KR20210058636A - Optical device including achromatic phase doublet and method of driving the optical device with reduced chromatic aberration - Google Patents

Abstract

An optical device comprising achromatic phase doublet and a method of driving an optical device having reduced chromatic aberration are disclosed. The disclosed optical device comprises an electroactive lens having a layer of electroactive material. The electroactive lens is configured to apply a voltage to the electroactive material layer to form a doublet phase function comprising a kinoform phase function and a harmonic lens phase function.

Description

{Optical device including achromatic phase doublet and method of driving the optical device with reduced chromatic aberration}

The present disclosure relates to the field of optical systems, and more particularly, to an achromatic optical system having a variable focal length, and in particular, to an augmented reality or virtual reality (AR/VR) system. S, adjustable focus glasses, photographic and video camera lenses, as well as in a variety of optical devices for research and application purposes.

Various optics for research and application purposes, as well as in currently developed optics for a variety of applications, such as, for example, augmented reality or virtual reality (AR/VR) systems, adjustable focus glasses, photographic and video camera lenses. In devices, electroactive diffractive lenses, in particular liquid crystal (LC) lenses or polymer gel based lenses are currently used. One of the problems with these lenses is the dispersion of the refractive index of the lens material (liquid crystals or polymer gel), as well as chromatic aberrations resulting from the diffractive structure of the lenses being used, i.e., the refractive index of the material is light radiation. It depends on the wavelength of (optical radiation). Chromatic aberration is caused by different focal lengths for different radiation wavelengths and varies depending on the focal length of the lens. Lateral (transverse) chromatic aberration, also known as "zoom chromatic aberration", which can be seen as blurred "iridescent" bands around the edges of imaged objects and can be corrected by software means. There are also axial chromatic aberrations, also known as "position chromatic aberration", which can be seen as "rainbow" halos around light spots in the image and cannot be corrected by software means.

In order to improve the image quality, it would be advantageous to remove (compensate, correct) chromatic aberrations in the image, in particular, axial chromatic aberrations (position chromatic aberration). In adjustable lenses of the type described above, the focal length is adjusted by changing the phase function of the electroactive lens under the influence of the voltage applied to the electrodes. The optical power of these lenses can be changed by a wide variety of methods, but they do not participate in the task of compensating for chromatic aberrations.

In addition, important tasks for improving the aforementioned types of adjustable lenses include shortening the lens response time, reducing the lens thickness, and reducing the voltage on the electrodes required to adjust the lens.

In the prior art, the response time is generally shortened by reducing the adjustable lens thickness and/or increasing the voltage on the electrodes.

Reference US 8717681 B2 (BAE Systems PLC, announcement dated May 6, 2014) is an optical system containing two different liquids with a deformable membrane whose shape (curvature value) can be adjusted using piezoelectric actuators. Start. The two different liquids used in this optical system have different dispersion indices. Among the drawbacks of this solution, mention can be made of the need to use mechanical adjustment means, a long response time and a high operating voltage.

Reference US 7352514 B2 (Koninklijke Philips Electronics NV, Announced April 1, 2008) describes and contains two different non-mixed liquids whose interface forms a meniscus and whose shape changes depending on the applied voltage. The meniscus-forming interfacial layer between the two liquids discloses a decolorization lens system based on the electrowetting effect having wettability by the first liquid. Among the shortcomings of this solution, mention may be made of the high operating voltage as well as the long response time, the aperture size limited by the inertial effect of the liquids being used.

Reference CN 108845382 A (Hangzhou Dianzi University, November 20, 2018) provides a specific range of focal lengths relying on the lateral shift of the lenses to each other, where the diffractive surfaces of the two lenses are harmonics that reduce chromatic aberrations. The use of an Alvarez diffractive lens is disclosed. Among the drawbacks of this solution, one can mention the need for mechanical adjustment and large optical system dimensions.

References A. Marquez et al., a color erase diffraction lens written on a liquid crystal display published on February 1, 2006, doi.org/10.1364/OL.31.000392, is used in a liquid crystal display (LCD). It is proposed to reduce chromatic aberrations by multiplexing the phase functions for the wavelength. Among the shortcomings of this solution, one can mention the insufficient quality of the resulting image.

In reference US 9164206 B2 (University of Arizona, published Oct. 20, 2015) a solution is known for a system of chromatic varifocal lenses including diffractive and refractive lenses. In this prior art solution, chromatic aberrations are reduced by combining a fluid lens and a diffractive lens that is a liquid crystal lens. Among the drawbacks of this prior art solution, mention may be made of the need for mechanical adjustment of the fluid lens, a long response time, an aperture limited by the inertial effects of the liquid, as well as a high operating voltage on the electrodes. This prior art solution can be considered as the closest analog (prototype) of the claimed disclosure.

An optical device comprising a color erase phase doublet and a method of providing an optical device with reduced chromatic aberration are provided.

In addition, a color eraser lens having a variable focus is provided.

This portion of disclosing various aspects and embodiments of the claimed disclosure is intended to provide a brief overview of the claimed subject matter and embodiments thereof. Detailed features of technical means and methods for implementing combinations of features of the claimed disclosures are provided below. Neither this summary of the disclosure nor the detailed description provided below in conjunction with the accompanying drawings should be considered as defining the scope of the claimed disclosure. The scope of the legal protection of the claimed disclosure is defined only by the appended claims.

