Beam splitter

Abstract

In the present specification, a beam splitter and a use thereof are disclosed. The beam splitter can split a beam from a light source into a plurality of beams having a desired shape and intensity, and the beam splitter can be implemented with a simple configuration and process. For example, the beam splitter can be applied to configuration of various sensing devices, facial recognition devices and the like for 3D mapping.

Description

beam splitter

[0001] This application claims the benefit of priority to Republic of Korea Patent Application No. 10-2023-0141223, dated October 20, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present specification discloses a beam splitter and its use.

[0003] A beam splitter is an optical component that can generate two or more lights from one incident light.

[0004] Known traditional beam splitters include the so-called cube beam splitter, which is constructed using two right angle prisms, and the plate beam splitter, which is constructed using a thin and flat glass plate with a coating layer on its surface.

[0005] These beam splitters are used for a variety of applications.

[0006] For example, a beam splitter is necessary for the construction of an interferometer, which is an important component in various optical experiments and optical measurement equipment, and is also an important component in fields such as fiber optic telecommunication.

[0007] A beam splitter can also be applied to constructing a dot projector, which is required when constructing a sensing device such as a facial recognition device. For example, Patent Document 1 discloses an optical projection device for 3D mapping. Patent Document 1 uses a Diffractive Optical Element (DOE) to generate an optical replica for the 3D mapping.

[0008] <Prior Art Literature>

[0009] Patent Document

[0010] (Patent Document 1) Republic of Korea Publication No. 10-2016-0019113

[0011] The present specification discloses a beam splitter and its use. The beam splitter can split a beam from a light source into multiple beams having a desired shape and intensity, and the beam splitter can be implemented with a simple configuration and process. The beam splitter can be applied to various sensing devices for 3D mapping or facial recognition devices, for example.

[0012] The present specification discloses a beam splitter.

[0013] The term beam splitter refers to an optical device capable of splitting one incident beam into two or more beams.

[0014] The above beam splitter can split incident light of wavelength λ to generate two or more split lights. In the above, wavelength λ is the wavelength of light to be split, and this can be determined according to the purpose.

[0015] Unless otherwise specifically provided in this specification, an incident beam or incident light means a beam incident on the beam splitter, and a split beam or split light means a beam split by the beam splitter.

[0016] Fig. 1 shows an exemplary beam splitter (1000). The beam splitter (1000) of Fig. 1 splits an incident beam (B i ) with at least three split beams (B o1 , B o2 , B o3 ) is divided into

[0017] For example, the lower limit of the number of split beams generated from one incident beam by the beam splitter may be about 2, 3, 4, 5, 6, 7, 8, or 9, and the upper limit may be about 100, 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 14, 13, 12, 11, 10, or 9. The number of split beams is within a range that is greater than or equal to any lower limit arbitrarily selected from the lower limits listed above; Or, it may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above, and equal to or less than any upper limit arbitrarily selected from the upper limits listed above.

[0018] The beam splitter may include at least one geometric phase alignment layer. The geometric phase alignment layer is known as a device that records a wavefront of light on a recording medium using a holographic polarization interference pattern, and is a flat optical device that can be manufactured thinner than existing devices that utilize dynamic phase differences. The geometric phase alignment layer is also called a so-called PBP (pancharatnam berry phase) optical device.

[0019] The above geometric phase alignment layer may be a liquid crystal layer.

[0020] For example, the geometric phase alignment layer may include an aligned liquid crystal compound.

[0021] The geometric phase alignment layer may be a liquid crystal layer including an aligned liquid crystal compound. The alignment of the liquid crystal compound may be the geometric phase alignment. For example, the lower limit of the content of the aligned liquid crystal compound included in the liquid crystal layer may be about 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, or 95 wt% based on the total weight of the liquid crystal layer, and the upper limit may be about 100 wt%, 98 wt%, 96 wt%, 94 wt%, 92 wt%, or 90 wt% based on the total weight of the liquid crystal layer. The content is within a range that is equal to or greater than any one lower limit arbitrarily selected from the lower limits listed above; Or, it may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above, and equal to or less than any upper limit arbitrarily selected from the upper limits listed above.

[0022] The above liquid crystal layer may be an active liquid crystal layer or a passive liquid crystal layer. The term active liquid crystal layer refers to a liquid crystal layer in which the orientation of the liquid crystal compound within the liquid crystal layer is not fixed and can be switched by an external action (e.g., application of an external electric field), and the term passive liquid crystal layer refers to a liquid crystal layer in which the orientation of the liquid crystal compound is fixed and does not change by an external action. For example, the passive liquid crystal layer can be formed when the orientation of the so-called RM (Reactive Mesogen) is fixed by polymerization or the like after the orientation is fixed.

[0023] The liquid crystal compound of the above liquid crystal layer can be geometrically aligned to form the geometric phase alignment layer.

[0024] Within the liquid crystal layer, the liquid crystal compound may be in a so-called geometric phase alignment state. Geometric phase alignment refers to an alignment in which the liquid crystal layer (geometric phase alignment layer) functions as a so-called geometric phase lens or geometric phase grating due to the alignment of the liquid crystal compound.

[0025] The alignment configuration of the liquid crystal compound that enables the liquid crystal layer to function as the geometric phase lens or geometric phase grating is known.

[0026] If the alignment of the liquid crystal compound is an alignment capable of functioning as the geometric phase lens, the alignment may be referred to as a geometric phase lens alignment, and the geometric phase alignment layer may be referred to as a geometric phase lens alignment layer. If the alignment of the liquid crystal compound is an alignment capable of functioning as the geometric phase grating, the alignment may be referred to as a geometric phase grating alignment, and the geometric phase alignment layer may be referred to as a geometric phase grating alignment layer.

[0027] Geometric phase orientation can be generally defined as an orientation having spatially varying azimuth angles. For example, when the orientation is the orientation of a liquid crystal compound, the azimuth angle is formed by the direction of the in-plane optical axis of the liquid crystal compound.

[0028] FIG. 2 is a schematic diagram showing an exemplary geometric phase grating orientation (310), and FIG. 3 is a schematic diagram showing an exemplary geometric phase lens orientation (210).

[0029] The liquid crystal layer illustrated in Fig. 2 generates a corresponding grating profile through the in-plane orientation of the liquid crystal compound. The in-plane orientation of the liquid crystal compound can be defined by an azimuth angle (θ), which generates an optical phase difference T, which can be defined as 2θ by the azimuth angle.

[0030] Fig. 2 is a drawing showing an example of the alignment (310) of a liquid crystal compound in the geometric phase grating alignment. In Fig. 2, the X-axis and the Y-axis are virtual axes arbitrarily set at the center point (320) of the alignment. The alignment of the liquid crystal compound in the alignment can be defined by an azimuth angle (θ) that continuously changes along any specific direction (the Y-axis direction in the case of Fig. 2). In the alignment of Fig. 2, the pitch (P) is substantially fixed.

[0031] In this specification, the term pitch or pitch distance of geometric phase alignment is a distance determined by the rotation of a liquid crystal compound that rotates to have an azimuth that changes along an arbitrary direction in the plane, and is the distance between a point (point A) where one liquid crystal compound in an arbitrary direction in the plane exists and a point (point B) where a liquid crystal compound exists that has the same azimuth as the liquid crystal compound at point A when the liquid crystal compound rotates along an arbitrary direction in the plane (i.e., the distance between points A and B).

[0032] For example, the distance between points A and B in Fig. 4 may be the pitch or pitch distance. In this case, since points A and B have the same orientation direction of the liquid crystal compound, the pitch can be confirmed by measuring the distance between points A and B in a direction perpendicular to the same orientation direction.

[0033] This pitch or pitch distance can also be determined by the following formula: Equation 1.

[0034] [Formula 1]

[0035] P = 180×D / Ag

[0036] In Equation 1, P is the pitch or pitch distance, D is the distance between any two points within the direction in which the azimuth angle of the liquid crystal compound changes on the plane of the geometric phase alignment layer, and Ag is the smaller angle among the angles formed by the alignment directions of the liquid crystal compound present at the any two points. The D may be the distance between any two points included within one pitch.

[0037] For example, referring to FIG. 4, the pitch or pitch distance may be the distance between points A and B, but may also be obtained by substituting the smaller angle between the alignment direction of the liquid crystal compound at point A and the alignment direction of the liquid crystal compound at point B' into Equation 4 as Ag, with the distance between points A and B' being D.

[0038] In Equation 1, the units of D and P are not particularly limited as long as the same units are applied. In addition, the unit of Ag in Equation 1 is degree.

[0039] In this specification, when it is simply referred to as a pitch or pitch distance, it means that the change in azimuth occurs in one rotational direction, which may be called a normal pitch or normal pitch distance. Fig. 4 is an example of such a normal pitch. In Fig. 4, the rotation from the liquid crystal compound (LC1) at the starting point of one pitch to the liquid crystal compound (LC2) at the ending point of the pitch occurs clockwise along the direction of the azimuth change (the direction of the dotted arrow in Fig. 4).

[0040] When referred to herein as a two-way pitch or a two-way pitch distance, it means a pattern in which the rotational direction of the change in azimuth changes at least once along the direction of the change in azimuth. Such a pattern is exemplified in FIGS. 5 and 6.

[0041] In the pattern of Fig. 5, the rotation from the liquid crystal compound (LC1) at the starting point of one pitch to the liquid crystal compound (LC2) at the midpoint of the pitch is performed in a clockwise direction along the direction of azimuth change (the direction of the dotted arrow at the top of Fig. 5), and the rotation from the liquid crystal compound (LC2) at the midpoint to the liquid crystal compound (LC3) at the end point of the pitch is performed in a counterclockwise direction.

[0042] In the pattern of Fig. 6, as another example of the pattern of the two-way pitch, the rotation from the liquid crystal compound (LC1) at the starting point of one pitch to the liquid crystal compound (LC2) at the ending point of the pitch is performed in a clockwise direction along the direction of azimuth change (the direction of the dotted arrow at the top of Fig. 6), and the rotation from the liquid crystal compound (LC2) to the liquid crystal compound (LC3) at the ending point of the other pitch is performed in a counterclockwise direction.

[0043] In the present specification, a case where a change in the direction of rotation occurs within one pitch, as in FIG. 5, may be referred to as a 90-degree bidirectional pitch, and in the present specification, a case where a change in the direction of rotation occurs between one pitch and another pitch, as in FIG. 6, may be referred to as a 180-degree bidirectional pitch.

[0044] In this specification, the direction of azimuth change is any direction in which the pitch is completed by the azimuth change of the liquid crystal compound.

