RU2787075C1 - Annular image formation lens with multiple fields of view - Google Patents

Abstract

FIELD: optics.

SUBSTANCE: optical unit comprises an optical element and an image plane curvature correction element. The optical element is made in the form of an integral base optical element, comprises an integrated two-mirror focal system and at least one integrated two-mirror afocal system. Multiple switchable optical elements (SOEs) configured to switch between a first state of transmission of optical emission of the visible spectrum and a second state of absorption or reflection of optical emission of the visible spectrum are placed on the front side of the optical element. The image plane curvature correction element is located behind the optical element.

EFFECT: provided multiple fields of view with the possibility of switching between the multiple fields of view.

15 cl, 6 dwg, 1 tbl

Description

The technical field to which the invention belongs

The present invention relates generally to the field of optics, and more particularly to an optical system of a multi-field (zoom) lens for capturing an image ("imaging lens") used in imaging devices such as photo/video cameras, including in compact electronic devices.

State of the art

With the advent of compact electronic computing devices such as, but not limited to, mobile phones, smartphones, tablet computers, personal digital assistants (PDAs), communicators, netbooks, laptops, it has become necessary to provide such devices with image capture means, such as photo/video cameras. , to implement various functions related to capturing photo and video images at the user's command, video communication, user face recognition, "computer vision", etc. At the same time, there was a need to provide the possibility of changing the field of view of such lenses (“zooming”). Traditional camera lenses, in which the focal length (field of view) is changed by moving elements, in particular lenses and lens groups, are not suitable for use in compact electronic computing devices due to their large size.

It should be noted that, as is known in the field of zoom lenses, in order to implement a change in the field of view (hereinafter also abbreviated as FOV), it is necessary either to move one or more components of the optical system to physically change the focal length of the lens, or to use several lenses or cameras. , each of which has its own focal length value, switching between them as necessary under the control of the software, ensuring as smoothly as possible switching between lenses (cameras) without a “jumping” change in the field of view of the lens (camera) noticeable to the user.

In the case of a lens with moving components of the optical system, a very high precision of the assembly of the optical system and high-precision design elements are required that could provide the necessary tolerances in the optical system for the entire range of variable focal lengths. A combined version is also possible, in which to cover the entire required range of focal lengths, several interchangeable lenses or cameras are used, each of which uses a group of moving elements of the optical system. In this case, several assemblies with very high assembly accuracy are used, each of which consists of several optical elements.

US 8,599,497 (Raytheon Company, published Dec. 3, 2013) discloses a wide-angle, thin-profile zoom lens in which the zoom optical system includes a plurality of sub-apertures located around at least a portion of the outer periphery of one of the first and second facing lenses. inside surfaces. Each sub-aperture includes an element characterized by optical power. The disadvantages of this well-known solution include a rather low value of the relative aperture of the lens (high aperture value F #) and limited possibilities for correcting aberrations.

US 2010/0188856 (University of California, published 07/29/2010) discloses a lens with lens systems containing a plurality of reflective lenses that includes first and second inward facing surfaces, each of which is at least partially reflective. The lens further includes a first opening that is located around at least a portion of the outer periphery of one of the first and second inwardly facing surfaces, and a second opening located near the central region of the lens. Optical radiation propagating inside the lens between said first and second inwardly facing surfaces is reflected at least twice on at least one of the first and second inwardly facing surfaces as it propagates between the first hole and the second hole. The disadvantages of this well-known solution also include a rather low value of the relative aperture of the lens (high aperture value F #) and limited possibilities for correcting aberrations.

Disclosure of invention

This section, which discloses various aspects and embodiments of the claimed invention, is intended to provide a brief description of the claimed objects of the invention and embodiments. A detailed description of technical means and methods that implement combinations of features of the claimed inventions is given below. Neither this disclosure nor the following detailed description and accompanying drawings should be construed as defining the scope of the claimed invention. The scope of legal protection of the claimed invention is determined solely by the attached claims.

Taking into account the known solutions from the prior art discussed above, the objective technical problem solved by the invention is the need to create a compact lens with a variable field of view (focal length) that does not have moving components of the optical system, characterized by simplicity of design and assembly by eliminating the moving components of the optical system requiring high precision manufacturing and assembly.

The problem solved by the present invention is to create a lens without moving optical components, the optical system of which allows to obtain multiple fields of view with a high degree of aberration correction.

The technical result achieved by using the present invention is to provide multiple fields of view of the optical node with the ability to switch between the said multiple fields of view.