In view of the above mentioned drawbacks of the prior art, it is an object of the present disclosure to provide an optical system and method using an electroactive lens that, when used, achieves technical results including reducing chromatic aberrations in the optical system. Further, a shorter response time of the electroactive lens and a smaller thickness thereof are achieved, and the voltage to be applied to the electroactive lens is reduced for a suitable response time.

In order to achieve the above object, according to one aspect, the optical device includes an electroactive lens having an electroactive material layer, wherein the electroactive lens applies a voltage to the electroactive material layer to provide a keynoform phase function. And a harmonic lens phase function to form a doublet phase function.

The harmonic lens phase function may be an integer multiple of the kinoform phase function.

The kinoform phase function is a phase function having a maximum phase of 2π radians, the harmonic lens phase function is a phase function having a maximum phase of 2πN (N is an integer greater than or equal to 2), and the doublet phase function is the kinoform phase function and the It is formed by a combination of harmonic lens phase functions and may be a phase function having a maximum phase of 2π+2πN.

For example, N is an integer from 2 to rounded downward (ktΔn/2π-1), k is the wavenumber, t is the lens thickness, and Δn is optical anisotropy.

The electroactive lens is an adjustable electroactive lens, and the electroactive lens may be configured to adjust a focal length by changing a voltage applied to the electroactive material layer of the electroactive lens.

In one example, the electroactive lens may be a liquid crystal (LC) lens.

In another example, the electroactive lens may be a polymer gel-based lens.

The electroactive material layer includes a plurality of independent cells stacked along a propagation path of light, for example, each cell may have a phase function amplitude of 2π.

The electroactive lens includes a first electroactive lens that reproduces the kinoform phase function and a second electroactive lens that reproduces the harmonic lens phase function, and the first electroactive lens and the second electroactive lens have a broad meaning. It can be arranged without gaps along the path.

The optical device further includes a static lens, the electroactive lens is configured to reproduce any one of the kinoform phase function and the harmonic lens phase function, and the static lens is the kinoform phase function and the harmonic lens phase. It can be configured to reproduce the other one of the functions.

In addition, the optical device may further include a static lens that provides an additional refractive power shift.

In another aspect, an augmented reality system according to the present disclosure includes a waveguide; A display disposed to face an edge of a first surface of the waveguide; A first color erase phase doublet disposed between the display and the first surface of the waveguide; A second color erase phase doublet disposed on the other edge of the second surface opposite the first surface of the waveguide; And a third color erase phase doublet disposed to face the second color erase phase doublet with the waveguide interposed therebetween. Here, the first to second color erase phase doublets may be optical devices having the above-described configuration.

In another aspect, the present disclosure is directed to a method of providing an electroactive lens having reduced chromatic aberrations, the method comprising: acquiring a refractive power of a kenoform; Acquiring refractive power of the harmonic lens; Obtaining a harmonic lens phase function whose maximum phase is 2πN radians and N is an integer greater than 1; Obtaining a kinoform phase function whose maximum phase is 2π radians; Combining the harmonic lens phase function and the kinoform phase function to obtain a doublet phase function; And applying a voltage to the electroactive material of the electroactive lens to implement the doublet phase function.

In yet another aspect, the present disclosure is directed to a computer-readable medium storing instructions that, when executed by a processor, cause a processor to perform the method of the above-mentioned aspect.

In other aspects, the present disclosure also provides for an optical system comprising the optical device, as well as one or more electroactive lenses, image forming methods and optical devices, computer programs and program products, computer-readable media. Can be.

According to the disclosed embodiments, it is possible to provide a variable focus lens without chromatic aberration using electroactive lenses. In addition, according to the disclosed embodiments, it is possible to reduce the response time, thickness, and applied voltage of the variable focus lens.

1 shows a graph of the kinoform phase function.
2 shows a graph of the harmonic lens phase function.
3 is a graph of a color erase phase doublet phase function according to an embodiment.
4 shows a graph of voltage-phase properties of an electroactive material.
5 shows a graph of the voltage distribution along the aperture for a color erase phase doublet according to an embodiment.
6 shows a graph of residual modulation of refractive power (chromatic aberration) illustrating the minimum chromatic aberration achieved in an adjustable electroactive lens according to an embodiment.
7 shows a graph of a color erase phase doublet phase function according to an embodiment in which an adjustable electroactive lens is implemented as a stack of adjustable optical cells.
FIG. 8 illustrates a stacked structure of adjustable optical cells for implementing the color erase phase doublet phase function shown in FIG. 7.
9 shows graphs of a kinoform phase function, a harmonic lens phase function, and a color erase phase doublet phase function for implementing a static lens using an optical glass.
10 schematically illustrates the structure of a color erase phase doublet according to an embodiment.
11 schematically illustrates a structure of a color erase phase doublet according to another embodiment.
12 schematically illustrates a structure of an optical system including a color erase phase doublet according to another embodiment.
13 schematically illustrates the structure of an adjustable electroactive lens according to an embodiment.
14 schematically illustrates an augmented reality (AR) system comprising adjustable electroactive lenses according to an embodiment.

Hereinafter, an optical device including a color erase phase doublet and a method of driving an optical device having reduced chromatic aberration will be described in detail with reference to the accompanying drawings. In the following drawings, the same reference numerals refer to the same components, and the size of each component in the drawings may be exaggerated for clarity and convenience of description. In addition, the embodiments described below are merely exemplary, and various modifications are possible from these embodiments.

Hereinafter, what is described as "top" or "top" may include not only those directly above by contact, but also those that are above non-contact. Singular expressions include multiple expressions unless the context clearly indicates otherwise. In addition, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components unless specifically stated to the contrary.