[0045] In the present specification, when defining the normal pitch or the bidirectional pitch, the rotation direction is the direction that completes the smaller angle (90 degrees when the angle formed by the adjacent liquid crystal compounds is 90 degrees) among the angles formed by adjacent liquid crystal compounds, and is the direction along the azimuth change direction. In this case, the direction along the azimuth change direction is the direction that completes the small angle (or 90 degrees) from the liquid crystal compound that exists first to the liquid crystal compound that exists next along the azimuth change direction. For example, in Fig. 7, when the azimuth change direction is defined as the direction of the dotted one-way arrow, and liquid crystal compounds LC1 and LC2 change as illustrated above the dotted one-way arrow, the rotation direction between the liquid crystal compounds LC1 and LC2 is clockwise. The rotation direction varies depending on how the azimuth change direction is specified. For example, in the example of Fig. 7, if the azimuth change direction is defined as the direction from the left to the right in the drawing, the rotation direction becomes clockwise, but if it is defined as the direction from the right to the left, the rotation direction becomes counterclockwise. Therefore, in distinguishing the pattern of the normal pitch and the two-way pitch, the direction of the azimuth change is arbitrarily designated, but when all rotation directions are confirmed, one direction is designated as the direction of the azimuth change.

[0046] FIG. 8 is a schematic diagram of the orientation of a liquid crystal compound (LC) rotating along an arbitrary direction in the plane (the direction of an arrow in FIG. 8, which in the case of FIG. 2 is along the Y-axis direction), wherein the pitches (or pitch distances) are indicated by P1, P2, and P3. In a geometric phase grating orientation, the rate of change of the pitches is typically substantially fixed. For example, in FIG. 8, the pitches P1, P2, and P3 are substantially equal to each other. In a geometric phase grating orientation, the orientation of the liquid crystal compound may be an orientation having an azimuth that changes along at least one direction among the plane directions of the liquid crystal layer, and typically, the pitch due to the changing azimuth is substantially fixed constantly.

[0047] In the exemplary geometric phase grating orientation of Fig. 2, the azimuth angle of the liquid crystal compound is maintained constant along a plane direction (X-axis direction of Fig. 2) perpendicular to one direction in which the azimuth angle changes (Y-axis direction of Fig. 2), but the form of the geometric phase grating orientation is not limited thereto.

[0048] In this specification, the fact that the pitch of the change in azimuth is fixed and the azimuth is maintained constant means that there is substantially no change in the pitch and azimuth, and in this case, the fact that there is substantially no change may mean that even if there is a certain amount of minute change in the pitch and azimuth, the liquid crystal layer or optical film can effectively perform the function of the geometric phase grating as a whole.

[0049] In the geometric phase grating orientation described above, the pitch in one direction in which the azimuth changes can be adjusted according to the intended use of the geometric phase grating. Since the diffraction angle (refraction angle) due to the geometric phase grating orientation generally satisfies the following equation 2 depending on the pitch and the reference wavelength, an appropriate pitch can be set taking into account the desired refraction angle.

[0050] [Formula 2]

[0051] sinθ = λ / P

[0052] In Equation 2, θ is the diffraction angle, λ is the reference wavelength (unit: nm), and P is the pitch (unit: nm). The reference wavelength in Equation 2 is adjusted according to the wavelength of the beam to be diffracted, and the pitch is set according to the wavelength and the desired diffraction angle.

[0053] In the geometric phase lens orientation of Fig. 3, the liquid crystal layer also generates a corresponding lens profile through the in-plane orientation of the liquid crystal compound. The in-plane orientation of the liquid crystal compound can be defined by an azimuth angle (θ), which generates an optical phase difference T, and the optical phase difference T can be defined as 2θ by the azimuth angle.

[0054] In a geometric phase lens orientation, the azimuth angle (θ) of the liquid crystal compound continuously changes along the direction from the center (220) of the liquid crystal layer to the edge (230), thereby generating a changing pitch (P). The meaning of the pitch is the same as in the case of a geometric phase grating. In a geometric phase lens, the pitch can be expressed as a function of the distance (r) from an arbitrary point (in the case of FIG. 3, the center (220) of the liquid crystal layer).

[0055] In a geometric phase lens, the azimuth angle can satisfy the relationship of Equation 3 below depending on the distance.

[0056] [Formula 3]

[0057] θ(r) = {π×r 2} / {2×f×λ}

[0058] In Equation 3, θ(r) is the azimuth angle of the liquid crystal compound in the region of the liquid crystal layer a distance r (unit: mm) away from the center of the geometric phase lens alignment, r is the distance, f is the focal length of the geometric phase lens alignment, and λ is the reference wavelength (unit: mm).

[0059] In Equation 3, the reference wavelength is adjusted according to the wavelength of the beam to be diffracted, and the pitch of the geometric phase lens is set according to the focal length (f) to be achieved and the size of the liquid crystal layer according to Equation 3.

[0060] Fig. 9 is a drawing exemplarily showing the alignment of the liquid crystal compound along the Y-axis of the liquid crystal layer of Fig. 3. From Fig. 9, it can be confirmed that the rate of change in pitch is a function of the distance (r) from the center (220) of the liquid crystal layer. The rate of change in pitch becomes faster as the distance increases. For example, pitches P1, P2, and P3 in Fig. 9 have the relationships P1 > P2 and P1 > P3.

[0061] In the above geometric phase lens alignment, the alignment of the liquid crystal compound may be aligned to have an azimuth that changes with distance along at least one direction among the plane directions of the liquid crystal layer.

[0062] In the geometric phase lens orientation, the change in the azimuth angle can satisfy the above equation 3.

[0063] As can be seen from FIG. 3, the change in azimuth in the geometric phase lens orientation can appear radially within the plane of the liquid crystal layer. However, the shape in the geometric phase lens orientation is not limited thereto.

[0064] Whether the liquid crystal layer is in geometric phase alignment can be confirmed, for example, using a polarizing microscope. That is, in geometric phase alignment, the liquid crystal compound rotates with a changing azimuth angle, so when observed through a polarizing microscope, a pattern of lines with relatively dark shades and lines with relatively light shades repeats along the azimuth angle. Therefore, if the repetition of the line pattern is confirmed through a polarizing microscope, the liquid crystal layer can be considered to be in geometric phase alignment.

[0065] The pitch of the geometric phase alignment can also be determined from the image of the polarizing microscope. For example, in the case of a normal pitch in which the rotational direction of the liquid crystal compound in the alignment does not change along the azimuth change direction, the distance required for the liquid crystal compound to rotate 180 degrees from its initial state is the pitch, and since the dark line or light line appears when the rotation of 90 degrees is completed, the distance between the two outermost dark-shaded lines (or light-shaded lines) among the three adjacent dark-shaded lines (or light-shaded lines) in the polarizing microscope image can be roughly designated as the pitch.

[0066] The method for determining whether the liquid crystal layer is in geometric phase alignment and the pitch is not limited to the above.

[0067] The beam splitter disclosed herein includes at least one geometric phase alignment layer. The geometric phase alignment layer may be a geometric phase grating alignment layer.

[0068] The geometric phase alignment layer included in the above beam splitter may be controlled so that the so-called 0th order transmittance or intensity is above a certain level.

[0069] The above 0th order transmittance or intensity refers to the transmittance or intensity of light incident on the geometric phase alignment layer that is substantially transmitted without being diffracted by the geometric phase alignment layer or light that transmits the geometric phase alignment layer in the same direction as the incident light. The light that is transmitted without being diffracted by the geometric phase alignment layer or light that transmits the geometric phase alignment layer in the same direction as the incident light may be referred to as 0th order transmitted light in this specification.

[0070] The above contents are explained with reference to the drawings.

[0071] The geometric phase alignment layer is fundamentally a device for diffraction of light. Therefore, light incident on the geometric phase alignment layer is diffracted and transmitted, so the zeroth-order transmittance or intensity in a typical geometric phase alignment layer is designed to be essentially 0%.

[0072] Figure 10 is a schematic diagram showing a diffraction phenomenon in a conventional geometric phase grating alignment layer.

[0073] As shown in Fig. 10, a geometric phase grating alignment layer (1000) is applied to the light (B) i ) is incident, the incident light (B i ) along the counterclockwise and clockwise directions based on the incident direction, respectively, a constant diffraction angle (θ) L , θ R ) is emitted to form a diffracted light. For example, unpolarized light (B) is emitted from a geometric phase grating alignment layer. i ) is incident, at least two diffracted rays (D 1R , D 1L ) can be generated, usually the two diffracted rays (D 1R , D 1L ) is left-circularly polarized light, and the other is right-circularly polarized light. The diffracted light (D 1R , D 1L ) of the diffraction angle (θ) L , θ R) is determined according to the type of liquid crystal compound applied to the geometric phase grating alignment layer, the pitch and / or thickness of the alignment layer, etc.

[0074] In this specification, among the diffracted light, the incident light (B) i ) exists along the counterclockwise direction based on the incident direction, and the diffracted light that exists while forming a predetermined diffraction angle with the incident direction is classified into first order (1) according to the size of the diffraction angle. st order), 2nd (2 nd order) and higher orders of diffracted light or transmitted light. For example, referring to Fig. 12, when viewed from the side view of the geometric phase alignment layer (1001), the incident light (B i ) along the counterclockwise direction based on the direction of incidence, two diffracted rays (D 1R , D 2R ) exists. The above two diffracted rays (D 1R , D 2R ) are two diffraction angles θ along the incident direction and counterclockwise direction respectively. R1 and θ R2 In this case, the smallest diffraction angle (θ) among the plurality of diffraction angles R1 ) forming a diffraction beam (D 1R ) can be designated as the first diffracted ray or the first transmitted ray, and the next largest diffraction angle (θ R2 ) forming a diffraction beam (D 2R ) may be designated as the second-order diffracted light or the second-order transmitted light, and in the same way, third-order or higher diffracted light or transmitted light may also be designated (if any).

[0075] In this specification, among the diffracted light, the incident light (B) i ) exists along the clockwise direction based on the direction of incidence, and the diffracted light that exists while forming a predetermined diffraction angle with the direction of incidence is -1 order (-1) depending on the size of the diffraction angle. st order), -2nd (2nd order) and higher negative order (minus order) can be called diffracted light or transmitted light. For example, referring to Fig. 12, when viewed from the side view of the geometric phase alignment layer (1001), the incident light (B i ) along the clockwise direction based on the direction of incidence, two diffracted rays (D 1L , D 2L ) exists. The above two diffracted rays (D 1L , D 2L ) are two diffraction angles θ along the incident direction and clockwise direction respectively. L1 and θ L2 In this case, the smallest diffraction angle (θ) among the plurality of diffraction angles L1 ) forming a diffraction beam (D 1L ) can be designated as the -1st diffracted ray or the -1st transmitted ray, and the next largest diffraction angle (θ L2 ) forming a diffraction beam (D 2R ) can be designated as -2nd order diffracted light or -2nd order transmitted light, and in the same way, negative orders of -3rd or higher diffracted light or transmitted light can also be designated (if any).

[0076] In Fig. 10, undiffracted light (B T ) is indicated by a dotted line. The purpose of the conventional geometric phase grating alignment layer (1000) is to i ) is diffracted, so the undiffracted light (B T ) is controlled so that it is not actually created.

[0077] The geometric phase alignment layer (e.g., geometric phase grating alignment layer) included in the beam splitter disclosed in this specification is different from the prior art illustrated in FIG. 10 in that the 0th-order transmitted light (B T ) is configured to have a transmittance or intensity above a certain level. An example of this is shown in Fig. 11.

