JP2018045187A - Light flux division element and microscope device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light flux division element that can adjust a direction of dividing a light flux and an interval between the divided light fluxes without requiring for a mechanical work.SOLUTION: A light flux division element has: a first light flux division element 21 that has a liquid crystal layer in which a liquid crystal molecule oriented along a prescribed orientation direction is included, and divides linear polarization transmitting the liquid crystal layer into a first light flux and a second light flux in accordance with a voltage distribution to be applied to the liquid crystal layer, and causes the second light flux to be deflected at a first deflection angle along a set deflection direction with respect to the first light flux; a second light flux element 22 that has the liquid crystal layer in which the liquid crystal molecule oriented along the orientation direction is included, and in accordance with the voltage distribution to be applied to the liquid crystal layer, causes the second light flux transmitting the liquid crystal layer to be deflected at a second deflection angle with respect to the first light flux transmitting the liquid crystal layer; and a control unit 23 that controls the voltage distribution to be applied to the liquid crystal layer of the first light flux element 21 and the voltage distribution to be applied to the liquid crystal layer of the second light flux element 22 in accordance with the set deflection direction, the first deflection angle and the second deflection angle.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a light beam splitting element that splits a light beam, and a microscope apparatus that uses such a light beam splitting element.

  Conventionally, a differential interference method capable of visualizing the structure of a transparent sample by the interference of two light beams passing through positions close to each other of the sample, and a microscope based on the principle of differential interference method (hereinafter referred to as a differential interference microscope). ) Is known (see, for example, Patent Documents 1 and 2).

  In the differential interference method and differential interference microscope, a Nomarski prism is used to divide the light beam from the light source into two light beams and to match the two light beams transmitted through the sample into one.

JP-A-9-281401 JP 2003-5080 A

  In the differential interference method and the differential interference microscope, the contrast and resolution of the image of the sample change according to the distance between the two light beams when the two light beams pass through the sample (referred to as a shear amount). In general, the greater the shear amount, the better the contrast and the lower the resolution. Conversely, the smaller the shear amount, the lower the contrast and the higher the resolution. Therefore, the appropriate shear amount varies depending on the type of sample and the observation purpose of the sample. On the other hand, the amount of shear generated is determined according to the Nomarski prism used. Therefore, for example, every time a sample to be observed is replaced, the Nomarski prism attached to the differential interference microscope is required to be replaced with one that can generate an appropriate shear amount according to the sample.

  Further, depending on the sample, the direction in which the shear amount is generated, that is, the direction in which the two light beams are aligned when passing through the sample is also different. That is, in order to visualize the sample structure due to the interference of the two light beams, a phase difference corresponding to the sample structure needs to be generated between the two light beams. Therefore, for example, it is preferable that two light beams are arranged along the direction in which the thickness or refractive index of the sample changes. Therefore, conventionally, it has been necessary to rotate the sample in order to appropriately set the direction in which the two light beams are arranged. However, when the sample is rotated, portions other than the rotation axis may be out of the field of view due to the rotation of the sample. As described above, conventionally, in order to appropriately set the shear amount and the direction in which the shear amount is generated according to the sample, complicated mechanical work is required.

  Therefore, an object of the present invention is to provide a light beam splitting element that can adjust the direction of splitting a light beam and the interval between the divided light beams without requiring mechanical work.

  According to one aspect of the present invention, a light beam splitting element is provided. This beam splitting element has a liquid crystal layer containing liquid crystal molecules aligned along a predetermined alignment direction, and generates linearly polarized light that passes through the liquid crystal layer according to a voltage distribution applied to the liquid crystal layer. A first liquid crystal element that divides the light beam into a first light beam and a second light beam and deflects the second light beam with respect to the first light beam at a first deflection angle along a set deflection direction; A liquid crystal layer including liquid crystal molecules aligned along a direction, and transmitting the liquid crystal layer with respect to a first light flux passing through the liquid crystal layer according to a voltage distribution applied to the liquid crystal layer A second liquid crystal element that deflects the second luminous flux to be deflected at the second deflection angle, and a voltage applied to the liquid crystal layer of the first liquid crystal element according to the deflection direction, the first deflection angle, and the second deflection angle A controller for controlling the distribution and the voltage distribution applied to the liquid crystal layer of the second liquid crystal element.

  In this light beam splitting element, the control unit applies the first light beam and the second light beam to the liquid crystal layer of the first liquid crystal element such that the first light beam and the second light beam intersect at a predetermined distance from the second liquid crystal element. It is preferable to control the voltage distribution to be applied and the voltage distribution applied to the liquid crystal layer of the second liquid crystal element.