The use of the term "above" and similar designating terms may correspond to both the singular and the plural. Unless explicitly stated or contradictory to the steps constituting the method, these steps may be performed in an appropriate order, and are not necessarily limited to the stated order.

In addition, terms such as "... unit" and "module" described in the specification mean a unit that processes at least one function or operation, which may be implemented as hardware or software or a combination of hardware and software. .

Connections or connecting members of lines between components shown in the drawings are illustrative representations of functional connections and/or physical or circuit connections, and in an actual device, various functional connections, physical connections, alternative or additional, Or it can be represented as circuit connections.

The use of all examples or illustrative terms is merely for describing technical concepts in detail, and the scope is not limited by these examples or illustrative terms unless limited by the claims.

In order to improve the image quality, it would be advantageous to remove (compensate, correct) chromatic aberrations in the image, in particular, axial chromatic aberrations (position chromatic aberration).

In addition, an important task to improve the above mentioned types of adjustable lenses is to shorten the response time of the lens, reduce the thickness of the lens, and reduce the voltage required at the electrodes to adjust the lens.

It is known that the response time of an electroactive lens is proportional to the square of the thickness of the lens. For adjustable electroactive lenses, especially liquid crystal (LC) lenses, the response time is calculated according to the following equation:

Here, the main parameters that characterize the LC lens are the liquid crystal lens thickness t and the applied voltage V _on .

For various applications of an adjustable electroactive lens with eliminated (compensated) chromatic aberration, it would be advantageous to achieve the following effect, especially when the lens is used in augmented reality (AR) systems:

-Shorter response time (τ _Σ ),

-Smaller lens thickness (t), and

-Lower applied voltage (V _on ).

In order to achieve the above object, a "doublet" consisting of phase functions of two lenses, namely a kinoform and a harmonic lens, is proposed. The phase functions of the kenoform and harmonic lenses differ from the phase functions of traditional lenses in that they have a 2π (or 2πN) level of phase modulation that makes it possible to reduce the material thickness.

The present disclosure implements a "doublet" of two phase functions in one adjustable electroactive lens, which may take the form of, for example, an adjustable liquid crystal (LC) lens or an adjustable polymer gel based lens. It should be noted that the foregoing lens types are mentioned only by way of example, and that other kinds of materials and mechanical means may become apparent to those skilled in the art suitable for implementing the present disclosure. Using only one adjustable electroactive lens eliminates the need for mechanical means for optical system adjustment, reduces the required operating voltage, and reduces the response time of the adjustable electroactive lens while solving the task of reducing chromatic aberrations. In one exemplary embodiment of the present disclosure, an adjustable electroactive lens thickness of about 0.3 mm can be achieved.

A method of providing the "doublet" of phase functions in accordance with the claimed present disclosure will now be described. According to the present disclosure, a tunable electroactive lens provides a "suppressed phase doublet" by acquiring and combining phase functions with characteristics for two lenses, ie a kinoform and a harmonic lens. On the other hand, a balance between the refraction power of the kinoform and the refraction power of the harmonic lens is achieved, which makes it possible to eliminate (compensate) or at least reduce the chromatic aberrations.

According to the method of the present disclosure, the phase functions are obtained for the phase function "doublet" implemented by the adjustable electroactive lens according to the present disclosure, wherein the refraction powers of the kinoform and harmonic lens constituting the "doublet" are obtained. Here, the present disclosure will be discussed with respect to an example of a tunable electroactive lens in the form of a liquid crystal (LC) lens, but the present disclosure is not limited to the use of an LC lens, as an alternative, a tunable electroactive lens, for example, It should be understood that it may be in the form of a polymer gel based lens.

The maximum refractive power of a lens system composed of two lenses is obtained by summing the refractive powers of these two lenses. For an exemplary optical system including a kenoform and a harmonic lens, the maximum refractive power can be calculated using Equation 2 below:

Here, D ₀ is the maximum refractive power, D _k is the refractive power of the kinoform, and D _h is the refractive power of the harmonic lens.

At this time, the condition of achromaticity (the absence of chromatic aberrations) for this "system" of the lenses would be:

Where V _k is the Abbe number for the kinoform and V _h is the Abbe number for the harmonic lens.

Solving the system of equations consisting of the two equations provided above, the power of refraction for the kenoform can be calculated as follows:

The power of refraction for a harmonic lens is calculated as follows:

If the liquid crystal (LC) material E7 is considered as a material for a tunable electroactive lens, _{given a maximum power (D 0 ) of 4 diopters (dpt), the powers D k} and D _h for the kenoform and harmonic lenses Will be 1.3 dpt and 2.7 dpt, respectively. It should be noted that these values are used only as a typical example for describing the claimed disclosure, and are not intended to limit the scope of the disclosure to specific values.

In case a new adjustable electroactive lens is needed to implement the claimed disclosure, a thickness of the lens suitable for implementing an optical system having the above calculated properties will be derived. It should be noted that the present disclosure can also be implemented using an existing adjustable electroactive lens that will be appropriately adjusted by applying a required voltage value depending on the thickness of the existing lens, properties of the electroactive material, and the like.

