JPH04505374A - Fast optical protection using smectic liquid crystals - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] High-speed optical protection technology field using smectic liquid crystal The present invention relates generally to liquid crystal devices, and particularly to liquid crystal devices using smectic liquid crystals. The present invention relates to an optical limiter.

Background technology Liquid crystal materials are mainly classified into three types. These include smectic, nematic and and cholesteric liquid crystal materials.

Each such material has distinctive structural and operational properties. For example, nematic liquid Some types of crystalline materials are anisotropic and birefringent. In addition, some liquid Crystalline materials have a phase called smectic phase at one temperature and a phase called smectic phase at a different temperature. It may have the characteristics of a different phase called a nematic phase.

Additionally, there are several types of smectic liquid crystal materials. These two types are designated as smectic A and as smectic C. There is. Each type of smectic liquid crystal material has known special characteristics. vinegar A general feature of metic liquid crystal materials is that the liquid crystal materials are generally aligned parallel within the layer. This is something that there is a tendency to do. In contrast, nematic liquid crystals are generally aligned parallel to each other. However, the orientation within the layer does not tend to grow, and cholesteric and twisted nematic liquid crystals generally tend to be twisted or helically oriented. , all these things are well known. The LCD used here Orientation or liquid crystal structure depends on the alignment characteristics of the liquid crystal director. Assume that it is mentioned.

An example of the birefringent property of a nematic liquid crystal material in a conventional storage medium is the use of It controlled the scattering of light. For example, the ordinary refractive index and extraordinary refractive index of a liquid crystal are are the same and different from the refractive index of the medium, respectively, when an extraordinary optical refractive index appears. In this case, light is refracted and scattered at the interface between the liquid crystal and the medium, and when the ordinary refractive index appears, In this case, the light is transmitted without substantial refraction or scattering. Furthermore, pleochroism The dye is used together with a nematic liquid crystal material, which is sensitive to the dye. respond to the above-mentioned incident light, respond to a filter, or e.g. It is a response to absorbed light as a function of the structural properties of the material or dye.

Smectic liquid crystal materials are characterized by a structure that is generally linear or layered. ing. Smectic liquid crystal materials were not used until recently, and then is used for limited structure and some storage. The smectic phase is one In general, the corresponding nematic or cholesteric phase, which is always relevant for optical applications, is This also occurs at low temperatures. Early smectic liquid crystal materials had smectic phase properties. quality makes alignment or alignment of the liquid crystal structure more difficult than higher temperature phases. It wasn't used.

The Kerr effect, and more particularly the electro-optic Kerr effect, is an electrically induced birefringence.

The basis of Kerr effect theory is discussed in various literature. For example, are, double Wright by Dutchburn, Academic Press (London, 1976) ) and Optics and Razors by Matt Young, Sbringa --Burrage, New York, 1984). All disclosures in such books is included here for reference.

Light is commonly referred to as a form of electromagnetic radiation in a particular wavelength band or frequency range. This is a term that can be used. In this invention, light can be in the visible, ultraviolet and infrared. used to refer to electromagnetic radiation. Generally, light, electromagnetic energy or References to electromagnetic radiation refer to electromagnetic energy or shall mean electromagnetic radiation.

Self-focusing is the electromagnetic energy property of the material itself. focusing type of action on electromagnetic energy as a function of t This is a term used to indicate that a person has the ability to produce Further below As discussed below, the invention operates for self-focusing light as a function of the properties of the light. do.

Disclosure of invention Essentially, the invention prevents the transmission of incident electromagnetic radiation as a function of its properties. It's about doing. Preventing transmission includes, for example, scattering, defocusing, reflection and/or It is intended to prevent direct transmission of incident light due to absorption or absorption as described below. Taste.

Optical density or light density refers to the intensity of light per unit area.

For example, a beam of light with a certain cross-sectional area can be expanded to have the same total amount of light but a unit area. Try to grow a larger cross-sectional area so that the strength per unit area becomes smaller. Can be done.

For example, let light propagating in a specific direction P be an electric vector E and a magnetic vector B. can be expressed in terms of two quadrature components to be identified. , these vectors are perpendicular to each other and extend perpendicular to the propagation direction P. is well known. The invention, described in more detail below, is based on the electrical vector of incident light. Energy or peak power represented by Le E It is thought that it operates to perform optical restriction in response to.

In the preferred embodiment and best mode of the invention, such electromagnetic radiation is light, and more particularly radiation. It is a coherent light, and its characteristics include degree of interference, intensity, electric vector size, Incident energy, peak power, or a combination of two or more of these, and light The degree of scientific restriction is a function of the value of such properties.

