Pitch adjusting method of liquid crystal grating based on orthogonal electrode

Abstract

The invention provides a liquid crystal grating pitch adjusting method based on orthogonal electrodes, a liquid crystal grating comprises an upper substrate, a lower substrate opposite to the upper substrate and a liquid crystal layer located between the upper substrate and the lower substrate, and a plurality of upper strip-shaped electrodes P1 and a plurality of upper strip-shaped electrodes P2 are arranged on the side, close to the liquid crystal layer, of the upper substrate at intervals in the width direction. A plurality of lower strip-shaped electrodes P1 and a plurality of lower strip-shaped electrodes P2 are arranged on the side, close to the liquid crystal layer, of the lower substrate in the length direction at intervals, and the pitch of the liquid crystal grating is adjusted by applying coupling direct-current voltage while loading voltage on the upper strip-shaped electrodes P1 and the lower strip-shaped electrodes P1. According to the liquid crystal grating based on the orthogonal electrodes, coupling direct-current voltage is applied while voltage is loaded on the upper strip-shaped electrode P1 and the lower strip-shaped electrode P1, and therefore the pitch of the liquid crystal grating is adjusted. In addition, the liquid crystal grating is high in response speed, and the response time can reach submilliseconds.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of liquid crystal grating, and particularly relates to a pitch adjustment method of a liquid crystal grating based on orthogonal electrodes. BACKGROUND

[0002] A grating can modulate the phase or amplitude of a spatial electromagnetic wave, and is divided into two types of phase gratings and amplitude gratings according to different modulation effects. Liquid crystal materials are made into optical devices with grating characteristics, mainly by utilizing the response characteristics of liquid crystals to external fields, to obtain an external field adjustable liquid crystal grating. Compared with traditional gratings, the electric field regulated grating based on liquid crystals has significant advantages, such as small size, light weight, adjustable diffraction efficiency and high resolution. Through the development in recent years, liquid crystal gratings have wide application value in the fields of integrated optics, three-dimensional display and beam control. However, once the liquid crystal grating is prepared, the grating constant is fixed and cannot be adjusted, and the diffraction angle cannot be regulated. At present, the pitch adjustable liquid crystal grating is mainly realized by designing electrode structures or introducing complex driving voltages, and the phase grating based on traditional liquid crystals is difficult to realize fast response characteristics, which limits its application in the field of beam deflection. Chinese invention patent application CN 117215124 A discloses a pitch adjustable liquid crystal grating based on upper and lower transparent electrodes, different pitches of the liquid crystal layer are generated by respectively applying voltages to the upper and lower strip-shaped transparent electrodes, but the response time of the above-mentioned liquid crystal grating is ms, and the response is slow. Chinese invention patent application CN 117075395 A discloses a pitch adjustable liquid crystal phase grating with vertical and plane switching modes, different pitch electrodes are arranged on the surface of the liquid crystal layer, and different pitches of the liquid crystal layer can be generated by adjusting different voltage driving schemes, but the above-mentioned liquid crystal grating is based on one-dimensional grating pitch adjustment, and the response time is milliseconds, and the response is slow. SUMMARY

[0003] The technical problem solved by the application is that the existing liquid crystal grating pitch adjustment method is complex and slow in response.

[0004] The application provides a pitch adjustment method of a liquid crystal grating based on orthogonal electrodes, the liquid crystal grating comprising an upper substrate, a lower substrate arranged opposite to the upper substrate, and a liquid crystal layer located between the upper substrate and the lower substrate, a plurality of upper strip-shaped electrodes P1 and upper strip-shaped electrodes P2 are arranged on one side of the upper substrate close to the liquid crystal layer along the width direction at intervals, and a plurality of lower strip-shaped electrodes P1 and lower strip-shaped electrodes P2 are arranged on one side of the lower substrate close to the liquid crystal layer along the length direction at intervals, the pitch of the liquid crystal grating is adjusted by loading voltages on the upper strip-shaped electrodes P1 and the lower strip-shaped electrodes P1 and simultaneously applying a coupling direct current voltage.

[0005] Further, by loading voltage V1 to the upper strip electrode P1 and the lower strip electrode P1, the liquid crystal layer generates a small-pitch two-dimensional liquid crystal grating, and by loading voltage V2 to the upper strip electrode P1 and the lower strip electrode P1 and simultaneously applying a coupling direct current voltage V3, the liquid crystal layer generates a large-pitch two-dimensional liquid crystal grating.

