JP2006058713A - Liquid crystal optical element and optical head device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small liquid crystal optical element which is less in aberration of transmission wavefront against temperature change, is excellent in light condensing characteristics on an optical disk and is excellent in mass productivity. <P>SOLUTION: The liquid crystal optical element 4 is obtained by stacking two opposing transparent substrates 201, 202 with a frame-like sealing material 203 interposed to form a gap and filling the inner region of the frame-like sealing material 203 with a liquid crystal layer 204, wherein the overlapped region of the transparent substrates 201, 202, observed from the side of the transparent substrate 201 or 202, has a wide region and a narrow region having large and short distance from the frame-like sealing material 203 to the outer edge of the overlapped region, respectively. At least one gap reinforcing member 206 to prevent distortion of the two transparent substrates 201, 202 is laid in the gap in the wide region. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid crystal optical element mounted on an optical head device that changes the phase of laser light that is linearly polarized light, and an optical head device mounted with the liquid crystal optical element.

First, the configuration of the conventional optical head device 100 will be described with reference to FIG.
In FIG. 4, the light beam emitted from the semiconductor laser light source 1 is converted into substantially parallel light having an effective diameter 10 by the collimator lens 2, passes through the polarization beam splitter 3, and then enters the liquid crystal optical element 4. The light beam that has passed through the liquid crystal optical element 4 passes through the quarter-wave plate 5 and is focused on the recording medium 9 (DVD or the like) by the objective lens 6.

  The light beam reflected from the recording medium 9 passes through the objective lens 6, the quarter-wave plate 5 and the liquid crystal optical element 4 again, the optical path is changed by the polarization beam splitter 3, and passes through the condenser lens 13. It is condensed on the light receiver 14. When the light beam is reflected by the recording medium 9, the light beam is amplitude-modulated by the information recorded on the track surface of the recording medium 9 and is output as a light intensity signal by the light receiver 14. Recorded information is read from this light intensity signal (reproduced signal).

  In the example of FIG. 4, the wavelength of the light beam is 650 nm, for example, and an error of ± 20 nm may occur. The “effective diameter” is the main light beam diameter on the liquid crystal optical element in the geometrical optical design that is effectively used in the objective lens 6 when there is no positional deviation or change in the diameter of the light beam. To tell. The aperture ratio NA of the objective lens 6 is set to 0.65, and the effective diameter is set to φ3 mm.

  The objective lens 6 is provided with a tracking actuator 7 and wiring 8 for driving the actuator. The objective lens 6 is placed in the direction of arrow A in the figure (radial direction of the circular recording medium 9). By moving, the light beam condensed by the objective lens 6 is configured to accurately follow the track of the recording medium 9. By acting in this way, the light beam 11 is corrected to the light beam 12. Here, the tracking movable range of the objective lens 6 is about ± 0.5 mm.

  The liquid crystal optical element 4 shown here has a function of correcting wavefront aberration generated in the substrate of the recording medium 9. Further, the liquid crystal optical element control circuit 15 detects wavefront aberrations (mainly coma aberration and spherical aberration) generated in the substrate of the recording medium 9 by using the light intensity signal from the light receiver 14, and cancels the detected wavefront aberration. As described above, a voltage is applied to the transparent electrode pattern formed on the liquid crystal optical element 4 through the wiring 16, and the phase of the liquid crystal layer sandwiched between the transparent electrode patterns is locally modulated. Correct. By such control, the wavefront aberration is corrected so that the intensity of the light intensity signal becomes appropriate.

  In response to a demand for downsizing an information reproducing apparatus or an information recording apparatus on which the optical head device 100 is mounted, downsizing of the optical head device 100 and each component constituting the device is required. The liquid crystal optical element mounted on such a downsized optical head device 100 is, for example, rectangular and has a small shape of 5 mm × 3 mm.