It should be noted that the short response time of the adjustable electroactive lens, i.e., fast adjustment of the refractive power, can be achieved by reducing the lens thickness and/or increasing the applied voltage. Taking an adjustable electroactive lens as a specific, non-limiting example and used in the field of augmented reality (AR) systems, a response time of 0.9 seconds (τ _Σ ) and an applied voltage value (V) of 10 volts (V) is the lens thickness Can be used as input parameters to calculate. As an example of an electroactive material of a lens, it is possible to take a material Е7 having the following properties:

γ ₁ = 186 MPa·sec-rotational viscosity of liquid crystals

K ₃₃ = 18·10 ^-12 N-Frank's modulus of elasticity

ε ₀ = 8.85ㆍ10 ^-12 F/m-absolute dielectric constant

Δε = 13.8-dielectric anisotropy of liquid crystals

The threshold voltage (V _th ) is calculated according to the following equation:

Based on the characteristics provided above, the threshold voltage is 1.2 V.

For the purpose of calculating the required thickness of the adjustable liquid crystal lens, the response time consists of the relaxation time and the liquid crystals realignment time as follows:

Where τ _on is the liquid crystals realignment time and τ _off is the relaxation time.

The liquid crystals realignment time is calculated according to the following equation:

The relaxation time is calculated as follows:

Thus, the response time becomes:

The lens thickness (t) is calculated according to the following equation:

For the parameters mentioned above used as a non-limiting example, the lens thickness t is 31 μm.

The kinoform phase function and the harmonic lens phase function are obtained for the refraction power values of the kinoform and harmonic lens, respectively, as calculated above. The kinoform phase function is shown in FIG. 1 and the harmonic lens phase function is shown in FIG. 2. 1 and 2, the harmonic lens phase function may have a form that is an integer multiple of the kinoform phase function.

The harmonic lens phase function is obtained starting from a calculated or known lens thickness, subject to a quick adjustment of the refractive power of the lens, i.e. providing a short response time of an adjustable electroactive lens. The maximum phase of the harmonic lens phase function is 2πN radians, where N is an integer greater than or equal to 2 (N=2, 3, ...).

The harmonic lens phase function is calculated according to the following equation:

By applying the thickness (t) of 31 μm as calculated above to a doublet phase function having a maximum phase of 2π+2πN, and considering the Dh value of 2.7 dpt as calculated above, the following equation (13) is obtained. Can be:

Here, Δn is the optical anisotropy (refractive index anisotropy) of liquid crystals, which can be taken as 0.21 as a non-limiting example, and λ is a fundamental wavelength that can be taken as 0.588 μm as a non-limiting example.

Based on the foregoing, the value of N for the harmonic lens phase function can be calculated according to Equation 14 below:

In other words, N for the harmonic lens phase function is a rounded downward integer of (ktΔn/2π-1). Here, k is the wave number (2π/λ). Considering the parameters mentioned above, N will be equal to 10, that is, 2πN = 20π (see Fig. 2). It should be noted that the parameters mentioned above are mentioned as non-limiting examples only and are not intended to limit the scope of the present disclosure claimed by specific values. The parameters may vary depending on the type and properties of the electroactive material selected, the thickness of the tunable electroactive lens, the maximum required refractive power of the tunable electroactive lens, and the like.

The kinoform phase function (maximum phase 2π radians) is also intended to provide a quick adjustment of the refractive power of the lens.

The kinoform phase function is calculated according to Equation 15 below:

And the obtained kinoform phase function and harmonic lens phase function are combined to become a "doublet" phase function. Combining the phase functions, the refraction powers of the harmonic lens and the kenoform having a phase value equal to the sum of the phase values for the harmonic lens and the kinoform (which is equal to 2π+20π=22π radians in the considered non-limiting example). A "doublet" phase function is provided with a maximum refractive power equal to the sum (which is equal to 1.3 dpt+2.7 dpt=4 dpt in the non-limiting example considered). Combining the harmonic lens phase function and the kinoform phase function allows the diffraction dispersion of the kinoform to remove the material dispersion characteristic of the harmonic lens, and as a result, the chromatic aberration of the harmonic lens and the kinoform are minimal ( The residual) is substantially summed up with chromatic aberration. The profiles of the harmonic lens phase function and the kinoform phase function have slopes of the dispersion curve (dependence between the power and wavelength) that are opposite to each other, and by combining the harmonic lens phase function and the kinoform phase function, the residual refractive power is adjusted (wavelength dependent). Change in refractive power) occurs (refer to the graph in FIG. 6). The residual refractive power adjustment mentioned above causes chromatic aberrations, in particular axial aberrations ("position chromatic aberration"). Combining the phase functions according to the present disclosure results in very small residual power adjustment, and thus very low chromatic aberrations compared to prior art solutions.

On the other hand, considering the following Equation 16:

Here, ΔD is the residual refractive power adjustment (chromatic aberration), D0 is the maximum refractive power, and the larger the value of N, the lower the resulting chromatic aberrations in a given optical system. However, on the one hand, an increase in N causes an increase in the thickness of the adjustable electroactive lens, which in turn adversely affects the response time.

The minimum chromatic aberrations for the adjustable lens with the parameters discussed above can be eliminated as follows.

For the harmonic lens phase function (2πN), N may be given by Equation 14.

For example, if N is equal to 10 and D0 is 4 dpt, then the minimum chromatic aberrations (“position chromatic aberration”) for an adjustable electroactive lens with the parameters discussed above are 0.36 dpt. The value of the minimum chromatic aberrations is substantially defined by the balance between the maximum refractive power of the lens, the thickness of the lens and the response time.