In the first aspect of the present invention, the above problem is solved by an optical assembly comprising an optical element and an image plane curvature correction element, wherein the optical element is made in the form of a single main optical element; the optical element contains an integrated focal system with two mirrors, the optical element contains at least one integrated afocal system with two mirrors, a plurality of switchable optical elements (SOE) are placed on the front side of the optical element. The switchable optical elements (SOE) are configured to switch between the first and second states, the first state being the transmission state of the visible spectrum optical radiation and the second state being the absorption or reflection state of the visible optical radiation. The image plane curvature correction element is located behind the optical element.

The focal system with two mirrors contains the first concave reflective optical surface and the second convex reflective optical surface. At least one dual mirror afocal system comprises at least a first concave reflective optical surface and a second convex reflective optical surface. The following coatings are deposited on said reflective optical surfaces: a mirror coating on the first concave surface, with the possibility of changing the state between the state of transmission and the state of reflection on the second convex surface. Both the focal system and the afocal systems are formed in said integral main optical element.

Switchable optical elements are configured to compensate for the curvature of at least one concave surface of the afocal system, forming a substantially flat front surface of the optical element. At least one surface of the switchable optical elements is coated with a reflective optical coating, while the switchable optical elements themselves are made of the same optical material as the main optical element. In one or more embodiments, at least one surface of the switchable optical elements is coated with electrochromic glass.

Switchable optical elements (SOE) have a flat first optical surface and a second optical surface, the curvature of which corresponds to the curvature of the reflective optical surfaces of the focal system with two mirrors and/or at least one afocal system with two mirrors, and are located on the second reflective optical surfaces of the focal system with two mirrors and/or at least one afocal system with two mirrors, forming a flat surface, which is located on the normal with respect to the optical axes. The optical element has a concave central section.

The image plane curvature correction element may be in the form of at least one lens and placed between the optical element and the image sensor of the imaging device using the optical assembly according to the invention.

In the second aspect of the present invention, the above problem is solved by the imaging apparatus comprising the optical assembly of the above first aspect.

In the third aspect of the present invention, the above problem is solved by a method for generating a plurality of fields of view of an imaging lens, the method comprising the steps of: passing incident optical radiation into a solid main optical element through at least two switchable optical elements (SOEs) placed on the front surface of the optical element. element, wherein the optical radiation inside the optical element undergoes at least one internal reflection by means of a focal system with two mirrors integrated into the optical element and at least one afocal system with two mirrors integrated into the optical element, and is output to the image sensor, forming an image with multiple fields of view (FOV) on the image sensor, and each of the at least two SOEs is switched between an open state in which the SOE transmits optical radiation and a closed state in which the SOE both reflects and/or absorbs optical radiation. optical radiation, thus switching the corresponding FOV on the image sensor.

Brief description of the drawings

The drawings are given in this document to facilitate understanding of the essence of the present invention. The drawings are schematic and not to scale. The drawings are for illustrative purposes only and are not intended to define the scope of the present invention.

On FIG. 1 is a schematic sectional view of part of an optical assembly according to the invention;

On FIG. 2 is a schematic view of views A, B, C illustrating the switching of fields of view in an optical assembly according to the invention by means of respective switchable optical elements;

On FIG. 3 schematically illustrates a two-mirror focal system and at least one two-mirror afocal system implemented in an exemplary embodiment of an optical assembly according to the invention;

On FIG. 4 is a schematic sectional view of a part of an optical assembly according to the invention in an embodiment, showing the surfaces on which the switchable optical coating has been applied;

On FIG. 5 is a front perspective view of the optical assembly of the present invention;

On FIG. 6 illustrates the field of view (FOV) switching of an optical assembly according to the invention depending on the state of the switched optical elements (SOE).

Implementation of the invention

In a first aspect, the present invention relates to a multiple-field-of-view (zoom) optical system for use in an imaging (capturing) device ("imaging lens"). Said optical system is also referred to in the context of the present description as an optical assembly. A lens containing such an optical assembly may be referred to as a "ring" imaging lens based on the shape of the switchable optical elements (SOEs), which in non-limiting embodiments are substantially concentric rings when viewed from the front surface of the optical assembly (see FIG. . five).

On FIG. 1 is a schematic sectional view of a portion of an optical assembly according to the invention. The basis of the optical node is the optical element 1, made in the form of a solid main optical element. In addition, the optical assembly also includes an element 6 for correcting the curvature of the image plane.

On the marked surfaces of the optical element 1, a mirror coating 2 is applied. The optical element 1 provides the formation of several different channels of the field of view (FOV) due to the presence of one or more curved sections on the front surface of the optical element 1.