Next, a configuration example of the liquid crystal optical element 4 mounted on the optical device 100 (see FIG. 4) and an operation when the liquid crystal optical element 4 is thermally deformed will be described.
As shown in FIGS. 5 and 6, the liquid crystal optical element 4 is generally a frame-shaped sealing material 203 in which the outer edge portion of the transparent substrate 201 and the outer edge portion of the transparent substrate 202 are formed with a constant width of about 100 μm, for example. Is fixed with a gap width of 6 μm.

  Further, the shape of the frame-shaped sealing material 203 constituting the liquid crystal optical element 4 is a circle including a perfect circle (hereinafter, substantially circular) in which the ratio of the length to the major axis and the minor axis is 1.0 or more and 1.3 or less. Or a rectangular shape including a square defined in the same manner (hereinafter referred to as a substantially square shape) (see, for example, Patent Document 1).

  The liquid crystal optical element 4e shown in FIG. 5 and FIG. 6 shows an example in which the outer edge portions of the transparent substrate 201 and the transparent substrate 202 are substantially circular or square (as shown in the figure, an elliptical shape is shown). The structure is fixed by the frame-shaped sealing material 203 of FIG. 7 and has more preferable characteristics than the liquid crystal optical element 4f formed by the rectangular frame-shaped sealing material 203 shown in FIG.

Here, the characteristics of the liquid crystal optical element 4e having the above-described substantially circular frame-shaped sealing material 203 and the liquid crystal optical element 4f having the rectangular frame-shaped sealing material 203 will be described below.
Liquid crystal layers in the liquid crystal optical elements 4e and 4f due to an increase in the temperature of an external environment in the information reproducing apparatus mounted with the optical device 100 described above or an information recording / reproducing apparatus, or a temperature increase in other components constituting the apparatus. May expand. At that time, the transparent substrates 201 and 202 constituting the liquid crystal optical elements 4e and 4f bend toward the outside of the element.

FIG. 8 shows a cross-sectional shape when the liquid crystal optical elements 4e and 4f are bent.
FIG. 8A shows a liquid crystal optical element 4e having a substantially circular or substantially square frame-shaped sealing material 203 when the liquid crystal layer 204 is heated due to a temperature rise in the external environment (FIG. 5, FIG. 5). 6B), and FIG. 8B is a schematic diagram showing the cross-sectional shape of the liquid crystal optical element 4f having the same rectangular frame-shaped sealing material 203 (see FIG. 7).

  As shown in FIG. 8B, when heat is applied to the liquid crystal layer 204 from the outside, the liquid crystal optical element 4f having the rectangular frame-shaped sealing material 203 has an X1-X2 cross section (short-side cross section, see FIG. 6). , Y1-Y2 cross section (long side cross section, see FIG. 6), the transparent substrates 201 and 202 are deformed. That is, the liquid crystal layer 204 expands due to the temperature increase in the external environment described above. On the other hand, since the frame-shaped sealing material 203 hardly expands, the thickness of the liquid crystal layer 204 is thick at the center and thin at the outer edge.

  From the above description, in the liquid crystal optical element 4f in which the gap is uniformly manufactured without applying heat, the thickness of the central portion and the thickness of the outer edge portion should be equal in the X1-X2 cross section and the Y1-Y2 cross section. However, when heat is applied to the element 4f, it can be seen that due to the expansion of the liquid crystal layer 204, the curvature radii of both cross-sectional shapes of the liquid crystal layer 204 and the transparent substrates 201 and 202 differ. As described above, if the curvature radii are different between the X1-X2 cross section and the Y1-Y2 cross section, the liquid crystal optical element 4f is emitted when the liquid crystal optical element 4f is mounted on the optical device 100 (see FIG. 4). Astigmatism occurs in the light beam 2.