The obtained "doublet" phase function can be used in a new adjustable electroactive lens in which the required parameters (especially thickness, phase profile) are calculated as described above, or in an existing adjustable electroactive lens by applying the required voltage values. Is implemented. In order to apply a voltage, it is necessary to calculate the voltage to be applied to the electrodes acting on the electroactive material of the lens (eg, controlling the liquid crystals in the case of a liquid crystal (LC) electroactive lens). To this end, a voltage map for the electrodes of the adjustable electroactive lens is formed. The voltage map is calculated based on the voltage-phase properties of the electroactive material of the adjustable electroactive lens. The dependencies between voltage and phase and the use of those dependencies in a "doublet" phase function are illustrated in Figures 3-5. 5 shows a graph of the voltage distribution along the aperture for a color erase phase doublet according to an embodiment. For example, when the voltage-phase characteristic of the electroactive material is the same as the graph of FIG. 4, the voltage map for obtaining the doublet phase function shown in FIG. 3 may be the same as that of FIG. 5.

In the case of a conventional lens, voltage-phase characteristics can be measured in various ways known from the prior art (eg, Chen RH Liquid crystal displays: fundamental physics and technology.- John Wiley & Sons, 2011, or Den Boer W. Active matrix liquid crystal displays: fundamentals and applications.- Elsevier, 2011). Then, a voltage function profile is determined for a "doublet" phase function based on the measured voltage-phase characteristics (see Fig. 5), and the obtained voltage function profile is then "corresponding to the obtained voltage function profile. It is applied to the adjustable electroactive lens by applying a voltage to the electrode controlling the electroactive lens according to the "voltage map".

As one of the possible embodiments of the present disclosure, in an optical system in which chromatic aberrations are compensated, a very large amplitude (22π) of the doublet phase function is a phase function of 2π, as shown in FIGS. 7 and 8 as a non-limiting example. The response time is further shortened by implementing an electroactive lens that can be adjusted in the form of a stack of LC cells divided into 11 independent liquid crystal (LC) cells (LC1, LC2, ..., LC10, LC11) each having an amplitude. Can be (the speed of motion is increased). For example, FIG. 7 shows a graph of a phase function of a color erase phase doublet according to an embodiment in which an adjustable electroactive lens is implemented as a stack of adjustable optical cells, and FIG. 8 is a graph of the color erase phase double shown in FIG. 7. It illustrates a stacked structure of adjustable LC cells (LC1, LC2, ..., LC10, LC11) to implement the phase function of Lit. A plurality of LC cells LC1, LC2, ..., LC10, LC11 may be stacked along a propagation path of light.

In this case, the phase function amplitude will be reduced by 11 times, which will shorten the response time of the optical system in proportion to the square of one lens thickness, and thus the response time will be reduced by 121 times. On the other hand, the total thickness of the stack will be about 3.3 mm, based on the parameters provided above as a non-limiting example, which is for most applications of the claimed disclosure, in particular augmented reality (AR) system applications. It is generally suitable for Here, the number of LC cells LC1, LC2, ..., LC10, LC11 is merely exemplary, and other numbers of LC cells may be stacked. In addition, although the LC cells LC1, LC2, ..., LC10, and LC11 are illustrated in FIG. 8 by way of example, cells of a plurality of polymer gels may be stacked instead of the LC cell.

Within the legal protection scope of the present disclosure, the color erase phase "doublet" is not implemented as an electroactive lens based on a liquid crystal electroactive material or a polymer gel, but may also be implemented in a static lens in the form of an optical glass. In this case, the static lens can be made into a profile that physically reproduces the "doublet" profile of the kenoform and harmonic lenses. In this case, the lens thickness can be calculated according to Equation 17 below:

By way of non-limiting example, the thickness of such a lens will be about 3.3 mm, based on the exemplary parameters provided above (maximum refractive power of 4 dpt, N=11), which refers to this lens in the art. While also making it suitable for application in various optical systems in, a technical effect of eliminating chromatic aberrations, in particular "position chromatic aberration", will also be achieved for such a lens. For example, FIG. 9 shows a graph of a kinoform phase function, a harmonic lens phase function, and a color erase phase doublet phase function for implementing a static lens using an optical glass.

In another embodiment, the color erase phase doublet may be formed by two adjustable electroactive lenses, one reproducing the kinoform phase function and the other reproducing the harmonic lens phase function. In this embodiment, the lenses are arranged one after another in the path of light radiation propagation, in particular without an air gap between the lenses.

For example, FIG. 10 schematically illustrates a structure of a color erase phase doublet according to an embodiment. Referring to FIG. 10, the color erase phase doublet 1 includes a first adjustable electroactive lens 2 and a second adjustable electroactive lens 3. The first adjustable electroactive lens 2 and the second adjustable electroactive lens 3 can be arranged without gaps along the path of light radiation propagation. One of the first adjustable electroactive lens 2 and the second adjustable electroactive lens 3 can reproduce the kinoform phase function, and the other can reproduce the harmonic lens phase function. Such a color erase phase doublet 1 may be a color erase lens having a variable focus.

In another embodiment, the color erase phase doublet may be formed by a combination of an adjustable electroactive lens and a static lens. In this case, the adjustable electroactive lens and the static lens are sequentially arranged in the optical radiation propagation path, so that one of the adjustable electroactive lens and the static lens can implement a kinoform phase profile, and the other is a harmonic lens phase profile. Can be implemented. This embodiment may be advantageous for some applications of the optics being discussed, such as, by way of non-limiting example, a lens in a telescope or binocular. However, in this embodiment the minimum chromatic aberrations can be achieved for only one refractive power value (only one focal length), while adjusting the optical system to other refractive power values leads to an increase in chromatic aberrations.