[0078] There is no special limitation on the method of generating the 0th-order transmitted light as described above for the geometric phase alignment layer, and for example, the incident light (B) to be split i ) is a method for selecting the type of liquid crystal compound to be applied to the geometric phase alignment layer, considering the wavelength of the incident light (B) to be split. i ) and / or a method of adjusting the pitch of the geometric phase alignment layer by considering the wavelength of the incident light (B) to be split i ) can be applied to adjust the thickness of the geometric phase alignment layer by considering the wavelength.

[0079] For example, the 0th-order transmitted light can be generated by adjusting the thickness of the geometric phase alignment layer and / or the refractive index anisotropy of the liquid crystal compound forming the alignment layer according to the following Equation 4.

[0080] [Formula 4]

[0081] △n × T - λ / 2 ≠ 0

[0082] In Equation 4, △n is the refractive index anisotropy of the liquid crystal compound forming the geometric phase alignment layer, T is the thickness of the geometric phase alignment layer, and λ is the wavelength of light to be split.

[0083] The above △n is confirmed in a state where the liquid crystal compound forming the geometric phase alignment layer is uniaxially (homogeneously) aligned, and is the refractive index anisotropy for the wavelength λ, i.e., the light to be split.

[0084] Additionally, the same units apply to T and λ in Equation 4. In one example, the units of T and λ for the calculation of Equation 4 can be nm or μm.

[0085] Since the 0th-order transmitted light is minimized when the geometric phase alignment layer has a thickness corresponding to the so-called HWP (Half Wave Plate) for incident light, the 0th-order transmitted light can be generated and the degree of the 0th-order transmitted light can be controlled by adjusting the refractive index anisotropy and / or thickness of the liquid crystal compound forming the geometric phase alignment layer according to the above equation 4.

[0086] For example, the ratio of △n×T to λ / 2 in the above equation 4, i.e., (2×△n×T) / λ, may be within a predetermined range while not being 1. In this range, 0th-order transmitted light can be generated, and the degree of generation of the 0th-order transmitted light can be controlled according to the desired level of transmittance or intensity.

[0087] For example, the lower limit of the above (2×△n×T) / λ may be about 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9 or 0.95, and the upper limit may be about 1, 0.99, 0.95, 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55 or 0.5. The above (2×△n×T) / λ is within a range that is less than or equal to any one upper limit arbitrarily selected from the upper limits listed above; Or, it may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above, and equal to or less than any upper limit arbitrarily selected from the upper limits listed above. In this case, (2×△n×T) / λ is not 1.

[0088] In another example, the lower bound of (2×△n×T) / λ may be about 1, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45 or 1.5, and the upper bound may be about 3, 2.95, 2.9, 2.85, 2.8, 2.75, 2.7, 2.65, 2.6, 2.55, 2.5, 2.45, 2.4, 2.35, 2.3, 2.25, 2.2, 2.15, 2.1, 2.05, 2.00, 1.95, 1.9, 1.85, 1.8, 1.75, 1.7, 1.65, It can be about 1.6, 1.55, 1.5, 1.45, 1.4, 1.35, 1.3, 1.25, 1.2, 1.15, 1.1 or 1.05. The (2×△n×T) / λ can be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above; or within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above and equal to or less than any upper limit arbitrarily selected from the upper limits listed above. Even in this case, the (2×△n×T) / λ is not 1.

[0089] In another example, the thickness of the geometric phase alignment layer and / or the refractive index anisotropy of the liquid crystal compound forming the alignment layer can be adjusted so that the value of K in Equation 5 below is within a predetermined range.

[0090] [Formula 5]

[0091] K = sin 2 {(π×△n×T) / λ}

[0092] In Equation 5, △n is the refractive index anisotropy of the liquid crystal compound forming the geometric phase alignment layer, T is the thickness of the geometric phase alignment layer, and λ is the wavelength of light to be split.

[0093] The above △n is confirmed in a state where the liquid crystal compound forming the geometric phase alignment layer is uniaxially (homogeneously) aligned, and is the refractive index anisotropy for the wavelength λ, i.e., the light to be split.

[0094] In Equation 5, the same units apply to T and λ. In one example, the units of T and λ for the calculation of Equation 5 can be nm or μm.

[0095] In one example, the lower bound of K in Equation 5 may be about 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, or 0.8, and the upper bound may be about 1.5, 1.4, 1.3, 1.2, 1.1, 1.0, 0.95, 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, or 0.6. K may be within a range that is greater than or equal to any lower bound selected from the lower bounds listed above; or within a range that is less than or equal to any upper bound selected from the upper bounds listed above; or within a range that is greater than or equal to any lower bound selected from the lower bounds listed above and less than or equal to any upper bound selected from the upper bounds listed above.

[0096] In the above equations 4 and 5, λ is the wavelength of the light to be split, as described above. However, for example, when the light to be split is light in the infrared region (e.g., any wavelength within the region of about 600 to 2,000 nm, or any wavelength within the region of 700 to 1,500 nm), it is sometimes difficult to measure the refractive index anisotropy △n of the liquid crystal compound. In such a case, the shape of the alignment layer can be adjusted based on light with a wavelength of 550 nm to form a beam splitter.

[0097] For example, in order to form a desired beam splitter, the thickness of the geometric phase alignment layer and / or the refractive index anisotropy of the liquid crystal compound forming the alignment layer can be adjusted according to Equation 6 below.

[0098] [Formula 6]

[0099] △n × T - λ / 2 ≠ 0

[0100] In Equation 6, △n is the refractive index anisotropy of the liquid crystal compound forming the geometric phase alignment layer at a wavelength of 550 nm, T is the thickness of the geometric phase alignment layer, and λ is 550 nm.

[0101] The above △n can be confirmed in a state where the liquid crystal compound forming the geometric phase alignment layer is uniaxially (homogeneously) aligned.

[0102] In Equation 6, the unit of T can be nm.

[0103] For example, the ratio of △n×T of the above equation 6 to λ / 2, i.e., (2×△n×T) / λ, may be within a predetermined range while not being 1. In this range, 0th-order transmitted light can be generated for light in the infrared region, and the degree of generation of the 0th-order transmitted light can be controlled according to the desired level of transmittance or intensity.

[0104] For example, the lower limit of the above (2×△n×T) / λ may be about 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9 or 0.95, and the upper limit may be about 1, 0.99, 0.95, 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55 or 0.5. The above (2×△n×T) / λ is within a range that is less than or equal to any one upper limit arbitrarily selected from the upper limits listed above; Or, it may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above, and equal to or less than any upper limit arbitrarily selected from the upper limits listed above. In this case, (2×△n×T) / λ is not 1.

[0105] In another example, the lower bound of (2×△n×T) / λ may be 1, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5 or 1.6, and the upper bound may be 3, 2.95, 2.9, 2.85, 2.8, 2.75, 2.7, 2.65, 2.6, 2.55, 2.5, 2.45, 2.4, 2.35, 2.3, 2.25, 2.2, 2.15, 2.1, 2.05, 2.00, 1.95, 1.9, 1.85, 1.8, 1.75, 1.7, It can be about 1.65, 1.6, 1.55, 1.5, 1.45, 1.4, 1.35, 1.3, 1.25 or 1.2. The (2×△n×T) / λ can be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above; or within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above and equal to or less than any upper limit arbitrarily selected from the upper limits listed above. Even in this case, the (2×△n×T) / λ is not 1.

[0106] The value obtained by applying 550 nm as λ in the above equation 5 and substituting the refractive index anisotropy of the liquid crystal compound based on the wavelength of 550 nm as △n (hereinafter, K 550 ) can also be adjusted.

[0107] In another example, the thickness of the geometric phase alignment layer and / or the refractive index anisotropy of the liquid crystal compound forming the alignment layer can be adjusted so that the value of K in Equation 5 below is within a predetermined range.

[0108] For example, the above K 550 The lower limit of K may be about 0, 0.00005, 0.0001, 0.0003, 0.0005, 0.0007, 0.0009, 0.001, 0.0015 or 0.002, and the upper limit may be about 0.5, 0.1, 0.05, 0.01, 0.008, 0.006, 0.004, 0.003 or 0.001.550 It may be within a range that is greater than or equal to a lower limit arbitrarily selected from the lower limits listed above; or within a range that is less than or equal to a upper limit arbitrarily selected from the upper limits listed above; or within a range that is greater than or equal to a lower limit arbitrarily selected from the lower limits listed above and less than or equal to a upper limit arbitrarily selected from the upper limits listed above.

[0109] In another example, the zero-order transmitted light can be generated by adjusting the alignment pattern of the liquid crystal compound included in the geometric phase alignment layer. For example, the zero-order transmitted light can be generated even when defects in the alignment are induced by inducing discontinuous changes in the alignment angle and / or changes in the pitch of the liquid crystal compound.

[0110] The method of generating the above 0th-order transmitted light and adjusting its degree is not limited to the above.

[0111] The lower limit of the transmittance or intensity of the above 0th order transmitted light may be about 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 7%, 9%, 11%, 13%, 15%, 17%, 19%, 21%, 23%, 25%, 27%, 29%, 31% or 33%, and the upper limit may be about 70%, 68%, 66%, 64%, 62%, 60%, 58%, 56%, 54%, 52%, 50%, 48%, 46%, 44%, 42%. It can be about 40%, 38%, 36%, 34%, 32%, 30%, 28%, 26%, 24%, 22%, 20%, 18%, 16%, 14%, 12%, 10%, 8%, 6% or 4%. The transmittance or intensity can be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above; or within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above and equal to or less than any upper limit arbitrarily selected from the upper limits listed above.

[0112] As illustrated in Fig. 11, the geometric phase alignment layer is formed by incident light (B i ) from the above 0th order transmitted light (B T ) with the first-order diffraction beam (D 1R ) and -1st order diffracted light (D 1L ) may be configured to generate at least three split beams from the incident beam. In such a case, the beam splitter may generate at least three split beams from the incident beam.

[0113] In the above case, the sum of the transmittance or intensity of the 0th-order transmitted light, the transmittance or intensity of the 1st-order diffracted light, and the transmittance or intensity of the -1st-order diffracted light can be adjusted. For example, the lower limit of the sum of the transmittance or intensity can be about 80%, 85%, 90%, or 95%, and the upper limit can be about 100%, 99%, 98%, 97%, 96%, or 95%. The sum of the transmittance or intensity can be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above; within a range that is equal to or less than any upper limit arbitrarily selected from the upper limits listed above; or within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above and equal to or less than any upper limit arbitrarily selected from the upper limits listed above.

[0114] The average (arithmetic mean) of the transmittance or intensity of the 0th-order transmitted light, the transmittance or intensity of the 1st-order diffracted light, and the transmittance or intensity of the -1st-order diffracted light can be adjusted. For example, the lower limit of the average of the above transmittance or intensity may be about 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 7%, 9%, 11%, 13%, 15%, 17%, 19%, 21%, 23%, 25%, 27%, 29%, 31% or 33%, and the upper limit may be about 70%, 68%, 66%, 64%, 62%, 60%, 58%, 56%, 54%, 52%, 50%, 48%, 46%, 44%, 42%, 40%, It can be about 38%, 36%, 34%, 32%, 30%, 28%, 26%, 24%, 22% or 20%. The average can be within a range that is greater than or equal to any lower limit arbitrarily selected from the lower limits listed above; or within a range that is less than or equal to any upper limit arbitrarily selected from the upper limits listed above; or within a range that is greater than or equal to any lower limit arbitrarily selected from the lower limits listed above and less than or equal to any upper limit arbitrarily selected from the upper limits listed above.

