has a convex reflecting surface 22 facing the concave reflecting surface 12 of the primary mirror 10.

The secondary mirror 20 is arranged such that the convex reflective surface 22 receives light reflected by the concave reflective surface 12 and directs the light through the primary mirror central aperture 14 to the rear relative to the primary mirror 10.

The adaptive lens 30 is disposed at the rear with respect to the main reflective lens 10 to receive the light reflected by the sub-mirror 20. The adaptive lens 30 is controllable to adjust the focus of the catadioptric lens 1.

The rear optical unit 40 comprises a diaphragm aperture and is adapted to transmit light from the secondary mirror 20 towards the imaging plane 50 of the sensor.

In one embodiment, the concave reflective surface 12 is a spherical surface.

In an alternative embodiment, the concave reflective surface 12 is an aspheric surface.

In an alternative embodiment, the concave reflective surface 12 is a tapered surface.

In one embodiment, the convex reflective surface 22 is a spherical surface.

In an alternative embodiment, the convex reflective surface 22 is an aspheric surface.

In an alternative embodiment, the convex reflective surface 22 is a tapered surface.

In the embodiment shown in fig. 1, a secondary mirror central aperture 24 coaxial with the optical axis X is obtained in the secondary mirror.

In the embodiment shown in fig. 3, a lens 60 having negative optical power is arranged in the sub-mirror central hole 24 or near the sub-mirror central hole 24, which lens is adapted to cause light rays from the central portion 2a (such as the bottom wall or the top wall) of the observation object 2 to converge toward the main-mirror central hole 14 so as to enlarge the angle of view of the central portion 2a of the observation object 2.

In the embodiment shown in fig. 4, the secondary mirror 20 lacks a central aperture. In this case, considering that the observation object forms a side wall 2b (for example, substantially parallel to the optical axis X) and at least one lateral wall 2a (substantially perpendicular to the optical axis X and coaxial thereto), only those rays coming from the side wall 2b of the object 2 will be sent to the imaging plane of the sensor. In fact, the light coming from the transversal wall 2a is blocked by the continuous rear wall 20' of the secondary mirror 20.

In one embodiment, the adaptive lens 30 is arranged at the rear of the rear optical unit 40, i.e. between the rear optical unit 40 and the imaging plane 50 of the sensor when the sensor is coupled to the catadioptric lens 1.

In one embodiment variant, the adaptive lens 30 is arranged inside the rear optical unit 40, i.e. between the lenses constituting the rear optical unit 40.

In one embodiment, adaptive lens 30 is a liquid lens.

In one embodiment, the post-optical unit 40 has a positive power.

In one embodiment, the rear optical unit 40, represented in the optical schematic by a generic optical element, may be composed of one or more lenses.

The diaphragm aperture of the system comprised in the rear optical unit 40 may be fixed or variable.

In one embodiment, the rear optical unit 40 is a fixed focus with a suitable focal length, has a fixed or variable aperture, and has a mechanism for adjusting the focus, such as by a manual ring.

The focusing mechanism of the rear optical unit 40 may also be made of an integrated liquid lens. In this case, the liquid lens 30 described in the general embodiment may coincide with an integrated liquid lens.

In a variant embodiment, the rear optical unit 40 is a variable focus lens with a fixed or variable aperture and a variable focal length, which allows to vary the size of the image circle produced by the lens.

In the embodiment shown in fig. 2, the secondary mirror 20 is attached to a window 70, which is located in the window 70 in a plane orthogonal to the optical axis X and is transparent to visible light and near infrared light. For example, the window 70 is made of glass.

The window 70 may also be mechanically attached to the primary mirror 10.

In one embodiment variant, the secondary mirror 20 is mechanically attached to a support arranged at a distance from the primary mirror 10.

The operation principle of the catadioptric lens 1 will now be described.

The optical design of the lens is such that the entrance pupil is located in front of the lens, for example at a distance varying between 300mm and 0mm from the front of the lens.

If the viewing object 2 is arranged between the entrance pupil of the lens and the lens 1 (fig. 1), light rays from the outer side wall 2b of the object, i.e. from the wall substantially parallel to the optical axis X, are collected by the primary mirror 10 at a viewing angle α, reflected back to the secondary mirror 20, and further reflected by the secondary mirror 20 towards the primary mirror central aperture 14.