For example, FIG. 11 schematically illustrates a structure of a color erase phase doublet according to another embodiment. Referring to FIG. 11, the color erase phase doublet 4 includes an adjustable electroactive lens 5 and a static lens 6. The adjustable electroactive lens 5 and the static lens 6 can be arranged without gaps along the path of light radiation propagation. One of the adjustable electroactive lens 5 and the static lens 6 can reproduce the kinoform phase function, and the other can reproduce the harmonic lens phase function. The static lens 6 can be made of glass, for example.

In yet another embodiment, the optics may include a combination of an adjustable electroactive lens and a static lens that provides additional adjustment of the power of refraction. In this embodiment, the adjustable electroactive lens implements a doublet phase function according to the present disclosure having a refractive power in the range of -4 dpt to +4 dpt, as a non-limiting example, and may be made of glass, for example. The phase function of a static lens may, as a non-limiting example, give a resulting range of refractive power from 0 to +8 dpt.

For example, FIG. 12 schematically illustrates the structure of an optical system including a color erase phase doublet according to another embodiment. Referring to FIG. 12, the optical system 7 may include a color erase phase doublet 8 and a static lens 9. The color erase phase doublet 8 can be implemented by an adjustable electroactive lens with a doublet phase function. The color erase phase doublet 8 may have a refractive power range of, for example, -4 dpt to +4 dpt. The static lens 9 can provide an additional power shift of +4 dpt, for example. Then, the optical system 7 can provide a resulting refractive power range of 0 to +8 dpt. Alternatively, the static lens 9 may provide a negative additional refractive power shift. For example, the static lens 9 may provide an additional power shift of -4 dpt, for example. In this case, the optical system 7 can provide a resulting refractive power range of -8 dpt to 0 dpt.

13 schematically illustrates the structure of an adjustable electroactive lens according to an embodiment of the present disclosure. The adjustable electroactive lens 10 is, by way of non-limiting example, an adjustable liquid crystal (LC) lens or an adjustable polymer gel based lens. Referring to FIG. 13, the adjustable electroactive lens 10 includes an upper substrate 11 and a lower substrate 19. According to the present disclosure, the materials of the upper substrate 11 and the lower substrate 19 of the tunable electroactive lens 10 are, as non-limiting examples, from materials that are transparent in the visible wavelength range, such as glass, plastic, and quartz. Is selected. According to the present disclosure, the thickness of the upper substrate 11 and the lower substrate 19 is in the range of 3 μm to 20 μm. The principles of selection of a substrate thickness based on specific substrate materials in a given embodiment of the present disclosure are well known in the art.

Further, the adjustable electroactive lens 10 includes an upper electrode 12 disposed on the lower surface of the upper substrate 11 and a lower electrode 13 disposed on the upper surface of the lower substrate 19. The upper electrode 12 is a ground electrode, and the lower electrode 13 is an electrode patterned to implement the adjustment of the electroactive lens and the color erase phase doublet when a voltage is applied according to the "voltage map" as described above. to be. The upper electrode 12 and the lower electrode 13 are any suitable transparent conductive material, in particular indium-tin oxide (ITO), indium oxide, tin oxide, indium-zinc oxide. ) (IZO), zinc oxide, or the like. As a non-limiting example, the upper electrode 12 and the lower electrode 13 have a thickness of about 30 nm to about 200 nm, and, consequently, may optionally consist of several individual layers. The lower electrode 13 may have an electrode pattern of any suitable shape, in particular concentric rings, strips, or the like.

The adjustable electroactive lens 10 may include a layer of electroactive material 14 disposed between the upper electrode 12 and the lower electrode 13. When the adjustable electroactive lens 10 is a liquid crystal (LC) lens, the electroactive material layer 14 may be a liquid crystal layer. In other embodiments, for example, where the adjustable electroactive lens 10 is a polymer gel based lens, the electroactive material layer 14 may be a polymer gel.

In addition, the adjustable electroactive lens 10 includes a spacer 15 defining the thickness of the electroactive material layer 14, and a supply (control) electrode 17 connecting the adjustable electroactive lens 10 and a voltage supply unit. , And an insulating layer 18 may be further included. When the electroactive material layer 14 is a liquid crystal layer, the tunable electroactive lens 10 may further include an alignment layer 16 that enables liquid crystals in the liquid crystal layer to be aligned. For example, the spacer 15 may be made of mylar, glass or quartz. The alignment layer 16 may be made of, for example, polyvinyl alcohol (PVA), polyimide (PI), nylon 6,6, or the like. The supply (control) electrode 17 can be made of, for example, aluminum, indium-tin oxide, nickel and other materials. The insulating layer 18 may be made of, for example, silicon dioxide.

The arrows in FIG. 8 indicate the directions of polishing performed for the purpose of aligning/aligning liquid crystals in the cell. Reference numeral k denotes a wave vector, and reference numeral E denotes a polarization state of incident light radiation.

The adjustable electroactive lens 10 may have a rectangular, circular or any other suitable aperture shape depending on the selected shape of the electrode pattern. The lens opening shape is not limited to circular and rectangular shapes, and, in particular, may be a rectangular, polygonal or curved shape, that is, according to the present disclosure, the opening of the adjustable electroactive lens 10 is an actual requirement for the optical system. It should be noted that it can have any shape determined by the specifications, size limitations of the electrodes, the shape and size required, and the like.