[0006] Further, the liquid crystal grating requires 120 μs in the rising process of the first-order diffraction light intensity and 840 μs in the falling process.

[0007] Further, the upper substrate and the lower substrate are made of glass, and the upper and lower strip electrodes P1 and P2 are made of indium tin oxide transparent conductive material.

[0008] Further, the width G of the upper and lower strip electrodes P1 and P2 is the same, and the gap width W between the adjacent strip electrodes P1 and P2 is the same and greater than G.

[0009] Further, the liquid crystal layer is a blue phase liquid crystal, and the ratio is 85.59wt.% BP06, 3.5wt.% R5011, 5.32wt.% RM257, 5.32wt.% C12A, 0.27wt.% RG184, and the characteristic parameters are: no=1.498, ne=1.656, ΔnS=0.15, ES=5.8V / μm.

[0010] The present application has the following beneficial effects: the liquid crystal grating based on the orthogonal electrode adjusts the liquid crystal grating pitch by loading voltage to the upper strip electrode P1 and the lower strip electrode P1 and simultaneously applying a coupling direct current voltage, and the operation is simple and efficient. In addition, the liquid crystal grating has fast response speed, and the response time can reach sub-millisecond. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 The liquid crystal grating based on the orthogonal electrode of the present application is shown in the structural diagram.

[0012] Figure 2 The small-period two-dimensional grating arrangement of the liquid crystal grating based on the orthogonal electrode of the present application is shown.

[0013] Figure 3 The diffraction diagram of the small-period two-dimensional grating of the liquid crystal grating based on the orthogonal electrode of the present application is shown.

[0014] Figure 4 The large-period two-dimensional grating arrangement of the liquid crystal grating based on the orthogonal electrode of the present application is shown.

[0015] Figure 5 The diffraction diagram of the large-period two-dimensional grating of the liquid crystal grating based on the orthogonal electrode of the present application is shown.

[0016] Figure 6, a response time diagram of the liquid crystal of the liquid crystal grating based on orthogonal electrodes of the present invention.

[0017] Figure 7 , the present invention is based on the phase distribution diagram of each position in the liquid crystal layer of the liquid crystal grating of the orthogonal electrodes. DETAILED DESCRIPTION

[0018] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0020] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0021] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined. Example

[0022] like Figure 1As shown, a liquid crystal grating based on orthogonal electrodes includes an upper substrate 1, a lower substrate 2 arranged opposite to the upper substrate 1, and a liquid crystal layer 3 between the upper substrate 1 and the lower substrate 2. The upper substrate 1 is provided with a plurality of upper strip electrodes P1 and P2 along the width direction at intervals near the side close to the liquid crystal layer 3. The lower substrate 2 is provided with a plurality of lower strip electrodes P1 and P2 along the length direction at intervals near the side close to the liquid crystal layer 3. The widths G of the upper and lower strip electrodes P1 and P2 are the same, and the gap widths W between adjacent strip electrodes P1 and P2 are the same and greater than G. The upper and lower substrates 1 and 2 are made of glass, and the upper and lower strip electrodes P1 and P2 are made of indium tin oxide transparent conductive material. The liquid crystal layer is blue phase liquid crystal with a ratio of 85.59wt.% BP06, 3.5wt.% R5011, 5.32wt.% RM257, 5.32wt.% C12A, and 0.27wt.% RG184, and has the following characteristic parameters: no=1.498, ne=1.656, ΔnS=0.15, and ES=5.8V / μm.

[0023] A pitch adjustment method of a liquid crystal grating based on orthogonal electrodes, by loading voltage to the upper strip electrode P1 and the lower strip electrode P1 while applying a coupling direct current voltage, a spatial periodic electric field distribution is generated by the double-sided electrodes, so as to adjust the pitch of the liquid crystal grating.

[0024] By loading voltage V1=150V to the upper strip electrode P1 and the lower strip electrode P1, the field strength is the strongest in the cross electrode area and the weakest in the gap intersection, and the intensity in the single electrode coverage area is moderate. The liquid crystal molecules are arranged along the electric field, and the liquid crystal has a central symmetric gradient refractive index distribution. At this time, the grating shows a periodic refractive index change caused by a non-uniform electric field, and a small-pitch two-dimensional liquid crystal grating is generated as shown in Figure 2 When the incident light passes through the liquid crystal layer 3, diffraction will occur, and the diffraction effect diagram is as shown in Figure 3 .