  Furthermore, in this light beam splitting element, the first liquid crystal element has a first transparent electrode and a second transparent electrode facing each other with the liquid crystal layer interposed therebetween, and the first transparent electrode is in the first direction. A plurality of partial electrodes arranged along the same, adjacent partial electrodes of the plurality of partial electrodes are connected via a resistor, and the second transparent electrode is a first electrode orthogonal to the first direction. The plurality of partial electrodes arranged along the direction 2 are connected to each other through the resistors, and the control unit has the first transparent electrode. The deflection direction between the partial electrode at one end and the partial electrode at the other end of the plurality of partial electrodes, and between the partial electrode at one end and the partial electrode at the other end of the plurality of partial electrodes included in the second transparent electrode, and It is preferable to apply a voltage corresponding to the first deflection angle.

  In addition, the controller controls the first liquid crystal element so that the second deflection angle is opposite to the first deflection angle and the second deflection angle is larger than the first deflection angle. It is preferable to control the voltage distribution applied to the liquid crystal layer and the voltage distribution applied to the liquid crystal layer of the second liquid crystal element.

  Further, the control unit applies the voltage distribution applied to the liquid crystal layer of the first liquid crystal element and the liquid crystal of the second liquid crystal element so that the refractive index for the linearly polarized light component parallel to the alignment direction changes along the deflection direction. It is preferable to control the voltage distribution applied to the layer.

  According to another aspect of the present invention, a microscope apparatus is provided. This microscope apparatus divides a linearly polarized light into a first light beam and a second light beam arranged along a set deflection direction, and the first light beam according to a set shear amount. A light beam splitting element that tilts the second light beam with respect to the first light beam, a lens that directs the first light beam and the second light beam toward the sample at intervals according to the shear amount, the first light beam and the first light beam that have passed through the sample And an imaging unit that images the sample with one luminous flux obtained by combining the two luminous fluxes. The light beam splitting element includes a liquid crystal layer including liquid crystal molecules aligned along a predetermined alignment direction, and first linearly polarized light that passes through the liquid crystal layer according to a voltage distribution applied to the liquid crystal layer. A first liquid crystal element that divides the second luminous flux with respect to the first luminous flux and deflects the second luminous flux along the predetermined deflection direction at a first deflection angle corresponding to the shear amount. A liquid crystal layer including liquid crystal molecules aligned along a predetermined alignment direction, and the first light flux transmitted through the liquid crystal layer according to a voltage distribution applied to the liquid crystal layer A second liquid crystal element that crosses the first light beam and the second light beam at the front focal position of the lens by deflecting the second light beam transmitted through the liquid crystal layer at a second deflection angle corresponding to the shear amount; , The liquid crystal of the first liquid crystal element according to the deflection direction, the first deflection angle, and the second deflection angle And a control unit for controlling the voltage distribution applied to the liquid crystal layer of the voltage distribution and a second liquid crystal element to be applied to.

  The light beam splitting element according to the present invention has an effect that the direction in which the light beam is split and the interval between the split light beams can be adjusted without requiring mechanical work.

It is a schematic block diagram of the microscope apparatus which has the light beam splitting element which concerns on one Embodiment of this invention. It is a schematic block diagram of a light beam splitting element. (A) is a schematic front view of a 1st liquid crystal element, (b) is a schematic side sectional view of the 1st liquid crystal element in the line shown by arrow A, A 'of (a). It is a figure which shows arrangement | positioning of each transparent electrode which a 1st liquid crystal element has. It is a figure which shows the relationship between the voltage applied between the partial electrodes of the both ends of each transparent electrode, the voltage applied to one transparent electrode, and the voltage applied to the other transparent electrode. (A) is a figure explaining the relationship between the positional relationship of each liquid crystal element of a light beam splitting element and a condenser lens, and the inclination and shear amount of an extraordinary ray with respect to the optical axis, and (b) is the focal length of the condenser lens. FIG. 6 is a diagram illustrating an example of a table representing a relationship between a deflection angle of an extraordinary ray by each liquid crystal element and a shear amount.

  Hereinafter, a light beam splitter according to one embodiment will be described with reference to the drawings. This light beam splitting element has two liquid crystal elements arranged along the optical axis. Each liquid crystal element has a plurality of partial electrodes in which one of two transparent electrodes facing each other across the liquid crystal layer is arranged along the first direction, and the other transparent electrode is in the first direction. And a plurality of partial electrodes arranged along a second direction orthogonal to the first direction. The light beam splitting element converts the linearly polarized light that passes through each liquid crystal element according to the voltage distribution applied to the liquid crystal layer, which is given by adjusting the voltage applied between the partial electrodes at both ends of each transparent electrode. The light beam is divided into two light beams, and the deflection direction in which the two light beams are arranged and the angle between the two light beams are controlled.