The voltage applied to the electrodes 12 and 13 changes the orientation of the liquid crystals in the embodiment with the adjustable liquid crystal (LC) lens or the orientation of the polymer gel crystals in the embodiment of the electroactive lens based on the polymer gel. The refractive index value changes accordingly. According to the present disclosure, since the electrodes 12, 13 are arranged in an electrode pattern shape over substantially the entire surface of the adjustable electroactive lens 10 and a specific voltage is applied to each of the electrodes 12, 13, the required refractive power A voltage profile ("voltage map") corresponding to the required phase profile of the adjustable lens with (which is, according to the present disclosure, a "suppressed phase doublet" as described above) is generated accordingly. The voltage profile is converted to a phase profile using a voltage-phase dependence (see Fig. 4), which voltage-phase dependence is a property of any optically active material (for more details, see, e.g. Chen RH Liquid crystal displays: fundamental physics and technology.- John Wiley & Sons, 2011, or Den Boer W. Active matrix liquid crystal displays: fundamentals and applications.- See Elsevier, 2011).

The electrodes 12 and 13 of the adjustable electroactive lens 10 may comprise patterns of any shape suitable for the particular use of the optics being discussed. In particular, the electrodes 12 and 13 may have a concentric circle, parallel strips, polygonal array shape, or any irregular shape depending on the desired shape of the image discretes. The choice of the shape of the electrodes 12, 13 is defined, for example, by the type of adjustable electroactive lens 10 that must be created for a given embodiment.

The adjustable electroactive lens 10 can be made in a polarization dependent or polarization independent arrangement. So, for example, to create an adjustable electroactive lens 10 whose transmittance does not depend on the polarization of the incident light, an electrode in the shape of parallel strips (for focusing light having both x and y directions of polarization) ( 12, 13) will be selected. In addition, concentric ring electrodes can also be selected to focus light with polarizations of both x and y. In addition, the choice of the configuration of the electrodes 12 and 13 will be defined by the need to reduce the thickness of the optical system (ring electrodes are selected at this time) or to simplify the manufacture of the electrodes 12 and 13 (strip electrodes are selected at this time). I can. Various means and methods for focusing polarized and unpolarized light will be apparent to those skilled in the art. As an example, a method for focusing light is described in Sun Y. N. et al. Development of liquid crystal adaptive lens with circular electrodes for imaging application //Integrated Optics: Devices, Materials, and Technologies VII. -International Society for Optics and Photonics, 2003.-Т. 4987.-Disclosed in С.209-220.

The adjustable electroactive lens may comprise (or consist substantially of) at least one adjustable optical cell. The tunable optical cells can have various configurations and can be arranged in specific ways with respect to each other. Further, if there is more than one tunable optical cell, the tunable optical cells may be connected by a waveguide. In one of the non-limiting embodiments, the waveguide connects the adjustable electroactive lenses and the source of virtual images, and in another embodiment, the waveguide connects the adjustable electroactive lens directly to the source of the virtual images, and the real world It is arranged between adjustable electroactive lenses arranged on the side. This optical system arrangement is particularly applicable to augmented reality (AR) systems that need to have sufficient sharpness to enable viewing of virtual images and observation of the real world without chromatic aberrations.

An optical device of the present disclosure comprising at least one tunable electroactive lens capable of implementing a color erase phase "doublet" as described above, to eliminate or reduce (compensate) chromatic aberrations, in particular "position chromatic aberration" In addition, it can be used in different optical devices and systems where it is desirable to reduce the thickness of the adjustable electroactive lens and shorten the response time of that lens. As a non-limiting example, an optical device may be used, for example, a camera of a smartphone, tablet or other portable computer, a photographic camera in which an adjustable electroactive lens is used to generate images with reduced chromatic aberrations on the sensor of the capturing system. It can be used in photo or video capturing systems.

Another possible application for the optical device of the present disclosure is that the adjustable electroactive lens can be used in the structure of glasses for the user to see the real world while compensating for refractive errors in one or both eyes of the user. It relates to multifocal spectacles for vision correction, and in this case, the refractive power value of the implemented electroactive lens is corrected by refractive anomalies of the user's eyes.

One or more possible applications of the optical device of the present disclosure are, wherein the image from the display (where the present disclosure is implemented in a VR system) is transmitted to the eyes of the user while removing or reducing chromatic aberrations through an adjustable electroactive lens. Or, augmented or virtual reality (AR/VR) systems in which a user views the real world overlaid with augmented reality images in the AR system. Then, in the case of the AR system according to the present disclosure, the optical device may also be used with or without correction of refraction anomalies of the user's eyes.

14 schematically illustrates an augmented reality (AR) system including adjustable electroactive lenses according to an embodiment. Referring to FIG. 14, the AR system 100 includes a waveguide 110, a display 120 disposed facing one edge of the first surface 111 of the waveguide 110, and a plurality of color erase phase doublets 131. , 132, 133). For example, the first color erase phase doublet 131 may be disposed between the first surface 111 of the waveguide 110 and the display 120. The first color erase phase doublet 131 may be disposed in contact with the first surface 111 of the waveguide 110, for example. In addition, the second color erase phase doublet 132 may be disposed on the other edge of the second surface 112 opposite to the first surface 111 of the waveguide 110, and the third color erase phase doublet 133 Silver may be disposed on the other edge of the first surface 111 of the waveguide 110. For example, the second color erased phase doublet 132 is disposed in contact with the second surface 112 of the waveguide 110, and the third color erased phase doublet 133 is the first surface 111 of the waveguide 110. ) Can be placed in contact with. The second color erase phase doublet 132 and the third color erase phase doublet 133 may be disposed to face each other with the waveguide 110 interposed therebetween.