In the embodiment shown in fig. 1, wherein the secondary mirror central aperture 24 passes through the secondary mirror 20, light rays from the lateral portion 2a of the object 2 (substantially orthogonal to the optical axis) pass through the secondary mirror central aperture 24 at the viewing angle β and pass through the primary mirror central aperture 14 without undergoing any reflection.

On the other hand, if the sub-mirror 20 lacks a central hole, an image of the lateral portion 2a of the object 2 is not produced (fig. 4).

In the embodiment shown in fig. 3, the light from the lateral portion 2a of the object 2 is collected by a lens 60 with negative optical power at a viewing angle γ and is made to pass through the primary mirror central aperture 14 without undergoing any reflection. By appropriately selecting the lens 60 having negative optical power, the angle of view of the lateral portion 2a of the object 2 can be enlarged.

The optical schematic of fig. 5 may be used to inspect the inner surface 2c of the side wall of the hollow object 2, which is schematically shown in the form of a cup in the example of fig. 5. In this case, in practice, the observation object 2 is arranged beyond the entrance pupil of the lens. Light rays from the inner side wall of the object pass through a single point P coincident with the entrance pupil of the lens 1.

The light is then collected by the primary mirror 10 at a viewing angle α, reflected back to the secondary mirror 20, and further reflected by the secondary mirror 20 toward the primary mirror central aperture 14.

Light from the lateral portion 2a of the viewing object (in this example the bottom wall of the object) passes through the secondary mirror central aperture 24 at the viewing angle β and directly reaches the primary mirror central aperture 14 without undergoing reflection.

If the secondary mirror 20 lacks a central aperture, no image of the bottom 2a of the object is produced (fig. 4).

If the light from the object bottom 2a passes through a lens 60 (fig. 3) with negative optical power at a viewing angle gamma, which is arranged close to the secondary mirror central aperture 24, the light then reaches the primary mirror central aperture 14 without being reflected. By properly selecting this lens with negative optical power 60, the viewing angle of the bottom of the object 2a can be enlarged.

All light rays passing through the primary mirror central aperture 14 then pass through the adaptive lens 30 (or liquid lens) and the rear optical unit 40 (not necessarily in the order of the various embodiments described above) and form an image on the imaging plane 50 coincident with the sensor.

For example, the inspection object 2 may be a cylindrical or frustoconical object, a planar object, a toroidal object, a hemispherical object, a conical object. More generally, the object has a random shape.

Fig. 6 shows an example of a practical implementation of the catadioptric lens 1. Of particular note are those portions associated with the adaptive lens 30, the front optical units 10, 20, and the rear optical unit 40.

Fig. 7 shows an example of an object 2 that can be inspected by means of a catadioptric lens 1. The object has: a first cylindrical portion 202, such as a threaded portion, having a first diameter D1; and a second cylindrical portion 204 having a second diameter D2 that is greater than the first diameter D1. The second cylindrical portion 204 is disposed rearwardly relative to the first cylindrical portion 202, i.e., it is a greater distance from the catadioptric lens 1.

Fig. 8 shows an image of the top and side walls of two cylindrical surfaces 202, 204, wherein the wall with the first diameter D1 is focused by the optical power acting on the adaptive lens 30.

Fig. 9 shows an image of the top and side walls of two cylindrical surfaces 202, 204, wherein the wall with the second diameter D2 is focused by varying the optical power of the adaptive lens 30.

Thanks to the catadioptric lens 1 described above, it is thereby possible to focus on the lateral portion 2a with respect to the optical axis, such as the top or bottom of the object and the outer side wall 2b or inner side wall 2c of the object 2, simultaneously.

Due to the adaptive lens, the focal region of the system can be quickly and remotely changed by the optical power acting only on the adaptive lens. This allows to inspect objects of different diameters or different sizes of the outer wall of the object, which do not need to be manually applied to the lens, but by simply changing the optical power of the adaptive lens.

The subject of the utility model is also an artificial vision device comprising a catadioptric lens 1 as described above and a sensor forming an imaging plane 50, the imaging plane 50 being adapted to receive light from a rear optical unit 40 of the catadioptric lens 1.