The above-mentioned prevention of direct transmission of incident light is achieved by, for example, the Rayleigh limit. gh　11m1t) and/or concentrate the light on a point beyond 11m1t), In order to then achieve a relatively low light intensity in the area protected by this invention This is done by sufficiently diffusing the light.

Generally, in the present invention, a device responsive to incident electromagnetic radiation a first medium through which the incident electromagnetic radiation is transmitted; the first medium, which acts to refract the electromagnetic rays at the interface with the first medium; and liquid crystal means arranged in the. Such media include glass, plastic, etc. It can be a surface, preferably a glass plate. More preferably a pair of gas The liquid crystal material is sandwiched between the lath plates.

In one aspect of the invention, the optical limiter includes a smectic liquid crystal between the boundary media. However, the liquid crystals are generally oriented in layers that are oriented perpendicular to the medium. good Preferably, each such medium has a surface.

In another aspect of the invention, the optical limiter is oriented in layers between a pair of surfaces. Smectic liquid crystal material, input side for receiving incident light, and light passing through the limiter. and the output side to go out from the limiter, and the liquid crystal to the optical input to automatically limit light from exiting that output side in response to the input. respond.

In yet another aspect of the invention, an optical device includes means for receiving incident light; means for delivering output light as an output of the output light, and directing the incident light to the output destination delivery means. means for obtaining light output from the device; and between the light receiving means and the sending means; automatically operates to limit the amount of output light as a function of the characteristic values of such incident light. It is equipped with an optical limiter to create a

These and other objects, other aspects, features, and embodiments of the invention will be apparent from the following detailed description of the invention. More will be revealed from Akira. Some detailed embodiments of this invention are listed here. , the invention should be determined from the claims and their scope of equivalents.

In order to accomplish the above and related objects, the present invention is more fully described and described below. With the features particularly pointed out in the claims, the following description and drawings are incorporated herein by reference. Although detailed specific examples of the present invention are shown, these are examples in which the principles of the invention can be used. These are just a few of the various examples.

〉〉　Brief explanation of the drawing 〉 Figure 1 shows the operation of this invention to transmit such light without restricting it. FIG. 2 is a schematic diagram of an optical limiter of FIG. 2 is a partially enlarged view of the optical limiter in FIG. 1, Figures 3A, 3B and 3C are nematic, cholesteric or threaded 1 is a schematic diagram showing the typical alignment properties of nematic and smectic liquid crystal materials FIG. 4 is a graph showing the optical power limiting characteristics of the optical limiter of the present invention. , the orthogonal axes are the microjoules of energy to the optical limiter and the optical limiter. It is calibrated in microjoules of energy output by the transmitter, Figures 5A through 5F show the input and and output electromagnetic energy pulse pair, approximately 3.9 microjoules to approximately 132 microjoules Comparison of times for each input energy pulse within a range of joules These are comparative graphs showing the FIG. 6 is an end view of a liquid crystal optical limiter according to a specific example of the present invention; FIG. 7 is a plan view of the liquid crystal optical limiter viewed in the direction of the arrow 7-7 in FIG. In this case, the liquid crystal alignment material and the rubbing direction are omitted. FIG. 8 is a side view of the optical limiter taken in the direction of arrow 8-8 of FIG. FIG. 9 is a plan view of a liquid crystal optical limiter similar to FIG. 7, but with a liquid crystal alignment material. and a rubbing direction that is generally parallel to the direction in which the electric field is applied, Figure 1θ shows a top view of a liquid crystal optical limiter similar to Figures 7 and 9; , indicating a liquid crystal alignment material and a rubbing direction that is generally perpendicular to the direction of applying the electric field. Figure 11 is a plan view of the improved liquid crystal optical limiter similar to Figure 7. can be, FIG. 12 shows that the direction of the electric vector is the long axis or the extra axis of the liquid crystal material. This method uses incident light that is polarized so that it is parallel to the 2 is a schematic diagram illustrating the preferred maximum optical limiting operation of the liquid crystal optical limiter of the invention, Figure 13 shows the effect of the electric vector as a function of the direction of the long sleeve of the liquid crystal molecules. , is a graph showing the dependence of power limitation of the optical limiter of the present invention, FIG. 14 shows an optical device using the liquid crystal optical limiter of the present invention, such as a shooting illuminator. Schematic illustrations of instruments, binoculars, telescopes, goggles, etc. Figure 15 shows the use of alternating electrodes to apply an electric field to a liquid crystal material. 1 is a partial perspective view of the improved liquid crystal optical limiter of the present invention for use in FIG.