  FIG. 1 is a schematic configuration diagram of a microscope apparatus having a light beam splitting element according to one embodiment of the present invention. As shown in FIG. 1, the microscope apparatus 100 is a differential interference microscope, and in order along the optical axis of the optical system of the microscope apparatus 100, the light source 1, the light beam splitting element 2-1 according to the present embodiment, The condenser lens 3, the objective lens 4, the light beam splitting element 2-2 according to the present embodiment, and the imaging unit 5 are included. A sample 10 is disposed between the condenser lens 3 and the objective lens 4. Note that the microscope apparatus 100 may have various compensation optical systems such as a spherical aberration compensation optical system on the optical path. Further, the microscope apparatus 100 may include a collimating optical system for making the light emitted from the light source 1 parallel light between the light source 1 and the light beam splitting element 2-1. Further, when the sample 10 is observed with the light reflected by the sample 10, the light beam splitting element 2-2 may be omitted. Further, instead of the condenser lens 3, an objective lens is arranged. In this case, for example, a beam splitter (not shown) is disposed between the beam splitter 2-1 and the light source 1. Then, the light reflected by the sample 10 passes through the objective lens and the light beam splitting element 2-1, and then is reflected by the beam splitter in the direction orthogonal to the optical axis direction of the objective lens and enters the imaging unit 5. The imaging unit 5 is arranged.

  The light source 1 outputs illumination light that is linearly polarized light having a predetermined polarization plane. For this purpose, the light source 1 includes, for example, a semiconductor laser. Alternatively, the light source 1 may have a gas laser such as an argon ion laser or a solid-state laser such as a YAG laser. Alternatively, the light source 1 includes, for example, a light-emitting element that emits light that is not linearly polarized light, such as a mercury lamp, a xenon arc lamp, or an incandescent light bulb, and a component having a predetermined polarization plane among light emitted from such a light-emitting element. And a polarizing plate that transmits the light to linearly polarized light.

  Furthermore, the light source 1 may include a plurality of light emitting elements that output light having different wavelengths. In this case, the light source 1 causes one of the light emitting elements to output illumination light in accordance with a control signal from a controller (not shown).

The light beam splitting element 2-1 is disposed between the light source 1 and the condenser lens 3. The light beam splitting element 2-1 splits the illumination light output from the light source 1 into two light beams arranged along a predetermined deflection direction, and crosses the two light beams at the front focal position of the condenser lens 3.
Details of the light beam splitting element 2-1 will be described later.

  The condenser lens 3 condenses each of the two light beams emitted from the light beam splitting element 2-1 on the sample 10. As described above, since the two light beams emitted from the light beam splitting element 2-1 intersect at the front focal position of the condenser lens 3, the two light beams reach the sample 10 in parallel with each other by the condenser lens 3. . Further, as the angle between the two light beams at the front focal position of the condenser lens 3 increases, the distance (that is, the shear amount) between the two light beams when passing through the sample 10 increases.

  The objective lens 4 condenses two light beams that have been emitted from the condenser lens 3 and transmitted through the sample 10. At that time, the two light beams pass through the objective lens 4 and intersect each other at an angle corresponding to the power of the objective lens 4 at the rear focal position of the objective lens 4.

  The beam splitting element 2-2 is disposed at a position farther from the objective lens 4 than the rear focal position of the objective lens 4, and converts the two beams emitted from the objective lens 4 into one beam. Thereby, interference resulting from the structure of the sample 10 occurs between the two light beams.

  The imaging unit 5 includes, for example, an image sensor in which a plurality of individual imaging elements such as CCDs or C-MOSs are arranged in an array. Furthermore, the imaging unit 5 may have an imaging optical system that forms an image of the sample 10 on the image sensor. And the imaging part 5 produces | generates the image of the sample 10 obtained by the interference which arises in the light beam obtained through the objective lens 4 and the light beam splitting element 2-2, and outputs the image to a controller.

  Hereinafter, details of the light beam splitting elements 2-1 and 2-2 according to the present embodiment will be described. Since the light beam splitting element 2-1 and the light beam splitting element 2-2 can have the same configuration, the light beam splitting element 2-1 will be described below.

  FIG. 2 is a schematic configuration diagram of the light beam splitting element 2-1. The light beam splitting element 2-1 includes a first liquid crystal element 21, a second liquid crystal element 22, and a control circuit 23. The first liquid crystal element 21 and the second liquid crystal element 22 are sequentially arranged from the light source 1 side along the optical axis OA of the optical system included in the microscope apparatus 100.

  The illumination light incident on the light beam splitting element 2-1 is orthogonal to the alignment direction of the liquid crystal molecules in the liquid crystal layer by the control circuit 23 controlling the voltage distribution applied to the liquid crystal layer of the first liquid crystal element 21. The light beam is split into a light beam having a polarization plane (that is, an ordinary ray) and a light beam having a polarization plane parallel to the orientation direction (that is, an extraordinary ray). An ordinary ray (first light beam) is emitted from the first liquid crystal element 21 as a light beam parallel to the optical axis OA. On the other hand, the extraordinary ray (second light flux) is transmitted in an arbitrary deflection direction with respect to the optical axis OA in accordance with the control of the voltage distribution applied to the liquid crystal layer of the first liquid crystal element 21 by the control circuit 23. The light is emitted from the first liquid crystal element 21 at a predetermined deflection angle.