Furthermore, in one embodiment, the artificial vision device includes a controller operatively connected to the adaptive lens 30 and configured to control the optical power of such adaptive lens in accordance with a desired lens focus.

To meet contingent needs, a person skilled in the art may make changes, adaptations and substitutions with other elements functionally equivalent to embodiments of catadioptric lenses and artificial vision devices according to the utility model, without departing from the scope of the following claims. Each feature described as belonging to a possible embodiment may be obtained independently of the other described embodiments.

Claims

1. A catadioptric lens comprising a lens body, characterized by comprising the following steps:

A primary mirror (10) having a concave reflective surface (12) extending around an optical axis (X) and facing forward to receive light from an observation object (2), the primary mirror having a primary mirror central aperture (14) therein coaxial with the optical axis (X); -a secondary mirror (20) coaxial with the optical axis (X) and having a convex reflective surface (22) facing the concave reflective surface (12) of the primary mirror (10), the secondary mirror (20) being arranged such that the convex reflective surface (22) receives light reflected by the concave reflective surface (12) and directs the light through the primary mirror central aperture (14) to the rear with respect to the primary mirror (10);

-an adaptive lens (30) arranged at the rear of the primary mirror (10) for receiving light reflected by the secondary mirror (20), the adaptive lens (30) being controllable to adjust the focus of the catadioptric lens; and

At least one rear optical unit (40) comprising a diaphragm aperture and adapted to transmit light from said secondary mirror (20) towards an imaging plane (50) of the sensor.

2. Catadioptric lens according to claim 1, wherein the concave reflecting surface (12) is a spherical surface.

3. Catadioptric lens according to claim 1, wherein the concave reflecting surface (12) is an aspherical surface.

4. A catadioptric lens according to any of claims 1 to 3, wherein the convex reflective surface (22) is a spherical surface.

5. A catadioptric lens according to any of claims 1 to 3, wherein the convex reflective surface (22) is an aspherical surface.

6. Catadioptric lens according to claim 1, characterized in that a secondary mirror central aperture (24) coaxial to the optical axis (X) is provided in the secondary mirror (20).

7. Catadioptric lens according to claim 6, wherein a lens (60) with negative optical power is arranged in the secondary mirror central aperture (24) or close to the secondary mirror central aperture (24), the lens with negative optical power being adapted to cause light rays from a central portion of the viewing object to converge towards a primary mirror central aperture (14) in order to magnify the viewing angle of the central portion of the viewing object.

8. Catadioptric lens according to claim 1, wherein the adaptive lens (30) is arranged at the rear with respect to the rear optical unit (40).

9. Catadioptric lens according to claim 1, wherein the adaptive lens (30) is arranged inside the rear optical unit (40).

10. Catadioptric lens according to claim 1, wherein the rear optical unit (40) is a fixed focus with a suitable focal length, has a fixed or variable aperture, and has a focus adjustment mechanism.

11. Catadioptric lens according to claim 1, wherein the rear optical unit (40) is a zoom objective with a fixed or variable aperture and a variable focal length allowing to vary the size of the image circle produced by the objective.

12. Catadioptric lens according to claim 1, wherein the secondary mirror (20) is attached to a window (70) which lies in a plane orthogonal to the optical axis (X) and is transparent to visible light and near infrared light.

13. Catadioptric lens according to claim 12, wherein the window (70) is mechanically integrated with the main mirror (10).

14. A catadioptric lens according to claim 3, wherein the concave reflecting surface (12) is a conical surface.

15. Catadioptric lens according to claim 5, wherein the convex reflecting surface (22) is a conical surface.

16. The catadioptric lens of claim 7, wherein the central portion of the viewing object comprises a bottom wall or a top wall.

17. Catadioptric lens according to claim 9, wherein the adaptive lens (30) is arranged between lenses constituting the rear optical unit (40).

18. Artificial vision device, characterized in that it comprises a catadioptric lens (1) according to claim 1 and a sensor forming an imaging plane (50), said sensor being adapted to receive light from the rear optical unit (40) of the catadioptric lens.

19. The artificial vision device of claim 18, further comprising: a controller is operatively connected to the adaptive lens (30) and configured to control the optical power of the adaptive lens in accordance with a desired focus of the adaptive lens.