[0115] The transmittance or intensity of the 0th order transmitted light (0 order leakage), the transmittance or intensity of the 1st order diffracted light (1 st order leakage) and the transmittance or intensity of the -1st order diffracted light (-1 st The standard deviation of the order leakage) can be adjusted. The standard deviation is the transmittance or intensity of the 0th order transmitted light (0 order leakage), the transmittance or intensity of the 1st order diffracted light (1 st order leakage) and the transmittance or intensity of the -1st order diffracted light (-1 st The order leakage) is T0, T1 and T-1, respectively, and their average is T avgAt one time, {[(T avg- T0) 2 +(T avg- T1) 2 +(T avg- T-1) 2 ] / 3} 0.5 is defined as follows. The upper limit of the standard deviation may be about 50%, 45%, 40%, 35%, 30%, 25%, 20%, 18%, 16%, 14%, 12%, 10%, 8%, 6%, 4%, 2%, 1.5%, 1% or 0%, and the lower limit may be about %, 0%, 0.2%, 0.4%, 0.6%, 0.8%, 0.9%, 1%, 1.5%, 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18% or 20%. The standard deviation is within a range that is less than or equal to any one upper limit arbitrarily selected from the upper limits listed above; Or, it may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above, and equal to or less than any upper limit arbitrarily selected from the upper limits listed above.

[0116] The above 0th order transmitted light (B T ) and first-order diffraction light (D 1R ) form an angle (θ) R ) and the above 0th order transmitted light (B T ) and -1st order diffraction light (D 1L ) of the smaller angles (θ) formed by L and θ R ) can be adjusted. The adjustment of this angle can be determined by adjusting the type of liquid crystal compound applied to the geometric phase alignment layer, the pitch and / or thickness of the alignment layer, etc. The angle (θ) R and θ L) may independently be about 1 degree, 2 degrees, 5 degrees, 7 degrees, 10 degrees, 15 degrees, 20 degrees, 25 degrees, 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees or 55 degrees, and the upper limit may independently be about 70 degrees, 65 degrees, 60 degrees, 55 degrees, 50 degrees, 45 degrees, 40 degrees, 35 degrees, 30 degrees, 25 degrees, 20 degrees or 15 degrees. The angle (θ) R and θ L ) may be within a range that is greater than or equal to a lower limit arbitrarily selected from the lower limits listed above; within a range that is less than or equal to a upper limit arbitrarily selected from the upper limits listed above; or within a range that is greater than or equal to a lower limit arbitrarily selected from the lower limits listed above and less than or equal to a upper limit arbitrarily selected from the upper limits listed above.

[0117] The above range of angles is the angle when the incident angle of the incident light is in the direction parallel to the normal of the beam splitter.

[0118] The geometric phase alignment layer (e.g., geometric phase grating alignment layer) included in the above beam splitter is configured to diffract the first-order light (D) from the incident light (Bi). 1R ), -1st order diffraction light (D 1L ), second-order diffraction light (D 2R ) and -2nd order diffracted light (D 2L ) may be configured to generate. An example of this is shown in Fig. 12. In a case such as the drawing, the geometric phase alignment layer may be configured to also generate 0th-order transmitted light. In this case, the transmittance or intensity of the 0th-order transmitted light may be within the range of the transmittance or intensity of the 0th-order transmitted light described in the geometric phase alignment layer described above. In this case, the beam splitter may generate at least 4 or more or 5 or more split beams from the incident beam.

[0119] In the above case, the average (arithmetic mean) of the transmittance or intensity of the 1st, -1st, 2nd and -2nd order diffracted light or, if present, the average (arithmetic mean) of the transmittance or intensity of the 1st, -1st, 2nd and -2nd order diffracted light and the 0th order transmitted light can be adjusted. For example, the lower limit of the average of the transmittance or intensity can be about 10%, 12%, 14%, 16%, 18%, 20%, 22% or 24%, and the upper limit can be about 50%, 48%, 46%, 44%, 42%, 40%, 38%, 36%, 34%, 32%, 30%, 28%, 26%, 24%, 22% or 20%. The above average may be within a range that is greater than or equal to a lower limit arbitrarily selected from the lower limits listed above; within a range that is less than or equal to a upper limit arbitrarily selected from the upper limits listed above; or within a range that is greater than or equal to a lower limit arbitrarily selected from the lower limits listed above and less than or equal to a upper limit arbitrarily selected from the upper limits listed above.

[0120] In the above case, the standard deviation of the transmittance or intensity of the 1st, -1st, 2nd and -2nd order diffracted light or, if present, the standard deviation of the transmittance or intensity of the 1st, -1st, 2nd and -2nd order diffracted light and the 0th order transmitted light can be adjusted. The transmittance or intensity of the 1st, -1st, 2nd and -2nd order diffracted light and the transmittance or intensity of the 0th order transmitted light are respectively T1, T-1, T2, T-2 and T0, and the average of the transmittance or intensity of the 1st, -1st, 2nd and -2nd order diffracted light is T avg1 , and the average of the transmittance or intensity of the 1st, -1st, 2nd and -2nd diffracted light and the transmittance or intensity of the 0th transmitted light is T avg2 At one time, the standard deviation of the transmittance or intensity of the first, -1st, 2nd and -2nd diffracted rays is {[(T avg1- T1) 2 +(T avg1-T-1) 2 +(T avg1- T-2) 2 +(T avg1- T2) 2 ] / 4} 0.5 , and the standard deviation of the transmittance or intensity of the 1st, -1st, 2nd and -2nd diffracted light and the transmittance or intensity of the 0th transmitted light is {[(T avg2- T1) 2 +(T avg2- T-1) 2 +(T avg2- T-2) 2 +(T avg2- T2) 2 +(T avg2- T0) 2 ] / 5} 0.5 is defined as follows. The upper limit of the standard deviation of the transmittance or intensity of the 1st, -1st, 2nd and -2nd order diffracted light or the standard deviation of the transmittance or intensity of the 1st, -1st, 2nd and -2nd order diffracted light and the 0th order transmitted light, if any, may be about 30, 28, 26, 24, 22, 20, 18, 16, 14, 12, 10, 8, 6, 4, 2, 1.5, 1 or 0, and the lower limit thereof may be about 0, 1, 1.5, 2, 4, 6, 8, 10, 12, 14, 16 or 18. The standard deviation is within a range that is equal to or less than any one upper limit arbitrarily selected from the upper limits listed above; Or, it may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above, and equal to or less than any upper limit arbitrarily selected from the upper limits listed above.

[0121] In the above case, the incident light and the first diffracted light (D 1R ) is the smaller angle (θ) R1 ) and incident light and -1st order diffracted light (D 1L ) is the smaller angle (θ) L1) can be adjusted respectively. The adjustment of this angle can be determined by adjusting the type of liquid crystal compound applied to the geometric phase alignment layer, the pitch and / or thickness of the alignment layer, etc. The angle (θ) R1 and θ L1 ) may independently be about 1 degree, 3 degrees, 5 degrees, 7 degrees, 9 degrees, 10 degrees, 15 degrees, 20 degrees, 25 degrees, 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees or 55 degrees, and the upper limit may independently be about 60 degrees, 55 degrees, 50 degrees, 45 degrees, 40 degrees, 35 degrees, 30 degrees, 25 degrees, 20 degrees or 15 degrees. The angle (θ) R1 and θ L1 ) may be within a range that is greater than or equal to a lower limit arbitrarily selected from the lower limits listed above; within a range that is less than or equal to a upper limit arbitrarily selected from the upper limits listed above; or within a range that is greater than or equal to a lower limit arbitrarily selected from the lower limits listed above and less than or equal to a upper limit arbitrarily selected from the upper limits listed above.

[0122] The above range of angles is the angle when the incident angle of the incident light is in the direction parallel to the normal of the beam splitter.

[0123] The above incident light and the above second diffracted light (D 2R ) is the smaller angle (θ) R2 ) and incident light and -2nd order diffracted light (D 2L ) is the smaller angle (θ) L2 ) can be adjusted respectively. The adjustment of this angle can be determined by adjusting the type of liquid crystal compound applied to the geometric phase alignment layer, the pitch and / or thickness of the alignment layer, etc. The angle (θ) R2 and θ L2) may independently be about 2 degrees, 4 degrees, 6 degrees, 8 degrees, 10 degrees, 15 degrees, 20 degrees, 25 degrees, 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, 55 degrees, 60 degrees, 65 degrees, 70 degrees, 75 degrees, 80 degrees or 85 degrees, and the upper limit may independently be about 90 degrees, 85 degrees, 80 degrees, 75 degrees, 70 degrees, 65 degrees, 60 degrees, 55 degrees, 50 degrees, 45 degrees, 40 degrees, 35 degrees, 30 degrees, 25 degrees, 20 degrees or 15 degrees. The angle (θ) R2 and θ L2 ) may be within a range that is greater than or equal to a lower limit arbitrarily selected from the lower limits listed above; within a range that is less than or equal to a upper limit arbitrarily selected from the upper limits listed above; or within a range that is greater than or equal to a lower limit arbitrarily selected from the lower limits listed above and less than or equal to a upper limit arbitrarily selected from the upper limits listed above.

[0124] The above range of angles is the angle when the incident angle of the incident light is in the direction parallel to the normal of the beam splitter.

[0125] The desired beam splitter can be manufactured by applying a geometric phase alignment layer, for example, a geometric phase grating alignment layer, by configuring it as described above.

[0126] In another example, the beam splitter may include, as the geometric phase alignment layer, the geometric phase grating alignment layer, wherein the geometric phase grating alignment layer may have a pattern in which the azimuth angle changes in a first direction in the plane and a pattern in which the azimuth angle changes in a second direction forming a predetermined angle with the first direction. In the above case, the geometric phase alignment layer may have two or more azimuth angle changing directions. The geometric phase alignment layer may also be configured to generate 0th-order transmitted light. In this case, the transmittance or intensity of the 0th-order transmitted light may be within the range of the transmittance or intensity of the 0th-order transmitted light described above.

[0127] In the geometric phase alignment layer, a smaller angle among the angles formed by the first and second directions can be adjusted. For example, a lower limit of the smaller angle among the angles formed by the first and second directions can be about 70 degrees, 72 degrees, 74 degrees, 76 degrees, 78 degrees, 80 degrees, 82 degrees, 84 degrees, 86 degrees, 88 degrees, or 90 degrees, and an upper limit thereof can be about 180 degrees, 160 degrees, 140 degrees, 120 degrees, 100 degrees, 90 degrees, 88 degrees, 86 degrees, 84 degrees, 82 degrees, or 80 degrees. The angle can be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above, and equal to or less than any upper limit arbitrarily selected from the upper limits listed above.