  On the other hand, in the case of the liquid crystal optical element 4e in which the shape of the frame-shaped sealing material 203 is substantially circular or substantially square, even if heat is applied and the liquid crystal layer 204 expands, it is shown in FIG. As described above, the radii of curvature of the liquid crystal layer 204 and the transparent substrates 201 and 202 having both cross-sectional shapes of the liquid crystal optical element 4e are equal. Thus, by making the shape of the frame-shaped sealing material 203 into a substantially circular shape or a substantially square shape, the fluctuation of the astigmatism component of the transmitted wavefront aberration accompanying the temperature rise can be suppressed as much as possible.

JP 2002-184017 A (page 3-4, FIGS. 1 and 2)

  This conventional liquid crystal optical element 4e is not particularly problematic when manufactured alone, but the following problems occur when a large number of liquid crystal optical elements 4e are formed simultaneously in a series of steps. .

First, a manufacturing method for obtaining a general liquid crystal optical element 4e at the same time will be described.
This conventional liquid crystal optical element 4e is manufactured using two large transparent substrates on which electrodes and the like are formed. That is, two large pieces of transparent substrates are arranged in a matrix and bonded together with a predetermined gap through a plurality of frame-shaped sealing materials 203 mixed with spacers to form a plurality of cells integrally.

  After that, the scribe break method is used to form a plurality of strip-shaped cells by cutting the transparent substrate into strips for each line-shaped cell arranged in a row, and then liquid crystal is simultaneously applied to the plurality of cells arranged in a row. Then, the liquid crystal inlet 205 is sealed to form a strip-shaped liquid crystal cell.

  The individual liquid crystal cells in the strip-shaped liquid crystal cell are cut into single pieces by a scribe break method or a dicing method, and a plurality of liquid crystal optical elements 4e are simultaneously manufactured.

  However, particularly when the shape of the frame-shaped sealing material 203 is square and the shape of the transparent substrate 202 is rectangular, or the shape of the transparent substrate 202 is square or rectangular, and the shape of the frame-shaped sealing material 203 is substantially circular. The shaped liquid crystal optical element 4e, that is, the overlapping region of the transparent substrates 201 and 202 has a wide region and a narrow region from the frame-shaped sealing material 203 to the outer edge of the overlapping region when viewed from the transparent substrate 201 or 202 side. In the case of the liquid crystal optical element 4 having the following, the following problems occur in the cutting process of the two bonded transparent substrates 201 and 202.

  The distance from the ends of the transparent substrates 201 and 202 to the frame-shaped sealing material 203, specifically, in the liquid crystal optical element 4e in FIG. 5, the frame-shaped seals from the ends of the transparent substrates 201 or 202 in the A region and the B region. Since the space to the material 203 is different, in the cutting process of the two bonded transparent substrates 201 and 202 (in the process of cutting the substrate by the scribe break method or the dicing method described above), compared to the A region In the region B far from the frame-shaped sealing material 203, the support by the frame-shaped sealing material 203 is weak and the transparent substrates 201 and 202 are greatly bent.

  As a result, the end surfaces of the transparent substrates 201 and 202 may not be cut vertically, microcracks may be generated in the substrates, or the substrate may be cracked in severe cases. Such a phenomenon not only lowers the reliability of the liquid crystal optical element 4e, but also reduces the manufacturing yield, and can be a factor for producing an element whose outer dimensions are not constant.

  Therefore, an object of the present invention is the above-mentioned problem, which is a small-sized liquid crystal optical element that is small in astigmatism fluctuation and excellent in mass productivity even when the external environment changes, and an optical device equipped with the same. Is to provide a pickup.

The liquid crystal optical element and the optical head device of the present invention use the following means in order to solve the above problems.
The liquid crystal optical element of the present invention is a liquid crystal optical element in which two transparent substrates facing each other are overlapped via a frame-shaped sealing material to form a gap, and a liquid crystal layer is disposed in an inner region of the frame-shaped sealing material. The overlapping area of the transparent substrate has a wide area and a narrow area from the frame-shaped sealing material to the outer edge of the overlapping area when viewed from the transparent substrate side, and two transparent layers are formed in the gap in the wide area. At least one gap reinforcing member for preventing the substrate from being bent is provided.