In this structure, the virtual image displayed on the display 120 may be transmitted to the user's eyes through the first color erase phase doublet 131, the waveguide 110, and the third color erase phase doublet 133. In addition, the real world landscape may be transmitted to the user's eyes through the second color erase phase doublet 132, the waveguide 110, and the third color erase phase doublet 133.

AR system 100 can operate in two different modes. In the first mode, the first color erase phase doublet 131 may be used to convert a virtual image into a refractive power corrected by a value of refraction or higher of the user's eyes caused by presbyopia, myopia, or the like. The second color erase phase doublet 132, if necessary, also the third color erase phase doublet 133 may be used to compensate for refraction anomalies of the user's eyes when observing the real world through the AR system 100.

In the second mode, the AR system 100 operates without correcting the refractive error of the user's eyes (this is the case of a user with corrected vision), whereas the second color erase phase doublet 132 is the third color erase phase. It serves to compensate for the refractive power induced by the doublet 133, which, in turn, serves to move the virtual image from the display 120 to the user's eyes through the waveguide.

Those skilled in the art will appreciate that the above description and drawings show only some of the possible examples of techniques and materials and technical means in which embodiments of the present disclosure may be implemented. The detailed description of the embodiments provided above is not intended to limit or define the scope of legal protection of the present disclosure.

Other embodiments that may be included by the scope of the present disclosure may occur to those of ordinary skill in the art after careful reading of the detailed description provided above with reference to the accompanying drawings, and all such obvious modifications, changes and /Or equivalent substitutes are believed to be included within the scope of this disclosure. All prior art references cited and discussed herein are incorporated into this disclosure by reference, where applicable.

Although the present disclosure has been described and illustrated with reference to different embodiments, those skilled in the art may make different changes to its form and specific details without departing from the scope of the present disclosure, and such changes are as follows. It will be understood that it is defined only by the claims provided in and their equivalents.

1, 4, 8, 131, 132, 133..... Suppression phase doublet
2, 3, 5, 10..... adjustable electroactive lens
6, 9.....static lens 7.....optical system
11, 19.....substrate 12, 13, 17.....electrodes
14.....electroactive material layer 15.....spacer
16.....alignment layer 18.....insulation layer
100.....Augmented Reality System 110.....Doparo
120.....display

Claims (15)

It comprises an electroactive lens having an electroactive material layer,
Wherein the electroactive lens is configured to apply a voltage to the electroactive material layer to form a doublet phase function consisting of a kinoform phase function and a harmonic lens phase function. The method of claim 1,
Wherein the harmonic lens phase function is an integer multiple of the kinoform phase function. The method of claim 2,
The kinoform phase function is a phase function having a maximum phase of 2π radians, the harmonic lens phase function is a phase function having a maximum phase of 2πN (N is an integer greater than or equal to 2), and the doublet phase function is the kinoform phase function and the An optical device, which is a phase function formed by a combination of harmonic lens phase functions and has a maximum phase of 2π+2πN. The method of claim 3,
N is an integer from 2 to rounded downward (ktΔn/2π-1), k is the wave number, t is the lens thickness, and Δn is optically anisotropic. The method of claim 1,
Wherein the electroactive lens is an adjustable electroactive lens, and the electroactive lens is configured to adjust a focal length by changing a voltage applied to the electroactive material layer of the electroactive lens. The method of claim 5,
The electroactive lens is a liquid crystal (LC) lens. The method of claim 5,
The electroactive lens is a polymer gel-based lens, optical device. The method of claim 1,
Wherein the electroactive material layer comprises a plurality of independent cells stacked along a propagation path of light, each cell having a phase function amplitude of 2π. The method of claim 1,
The electroactive lens includes a first electroactive lens that reproduces the kinoform phase function and a second electroactive lens that reproduces the harmonic lens phase function, and the first electroactive lens and the second electroactive lens have a broad meaning. Optical devices, arranged without gaps along the path. The method of claim 1,
It further includes a static lens,
The electroactive lens is configured to reproduce any one of the kinoform phase function and the harmonic lens phase function, and the static lens is configured to reproduce the other one of the kinoform phase function and the harmonic lens phase function. Device. The method of claim 1,
The optical device further comprising a static lens that provides an additional power shift. Waveguide;
A display disposed to face an edge of a first surface of the waveguide;
A first color erase phase doublet disposed between the display and the first surface of the waveguide;
A second color erase phase doublet disposed on the other edge of the second surface opposite the first surface of the waveguide; And
Including; a third color erase phase doublet disposed to face the second color erase phase doublet with the waveguide interposed therebetween,
The first to second color erase phase doublets are the optical device according to any one of claims 1 to 11, wherein the augmented reality system. A method of driving an optical device comprising an electroactive lens having an electroactive material layer, the method comprising:
Acquiring refractive power of the kenoform;
Acquiring refractive power of the harmonic lens;
Obtaining a kinoform phase function whose maximum phase is 2π radians;
Obtaining a harmonic lens phase function whose maximum phase is 2πN radians and N is an integer greater than 1;
Combining the harmonic lens phase function and the kinoform phase function to obtain a doublet phase function; And
And applying a voltage to an electroactive material layer of the electroactive lens to implement the doublet phase function. The method of claim 13,
N is an integer from 2 to rounded down (ktΔn/2π-1), k is the wave number, t is the lens thickness, and Δn is optically anisotropic. A computer-readable medium storing instructions that, when executed by a processor, cause the processor to perform the method of claim 13 or claim 14.

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