[0128] Fig. 18 is a drawing exemplarily showing the form of the liquid crystal alignment of the liquid crystal compound in the geometric phase alignment layer of this type. The change in the alignment direction of the actual liquid crystal compound may be discontinuous or continuous as shown in Fig. 18, but in Fig. 18, the alignment direction of the liquid crystal compound at any specific point is described for the convenience of explanation. That is, for example, the change in the alignment direction in the topmost row of Fig. 18 is described as changing discontinuously at 30 degrees, 60 degrees, 90 degrees, 120 degrees, and 160 degrees in the row direction, but the alignment of the actual liquid crystal compound may change smoothly and continuously from 30 degrees to 160 degrees. The numbers in each square in Fig. 18 represent the angle formed by the optical axis direction of the liquid crystal compound at each point and the optical axis direction of the liquid crystal compound designated as 0 degrees, assuming that the optical axis direction of the liquid crystal compound located in the square at the upper right corner of the geometric phase alignment layer (1001) (the square filled with a dotted line in the drawing) is 0 degrees. In Fig. 18, the first direction is one of the horizontal and vertical directions in the drawing, the second direction is the other of the horizontal and vertical directions in the drawing, and the angle formed by the first and second directions is approximately vertical.

[0129] In the case of the traditional geometric phase grating alignment illustrated in FIG. 2, there is virtually no change in azimuth in any azimuth change direction (the Y-axis direction in FIG. 2) and in the perpendicular direction (the X-axis direction in FIG. 2), but the geometric phase alignment layer can be configured so that azimuth change is confirmed in the two directions described above. The advantage of such a geometric phase alignment layer is that four or more split beams can be generated from one incident light beam even through a single alignment layer. In this case, the split beams can appear in the form of, for example, split beams (D1 to D9) illustrated in FIG. 19. FIG. 19 is an example of a split beam observed in a plan view in a geometric phase alignment layer (1001) illustrated in FIG. 12, etc.

[0130] The geometric phase alignment layer can be manufactured so that the pitch identified in the first direction and the pitch identified in the second direction have a predetermined relationship. For example, the geometric phase alignment layer can be configured so that P1 / P2 of the following equation 7 is within a predetermined range.

[0131] [Formula 7]

[0132] P1 / P2

[0133] In Equation 7, P1 is the pitch of the pattern whose azimuth changes in the first direction within the plane, and P2 is the pitch of the pattern whose azimuth changes in the second direction within the plane. The meaning of the pitch is as defined herein.

[0134] The lower limit of P1 / P2 in Equation 7 may be about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1.0, and the upper limit may be about 2, 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, 1.1 or 1.0. The P1 / P2 may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above; within a range that is equal to or less than any upper limit arbitrarily selected from the upper limits listed above; or within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above and equal to or less than any upper limit arbitrarily selected from the upper limits listed above. The pitch can be controlled within the above range by considering the number of desired split beams and / or split shape.

[0135] The above beam splitter can split one incident beam into multiple split beams. The lower limit of the number of split beams generated by the beam splitter from one incident beam may be about 2, 3, 4, 5, 6, 7, 8, or 9, and the upper limit may be about 100, 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 14, 13, 12, 11, 10, or 9. The number of split beams is within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above; Or, it may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above, and equal to or less than any upper limit arbitrarily selected from the upper limits listed above.

[0136] In one example, the beam splitter may include two or more geometric phase alignment layers.

[0137] For example, the beam splitter may include a first geometric phase alignment layer and a second geometric phase alignment layer. The geometric phase alignment layers may be arranged such that light transmitted through one of the first and second geometric phase alignment layers is incident on the other geometric phase alignment layer.

[0138] In this specification, among the first and second geometric phase alignment layers, the alignment layer onto which the incident beam is incident may be referred to as the first geometric phase alignment layer, and the alignment layer onto which the transmitted light and / or diffracted light transmitted after the incident beam passes through the first geometric phase alignment layer may be referred to as the second geometric phase alignment layer.

[0139] At least one or both of the first and second geometric phase alignment layers may be any of the aforementioned geometric phase alignment layers. In another example, at least one or both of the first and second geometric phase alignment layers may be the aforementioned geometric phase grating alignment layers.

[0140] The transmittance or intensity of the 0th-order transmitted light of each of the first and / or second geometric phase alignment layers may be within the range described above.

[0141] FIG. 13 is an example in which the geometric phase alignment layers of FIG. 11 are used as the first and second geometric phase alignment layers (10011, 10012).

[0142] In this case, the incident beam (B i ) is incident on the first geometric phase alignment layer (10011), the above-mentioned 0th-order transmitted light (B T1 ), first-order diffraction light (D 1R ) and -1st order diffracted light (D 1L ) can be generated at least. Then, the generated 0th-order transmitted light (B T1 ), first-order diffraction light (D 1R ) and -1st order diffracted light (D 1L ) are incident on the second geometric phase alignment layer (10012). In this way, the 0th-order transmitted light (B) incident on the second geometric phase alignment layer (10012) T1 ), first-order diffraction light (D 1R ) and -1st order diffracted light (D 1L ) each have at least three zero-order transmitted rays (B T21 , B T22 , B T23 ), first-order diffraction light (D 1R1 , D 1R2 , D 1R3 ) and -1st order diffracted light (D 1L1 , D 1L2 , D 1L3 ) can be generated. Therefore, by the arrangement as above, one incident beam (Bi) can be generated into at least nine split beams (BT21 , B T22 , B T23 , D 1R1 , D 1R2 , D 1R3 , D 1L1 , D 1L2 , D 1L3 ) can be created.

[0143] In order to generate at least nine split beams as described above, the pitch of each of the first and second geometric phase alignment layers can be adjusted. As described above, the diffraction angle in the geometric phase alignment layer can vary depending on the pitch. In order to generate at least nine split beams in the form of FIG. 13, the pitch of the first and second geometric phase alignment layers is adjusted to generate nine split beams (B T21 , B T22 , B T23 , D 1R1 , D 1R2 , D 1R3 , D 1L1 , D 1L2 , D 1L3 ) can be adjusted so that at least some of them do not overlap.

[0144] Therefore, in one example, the pitch of the first geometric phase alignment layer and the pitch of the second geometric phase alignment layer may be different from each other.

[0145] For example, the pitch of the first and second geometric phase alignment layers can be adjusted so that P2 / P1 is within a predetermined range.

[0146] The above P1 is the pitch of one of the first and second geometric phase alignment layers, and P2 is the pitch of the other of the first and second geometric phase alignment layers.

[0147] In one example, P1 may be the pitch of the first geometric phase alignment layer (the alignment layer onto which the incident beam is incident), and P2 may be the pitch of the second geometric phase alignment layer (the alignment layer onto which the transmitted light and / or diffracted light transmitted through the first geometric phase alignment layer is incident).

[0148] The lower limit of the above P2 / P1 may be about 0.1, 0.3, 0.5, 0.7, 1, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.9 or 3.0, and the upper limit may be about 10, 9, 8, 7, 6, 5, 4.9, 4.8, 4.7, 4.6, 4.5, 4.4, 4.3, 4.2, 4.1, 4.0, 3.9, 3.8, 3.7, 3.6, 3.5, 3.4, 3.3, 3.2, 3.1, 3.0, 2.8, It can be about 2.6, 2.4, 2.2, 2.0, 1.8, 1.6, 1.4, 1.2, 1.0, 0.8, 0.6 or 0.4. The P2 / P1 can be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above; or within a range that is equal to or less than any upper limit arbitrarily selected from the upper limits listed above; or within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above and equal to or less than any upper limit arbitrarily selected from the upper limits listed above. The pitch can be controlled within the above range in consideration of the number of desired split beams.

[0149] In the above case, the first and second geometric phase alignment layers may be arranged so that a smaller pitch (e.g., P1) exists within a larger pitch (e.g., P2) among the pitches of the first and second geometric phase alignment layers.

[0150] Fig. 14 is a drawing exemplarily showing the pitch of the first and second geometric phase alignment layers of this type. In Fig. 14, the numbers in each square indicate the angle formed by the optical axis direction of the liquid crystal compound located in the leftmost square (the square filled with a dotted line in the drawing) of the first geometric phase alignment layer (10011) along the direction of azimuth change (the horizontal direction in Fig. 14) and the optical axis direction of the liquid crystal compound designated as 0 degrees. In reality, the change in the alignment direction of the liquid crystal compound may not change intermittently as shown in Fig. 14, but may change continuously. However, in Fig. 14, the alignment direction of the liquid crystal compound at any specific point is described for the convenience of explanation. That is, for example, although the alignment direction of the liquid crystal compound within the pitch P1 of FIG. 14 is described as changing intermittently from 0 degrees, 30 degrees, 60 degrees, 90 degrees, 120 degrees, 150 degrees, and 0 degrees, in reality, the alignment of the liquid crystal compound is mostly a case where it changes continuously and smoothly from the leftmost 0 degree direction to the rightmost 0 degree direction within P1. FIG. 14 is a case where the P2 / P1 is approximately 2.7. Through the drawing, it can be seen that the pitch (P1) of the first geometric phase alignment layer (10011) exists within the pitch (P2) of the second geometric phase alignment layer (10012).

[0151] In the beam splitter including the first and second geometric phase alignment layers disclosed herein, the smaller angle between the angle formed by the azimuth change direction in the first geometric phase alignment layer and the azimuth change direction in the second geometric phase alignment layer can be adjusted. As described above, the azimuth change direction in the present specification is any direction in which the pitch is completed by the azimuth change of the liquid crystal compound. This azimuth change direction may exist in one direction in one geometric phase alignment layer, or may exist in two or more directions. For example, this direction is one direction of the horizontal direction in FIG. 14. In addition, in the example of the geometric phase grating alignment layer in FIG. 2, the azimuth change direction is the Y-axis direction. In the example of FIG. 2, a constant azimuth is maintained in the X-axis direction without any azimuth change, and therefore, the X-axis direction is not an azimuth change direction.

[0152] In the example of Figure 3, there are multiple radial directions of azimuth change.

[0153] When there are two or more azimuth change directions of the first and / or second geometric phase alignment layers, when confirming the angle formed by the azimuth change directions, any azimuth change direction of the first and / or second geometric phase alignment layers may be selected.

[0154] In the beam splitter including the first and second geometric phase alignment layers, the lower limit of the smaller angle among the angles formed by the azimuth change direction in the first geometric phase alignment layer and the azimuth change direction in the second geometric phase alignment layer may be about 0 degrees, 5 degrees, 10 degrees, 15 degrees, 20 degrees, 25 degrees, 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, 55 degrees, 60 degrees, 65 degrees, 70 degrees, 75 degrees, 80 degrees, or 85 degrees, and the upper limit may be about 170 degrees, 160 degrees, 150 degrees, 140 degrees, 130 degrees, 120 degrees, 110 degrees, 100 degrees, 90 degrees, 85 degrees, 80 degrees, 75 degrees, 70 degrees, 65 degrees, 60 degrees, It can be about 55 degrees, 50 degrees, 45 degrees, 40 degrees, 35 degrees, 30 degrees, 25 degrees, 20 degrees, 15 degrees, 10 degrees, or 5 degrees. The angle can be within a range that is greater than or equal to any lower limit arbitrarily selected from the lower limits listed above; or within a range that is less than or equal to any upper limit arbitrarily selected from the upper limits listed above; or within a range that is greater than or equal to any lower limit arbitrarily selected from the lower limits listed above and less than or equal to any upper limit arbitrarily selected from the upper limits listed above.