[0025] By loading voltage V2=100V to the upper strip electrode P1 and the lower strip electrode P1 while applying a coupling direct current voltage V3=100V, the ions are accumulated at the electrode edges by the direct current, and the vertical electric field is greater than the parallel electric field of the electrode, so as to realize a new electric field distribution, induce the liquid crystal refractive index arrangement to change, and generate a large-pitch two-dimensional liquid crystal grating in the liquid crystal layer 3 as shown in Figure 4 When the incident light passes through the liquid crystal layer 3, diffraction will occur, and the diffraction effect diagram is as shown in Figure 5 . The response time of the liquid crystal is as shown in Figure 6 The time required for the rising process of the first-order diffraction light intensity of the liquid crystal grating is 120μs, and the time required for the falling process is 840μs.

[0026] By applying a voltage V2 = 100V to the upper strip electrode P1 and the lower strip electrode P1, the phase distribution diagram of each position in the liquid crystal layer 3 is as follows: Figure 7 As shown, the director vectors of the liquid crystal molecules in the liquid crystal layer 3 are deflected under the action of the electric field, resulting in changes in the refractive index at different positions in the liquid crystal layer 3. Since the double-sided electrode structure produces a centrally symmetrical gradient refractive index distribution, it further affects the phase distribution of the diffracted light after passing through the liquid crystal layer 3.

[0027] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and alterations made to the technical solutions of the present invention by those skilled in the art should fall within the scope of protection defined by the claims of the present invention.

[0028] Other parts of the present invention not described in detail belong to the prior art and will not be described here in detail.

[0029] Although the present invention has been described in conjunction with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can implement various changes, substitutions and modifications to the subject matter listed here without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined by the claims.

Claims

1. A method for adjusting the pitch of a liquid crystal grating based on orthogonal electrodes. The liquid crystal grating comprises an upper substrate, a lower substrate disposed opposite the upper substrate, and a liquid crystal layer located between the upper and lower substrates. A plurality of upper strip electrodes P1 and upper strip electrodes P2 are provided at intervals along the width direction on the side of the upper substrate close to the liquid crystal layer. A plurality of lower strip electrodes P1 and lower strip electrodes P2 are provided at intervals along the length direction on the side of the lower substrate close to the liquid crystal layer. It is characterized by: The pitch of the liquid crystal grating is adjusted by applying a coupling DC voltage while applying a voltage to the upper strip electrode P1 and the lower strip electrode P1.

2. The liquid crystal grating pitch adjustment method based on orthogonal electrodes according to claim 1, characterized in that: By applying voltage V1 to the upper strip electrode P1 and the lower strip electrode P1, the liquid crystal layer generates a two-dimensional liquid crystal grating with a small pitch. By applying voltage V2 to the upper strip electrode P1 and the lower strip electrode P1 and applying a coupled DC voltage V3 at the same time, the liquid crystal layer generates a two-dimensional liquid crystal grating with a large pitch.

3. The liquid crystal grating pitch adjustment method based on orthogonal electrodes according to claim 1, characterized in that: The time required for the first-order diffraction light intensity of the liquid crystal grating to rise is 120 μs, and the time required for the first-order diffraction light intensity to fall is 840 μs.

4. The liquid crystal grating pitch adjustment method based on orthogonal electrodes according to claim 1, characterized in that: The upper substrate and the lower substrate are made of glass, and the upper and lower strip electrodes P1 and P2 are made of indium tin oxide transparent conductive material.

5. The liquid crystal grating pitch adjustment method based on orthogonal electrodes according to claim 1, characterized in that: The widths G of the upper and lower strip electrodes P1 and P2 are the same, and the widths W of the gaps between adjacent strip electrodes P1 and P2 are the same and greater than G.

6. The liquid crystal grating pitch adjustment method based on orthogonal electrodes according to claim 1, characterized in that: The liquid crystal layer is a blue phase liquid crystal with a ratio of 85.59wt.% BP06, 3.5wt.% R5011, 5.32wt.% RM257, 5.32wt.% C12A, and 0.27wt.% RG184, and characteristic parameters are: no=1.498, ne=1.656, ΔnS=0.15, and ES=5.8V∕μm.

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