BEST MODE FOR CARRYING OUT THE INVENTION optical limiter 10 Reference will now be made in detail to the drawings, in which like reference numbers refer to similar numbers in some of the drawings. In FIG. 1, which is referred to first, this invention The liquid crystal optical limiter is shown as 10. The optical limiter IO connects the pair of media 14. a liquid crystal material 12 sandwiched between 16 and 16, such medium preferably 8.20 or a material from which a means of defining a surface is obtained, such as a glass plate, plus This is a tick board, etc.

Liquid crystal material 12 is a smectic liquid crystal material, optionally smectic; Or it is a material that exhibits the characteristics described here. Working smectic liquid crystal is a liquid crystal material that exhibits the properties of a smectic liquid crystal material, such as orientation. In particular, liquid Crystalline materials 12 are generally oriented parallel to each other and perpendicular to plane 18.20. Orient in layers. Additionally, the liquid crystal in each layer is typically parallel to the other liquid crystal materials in each layer. Orient to. Smectic A liquid crystal materials exhibit the above properties and other behaviors described herein. 1 is an example of a suitable type of liquid crystal material exhibiting properties.

Liquid crystal material 12 may have positive or negative dielectric anisotropy. liquid crystal The material behaves as a smectic liquid crystal material and is therefore operationally smectic. It is preferable that the material be classified according to the following criteria. Other materials can also be used, but Smectic or operation as an example that can be used in this invention Physically smectic liquid crystal materials include the following four types of materials, each of which has a Consists of formulas in fixed proportions to produce the same product. To minimize space, Use abbreviations as follows:

K-24 is the following formula, 4-cyano-4'-n-octylbiphenyl represented by

K-30 is K-36 is the following formula, It is 4-cyano-4'-n-dodecanylbiphenyl represented by

The above three materials are sold by British Drug House (BDH). It is.

2LI-1844 is sold by Merck.

Examples of operational nematic liquid crystal materials useful in this invention are shown below.

Each of such materials 1, 2.3 or 4 can be used in this invention. Ru.

Material 1 is a combination of the following components in weight percent:

K-2413, 9% -3026,9% -3629,5% 2LI-184430,0% Material 2 is a combination of the following components in weight percent:

K-2419, 2% -3038,4% -3642,4% Material 3 is a combination of the following components in weight percent:

K-2418,696 -3033,2% -3636,796 2LI-184413,496 Material 4 is a combination of the following components in weight percent:

K-2417, 1% -3034,296 -3637,6% 2Li1844 11.096 From FIG. 1, the alignment characteristics of the liquid crystal material 12 can be seen. In particular, liquid crystal, i.e. liquid crystal structure are oriented in a plurality of layers 22a, 22b, etc.

The layers 22a, 22b, etc. are oriented parallel to each other and are oriented relative to the plane 18.20. It extends vertically. Furthermore, the structure or orientation of liquid crystals in any layer is parallel. For example, the orientation vectors of liquid crystals in any layer are generally parallel to each other and perpendicular to the direction. The orientation of the liquid crystal, that is, the orientation of its orientation vector is the plane 18.2 parallel to 0.

It is known that smectic liquid crystal materials generally tend to be oriented in layers. , to promote the orientation of layers 22a, 22b in a direction perpendicular to plane 18.20. Preferably, such a surface is provided with a liquid crystal alignment layer. Such an alignment layer may be For example, it is conventional in twisted nematic liquid crystal cells. -Example for surface 18.20 A polyvinyl alcohol layer 24.26 provided on each layer 24.2. Each of 6 is a straight line using conventional woven fabric, cushioning material, etc., such as cotton, polyaramid fiber, etc. being rubbed in the direction. Other alignment layer materials that are rubbed in a linear direction as described above You can also use Liquid crystal materials tend to align generally parallel to the rubbing direction There is.

In the liquid crystal cell of the optical limiter lO, the plate 14.16 is the alignment layer 24.26 Assemble so that the linear directions of each rubbing are parallel to each other. as shown In addition, the preferred orientation state of the liquid crystal material in the optical limiter is determined by the appearance of the bookshelf, i.e. multiple parallel bookshelves (liquid crystal layers) each with multiple books (e.g. showing liquid crystal molecules); 22a, 22b, etc.).

The plates 14,16 can be of any shape. For example, if such a board is It can be made into a square. Preferably the plates 14.16 are flat or planar. or at least have a flat or planar surface. Furthermore, regarding uniformity , the thickness of the plate is preferably uniform to avoid light distortion unintentionally. board or its surface may be other than flat, for example curved, and/or intentionally Can be made with non-uniform thickness to help focus or perform other functions. Ru. Furthermore, the plates 14,16 can be of the same material, but they are of different materials. For example, these can be refracted differently to achieve the type of behavior described above. It may have a percentage.