[0155] In a beam splitter including the first and second geometric phase alignment layers, the smaller angle among the angles formed by the azimuth change direction in the first geometric phase alignment layer and the azimuth change direction in the second geometric phase alignment layer can be confirmed through the shape of the generated split beam.

[0156] For example, if the pitch shape of each of the first and second geometric phase alignment layers (10011, 10012) illustrated in FIG. 13 is the shape illustrated in FIG. 14, and the direction of azimuth change in the first geometric phase alignment layer and the direction of azimuth change in the second geometric phase alignment layer are approximately parallel, the nine split beams illustrated in FIG. 13 can be confirmed in a shape as in FIG. 15 when observed from a planar view.

[0157] For example, if the pitch shape of each of the first and second geometric phase alignment layers (10011, 10012) illustrated in FIG. 13 is the shape illustrated in FIG. 14, and the direction of azimuth change in the first geometric phase alignment layer and the direction of azimuth change in the second geometric phase alignment layer are approximately perpendicular, the nine split beams illustrated in FIG. 13 can be confirmed in a shape as in FIG. 16 when observed from a planar view.

[0158] In this way, the direction of the azimuth change can be adjusted by considering the arrangement of the intended split beam.

[0159] The above beam splitter can split one incident beam into multiple split beams. The lower limit of the number of split beams generated by the beam splitter from one incident beam may be about 2, 3, 4, 5, 6, 7, 8, or 9, and the upper limit may be about 100, 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 14, 13, 12, 11, 10, or 9. The number of split beams is within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above; Or, it may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above, and equal to or less than any upper limit arbitrarily selected from the upper limits listed above.

[0160] The plurality of split beams generated from the beam splitter may include one or more beams selected from the group consisting of non-polarized beams; linear beams; and circularly polarized beams and elliptically polarized beams.

[0161] In the beam splitter of the above-described type, at least some of the plurality of split beams may be circularly polarized beams or elliptically polarized beams. For example, the lower limit of the ratio of circularly polarized beams or elliptically polarized beams among the plurality of split beams split by the beam splitter of the above-described type may be about 30%, 35%, 40%, 45%, 50%, 55%, 60%, or 65%, and the upper limit may be about 100%, 95%, 90%, 85%, 80%, 75%, 70%, or 65%. The ratio may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above; or within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above, and equal to or less than any upper limit arbitrarily selected from the upper limits listed above.

[0162] Another solar beam splitter disclosed herein may include a first geometric phase alignment layer and a second geometric phase alignment layer. The geometric phase alignment layers may be arranged such that light transmitted through one of the first and second geometric phase alignment layers is incident on the other geometric phase alignment layer.

[0163] In this specification, among the first and second geometric phase alignment layers, the alignment layer onto which the incident beam is incident may be referred to as the first geometric phase alignment layer, and the alignment layer onto which the transmitted light and / or diffracted light transmitted after the incident beam passes through the first geometric phase alignment layer may be referred to as the second geometric phase alignment layer.

[0164] In the above beam splitter, either one of the first and second geometric phase alignment layers may have the above-described bidirectional pitch, or both the first and second geometric phase alignment layers may have the above-described bidirectional pitch.

[0165] At least one or both of the first and second geometric phase alignment layers may be the aforementioned geometric phase alignment layers. At least one or both of the first and second geometric phase alignment layers may be the aforementioned geometric phase grating alignment layers.

[0166] When the first and / or second geometric phase alignment layers are the geometric phase alignment layers described above, the transmittance or intensity of the zero-order transmitted light of the first and / or second geometric phase alignment layers may be within the range described above.

[0167] As described above, the bidirectional pitch is a pattern in which the rotational direction of the change in the azimuth angle of the geometric phase alignment layer changes at least once along the direction of the azimuth angle change, and such patterns include a 90-degree bidirectional pitch pattern in which a change in the rotational direction occurs within one pitch, as illustrated in FIG. 5, and a 180-degree bidirectional pitch pattern in which a change in the rotational direction occurs between one pitch and another, as illustrated in FIG. 6.

[0168] In one example of the above solar, one of the first and second geometric phase alignment layers (e.g., the first geometric phase alignment layer) may have a 90 degree bidirectional pitch, and the other of the first and second geometric phase alignment layers (e.g., the second geometric phase alignment layer) may have a 180 degree bidirectional pitch.

[0169] In another example, both the first and second geometric phase alignment layers may have a 90 degree bi-directional pitch, or a 180 degree bi-directional pitch.

[0170] FIG. 17 is an example of a first geometric phase alignment layer (10011) and a second geometric phase alignment layer (10012) having a bidirectional pitch as described above. The meaning of each number written in the box in FIG. 17 is the same as in FIG. 14. In this case, the change in the alignment direction of the actual liquid crystal compound does not change discontinuously as shown in FIG. 17, but may change continuously. However, in FIG. 17, the alignment direction of the liquid crystal compound at a specific point is written for the convenience of explanation. For example, the alignment direction of the liquid crystal compound within the pitch P11 in FIG. 17 is written as if it changes discontinuously from 0 degrees, 30 degrees, 60 degrees, and 90 degrees, but in reality, the alignment of the liquid crystal compound mostly changes smoothly and continuously from 0 degrees to 90 degrees.

[0171] Referring to FIG. 17, in the case of the first geometric phase alignment layer (10011), it is a 90-degree bidirectional pitch in which two regions (P11 and P12) with different rotational directions exist within one pitch (P11+P12), and in the case of the second geometric phase alignment layer (10012), it can be seen that after one pitch P21 is completed, another pitch P22 is completed in a rotational direction different from that of pitch P21.

[0172] Even in a beam splitter of this type, the splitting of the incident beam can be in a form as illustrated in, for example, Fig. 15 or Fig. 16.

[0173] However, when a two-way pitch of the above type is applied, the 0th-order transmitted light, the 1st-order diffracted light, and the -1st-order diffracted light split in the geometric phase alignment layer (10011, 10012) can be obtained in a substantially unpolarized state. Therefore, in this case, at least 9 split beams (B) obtained from one incident beam (Bi) T21 , B T22 , B T23 , D 1R1 , D 1R2 , D 1R3 , D1L1 , D 1L2 , D 1L3 ) can be obtained mostly in the above non-polarized state.

[0174] In order to generate at least nine split beams, the pitches of the first and second geometric phase alignment layers can also be adjusted in the above-described manner. For example, by adjusting the pitches of the first and second geometric phase alignment layers, at least nine split beams (B) can be generated, as illustrated in FIG. 13. T21 , B T22 , B T23 , D 1R1 , D 1R2 , D 1R3 , D 1L1 , D 1L2 , D 1L3 ) can be obtained.

[0175] In one example, the pitch of the first geometric phase alignment layer and the pitch of the second geometric phase alignment layer may be different from each other in the above-described solar cell.

[0176] For example, in the above solar cell, the pitch of the first and second geometric phase alignment layers can be adjusted so that P2 / P1 (wherein P1 is the pitch of one of the first and second geometric phase alignment layers, and P2 is the pitch of the other of the first and second geometric phase alignment layers) is within a predetermined range.

[0177] In one example, P1 may be the pitch of the first geometric phase alignment layer (the alignment layer onto which the incident beam is incident), and P2 may be the pitch of the second geometric phase alignment layer (the alignment layer onto which the transmitted light and / or diffracted light transmitted through the first geometric phase alignment layer is incident).

[0178] The lower limit of the above P2 / P1 may be about 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.9 or 3.0, and the upper limit may be about 5, 4.9, 4.8, 4.7, 4.6, 4.5, 4.4, 4.3, 4.2, 4.1, 4.0, 3.9, 3.8, 3.7, 3.6, 3.5, 3.4, 3.3, 3.2, 3.1 or 3.0. The above P2 / P1 is within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above; Or within a range that is less than or equal to any upper limit arbitrarily selected from the upper limits listed above; or within a range that is greater than or equal to any lower limit arbitrarily selected from the lower limits listed above and less than or equal to any upper limit arbitrarily selected from the upper limits listed above. The pitch can be controlled within the above range taking into account the number of desired split beams.

[0179] The first and second geometric phase alignment layers may be arranged such that a smaller pitch (e.g., P1) exists within a larger pitch (e.g., P2) among the pitches of the first and second geometric phase alignment layers.

[0180] Fig. 17 exemplarily shows the pitches of the first and second geometric phase alignment layers of this type. Fig. 16 shows a case where P2 / P1 is approximately 2.7. From the drawing, it can be seen that the pitch (P11+P12) of the first geometric phase alignment layer (10011) exists within the pitch (P21 or P22) of the second geometric phase alignment layer (10012).

[0181] In a beam splitter including the first and second geometric phase alignment layers of the above-described sun, a smaller angle among the angles formed by the azimuth change direction in the first geometric phase alignment layer and the azimuth change direction in the second geometric phase alignment layer can be adjusted. The reason for adjusting this angle is as described above with reference to FIGS. 15 and 16.

[0182] In the beam splitter including the first and second geometric phase alignment layers, the lower limit of the smaller angle among the angles formed by the azimuth change direction in the first geometric phase alignment layer and the azimuth change direction in the second geometric phase alignment layer may be about 0 degrees, 5 degrees, 10 degrees, 15 degrees, 20 degrees, 25 degrees, 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, 55 degrees, 60 degrees, 65 degrees, 70 degrees, 75 degrees, 80 degrees, or 85 degrees, and the upper limit may be about 170 degrees, 160 degrees, 150 degrees, 140 degrees, 130 degrees, 120 degrees, 110 degrees, 100 degrees, 90 degrees, 85 degrees, 80 degrees, 75 degrees, 70 degrees, 65 degrees, 60 degrees, It can be about 55 degrees, 50 degrees, 45 degrees, 40 degrees, 35 degrees, 30 degrees, 25 degrees, 20 degrees, 15 degrees, 10 degrees, or 5 degrees. The angle can be within a range that is greater than or equal to any lower limit arbitrarily selected from the lower limits listed above; or within a range that is less than or equal to any upper limit arbitrarily selected from the upper limits listed above; or within a range that is greater than or equal to any lower limit arbitrarily selected from the lower limits listed above and less than or equal to any upper limit arbitrarily selected from the upper limits listed above.

[0183] As described above, the direction of the azimuth change can be adjusted by considering the arrangement of the intended split beam.

[0184] The beam splitter of the above type can also split one incident beam into multiple split beams. The lower limit of the number of split beams generated by the beam splitter from one incident beam may be about 2, 3, 4, 5, 6, 7, 8, or 9, and the upper limit may be about 100, 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 14, 13, 12, 11, 10, or 9. The number of split beams is within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above; Or, it may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above, and equal to or less than any upper limit arbitrarily selected from the upper limits listed above.