In one or more non-limiting embodiments, the curved sections are in the form of concentric circles on the front surface of the optical element 1. The curved sections are essentially annular recesses on the front surface of the optical element 1 having at least one concave surface and at least one flat surface oriented parallel to the plane of the front surface of the optical element 1.

Said curved surface areas of the optical element 1 are filled with curvature-compensating curved sections of switchable optical elements (SOE) 3, 4, 5, which fill the corresponding curved surface areas, compensating their curvature in such a way that their front surfaces form one essentially flat surface with the front surface optical element 1.

Each switchable optical element (SOE) 3, 4, 5 forms its own field of view (FOV) channel. It should be noted that in the context of the present description, as a non-limiting example, options are considered in which the number of fields of view and, accordingly, switchable optical elements is three, however, other embodiments are also possible in which the number of fields of view and, accordingly, switchable optical elements can be be two or four or more.

It should also be noted that in the context of the present description, a switchable optical element and a field of view channel may be referred to interchangeably for convenience of description, with each switchable optical element (SOE) being responsible for a respective field of view (FOV) channel.

The main optical element in the claimed optical node allows you to form on the sensor 7 image at the same time several images corresponding to different fields of view (FOV). Switchable optical elements allow you to separate these images with different FOV and get the desired image on the sensor. Thus, the field of view of the optical assembly changes substantially at the image sensor 7 . Since the invention provides for a plurality (two or more) of different FOVs, such a change in FOV is a function of changing the field of view ("zoom").

The switching of the channels of the different FOVs takes place via the respective switchable optical elements (SOEs). Each switchable optical element contains at least one surface that can change its properties of transmission and reflection and/or absorption of optical radiation, due to which the "switching" of the switchable optical elements occurs, due to which the switchable optical elements can be considered as "open" or “closed” to optical radiation. Such "switching" can be realized by having an appropriate coating applied on the respective surface of the SOE, such as liquid crystal switchable mirror (LCSM) and electrochromic mirror (ECM) type coating as a non-limiting example. The switchable mirrors are electronically controlled by the voltage levels on the transparent electrodes to switch between a reflective translucent state and an almost transparent state. An example of an ECM is a Suspended Particles Display (SPD) device. In SPDs, the switching effect is achieved by electronically adjusting light absorption by controlling the orientation of the rod-like particles between two transparent electrodes. An example of an LCSM is the CLC. When a beam of light propagates along the axis of the helix, Bragg reflection occurs in the wavelength range no*P ≤ λ ≤ ne * P (where P is the CLC pitch and no and ne are the ordinary and extraordinary refractive indices of the liquid crystal). When left-handed circularly polarized light strikes a CLC with a right-handed helix, it passes without reflection. Conversely, if left-handed circularly polarized light is incident on the CLC with a left-handed helix, then it is completely reflected.

The reflection states of a CLC mirror are efficiently switched using low voltage square waves. Typically, within 10 ms, the molecules have enough time to partially rotate to obtain a tilted texture, thereby achieving a partial reflection state. Also, within 20 ms, the molecules usually rotate completely vertically in order to end up with a completely transparent state. In the initial state, cholesteric liquid crystals (CLCs) are a Bragg mirror with total reflection in the wavelength range λ.

Referring to FIG. 2 and 6, the operating principle of the optical assembly according to the invention will now be described using an example of an embodiment that uses three SOEs and implements three fields of view (FOV), respectively.

On FIG. 2 shows views A, B and C illustrating the formation of the first field of view (FOV1), the second field of view (FOV2) and the third field of view (FOV3), respectively. On FIG. 6 illustrates in tabular form the switching of the respective fields of view depending on the "open" and "closed" states of the respective SOEs.

Referring to view A in Fig. 2, SOE 3 is switched to "open" ("transparent") mode. The optical radiation passing through the SOE 3 is internally reflected inside the optical element 1 and finally hits the image sensor 7 of the imaging device, forming an image with a field of view FOV1 (see Fig. 6). SOE 4 and 5 are in this case in a "closed" state (their respective coatings reflect and/or absorb optical radiation).