  Further, the gap reinforcing member in the liquid crystal optical element of the present invention is formed of a seal material made of the same material as the frame-shaped seal material, and a spacer for defining the gap is mixed in the seal material.

  Furthermore, the gap reinforcing member in the liquid crystal optical element of the present invention is provided in the vicinity of the outer edge of the overlapping region of the two transparent substrates.

  Furthermore, the gap reinforcing member in the liquid crystal optical element of the present invention is provided at each of the four corners of the transparent substrate.

  Furthermore, the gap reinforcing member in the liquid crystal optical element of the present invention is provided at two locations on one short side and one location on the other short side of the transparent substrate.

  The liquid crystal optical element of the present invention is a liquid crystal optical element in which two transparent substrates facing each other are overlapped via a frame-shaped sealing material to form a gap, and a liquid crystal layer is disposed in an inner region of the frame-shaped sealing material. The frame-shaped sealing material and the gap reinforcing member are integrated, and the sealing material is provided over the entire edge of the transparent substrate from the boundary between the liquid crystal layer and the frame-shaped sealing material.

  The shape of the frame-shaped sealing material in the liquid crystal optical element of the present invention is a substantially circular shape or a substantially square shape.

  Furthermore, the shape of the frame-shaped sealing material in the liquid crystal optical element of the present invention is an ellipse or a rectangle, and the seal width on the short side of the transparent substrate is narrower than the seal width on the long side. .

  The optical head device of the present invention includes an objective lens that condenses a light beam emitted from a laser light source onto a recording medium, and a light receiver that receives reflected light from the recording medium. The liquid crystal optical element is disposed in the optical path between the two.

  According to the present invention, the light beam emitted from the semiconductor laser light source 1 can always obtain a constant light collection characteristic by the objective lens 6 under various environments, and specifically, mounted on the optical head device 100. Even if the liquid crystal optical element 4 is heated due to a change in the external environment and the liquid crystal optical element 4 is thermally deformed, a small liquid crystal that suppresses astigmatism in this member as much as possible and is excellent in mass productivity. The optical element 4 and the optical head device 100 on which the optical element 4 is mounted can be provided.

FIGS. 1 to 3 are a plan view and a side view, respectively, showing a configuration example of the liquid crystal optical elements 4a to 4d in the optimum embodiment of the present invention.
In the liquid crystal optical elements 4a to 4c of the present invention shown in FIGS. 1 and 2, two transparent substrates 201 and 202 facing each other are overlapped with a frame-shaped sealing material 203 to form a gap. In the liquid crystal optical element 4 in which the liquid crystal layer 204 is arranged in the inner region of the sealing material 203, the overlapping region of the transparent substrates 201 and 202 is the outer edge of the overlapping region from the frame-shaped sealing material 203 when viewed from the transparent substrate 201 or 202 side. Adopting a configuration in which at least one gap reinforcing member 206 for preventing the bending of the two transparent substrates 201 and 202 is disposed in a gap in the wide region, with a wide region and a narrow region. Yes.

  These liquid crystal optical elements 4a to 4c according to the present invention have a configuration in which a gap reinforcing member for preventing the bending of two transparent substrates is disposed outside the frame-shaped sealing material 203, particularly in FIG. Like the liquid crystal optical element 4d shown in the figure, the configuration in which the reinforcing member is disposed over the entire outside of the frame-shaped sealing agent 203 is the most preferable mode for solving the problems in the conventional configuration described above. .

  With reference to the drawings, the specific arrangement and action of the gap reinforcing member 206 of the liquid crystal optical elements 4a to 4d of the present invention described above and the manufacturing method of the liquid crystal optical elements 4a to 4d will be described in detail.