Further, as described below, the liquid crystal cell forming the optical limiter 1o in FIG. Applying an electric field to the liquid crystal material causes the liquid crystal material to be oriented in a preferred direction parallel to plane 18.20. Electrodes 30.32 may be provided for orientation. Electrodes are used for liquid crystal displays, etc. Conventional electrode materials used, such as indium tin oxide (sometimes referred to as ITO), Each layer can be Between the electrodes 3°32, for example, a conventional circuit and/or a power source (not shown, applying voltage using leads connected to This causes an electric field to be applied through the liquid crystal material 12 in a direction generally parallel to the plane 18.20. is applied. When the liquid crystal material 12 has positive dielectric anisotropy, the liquid crystal material 12 The liquid crystal material tends to align parallel to the applied electric field, and the liquid crystal material has a negative dielectric anisotropy. If the liquid crystal material is oriented, it is generally oriented perpendicular to the direction of the electric field. In either case, the orientation of the liquid crystal material is explained here and The orientation is as shown in the bookshelf.

sealing the liquid crystal material in the internal volume 38 of the liquid crystal cell forming an optical limiter; In order to applied to the area. Additionally, in areas where there are no electrodes between plates 14.16, conventional Place a glue or spacer material, e.g. glass spacer, and seal in place with epoxy. Can be sealed. Materials other than epoxy may be used for such sealing. Wear.

f Operation of optical limiter 10 As seen in FIG. 1, incident light 42, for example incident light from a laser (laser light) hits the input side 44 of the optical limiter 100. Such incident light 42 is light relatively lower than the limit level required for optical limiting operation of optical limiter 10. (small) Develop the magnitude of the electric vector, energy or peak power. child Therefore, such light is transmitted to the output side 46 of the optical limiter 1o and is substantially The light output 48 is obtained without any attenuation or limitation. preferably If the incident light 42 has video characteristics, the characteristics will be the same as the output light 48. , so that the optical limiter 1o is essentially transparent or almost It is clear that it is almost transparent.

However, in FIG. 2, incident light 42' impinges on optical limiter 10. In FIG. It takes The incident light 42' is at a critical level required for optical limiting operation of the optical limiter 1o. A relatively large electric vector, a large amount of energy or peak power, higher than Cultivate your sense of well-being. Therefore, the optical limiter 1o limits the power of the optical output 48'. It works like that. In order to effect such a limitation on the power of the optical output 48', the following It is thought that something like this will happen.

Liquid crystal material 12 self-focuses in response to incident light and forms a fiber optic member. 　optic　member) propagates light a little bit. become. In FIG. 2, a wavefront 50 of light passing through liquid crystal material 12 is shown. inside this wave front The refractive index of the liquid crystal material 12 in the vicinity of the core 52 is determined before such light impinges on it. It is clear that the refractive index is slightly higher. For example, whether it is indicated by 54 or liquid crystal toward the further perimeter or outer boundary of the wavefront The refractive index of the material is slightly higher than the refractive index exhibited before such light impinges on it. However, it is also clear that the amount of such increase is smaller than that occurring near the center 52. be. Is the refractive index of liquid crystal material 12 across wavefront 50 likely non-linear? It seems to be very continuous. Such variations in the refractive index of the liquid crystal material are explained above. Arouse self-concentration.

The wavefront 50 is transmitted through the liquid crystal material 12 as a plane wavefront depending on the degree of interference of the incident light 42'. After the wavefront has traveled some distance through the liquid crystal material, It is thought that there is a tendency to curve as shown in the figure. Such curvature is caused by bending, as described above. This is thought to be due to fluctuations in the refractive index.

Furthermore, self-focus tends to increase or continue until the Rayleigh limit is reached. In this case, continuous propagation of light through the liquid crystal material is shown at 56 in FIG. As shown, this occurs in a manner similar to propagation through fiber optics. subordinate As is well known in the field of light propagation through fiber optics, According to principles such as total internal reflection, such light is transmitted to an effective fiber optic section, as shown at 58. It is interrupted between the side boundaries of the material 56.

Such light 58 is propagated in the direction of plane 20 where active fiber optic member 56 ends. (In this description, alignment layer 24.26 is the same as surface 18.20. It is understood that ) When the light 58 passes through the effective fiber optic member 56, such Some of the light tends to be refracted at the interface with surface 20 so that the light enters plate 16; There is a tendency for some of the light to be totally internally reflected at the interface with such an interface 20; Some of the light tends to pass through without being refracted; For example, entering the plate 16 forming material via the surface can include effective fiber optic member 56 and surface 2. It depends on the angle at which light enters the interface with zero. Furthermore, some of the light entering the plate 16 is The relationship between the medium 62 existing beyond the output surface 60, such as air, and the output surface 60 of the plate 20 Total internal reflection, refraction or transmission may occur at the interface. The possibility of the progression of light mentioned above, This is indicated by an arrow in FIG. 2 for clarity.