In the situation in view B in FIG. 2 in the "open" state is SOE 4, and SOE 3 and 5 - in the "closed" state. The incident optical radiation enters the optical element 1 through the SOE 4 and is reflected, in particular from the "closed" SOE 3, as a result, hitting the image sensor 7 after multiple internal reflections within the optical element 1. It should be noted that this internal reflection is due to the presence of a mirror coating 2 on the front and rear surfaces of the optical element 1. At the same time, on the way to the image sensor 7, the optical radiation is internally reflected more times than when SOE 3 is open, as shown in view A of FIG. 2. In this way, the optical path of radiation within the optical element 1 is lengthened and, accordingly, it becomes possible to realize an increased focal length compared to the case when SOE3 is “opened”. An image with a different field of view (FOV2) is formed on the image sensor 7 compared to the situation in view A of FIG. 2.

In the situation in view C in FIG. 2 in the "open" state is SOE 5, and SOE 3 and 4 are "closed". Accordingly, the incident optical radiation enters the optical element 1 through the open SOE 5 and undergoes even more multiple internal reflections within the optical element 1 on its way to the image sensor 7 . In this situation, the optical emission path is even longer and, accordingly, an image with a different field of view (FOV3 in Fig. 6) is formed on the image sensor 7 compared to the situations described above with reference to views A and B of Figs. 2.

Referring to FIG. 3, the optical structure of the main optical element 1 in the claimed node can be characterized as follows.

The first (wide) field of view is provided by a two-mirror focal system implemented by a pair of optical surfaces 9, including a central surface on the front side of the optical element and a corresponding surface on the rear side of the optical element 1. Incident radiation entering the optical element 1 through the "open » SOE 3 hits the concave surface on the rear side of the optical element 1 (the first concave surface), reflected from it inside the optical element 1, becomes convergent and reflected on the central surface on the front side of the optical element 1 (the second convex surface). The second convex optical surface reflects optical radiation into the optical element 1 and focuses it on the image sensor.

Said two optical surfaces are of Ritchey-Chrétien design, which is characterized by the absence of third-order coma and spherical aberration. Astigmatism is reduced to acceptable values due to the aspherization of mirror surfaces. Image curvature is corrected by an image plane curvature correction element located between the secondary mirror (second convex surface) and the image plane. The focal optical design thus developed is free from major geometric aberrations, which ensures image quality in the focal plane limited by diffraction.

The second (narrower) field of view is provided by the dual-mirror afocal system represented by the pair of optical surfaces 10 in FIG. 3. This two-mirror afocal system is added to the two-mirror focal system described above and provides magnification M1 of the image compared to the first (wide) field of view described above.

The incident radiation forming the second field of view (see FOV2 of FIG. 6) is incident on the first concave optical surface of the two-mirror afocal system, becomes convergent, and is reflected onto the second optical surface. The second convex optical surface makes the optical radiation collimated and reflects it onto the first optical surface of the focal system with two mirrors.

Position 11 in Fig. 3 shows another afocal system with two mirrors, forming an image with another field of view (FOV3), but with a different image magnification (M _n ). In general, the principle of operation of this afocal system with two mirrors, indicated by the position 11, is similar to the afocal system with two mirrors described above, while the mentioned another afocal system with two mirrors reflects collimated optical radiation onto the first optical surface of the afocal system with two mirrors described above.

The above-described combination of a two-mirror focal system and at least one two-mirror afocal system provides a cascaded optical system based on a combination of focal and afocal portions, which makes the optical system compact and capable of forming many different FOVs. The optical system with the ability to "zoom" forming a plurality of FOV has a small thickness. In addition, an important technical effect is the possibility of creating an optical system with the ability to switch fields of view based on one solid main optical element, excluding groups of movable optical elements and the need to use multiple lenses/cameras for different fields of view.

Switchable optical elements (SOE) 3, 4, 5, placed on the curved sections of the front surface of the optical element 1, perform two main functions. The first function is to compensate for the curvature of said curved portions, providing a flat front surface. The location of the SOE on the front surface of the optical element 1 is illustrated in FIG. 5 which shows a perspective view from the front of the optical element.

The second function of the SOEs 3, 4, 5 is to switch between the channels of the respective FOVs generated by the respective dual mirror focal system and one or more dual mirror afocal systems integrated in the optical element 1 as described above.

It should be noted that the above two functions are performed simultaneously by all but the last SOE (located closest to the outer edge of the front surface of the optical element), since it is located on a substantially flat surface of the optical element, and not on a curved surface area.

In at least one exemplary embodiment, the optical material from which the SOEs are made is the same material from which the main optical element is made.