  As shown in FIG. 1A, the liquid crystal optical element 4a according to the first embodiment of the present invention fixes a transparent substrate 201 and a transparent substrate 202 with a frame-shaped sealing material 203 mixed with a spacer, and a liquid crystal layer on the inside thereof. 204 is arranged. Further, the shape of the frame-shaped sealing material 203 is substantially circular (in the drawing, a case where the shape is a perfect circle) is shown, and like the frame-shaped sealing material 203, a gap mixed with a spacer is used. Reinforcing members 206 are arranged at the four corners. As described above, in this configuration, the frame-shaped sealing material 203 has a substantially circular shape as in the conventional configuration. Therefore, even if the external environment changes (temperature increases), the conventional liquid crystal optical element 4e (see FIG. 5 and FIG. 6), a small liquid crystal optical element 4a in which the generation of astigmatism is minimized can be obtained.

  Since the liquid crystal optical element 4a of the present invention has the gap reinforcing members 206 at the four corners of the rectangular transparent substrate 202 as described above, the substrate is cut when a large number of the liquid crystal optical elements 4a are manufactured simultaneously. There is no conventional configuration that can prevent the bending of the transparent substrates 201 and 202 in the process, can obtain a reliable liquid crystal optical element 4a, and can be a liquid crystal optical element 4a excellent in mass productivity. It has the effect. The reason will be described below.

  The liquid crystal optical element 4a of the present invention is a space from the frame-shaped sealing material 203 to the end portions of the transparent substrates 201 and 202 like the region B in FIG. 5 described in the background art, and there is no sealing material in a wide space. It can be seen that there is no area. Therefore, the gap reinforcing member 206 constituting the liquid crystal optical element 4a prevents the bending of the transparent substrates 201 and 202 in the above-described substrate cutting step, and the substrate cannot be cut vertically at the outer edges of the transparent substrates 201 and 202. Thus, it is possible to prevent a phenomenon that a microcrack is generated or a substrate is cracked when it is severe. Thus, when a large number of liquid crystal optical elements 4 are manufactured at the same time, the configuration of the liquid crystal optical element 4a in the first embodiment of the present invention is advantageous.

  Further, as shown in FIG. 1B, the shape of the frame-shaped sealing material 203 in contact with the frame-shaped sealing material 203 and the liquid crystal layer 204 is an ellipse (the length of the major axis and the minor axis in an ellipse included in the substantially circular shape). When the liquid crystal optical element 4b has a thickness ratio of 1.3 or more), the width of the short-side frame-shaped sealing material 203 is set to the width of the long-side frame-shaped sealing material 203 by the liquid crystal optical element. It is preferable to make it wide according to the size of the element 4. The reason will be described below.

  As described in the background art, if the shape of the frame-shaped sealing material 203 of the liquid crystal optical element 4 is simply an ellipse, the amount of variation in the astigmatism of the transmitted wavefront aberration increases as the environmental temperature increases. . Therefore, in the liquid crystal optical element 4b of the present invention, in order to reduce the amount of fluctuation of the astigmatism of the transmitted wavefront aberration, the ratio of the long side width to the short side of the oval seal shape is 0.8 or less, that is, The width of the short-side frame-shaped sealing material 203 was formed to be about 20% wider than the width of the long-side frame-shaped sealing material 203.

  By forming the long-side frame-shaped sealing material 203 in this way, the substrate is easily deformed as the liquid crystal layer 204 expands due to heat. As a result, as shown above, the frame-shaped sealing material Even if the shape of 203 is not substantially circular, the generation of astigmatism can be suppressed as much as possible with respect to external environmental changes, as in the configuration example described above.

  In the liquid crystal optical elements 4a and 4b described above, an example in which a seal material mixed with a spacer is used for the gap reinforcing member 206 is shown. However, this is the same at the same time when the frame-shaped seal material 203 is formed. This is in consideration of the manufacturing advantage that the gap reinforcing member 206 can be formed of a material.