Furthermore, regarding the light reflected by any of the surfaces 20.60 and returning into the liquid crystal material I2, and for any light that may escape through the sidewalls of the active fiber optic material 56. continues to progress through the liquid crystal material 12 and separates the optical limiter present in the liquid crystal cell. reflection and/or total internal reflection at the interface of the The total power, density, etc. of the transmitted light 48' is reduced. Also, some of the light , may be reflected or backscattered toward the source of the incident light 42'.

If the liquid crystal material 12 is not oriented as described above, electrodes 30.32 may be used to Applying an electric field to the liquid crystal material. Such an electric field reconfigures the bookshelf orientation shown and described above. to be accomplished.

Possibility of liquid crystal orientation 3A, 3B and 3C illustrate the typical alignment characteristics of liquid crystal materials. do. In Figure 3A, nematic liquid crystal materials are typically oriented parallel to each other, but e.g. For example, it is clear that this is not the type of in-place alignment exhibited by smectic liquid crystal materials. I know. In Figure 3B, cholesteric liquid crystal material and twisted nematic liquid Figure 2 illustrates the helical or twisted orientation assumed by the crystalline material. Furthermore, in Figure 3C , the orientation of the smectic liquid crystal material, i.e. the liquid crystal structure is parallel and in-position. Therefore, the liquid crystal molecules are organized in each layer (e.g., as described above with respect to Figure 1). (such as layer 22a, layer 22b, etc.) shown in FIG.

A smectic liquid crystal material having a bookshelf type orientation as shown and described above is described herein. It is believed that this is necessary for the operation of this invention. However, similar or different Other types of liquid crystal materials that are oriented in a similar manner operate similarly to the light described here. It is possible to obtain a chemically limiting effect, and this invention also addresses the possibility of such an equivalent. It is inclusive.

Referring briefly to FIG. 4, this shows the above liquid crystal cell optical limiter 10. A graph showing m test data is shown. Along the horizontal axis (bottom, i.e. rXJ axis) , the energy in microjoules for the input, i.e. the incident light 42.42' or the value of power is shown and also along the vertical axis (horizontal or "y" axis) , the energy or power in microjoules for the output light 48.48' - value is shown. The power of the output light is approximately 5 or 6 microjoules when the input light is It can be seen that it is a linear function of the input optical power until it reaches the power level of the input light. .

Above that power level, the optical limiter lO will reduce the input power level to about 2 Reduce the output power level to approximately 2.5 to 4 microjoules while increasing to 7 microjoules. There is a tendency to limit even the amount of juice.

Figures 5A to 5F show the liquid crystal cell optical limiter for various power inputs. 1 shows a graph for comparing the optical responses of 10. Graphs in Figures 5A to 5F has the same scale along the horizontal axis, i.e. from zero to 16 nanoseconds, and the incident light 42.42' indicates the duration of the pulse. Graphs in Figures 5A to 5F The scale along the vertical axis for each is also the same, i.e. from zero to one. However, such a scale is standardized and the specific Data is shown normalized from zero to the maximum input power. Therefore, the In graph 70 of Figure 5A, the peak of input light curve 70' is 3.9 microvolts. In graph 78 of FIG. 5E, the peak of input light curve 78' is 27 microjoules, etc., these will become clear when considering such diagrams. .

Referring to graphs 70-80, the 3,9 microjug shown by curve 70' For a relatively low input power of the tool, the output power is also shown as curve 70. It can be seen that the amount is approximately 3.9 microjoules. indicated by curve 72' For a relatively low but slightly larger input power of 6 or 7 microjoules, 7 The output power is also limited to only about 5.6 microjoules, as indicated by 2#. It will be limited. An even larger amount of 16 microjoules is shown by curve 74'. For the input power, the output power is also about half as shown at 74″, i.e. It will be limited to about 8.3 microjoules, and this limit is about 6 nanoseconds. occurs in a relatively short period of time.

As seen in Figures 5D and 5E, the optical power limit is the power of the incident light. with an increase in incident power of 22 and 27 microjoules, respectively. , the output powers are 8.2 and 7.5 microjoules, respectively.

From the graphs in Figures 5D and 5E, it can be seen that as the incident light power increases, The power of the output light becomes smaller, and the maximum limit of the output light power becomes faster, e.g. It can be seen that these times are about 4 nanoseconds and about 3 nanoseconds, respectively.