That at least one optical surface of each SOE is planar allows the incident optical radiation forming the selected FOV to enter the SOE without aberrations. The other optical surface SOE has the same curvature as the second convex optical surface of the corresponding two-mirror afocal system described above. In addition, each SOE strictly follows the shape of the curved portion of the front surface of the optical element 1, without any gaps between the surface of the SOE and the surface of the curved portion of the front surface of the optical element. This makes it possible to eliminate the refraction of optical radiation entering the optical element through the corresponding SOE.

Each SOE refers to a corresponding one of the FOV channels because the curvature of the optical surface for each afocal system is different. However, as mentioned above, the last SOE (as a non-limiting example, located closer to the outer edge of the optical element 1) does not have curvature, since all of its surfaces are essentially flat.

The switching of the state ("opening"/"closing") of each of the switched optical elements is realized by a special optical coating deposited on one of the optical surfaces of the SOE (in particular, on the second, in the general case - concave (flat for the last SOE) optical surface ).

Due to this optical coating, the corresponding optical surface SOE has two states:

a) transparent

b) reflective.

In state a) SOE transmits the incident optical radiation into the main optical element of the inventive optical assembly. In state b), the SOE acts as a second mirror in the corresponding dual-mirror afocal system, or blocks optical emission for a given FOV channel.

In addition, in one or more non-limiting embodiments of the invention, the SOE may also have an electrochromic glass on a flat optical surface corresponding to the front surface of the optical element 1, which further blocks the incident optical radiation for a given FOV channel. The last (as a non-limiting example, located closest to the outer edge of the optical element 1) SOE has only this function.

In at least one non-limiting embodiment of the present invention, the design of the optical element 1 is characterized by the following features.

The front and back sides of the optical element 1 have a mirror coating 2 as shown in FIG. 1 and act as mirrors.

Referring to FIG. 4, in one or more non-limiting embodiments of the optical assembly of the invention, a liquid crystal switchable mirror coating (LCSM) may be applied to the concave optical surfaces located on the curved portions of the front surface of the optical element 1. On FIG. 4, reference numeral 2 denotes the mirror coating on the surface of the rear side of the optical element 1. Reference numeral A in FIG. 4 denotes a concave area in the center of the front surface of the optical element 1, which is also coated with a mirror coating 2. Positions B, C and D indicate the concave optical surfaces on the curved sections of the front side of the optical element 1, which are coated with LCSM. These surfaces can be in one of two states. In one state they transmit optical radiation (photopic transmittance >87%), in the other state they act as mirrors (photopic reflectance >87%).

With respect to the selectable field of view channels (FOV1-FOV3) provided by the respective SOEs 3, 4, 5, as shown in FIG. 4, the LCSM states are characterized as follows:

FOV1 (SOE 3): B - transmission, C and D - reflection;

FOV2 (SOE 4): C - transmission, B and D - reflection;

FOV3 (SOE 5): D - transmission, B and C - reflection.

Thus, in one or more non-limiting embodiments of the optical assembly of the invention, said FOV channel "switching" may be implemented by using an LCSM whose states may change between a transmit state and a reflective state. However, LCSM as an optical material that implements such switching has some disadvantages, such as, in particular, the imperfection of the separation of transmission and reflection states, the occurrence of "noise" and image artifacts. In this regard, to at least partially compensate for these disadvantages of LCSM, the above-mentioned electrochromic glass can be used, placed in front of each SOE forming the corresponding FOV channel.

As mentioned above, the rear side of the optical element 1 and the surface A are mirror coated and act as mirrors.

In yet another embodiment, on surfaces B and C of FIG. 4, a translucent coating can be applied (transmission of optical radiation 50%, reflection of optical radiation 50%). Surface B transmits optical radiation corresponding to the FOV1 channel, reflects the radiation corresponding to the FOV2 and FOV3 channels. Surface C transmits the radiation corresponding to the FOV2 channel, reflects the radiation corresponding to the FOV3 channel.

In this embodiment, electrochromic glass (ECG) is applied to the first optical surfaces (located in the plane of the front side of the optical element 1) SOE 3, 4, 5. ) and the state in which it absorbs the incident optical radiation (absorption state). In a state in which the ECG of only one of the SOEs transmits the incident optical radiation, and the ECGs of the remaining SOEs absorb the optical radiation, the image sensor of the imaging apparatus receives the optical radiation corresponding to only one FOV channel.

With respect to the selectable field of view channels (FOV1-FOV3) provided by the respective SOEs 3, 4, 5, as shown in FIG. 4, ECG states are characterized as follows:

FOV1: B - transmission, C and D - absorption;

FOV2: C - transmission, B and D - absorption;

FOV3: D - transmission, B and C - absorption.