  However, the material and arrangement process of the gap reinforcing member 206 are not limited to this, and a material different from the frame-shaped sealing material 203 as long as the gap of the liquid crystal optical elements 4a and 4b can be controlled. The spacers may be arranged in different steps. The spacers are not mixed in the frame-shaped sealing material 203, and the spacers are dispersed in advance at the positions where the liquid crystal layer 204 is disposed. It does not matter as a form mixed with.

  Further, in the liquid crystal optical elements 4a and 4b described above, the configuration example in which the shape of the frame-shaped sealing material 203 is substantially circular or oval has been shown, but the shape of the frame-shaped sealing material 203 is changed to that of the liquid crystal optical element 4a. In the case of the liquid crystal optical element 4b, the same effect as described above can be obtained.

  Furthermore, although the liquid crystal optical elements 4a and 4b described above have shown configuration examples using the rectangular transparent substrates 201 and 202, the shape of the substrate is not limited to this, and the effects of the present invention can be obtained. Other configurations that can be used, for example, a transparent substrate having a square shape, a polygonal shape, or a circular shape may be used.

Here, a method for manufacturing the liquid crystal optical elements 4a and 4b in Embodiment 1 will be briefly described.
In the liquid crystal optical elements 4a and 4b of the present invention, a plurality of frame-shaped sealing materials 203 in which one large transparent substrate is arranged in a matrix and at least one gap reinforcing member 206 are arranged in a printing process, and the other Are bonded together to form a plurality of cells integrally with a predetermined gap defined by a spacer.

  Subsequent manufacturing steps are the same as before, and the scribe break method is used to form a plurality of strip-shaped cells by cutting each strip-shaped cell in a line into a long strip, and then aligning in this line. Liquid crystal is simultaneously injected into a plurality of cells, and the liquid crystal injection port 205 is sealed to form a strip-like liquid crystal cell.

  The individual liquid crystal cells in the strip-shaped liquid crystal cell are cut into single pieces by a scribe break method or a dicing method, and a plurality of liquid crystal optical elements 4a and 4b are manufactured simultaneously.

  As described above, the liquid crystal optical elements 4a and 4b can be manufactured by changing only the mask for printing the sealing material with respect to the conventional manufacturing method, and the other processes can be manufactured by the same process as before.

  Next, the configuration of the liquid crystal optical element 4c in Embodiment 2 of the present invention will be described. FIG. 2 is a plan view and a side view showing a configuration example of the liquid crystal optical element 4c in the present embodiment.

  As shown in this drawing, the liquid crystal optical element 4c in the present example is a rectangular short side constituting the liquid crystal optical element 4c, and two points outside the substantially circular frame-shaped sealing material 203; The only difference from the first embodiment is that the gap reinforcing member 206 is arranged at one point on the outer side of the substantially circular frame-shaped sealing material 203 near the center of the other short side. Since it is the same about other structures, the description about a common member is omitted.

  The liquid crystal optical element 4c shown here is particularly effective when a large number of gap reinforcing members 206 need only be disposed on the surface of the liquid crystal optical element 4 that requires the external dimension accuracy.

  In addition, since the manufacturing method of the liquid crystal optical element 4c of a present Example is fundamentally the same as the manufacturing method shown in Example 1, description here is abbreviate | omitted.

  Next, the configuration of the liquid crystal optical element 4d in Embodiment 3 of the present invention will be described. FIG. 3 is a plan view and a side view showing a configuration example of the liquid crystal optical element 4d in the present embodiment.

  As shown in the drawing, the liquid crystal optical element 4d in the present embodiment is provided with a frame-shaped sealing material 203 from the substantially circular frame-shaped sealing material shown in FIG. A form in which the frame-shaped sealing material 203 in contact with the layer 206 and a gap reinforcing member provided on the outside thereof are integrated is shown. This configuration can more stably prevent the bending of the substrate in the substrate cutting process compared to the configuration examples shown in the first and second embodiments, and when the liquid crystal optical element 4 is mass-produced, Specifically, it can be the most effective configuration for cutting the substrate satisfactorily.