[0185] The plurality of split beams generated from the beam splitter may include one or more beams selected from the group consisting of non-polarized beams; linear beams; and circularly polarized beams and elliptically polarized beams.

[0186] In the beam splitter of the above-described type, at least some of the plurality of split beams may be unpolarized beams. For example, the lower limit of the ratio of unpolarized beams among the plurality of split beams split by the beam splitter of the above-described type may be about 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%, and the upper limit may be about 100%, 95%, 90%, 85%, 80%, 75%, 70%, or 65%. The ratio may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above; or within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above, and equal to or less than any upper limit arbitrarily selected from the upper limits listed above.

[0187] In the various types of beam splitters described above, the thickness of each geometric phase alignment layer can be adjusted in consideration of the purpose. For example, each geometric phase alignment layer can be determined in a range that satisfies Equation 4 in consideration of the refractive index anisotropy of the liquid crystal compound forming the alignment layer, or the ratio of △n×T of Equation 4 to λ / 2, that is, (2×△n×T) / λ, can satisfy the range described above. For example, the thickness of the geometric phase alignment layer can be in a range of about 0.1 to 50 μm, but is not limited thereto.

[0188] Specific examples of the beam splitter disclosed in this specification may be configured in various forms in addition to those described above.

[0189] The beam splitter may include additional elements as required in addition to the one or two or more geometric phase alignment layers described above. For example, when the beam splitter includes the first and second geometric phase alignment layers, the beam splitter may additionally include a retardation film between the first and second geometric phase alignment layers.

[0190] The above-described phase difference film may be introduced, for example, to adjust the polarization state of the first and / or -1st order diffracted light, etc., among the light transmitted through the first geometric phase alignment layer. As described above, a geometric phase alignment layer, such as a geometric phase grating alignment layer, can generate at least 0th order transmitted light, 1st order diffracted light, and -1st order diffracted light when unpolarized light is incident, and depending on the configuration of the alignment layer, optically, the 0th order transmitted light among the light can be transmitted through the geometric phase alignment layer in the form of unpolarized light, and one of the 1st order and -1st order diffracted light can be transmitted through the geometric phase alignment layer as right-handed circularly polarized light, and the other can be transmitted through the geometric phase alignment layer as left-handed circularly polarized light.

[0191] A geometric phase alignment layer, for example, a geometric phase grating alignment layer, has the property of diffracting circularly polarized light (or elliptically polarized light) at a single diffraction angle. Therefore, in some cases, among the 0th-order transmitted light, 1st-order diffracted light, and -1st-order diffracted light that have passed through the first geometric phase alignment layer, the 1st-order and -1st-order diffracted light may not be split when passing through the second geometric phase alignment layer if they are in a left- or right-handed circular polarization state, or may be split with low efficiency. Therefore, in such cases, the polarization states of the 1st-order and -1st-order diffracted light may be changed to a polarization state (for example, unpolarized light or linear polarization) that can be effectively split by the second geometric phase alignment layer through the phase difference film.

[0192] The specific type of the above-mentioned phase difference film is not particularly limited, as long as it is selected to perform the above-mentioned function. For example, the phase difference film can be a so-called QWP (Quarter Wave Plate), which is a phase difference film capable of generating linear polarization from circularly polarized light (or elliptically polarized light). Various liquid crystal films and polymer stretch films capable of operating as the above-mentioned QWP are known in the industry.

[0193] In the above, QWP can be selected to represent a wavelength delay of λ / 4 of the wavelength of light to be split by the beam splitter.

[0194] For example, if the wavelength of light to be split by the beam splitter is λ, the in-plane phase difference of the QWP may be within a range of about (λ / 4-20) nm to (λ / 4+20) nm.

[0195] For example, if the wavelength of light to be split by the beam splitter is about 940 nm, the in-plane phase difference of the QWP may be in the range of about 210 nm to 250 nm based on 940 nm. In this case, the in-plane phase difference is a value d×(nx-ny) obtained by multiplying the value obtained by subtracting the refractive index ny in the fast axis direction from the refractive index nx in the slow axis direction of the QWP by the thickness d of the QWP.

[0196] In the above, the angle formed by the ground axis direction of the QWP and the azimuth change direction of the geometric phase alignment layer can be adjusted. For example, when the QWP is present between two geometric phase alignment layers, the lower limit of the angle formed by the ground axis direction of the QWP and the azimuth change direction of one of the two geometric phase alignment layers or the angle formed by the ground axis direction of the QWP and the azimuth change directions of both of the two geometric phase alignment layers may be about 0 degrees, 20 degrees, 40 degrees, 60 degrees, 80 degrees, 85 degrees, or 90 degrees, and the upper limit thereof may be about 180 degrees, 160 degrees, 140 degrees, 120 degrees, 100 degrees, 95 degrees, or 90 degrees. The above angle may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above, and equal to or less than any upper limit arbitrarily selected from the upper limits listed above.

[0197] Under this arrangement, the characteristics of the intended beam splitter can be secured.

[0198] The above beam splitter may also additionally include one or more anti-reflection layers (AR layers) at appropriate locations, taking into account appropriate separation efficiency.

[0199] As described above, the geometric phase alignment layer or geometric phase grating alignment layer included in the beam splitter may include an aligned liquid crystal compound (a geometric phase aligned liquid crystal compound). In this case, the beam splitter may additionally include an alignment film that regulates the alignment of the liquid crystal compound.

[0200] There is no particular limitation on the type of alignment film capable of regulating the geometric phase alignment described above. Various types of alignment films capable of implementing geometric phase grating or geometric phase lens alignment are known in the industry. For example, the alignment film can be formed through laser pattern exposure performed by overlapping straight and diffused light, as disclosed in the literature (Optics Express Vol. 27, Issue 3, pp. 2632-2642 (2019)). Alternatively, an alignment film formed using the so-called nanoimprinting method can also be applied.

[0201] The beam splitter may also further include a substrate film (inorganic or organic substrate film) for maintaining the geometric phase alignment layer or alignment film, and an adhesive layer (adhesive layer or adhesive layer) for attaching a plurality of layers constituting the beam splitter.

[0202] FIGS. 20 to 23 are exemplary laminated structures of a beam splitter including elements selected from the group consisting of the first and second geometric phase alignment layers (10011, 10012), the phase difference film (300), the alignment film (201, 202), the adhesion layer (500), and the substrate film (401, 402, 400). The beam splitter may have various structures in addition to the structures illustrated in FIGS. 20 to 23, and one or more of the configurations illustrated in FIGS. 20 to 23 may be omitted or the lamination order may be changed as long as the beam splitter functions.

[0203] The present specification also discloses a dot projector comprising the beam splitter described above. The dot projector may include a beam splitter of any one of the various aspects described above and a light source. The light source may be present so as to irradiate light to at least the beam splitter. The wavelength of light irradiated by the light source may be adjusted according to the intended use of the beam splitter or the dot projector.

[0204] For example, the lower limit of the wavelength of the irradiated light of the light source may be about 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, 910 nm, 920 nm, 930 nm, or 940 nm, and the upper limit may be about 2,000 nm, 1,500 nm, 1,000 nm, or 950 nm. The wavelength may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above; within a range that is equal to or less than any upper limit arbitrarily selected from the upper limits listed above; or within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above and equal to or less than any upper limit arbitrarily selected from the upper limits listed above.

[0205] The present specification also discloses a device comprising the beam splitter or dot projector. Such a device may be, for example, a sensing device, and more specifically, a sensing device for 3D mapping. Specific examples of such a sensing device include, but are not limited to, a facial recognition device.

[0206] There are no particular limitations on the method of implementing the sensing device or facial recognition device, or on the specific types of other components other than the beam splitter or dot projector. As long as the beam splitter or dot projector disclosed herein is used, the device can be implemented in various known ways.

[0207] The present specification discloses a beam splitter and its use. The beam splitter can split a beam from a light source into multiple beams having a desired shape and intensity, and the beam splitter can be implemented with a simple configuration and process. The beam splitter can be applied to various sensing devices for 3D mapping or facial recognition devices, for example.

[0208] Figure 1 is a schematic diagram of an exemplary beam splitter.

[0209] Figure 2 is a schematic diagram of a geometric phase grating orientation, which is an example of a geometric phase orientation.

[0210] Figure 3 is a schematic diagram of a geometric phase lens orientation, which is an example of a geometric phase orientation.

[0211] Figure 4 is a schematic diagram explaining normal pitch.

[0212] Figures 5 and 6 are schematic diagrams for explaining the two-way pitch.

[0213] Figure 7 is a drawing for explaining the direction of rotation.

[0214] Figure 8 is a drawing for explaining the pitch of the geometric phase grating orientation.

[0215] Figure 9 is a drawing for explaining the pitch of the geometric phase lens orientation.

[0216] Figure 10 is a drawing for explaining the operation of a conventional geometric phase grating alignment layer.

[0217] FIGS. 11 and 12 are drawings illustrating exemplary geometric phase alignment layers disclosed herein.

[0218] FIG. 13 is a drawing for explaining the operation of the exemplary first and second geometric phase alignment layers disclosed in the present specification.

[0219] FIG. 14 is a drawing for explaining the pitch shape of the exemplary first and second geometric phase alignment layers disclosed in the present specification.

[0220] FIGS. 15 and 16 are drawings for explaining the shape of a split beam split by an exemplary beam splitter disclosed in this specification.

[0221] FIG. 17 is a drawing for explaining the pitch shape of the exemplary first and second geometric phase alignment layers disclosed in the present specification.

[0222] FIG. 18 is a drawing for explaining the pitch shape of an exemplary geometric phase alignment layer disclosed in the present specification.

[0223] FIG. 19 is a drawing for explaining the shape of a split beam split by an exemplary beam splitter disclosed in this specification.

[0224] Figures 20 to 23 are drawings for explaining the stacked form of an exemplary beam splitter disclosed in the present specification.

[0225] Fig. 24 is a drawing showing the shape of light split by the beam splitter of Example 1.

[0226] Figure 25 is a drawing showing the shape of light split by the beam splitter of Example 2.

[0227] Fig. 26 is a drawing showing the shape of light split by the beam splitter of Example 3.

[0228] Figure 27 is a drawing showing the shape of light split by the beam splitter of Example 4.

[0229] Fig. 28 is a drawing showing the shape of light split by the beam splitter of Example 5.

[0230] Figure 29 is a drawing showing the shape of light split by the beam splitter of Example 6.

[0231] Figure 30 is a drawing showing the shape of light split by the beam splitter of Example 7.

[0232] Fig. 31 is a drawing showing the shape of light split by the beam splitter of Example 8.

[0233] Figure 32 is a drawing showing the shape of light split by the beam splitter of Example 9.

[0234] Figure 33 is an example of an alignment film for forming a geometric phase alignment layer.

[0235] Hereinafter, the beam splitter will be specifically described through examples, but the scope of the beam splitter is not limited by the following transmittance variable device.

[0236]

[0237] Example 1.