The disadvantages of a translucent coating include the fact that it has only 50% efficiency, as a result of which the throughput of the system is greatly reduced (due to significant light losses) and may have artifacts. These shortcomings are compensated to some extent by the use of ECG, as described above. In this case, the use of a translucent coating provides the cheapest implementation of the optical system according to the invention.

In a non-limiting exemplary embodiment, the optical assembly of the invention comprises two switchable optical elements (SOE 3 and SOE 4) that correspond to two FOV channels, FOV1 and FOV2, respectively.

In order to obtain on the image sensor of the image forming apparatus containing the optical assembly according to the invention, images with a field of view FOV1 SOE 4 blocks the incident optical radiation, and SOE 3 transmits the optical radiation. The optical radiation of the FOV1 channel enters the optical element 1 through the flat surface and passes through the concave surface without refraction because the optical materials of the SOE 3 and the optical element 1 are the same. In this case, the radiation passing through the SOE 3 is reflected from the mirror coating on the rear surface of the optical element 1 and from the mirror coating on the side of the optical surface A of FIG. 4 and, leaving the optical element 1, hits the surface of the image sensor of the imaging device in which the optical unit according to the invention is implemented.

To form the FOV2 channel, SOE 3 blocks the incident optical radiation and SOE 4 lets the incident optical radiation through. Meanwhile, since in this embodiment SOE 4 is the nearest SOE to the outer edge of the front side of the optical element 1, SOE 4 is flat and does not have a concave optical surface. The optical radiation corresponding to the FOV2 channel enters the optical element 1 through the flat surface SOE 4. It is then reflected from the corresponding concave surface of the rear side of the optical element 1 and from the side of the concave optical surface A of FIG. 4, which, together with said concave surface of the rear side of the optical element 1, forms an afocal system with two mirrors with magnification M. After being reflected from said optical surface A SOE 3, the optical radiation follows the path of the optical radiation corresponding to the FOV1 channel, and finally hits the surface an image sensor of the imaging device in which the optical assembly according to the invention is implemented.

The embodiments of the optical system according to the invention described above are only some of the examples of the design of a one-piece main optical element 1. Table 1 below shows the design parameters that allow you to create a one-piece main optical element 1 that implements one focal system with two mirrors and two afocal systems with two mirrors within one solid optical element.

Tests have shown that exemplary embodiments of the optical system of the invention implement, for example, three FOV channels on a single image sensor, achieving sufficient image quality for the pixel sizes of most modern image sensors.

Table 1. Design parameters of an optical element with an image plane curvature corrector

Curvature radius R, mm Axial distance d, mm Optical material, n; v Conical constant, K Aspherical coefficient A4 Aspherical coefficient A6 Aspherical coefficient A8 Aspherical coefficient A10 1
HELL ∞ 6.3518 1.86; 40.578 2** -36.8117 -5.2887 MIRROR -1.00E+00 3** -26.2319 4.9648 MIRROR -1.00E+00 four* -28.1310 -5.3338 MIRROR -1.00E+00 five* -17.4579 5.0836 MIRROR -1.00E+00 6 -19.3837 -5.6338 MIRROR -2.15E+00 7 -21.4135 3.1561 MIRROR -5.16E+01 1.90E-04 -1.42E-05 8 6.4373 0.9543 -1.52E+01 1.82E-03 -3.05E-03 2.73E-04 nine 5.5788 0.3392 1.67; 19.245 1.06E+01 -1.07E-01 3.73E-02 -3.07E-03 -1.41E-03 10 2.0266 0.3157 1.39E+00 -1.44E-01 6.47E-02 -1.65E-02 7.47E-03 eleven 3.7308 0.5311 1.73; 40.508 -1.25E+01 -3.82E-02 -1.30E-02 -3.63E-03 4.42E-03 12 -4.8640 0.0701 -2.47E+37 -6.11E-02 -8.83E-03 7.21E-03 -1.03E-05 13 20.8070 0.5664 1.74; 49.296 -3.91E+02 -3.98E-02 -7.67E-03 1.32E-05 -2.17E-03 fourteen -7.6181 0.1154 2.91E+01 -2.39E-02 -3.01E-02 1.14E-02 -1.12E-03 15 ∞ 0.1000 1.517; 64.198 sixteen ∞ 0.1000 17 ∞

AD - aperture diaphragm

n is the refractive index for the wavelength d=0.586 µm;

ν is the Abbe number.

The surfaces used in the optical calculation are aspherical, described by the equation:

Where r is the radial coordinate;

c - surface curvature value, where c=1/R, R - surface curvature radius;

k - conic constant;

A ₄ ... A ₁₀ - aspherical coefficients.