Furthermore, as seen in Figure 5F, the power of the incident light is 132 microjoules. In this case, the output optical power is limited to 3.4 microjoules, and such a limit is approximately It happens in 1-2 nanoseconds.

If a large power input causes some concentrated heating of the liquid crystal material, the above operation Scientific limitations still tend to occur due to the speed at which they occur. Such heating is caused by liquid crystal bookshelves. Since the orientation can be changed, if you want to leave the bookshelf orientation on the liquid crystal, use the electric current as described above. Application of a field can be used.

6 to 9, m liquid crystals using the optical limiter 10 of the present invention are shown. Cell 80 is shown. Such a cell 80 includes glass plates 81.82 and glass spacers 83. 84, electrodes 85, 86, and a liquid crystal material 87 in an internal volume 88. . Seal the edges of the cell using epoxy sealant as described above and seal the liquid crystal. Preferably, no material is lost from the interior volume 88. The liquid crystal cell is approximately 0 ．． 01 mm to about 2 mm, preferably 0.1 to 0.8 mm -, more preferably a thickness of 0.1 to 0.5 mm, i.e. the glass plate 81 ．． The dimensions can be between .82 and .82. The preferred thickness is about 0.5 mm. Ru. Various planar dimensions, e.g. cell 8° length and width, extend substantially through the cell. Except that it is desired to maintain a uniform thickness, it is possible to vary, especially the absolute It's not a thing. Additionally, the desired behavior, the type of materials used, and the amount of light you are trying to limit Depending on the properties, etc., the dimensions can be varied as described here. Is the diagram clear? Although the alignment layer is not shown in FIGS. 6 to 8 for simplicity, it is preferable to Preferably, such an alignment layer is included in the liquid crystal cell 8o as described in FIG. . For such an example alignment layer 90, use of a liquid crystal material that develops positive dielectric anisotropy. It is shown in Figure 9. In particular, such an orientation accommodated on the inner surface of each of the glass plates 81,82 Layer 9o has a rubbing direction extending from one electrode towards the other. child Therefore, for example, when an electric field is applied between the electrodes 3o and 32, it has positive dielectric anisotropy. When the liquid crystal material 12 is used, the liquid crystal is moved in the rubbing direction of the alignment layer 90 by the electric field. Orient.

An example of using a liquid crystal material with negative dielectric anisotropy: the alignment layer 92 is placed in the 1081st layer. show. In particular, such orientation 89 is housed on the inner surface of each of the glass plates 81,82. 2 is the rubbing direction perpendicular to the line drawn from one electrode to the other. has.

For this reason, for example, when an electric field is applied between the electrodes 30 and 320, negative dielectric anisotropy occurs. When using a liquid crystal material 12 with Orient in the opposite direction.

FIG. 11 is a top view of an improved liquid crystal cell optical limiter 94. optical The shape of the mitter 94 is not square as is clear from the figure (rather, it is circular). The optical limiter 80 is similar to the optical limiter 80 described above except for this point. Parts shown in Figures 6 to 8 Similar parts are designated by reference numbers similar to those given above.

Therefore, the limiter 94 includes the glass plate 81' and the glass spacer 83', for example. For example, it includes electrodes 85', 86', liquid crystal material in the internal volume, etc.

In FIG. 12, a preferred embodiment of the optical limiter system is shown at 100. system In the system 100, the linear polarizer 102 polarizes the incident light 42', so that the electric beam vector E and magnetic vector B are perpendicular to the direction of propagation P, and the electric vector The direction of the vector is determined by the long sleeve or the different direction of the liquid crystal molecules 12 in the liquid crystal optical limiter lO. parallel to the normal axis. Attenuation of output optical power in response to input optical power or the amount of restriction is confirmed to be a function of the direction of the non-electrical vector E. Ta. In fact, the limit on the maximum power is that the electric vector E is the long-sleeved or abnormal axis of the liquid crystal molecules. Also, a smaller amount of restriction is achieved when the electric vector is parallel to This occurs when the axis has some angle other than parallel to such axis.

FIG. 13 shows the incident (input) light 42 in the direction of the long axis of the liquid crystal material 12. Power control for optical limiter 10 as a function of the direction of electric vector E Show the graph of the limit. The horizontal axis is microjoules for incident light 42.42' The power is expressed in microjoules of output light 48.48' on the vertical axis.

Various data points in the graph of FIG. 13, e.g. rXJ, "+", " *” and “square J” are electric currents parallel to the long axis of liquid crystal molecules. Electric vector angles, normal, 45 degrees, and 67 degrees to such long sleeves. The angle of torque is shown respectively.