  If the above-described liquid crystal optical elements 4a to 4d according to the present invention are mounted on the optical device 100 (see FIG. 4), the light beam emitted from the semiconductor laser light source 1 is always constant by the objective lens 6 in various environments. Specifically, even if thermal deformation occurs in the liquid crystal optical elements 4a to 4d mounted on the optical head device 100, the generation of astigmatism in this member is suppressed as much as possible, and mass production is achieved. An optical head device 100 equipped with excellent small liquid crystal optical elements 4a to 4d can be provided.

It is the top view and side view which showed the structural example of the liquid crystal optical element of this invention (Example 1). (Example 2) which is the top view and side view which showed the other structural example of the liquid crystal optical element of this invention. (Example 3) which is the top view and side view which showed the other structural example of the liquid crystal optical element of this invention. It is a conceptual diagram which shows an example of the general optical head apparatus by which a liquid crystal optical element is mounted. It is the top view and side view which showed the structure of the conventional liquid crystal optical element. It is a perspective view in the conventional liquid crystal optical element. It is the top view and side view which showed the other structure of the conventional liquid crystal optical element. It is a conceptual diagram for demonstrating the deformation | transformation phenomenon of an element when the external environmental change is added to the conventional liquid crystal optical element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor laser light source 2 Collimator lens 3 Polarizing beam splitter 4 Liquid crystal optical element 5 1/4 wavelength plate 6 Objective lens 9 Recording medium 10 Effective diameter 13 Condensing lens 14 Light receiver 15 Liquid crystal optical element control circuit 201 Substrate 202 Substrate 203 Frame shape Seal material 204 Liquid crystal layer 205 Inlet 206 Gap reinforcing member

Claims (9)

In a liquid crystal optical element in which two transparent substrates facing each other are overlapped via a frame-shaped sealing material to form a gap, and a liquid crystal layer is arranged in an inner region of the frame-shaped sealing material,
The overlapping area of the transparent substrate has a wide area and a narrow area from the frame-shaped sealing material to the outer edge of the overlapping area as seen from the transparent substrate side,
A liquid crystal optical element, wherein at least one gap reinforcing member for preventing bending of the two transparent substrates is disposed in the gap in the wide area.   2. The liquid crystal optical element according to claim 1, wherein the gap reinforcing member is formed of a seal material that is the same material as the frame-shaped seal material, and a spacer that defines a gap is mixed in the seal material.   The liquid crystal optical element according to claim 1, wherein the gap reinforcing member is provided in the vicinity of an outer edge portion of an overlapping region of the two transparent substrates.   The liquid crystal optical element according to claim 3, wherein the gap reinforcing member is provided at each of four corners of the transparent substrate.   4. The liquid crystal optical element according to claim 3, wherein the gap reinforcing member is provided at two locations on one short side and one location on the other short side of the transparent substrate. In a liquid crystal optical element in which two transparent substrates facing each other are overlapped via a frame-shaped sealing material to form a gap, and a liquid crystal layer is arranged in an inner region of the frame-shaped sealing material,
The frame-shaped sealing material and the gap reinforcing member are integrated, and a sealing material in which a spacer is mixed from the boundary between the liquid crystal layer and the frame-shaped sealing material to the end of the transparent substrate is provided. A liquid crystal optical element characterized by the above.   The liquid crystal optical element according to claim 1, wherein the frame-shaped sealing material has a substantially circular shape or a substantially square shape.   The shape of the frame-shaped sealing material is an ellipse or a rectangle, and the seal width on the short side of the rectangular transparent substrate is narrower than the seal width on the long side. The liquid crystal optical element according to any one of the above. An objective lens for condensing a light beam emitted from a laser light source onto a recording medium, and a light receiver for receiving reflected light from the recording medium,
9. An optical head device comprising the liquid crystal optical element according to claim 1 disposed in an optical path between the laser light source and the objective lens.

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