The main criterion for image quality for optical systems of this type is the transfer function modulus (MTF).

For image sensors of the conventional type, which in the context of the present invention can be represented by a CMOS (Complementary Metal Oxide Semiconductor) or CCD (Charge Coupled Device) type sensor, the target frequency is 200 lines per mm. In this case, the MTF value for a given frequency should be more than 0.2 (Rayleigh criterion).

Experimental studies have shown that the optical assembly according to the invention provides an image quality that satisfies the above criteria - the MTF value for a target frequency of 200 lines per mm in all cases of the invention did not fall below 0.2, that is, in all cases the Rayleigh criterion mentioned above was satisfied . As a non-limiting example, studies have shown that when implementing the invention, three FOVs (FOV1-FOV3) provided, for example, the following viewing angles:

FOV1: 10.6 degrees (F# - 2.5)

FOV2: 6.6 degrees (F# - 3.16)

FOV3: 4.6 degrees (F# - 3.44)

Switching the states of the SOE is provided under the control of the controller of the imaging apparatus in which the optical assembly according to the invention is implemented by connecting the SOE to one or more control units via electronic contacts, conductors, or the like. The control units may be one or more processors, microprocessors, ASICs, etc., as known to those skilled in the art, that can control the optical node according to the invention under the control of appropriate software, firmware, program element, module, etc. stored on one or more computer-readable media, as is known to those skilled in the art.

In yet another aspect of the invention, a method for generating a plurality of fields of view of an imaging lens may be provided, the method comprising the steps of passing incident optical radiation into an integral main optical element through at least two switchable optical elements (SOE) located on the front surface of the optical element , while the optical radiation inside the optical element undergoes at least one internal reflection by means of a focal system with two mirrors integrated into the optical element and at least one afocal system with two mirrors integrated into the optical element and is output to the image sensor, forming an image with several fields vision (FOV) on the image sensor, and each of at least two SOE is configured to switch between transmission of optical radiation and reflection and/or absorption of optical radiation, thus providing switching corresponding FOV.

The method for generating a plurality of fields of view of an imaging lens is implemented by the above-described optical assembly according to the above-described first aspect of the present invention, and can be applied to the imaging apparatus according to the second aspect of the present invention described above.

In the first step of the method, incident optical radiation, on the basis of which an image with at least one field of view (FOV) is formed on the image sensor, is transmitted by one of at least two SOEs switched to the state of optical radiation transmission. Switching between the respective fields of view on the image sensor is carried out depending on the "open" and "closed" states of the respective SOEs.

For example, referring again to FIG. 1-5, if SOE 3 is switched to the "open" ("transparent") mode, the incident optical radiation passes into the optical element 1 through SOE 3. If SOE 4 is in the "open" state, and SOE 3 and 5 are in the "closed" state ” state, the incident optical radiation enters the optical element 1 through SOE 4. If SOE 5 is in the “open” state, and SOE 3 and 4 are “closed”, the incident optical radiation enters the optical element 1 through the open SOE 5.

At the next stage of the method, the optical radiation passed inside the optical element is subjected to at least one internal reflection inside the optical element. At the same time, to form the first (wide) field of view, the method according to the invention uses a focal system with two mirrors integrated into the optical element and implemented by a pair of optical surfaces, including a central surface on the front side of the optical element and a corresponding surface on the rear side of the optical element. To form a second (or third, etc.) narrower field of view, the method according to the invention employs at least one afocal system with two mirrors, the implementation and principle of which are explained above and illustrated, in particular, in FIG. 3. It should be noted that the optical element according to the invention provides at least one afocal system with two mirrors, while the number of afocal systems may vary depending on the specific implementation of the invention and, accordingly, the invention can provide an appropriate number of fields of view on the image sensor imaging devices.

At the next stage of the method, the fields of view formed on the image sensor are switched by means of optical radiation that has entered the optical element and is subjected to at least one internal reflection within the optical element, as described above. Said switching is realized by the respective switching optical elements (SOE) by "switching" from the "open" state to the "closed" state and vice versa by using in the SOE and/or the optical element at least one optical surface configured to change the transmission properties and /or blocking (reflection, absorption) of optical radiation in response to control signals of low voltage electric current, issued, for example, by a processor controlling an image forming device, as described above.