An optical system 110 of the present invention is shown in FIG. In the system 110, one or more lenses and/or other optics that provide light to the optical limiter There is a target element 112. It also receives light from the optical limiter and from the system. There are also additional lenses and/or other optical elements 114 that obtain output light 116. . Elements 112 and 114 can be used, for example, for telescopes, camera lens systems, shooting sights, goggles, etc. It can be a part of a lens, binoculars, etc. Optical as part of system 110 The limiter limits the power of the output light 116 as described above, e.g. Optical element receiving 116! 14 to prevent damage to the downstream side.

FIG. 15 shows an improved arrangement of interlaced electrodes 130, 132. The optical limiter 128 shown in FIG. Such an electrode arrangement is, for example, electrode 30 in FIG. ．． Can be used in addition to or in place of 32. combined alternately When a voltage is applied to the electrodes 130, 132, an electric field is applied parallel to the plane 18. Thus, the desired liquid crystal alignment described above tends to be achieved. Also, they are combined alternately. A similar arrangement of electrodes can be used on the bottom plate in FIG. 15, but is preferred. In most cases, only one set of electrodes is used, i.e. the set on the top plate or the set on the bottom plate. energize the set at once so that the electric field is parallel to the planes but not between them. It is necessary to ensure that the voltage is applied as high as possible.

Industrial applicability As described above, the optical limiter of this invention is used to limit the power of optical output. This can be used to prevent downstream equipment from being damaged, e.g. by excessive power. You can prevent this from happening.

FIG, 3A FIG, 38 FIG, 3CFIG, 58 FIG, 5C FIG, 5F ：rs5 頗手Attle1; Kansu J I! Narrow bias FIG. 12 "Tsu Copy and translation of written amendment) Submission (Article 184-8 of the Patent Law) November 25, 1991

Claims (47)