[0238] An alignment film was formed on an isotropic alkali-free glass substrate (thickness: approximately 0.7 mm) using the nanoimprinting method. The alignment film was formed so that the liquid crystal compound formed a geometric phase grating alignment with a pitch of approximately 9.8 μm, as shown in Fig. 2. Fig. 33 is an image of the formed alignment film (nanoimprinting grating).

[0239] A coating solution containing a nematic liquid crystal compound (RM: Reactive Mesogen) is applied on the alignment film, and after maintaining it at about 70°C for about 2 minutes, it is cooled (around 40°C) to align the liquid crystal compound, and then UV rays are irradiated at about 400 mJ / cm using a Fusion UV system under a nitrogen atmosphere. 2A beam splitter was manufactured by forming a liquid crystal layer (geometric phase grating) with a thickness of about 2.6 μm by irradiating with a nematic liquid crystal compound. As the nematic liquid crystal compound, a liquid crystal compound (Merck, RMS03-013C) with a refractive index anisotropy (based on a wavelength of 550 nm) △n of about 0.12 was used. As a light source for a wavelength of 940 nm to confirm the characteristics of the beam splitter, Newport's LQC940-90E was used. Using the light source, light (Bi) with a wavelength of 940 nm was incident on the beam splitter (1000) as illustrated in Fig. 1.

[0240] Figure 24 is an image showing that the incident light is split into three light beams. The image was captured using THORLAB's DCC1645C-HQ (USB2.0 CMOS Camera, 1208×1024). Since the equipment does not include an IR cut filter, it can detect light with a wavelength of 940 nm.

[0241] It can be confirmed through the drawing that the desired light splitting effect can be obtained through the beam splitter.

[0242] The three lights in the drawing, referring to Fig. 1, are, from the left, the -1st order diffraction light (B o3 ), 0th order transmitted light (B o2 ) and first-order diffraction light (B o1 ) corresponds to.

[0243] The measurement results are as follows: -1st order diffraction light (B o3 ) was about 34%, and the 0th-order transmitted light (B o2 ) was about 32%, and the first-order diffraction light (B o1 ) was approximately 34%. The intensity was measured using a silicon detector of 918-UV-0D3R (Newport) and a power meter of Model 1918-R (Newport).

[0244]

[0245] Example 2.

[0246] A beam splitter was manufactured in the same manner as in Example 1, except that the thickness of the liquid crystal layer was adjusted to approximately 3.8 μm.

[0247] Fig. 25 is the result of confirming three split lights in the same manner as Example 1 for the beam splitter. Referring to Fig. 1, the three lights in the drawing are, from the left, -1st order diffraction light (B o3 ), 0th order transmitted light (B o2 ) and first-order diffraction light (B o1 ) corresponds to the measurement result of the -1st order diffraction light (B o3 ) was about 48%, and the 0th-order transmitted light (B o2 ) was about 4%, and the first-order diffraction light (B o1 ) was approximately 48%. From these results, it can be confirmed that the intensity of the split light can be adjusted by adjusting the thickness of the liquid crystal layer.

[0248]

[0249] Example 3.

[0250] Two geometric phase alignment layers were manufactured in the same manner as in Example 1. One alignment layer (the first alignment layer) was manufactured so that the pitch was approximately 9.8 μm and the thickness of the liquid crystal layer was approximately 2.7 μm, and the other alignment layer (the second alignment layer) was manufactured so that the pitch was approximately 3.24 μm and the thickness was approximately 2.7 μm. The liquid crystal compound for manufacturing the alignment layers was the same as in Example 1.

[0251] Next, as a QWP, a phase difference film having an in-plane phase difference of approximately 235 nm for a wavelength of 940 nm was prepared. A beam splitter was manufactured by sequentially laminating the first alignment layer, the QWP, and the second alignment layer. In the above, the azimuth change directions of the first and second alignment layers were approximately horizontal to each other, and the ground axis direction of the QWP was perpendicular to the azimuth change directions of the first and second alignment layers.

[0252] Figure 26 shows the results of confirming the split light in the same manner as in Example 1 for the beam splitter. In this case, the incident light was directed toward the first alignment layer among the first and second alignment layers. From the drawing, it can be confirmed that multiple split lights can be obtained through the beam splitter.

[0253]

[0254] Example 4.

[0255] A beam splitter was manufactured in the same manner as in Example 3, except that the angle formed by the azimuth change direction of the first alignment layer and the azimuth change direction of the second alignment layer was set to approximately 10 degrees, and the angle formed by the ground axis of the QWP and the azimuth change direction of the first alignment layer was set to approximately 90 degrees.

[0256] Figure 27 shows the results of confirming the split light in the same manner as in Example 1 for the above beam splitter. In this case, the incident light was incident toward the first alignment layer among the first and second alignment layers. From the drawing, it can be confirmed that the arrangement of the split light can be controlled by adjusting the angles of the two beam splitters.

[0257]

[0258] Example 5.

[0259] A beam splitter was manufactured in the same manner as in Example 3, except that the angle formed by the azimuth change direction of the first alignment layer and the azimuth change direction of the second alignment layer was set to approximately 90 degrees and QWP was not used.

[0260] Fig. 28 shows the results of confirming the split light in the same manner as in Example 1 for the above beam splitter. In this case, the incident light was incident toward the first alignment layer among the first and second alignment layers. From the drawing, it can be confirmed that multiple split lights can be obtained even without a QWP. However, since the application of a QWP can generate more split lights, the use of a QWP can be adjusted depending on the purpose.

[0261]

[0262] Example 6.

[0263] A beam splitter was manufactured in the same manner as in Example 5, except that a QWP was introduced between the first alignment layer and the second alignment layer, and the ground axis direction of the QWP was made at approximately 90 degrees to the azimuth change direction of the first alignment layer.

[0264] Fig. 28 shows the results of confirming the split light in the same manner as in Example 1 for the above beam splitter. In this case, the incident light was incident toward the first alignment layer among the first and second alignment layers. From the drawing, it can be confirmed that multiple split lights can be obtained even without a QWP. However, since the application of a QWP can generate more split lights, the use of a QWP can be adjusted depending on the purpose.

[0265]

[0266] Example 7.

[0267] As shown in Fig. 6, the alignment layer was formed to have a 180-degree bidirectional pitch. That is, as shown in Fig. 6, the alignment layer was formed so that a pattern in which a liquid crystal LC1 rotates 180 degrees clockwise to form a liquid crystal LC2, and a liquid crystal LC3 rotates 180 degrees counterclockwise from the liquid crystal LC2 is repeated. At this time, the distance from the liquid crystal LC1 to the liquid crystal LC2 is approximately 15 μm, and the distance from the liquid crystal LC2 to the liquid crystal LC3 is also approximately 15 μm.

[0268] The above liquid crystal layer was formed to a thickness of approximately 2.8 μm, and the same liquid crystal compound as in Example 1 was used as the liquid crystal compound.

[0269] Figure 29 shows the results of confirming split light in the same manner as in Example 1 for the above beam splitter. It can be confirmed that more than three split lights can be formed even using one alignment layer by adjusting the pitch shape.

[0270]

[0271] Example 8.

[0272] A beam splitter was manufactured by stacking the second alignment layer of Example 3 and the alignment layer of Example 7. At this time, the angle formed by the azimuth change directions of both alignment layers was set to be approximately 90 degrees.

[0273] Figure 30 shows the results of confirming the split light in the same manner as in Example 1 for the beam splitter. In this case, the incident light was incident toward the alignment layer of Example 7 among the two alignment layers. From the drawing, it can be confirmed that multiple split lights can be obtained from the beam splitter.

[0274]

[0275] Example 9.

[0276] Two alignment layers having a 180-degree bidirectional pitch of Example 7 were formed. In both alignment layers, the distance from liquid crystal LC1 to liquid crystal LC2 in Fig. 6 was approximately 15 μm, and the distance from liquid crystal LC2 to liquid crystal LC3 was also approximately 15 μm. However, one alignment layer (the first alignment layer) had a thickness of approximately 2.7 μm, and the other alignment layer (the second alignment layer) had a thickness of approximately 3.0 μm.

[0277] A beam splitter was manufactured by stacking the two alignment layers mentioned above. At this time, the angle formed by the azimuth change directions of both alignment layers was set to be approximately 90 degrees.

[0278] Figure 31 shows the results of confirming the split light in the same manner as in Example 1 for the beam splitter. In this case, the incident light was directed toward the first alignment layer among the two alignment layers. From the drawing, it can be confirmed that multiple split lights can be obtained from the beam splitter.

Claims

1. A first geometric phase alignment layer; and comprising a second geometric phase alignment layer, A beam splitter in which the first and second geometric phase alignment layers are arranged so that light transmitted through one of the first and second geometric phase alignment layers is incident on the other geometric phase alignment layer.

2. A beam splitter according to claim 1, wherein at least one of the first and second geometric phase alignment layers is a geometric phase grating alignment layer.

3. A beam splitter according to claim 1, wherein the first and second geometric phase alignment layers are each geometric phase grating alignment layers.

4. A beam splitter in which the transmittance of the 0th-order transmitted light of either one or each of the first and second geometric phase alignment layers in the first paragraph is 3% or more.

5. A beam splitter in which the pitches of the first and second geometric phase alignment layers are different from each other in the first paragraph.

6. A beam splitter in the first paragraph, wherein the ratio P2 / P1 of the pitch P2 of the second geometric phase alignment layer to the pitch P1 of the first geometric phase alignment layer is in the range of 0.1 to 10.

7. A beam splitter in accordance with claim 6, wherein the first and second geometric phase alignment layers are arranged such that a smaller pitch exists within a larger pitch among the pitches of the first and second geometric phase alignment layers.

8. A beam splitter in paragraph 1, wherein the smaller angle among the angles formed by the azimuth change direction in the first geometric phase alignment layer and the azimuth change direction in the second geometric phase alignment layer is within a range of 0 degrees to 175 degrees.

9. A beam splitter further comprising a phase difference film between the first and second geometric phase alignment layers in the first paragraph.

10. In the first paragraph, the first and second geometric phase alignment layers are each geometric phase grating alignment layers, A beam splitter wherein either of the first and second geometric phase alignment layers has a bidirectional pitch.

11. In the 10th paragraph, the first and second geometric phase alignment layers are beam splitters each having a bidirectional pitch.

12. A beam splitter in claim 11, wherein the first and second geometric phase alignment layers each have a 90 degree bidirectional pitch or a 180 degree bidirectional pitch.

13. A beam splitter in claim 11, wherein one of the first and second geometric phase alignment layers has a 90 degree bidirectional pitch and the other has a 180 degree bidirectional pitch.

14. A beam splitter in accordance with claim 10, wherein the transmittance of the 0th-order transmitted light of either or both of the first and second geometric phase alignment layers is 5% or more.

15. A beam splitter according to any one of paragraphs 1 to 14; and A dot projector comprising a light source configured to irradiate light to the beam splitter.

16. A sensing device comprising a beam splitter according to any one of claims 1 to 14.

17. A facial recognition device comprising a beam splitter according to any one of claims 1 to 14.

Images