The above technical solution provides the achievement of the following technical effects. Since in the proposed optical system (optical assembly) the field of view (“zooming”) is changed without the use of moving components of the optical system, which require high precision, alignment, the presence of one or more motors, etc., the proposed optical system provides the ability to create especially a compact imaging device suitable for use in modern compact user computing devices such as, as a non-limiting example, smartphones, tablet computers, portable personal computers (laptops, netbooks). Also, the invention can be used in imaging devices such as compact photo/video cameras with a relatively large range of focal lengths (zoom). At the same time, as shown above, the invention provides a sufficiently high image quality with minimal geometric aberrations. In addition, the absence of moving components in the optical system simplifies the assembly and manufacturing process of the imaging device containing such an optical system.

Those skilled in the art will appreciate that what has been described and shown in the drawings above are only some of the possible examples of techniques and facilities by which embodiments of the present invention may be implemented. The above detailed description of embodiments of the invention is not intended to limit or determine the scope of legal protection of the present invention.

Other embodiments that may be within the scope of the present invention may be contemplated by those skilled in the art upon careful reading of the foregoing description with reference to the accompanying drawings, and all such obvious modifications, alterations and/or equivalent substitutions are deemed to be within the scope of the present invention. All prior art references cited and discussed in this document are hereby incorporated into this specification by reference as far as applicable.

While the present invention has been described and illustrated with reference to various embodiments thereof, it will be understood by those skilled in the art that various changes may be made to its form and specific details without departing from the scope of the present invention, which is defined only the following claims and their equivalents.

Claims (24)

1. An optical assembly containing an optical element and an element for correcting the curvature of the image plane, moreover: the optical element is made in the form of a solid main optical element; the optical element contains an integrated focal system with two mirrors, the optical element contains at least one integrated afocal system with two mirrors, a plurality of switchable optical elements (SOE) are placed on the front side of the optical element; the switchable optical elements are configured to switch between the first and second states, wherein the first state is the state of transmission of optical radiation of the visible spectrum, and the second state is the state of absorption or reflection of optical radiation of the visible spectrum, moreover, the element for correcting the curvature of the image plane is located behind the optical element. 2. The optical assembly of claim 1, wherein the two-mirror focal system comprises a first concave reflective optical surface and a second convex reflective optical surface. 3. The optical assembly of claim 1, wherein the at least one dual mirror afocal system comprises at least a first concave reflective optical surface and a second convex reflective optical surface. 4. An optical assembly according to claim 2 or 3, wherein said reflective optical surfaces are coated with a state changeable state between a state of transmission and a state of reflection. 5. The optical assembly of claim 1, wherein both the two-mirror focal system and the at least one two-mirror afocal system are formed in said single-piece primary optical element. 6. An optical assembly according to claim 1, wherein the switchable optical elements are configured to compensate for the curvature of at least one concave surface of the afocal system, forming a substantially flat front surface of the optical element. 7. Optical assembly according to claim. 1, in which at least one surface of the switchable optical elements is coated with a reflective optical coating. 8. The optical assembly of claim 1, wherein at least one surface of the switchable optical elements is coated with electrochromic glass. 9. Optical assembly according to claim 7, wherein the switchable optical elements are made of the same optical material as the main optical element. 10. Optical assembly according to claim 7, in which the switchable optical elements have a flat first optical surface and a second optical surface, the curvature of which corresponds to the curvature of the concave reflective optical surfaces of the focal system with two mirrors and/or at least one afocal system with two mirrors. 11. Optical assembly according to claim 7, wherein the switchable optical elements are located on the second reflective optical surfaces of at least one afocal system with two mirrors, forming a flat surface, which is located on the normal with respect to the optical axes. 12. Optical assembly according to claim 7, in which the optical element has a concave central portion of a circular shape. 13. An optical assembly according to claim 1, wherein the image plane curvature correction element is in the form of at least one lens and is placed between the optical element and the image sensor of the imaging device. 14. The imaging device containing the optical node according to one of paragraphs. 1-13. 15. A method for generating a plurality of fields of view of an imaging lens, the method comprising the steps of: passing the incident optical radiation into the solid main optical element through at least two switchable optical elements (SOE) placed on the front surface of the optical element, at the same time, the optical radiation inside the optical element undergoes at least one internal reflection by means of a focal system with two mirrors integrated into the optical element and at least one afocal system with two mirrors integrated into the optical element and is output to the image sensor, forming an image with several fields of view (FOV) on the image sensor, and switching each of the at least two SOEs between an open state in which the SOE transmits optical radiation and a closed state in which the SOE both reflects and/or absorbs optical radiation, thereby switching the respective FOVs on the image sensor.

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