[Claims] 1. A smectic liquid crystal is provided between a pair of boundary surfaces, and the liquid crystal is Optical limiter characterized by orientation in generally vertically oriented layers. 2. The optical limiter according to claim 1, wherein the liquid crystal is made of smectic A liquid crystal. tta. 3. The light according to claim 1, wherein said liquid crystal consists essentially of smectic A liquid crystal. scientific limiter. 4. The optical limiter according to claim 1, wherein a plurality of said layers are oriented parallel to each other. Ta. 5. The liquid crystals in a layer are oriented generally perpendicular to the direction of the layer in which they are located. An optical limiter according to claim 1. 6. 2. The optical system of claim 1, wherein the liquid crystal is oriented generally parallel to said plane. limiter. 7. The optical limiter according to claim 1, wherein at least one of the surfaces ζ is flat. Ta. 8. 8. An optical limiter according to claim 7, wherein two of said surfaces are flat. 9. 9. The optical system of claim 8, wherein said two of said surfaces are generally parallel to each other. limiter. 10. an alignment means for aligning the liquid crystal generally parallel to the pair of boundary surfaces; The optical limiter according to claim 1, further comprising: an optical limiter according to claim 1; 11. The above-mentioned alignment means separates the liquid crystal on each surface from other liquid crystals on each surface. and the liquid crystal on one side is aligned parallel to the liquid crystal on the other side. 11. The optical limiter according to claim 10, further comprising means for directing the optical limiter. 12. The optical system according to claim 1, wherein the liquid crystal is oriented between the planes in a bookshelf-like orientation. target limiter. 13. The liquid crystal above responds to a specified level of incident electromagnetic energy and absorbs such electromagnetic energy. 2. An optical limiter according to claim 1, which causes self-concentration of energy. 14. 14. The optical system of claim 13, wherein the liquid crystal is responsive to incident coherent light. target limiter. 15. The liquid crystal responds to the electric vector of the electromagnetic energy and generates an electric vector of the electromagnetic energy. The optical system according to claim 13, which performs the self-focusing when the amount of light exceeds a specified value. limiter. 16. The above liquid crystal is the specified energy or peak power of the above incident electromagnetic energy. 16. The optical link of claim 15 operative to respond to at least one of: Mitta. 17. The liquid crystal has a refractive index as a function of the properties of electromagnetic energy incident on the liquid crystal. 2. An optical limiter according to claim 1, which operates to change characteristics. 18. The above liquid crystal self-concentrates the above electromagnetic energy, and the incident electromagnetic energy The optical limiting according to claim 17 is achieved to a certain extent as a function of the characteristics of Ta. 19. The above-mentioned liquid crystal responds to the electric vector of the above-mentioned incident electromagnetic energy, and Claim 18 states that the self-concentration is performed when the energy vector exceeds a predetermined value. optical limiter. 20. The above liquid crystal is the specified energy or peak power of the above incident electromagnetic energy. 19. The optical limiter of claim 18 operative to respond to at least one of tta. 21. In response to electromagnetic energy with characteristics below the specified value, the limiter effectively and the limiter automatically becomes transparent in response to an increase in the value of such a characteristic. The optical limiter according to claim 1, which reduces the transmission characteristics of the optical limiter. 22. The reduction in transmission properties is caused by the increased reflection of electromagnetic energy. The optical limiter according to claim 21. 23. Claim 22, wherein said reflection includes a substantial amount of total internal reflection. optical limiter. 24. The optical limiter according to claim 22, wherein the electromagnetic energy is light. . 25. The above-mentioned liquid crystal can be Claim No. 3, wherein said substantially transparent property is automatically restored upon removal of the magnetic energy. The optical limiter according to item 21. 26. Claim 25, wherein said amount is a quantitative amount on the order of about 20:1. optical limiter. 27. In response to incident coherent light, a liquid crystal transmits a wave of light that is transmitted through the liquid crystal. Tends to self-focus light by varying the index of refraction by different amounts across a surface An optical limiter according to claim 1. 28. When the characteristics of the incident light exceed a specified value, the liquid crystal In order to cause light scattering in the opposite direction, the self-concentration is performed to a certain extent. 28. The optical limiter according to claim 27. 29. Claim 28 wherein said scattering occurs by reflection of light on said one of said surfaces. Optical limiter as described. 30. The optical limiter according to claim 29, wherein the reflection is total internal reflection. . 31. Increases the energy and power of at least one of the incident electromagnetic energy As a result, the liquid crystal limits the transmission of electromagnetic energy through the liquid crystal. The optical limiter according to claim 1, which operates to shorten the time required for tta. 32. The limited amount of transmission of electromagnetic energy through the limiter is the amount of incident electromagnetic energy non-linear increase in the energy and power of at least one of - An optical limiter according to claim 1. 33. 33. The light of claim 32, wherein the liquid crystal responds to incident coherent light. scientific limiter. 34. The incident coherent light is in the form of a pulse, and the pulse exceeds a specified value. , the value of the optical output from the limiter will decrease as the input pulse increases. Optical limiter according to claim 33. 35. The optical limiter according to claim 1, wherein the liquid crystal has positive dielectric anisotropy. Ta. 36. The optical limiter according to claim 1, wherein the liquid crystal has negative dielectric anisotropy. Ta. 37. A method for applying an electric field to liquid crystal and aligning the liquid crystal structure in response to the applied electric field. The optical limiter of claim 1 further comprising a stage. 38. Orientation for aligning the liquid crystal generally parallel to the pair of interfaces. 38. The optical limiter of claim 37 further comprising means. 39. said means for applying an electric field applies an electric field generally parallel to said plane; the liquid crystal has positive dielectric anisotropy, and the alignment means comprises means for orienting such liquid crystal generally in the direction of an applied electric field. An optical limiter according to claim 38. 40. said means for applying an electric field applies an electric field generally parallel to said plane; the liquid crystal has negative dielectric anisotropy, and the alignment means A method for aligning such liquid crystals in a direction generally perpendicular to the direction of an applied electric field. 39. An optical limiter as claimed in claim 38, comprising a step. 41. The above liquid crystal responds to the incident light, and the above liquid crystal responds to the incident light, and the above liquid crystal responds to the ordinary axis and the extraordinary axis. an operation that has a refractive index and an extraordinary refractive index and limits transmission of light output from the limiter However, the incident light is linearly polarized and the electric vector of the incident light is parallel to the anomalous axis of the liquid crystal. 2. The optical limiter according to claim 1, wherein the optical limiter is larger than when . 42. Make sure that the distance between the above surfaces is about 0.0 l mm to about 2 mm. Optical limiter according to item 1. 43. Claim 42, wherein said distance is about 0.1 to 0.8 millimeters. optical limiter. 44. Claim 43, wherein said distance is about 0.1 to 0.5 millimeters. optical limiter. 45. A smectic liquid crystal material in which an optical limiter is oriented in layers between a pair of surfaces. , the input side for receiving the incident light and the light passing through the limiter and exiting from the limiter. and an output side for the above-mentioned liquid crystal to respond to a light input exceeding the specified value. Optical limiter that automatically limits light emitted from the output side . 46. means for receiving incident light, means for sending out output light as an output of the device, and means for receiving incident light; means for directing light to said output light delivery means to obtain light output from said device; between the light recording/receiving means and the sending means, as a function of the characteristic value of the incident light. and an optical limiter that operates to automatically limit the amount of output light. An optical device characterized by: 47. The optical limiter has a smectic liquid crystal between a pair of interfaces, Claim 46, wherein said liquid crystal is oriented in a layer generally oriented perpendicular to said plane. Optical device as described in section.