  The ordinary ray and the extraordinary ray emitted from the first liquid crystal element 21 are incident on the second liquid crystal element 22. The control circuit 23 controls the voltage distribution applied to the liquid crystal layer included in the second liquid crystal element 22, thereby adjusting the deflection angle of the extraordinary ray. As a result, the extraordinary ray is emitted so as to go to the front focal position of the condenser lens 3. On the other hand, the ordinary ray travels straight along the optical axis OA even after passing through the second liquid crystal element 22. Therefore, the ordinary ray and the extraordinary ray intersect at the front focal position of the condenser lens 3.

  Hereinafter, details of each liquid crystal element included in the light beam splitting element 2-1 will be described. In addition, since the 1st liquid crystal element 21 and the 2nd liquid crystal element 22 can be set as the same structure, below, the 1st liquid crystal element 21 is demonstrated.

  FIG. 3A is a schematic front view of the first liquid crystal element 21, and FIG. 3B is a diagram illustrating the first liquid crystal element 21 along the lines indicated by arrows A and A ′ in FIG. FIG. FIG. 4 is a diagram showing the arrangement of the transparent electrodes included in the first liquid crystal element 21.

  The first liquid crystal element 21 has two transparent substrates 31 and 32 arranged substantially parallel to the liquid crystal layer 30 so as to face each other across the liquid crystal layer 30 along the optical axis OA. The first liquid crystal element 21 includes a transparent electrode 33 disposed between the transparent substrate 31 and the liquid crystal layer 30, and a transparent electrode 34 disposed between the liquid crystal layer 30 and the transparent substrate 32. The liquid crystal molecules 37 contained in the liquid crystal layer 30 are sealed between the transparent substrates 31 and 32 and the seal member 38. The liquid crystal layer 30 has a thickness sufficient to give a predetermined deflection angle to the extraordinary ray of the illumination light transmitted by the first liquid crystal element 21, for example, 10 μm to 20 μm.

  The transparent substrates 31 and 32 are formed of a material that is transparent to the illumination light emitted from the light source 1, such as glass or resin. In addition, the transparent electrodes 33 and 34 are formed of, for example, a material in which tin oxide is added to indium oxide called ITO. Further, an alignment film 35 is disposed between the transparent electrode 33 and the liquid crystal layer 30. An alignment film 36 is disposed between the transparent electrode 34 and the liquid crystal layer 30. These alignment films 35 and 36 align the liquid crystal molecules 37 in a predetermined direction.

  The liquid crystal molecules 37 sealed in the liquid crystal layer 30 are, for example, homogeneously aligned. The alignment direction of the liquid crystal molecules 37 is greater than 0 degree (ie, parallel) and less than 90 degrees (ie, orthogonal) with respect to the polarization plane 312 of the incident illumination light, as indicated by an arrow 311. Is set to an angle of Thereby, the liquid crystal element 21 can divide the illumination light into an ordinary ray and an extraordinary ray. The angle formed by the alignment direction of the liquid crystal molecules 37 and the polarization plane 312 of the incident illumination light is preferably set to about 45 degrees so that the intensity of the ordinary light and the intensity of the extraordinary light are equal.

  As shown in FIG. 4, in the present embodiment, the transparent electrode 33 includes a plurality of linear partial electrodes 33-1 divided at equal intervals along the first direction 401 on a plane orthogonal to the optical axis OA. ~ 33-m (m is an integer of 2 or more). The plurality of partial electrodes 33-1 to 33-m cover the entire active region where the liquid crystal molecules 37 are driven. On the other hand, the transparent electrode 34 has a plurality of linear partial electrodes 34-1 to 34-34 divided at equal intervals along a second direction 402 orthogonal to the first direction 401 on a plane orthogonal to the optical axis OA. m (n is an integer of 2 or more). In FIG. 4, the gap between the partial electrodes is indicated by a line. Note that the first direction 401 and the second direction 402 may be set independently of the alignment direction of the liquid crystal molecules 37. Further, the first direction 401 and the second direction 402 may be the same in the first liquid crystal element 21 and the second liquid crystal element 22 or may be different. Further, the first direction 401 and the second direction 402 may be set independently with respect to the polarization plane of the incident light.

  In the transparent electrode 33, two adjacent partial electrodes are connected by an electrode (resistor) having the same electrical resistance. The control circuit 23 applies a voltage between the partial electrode 33-1 at one end of the partial electrodes 33-1 to 33-m and the partial electrode 33-m at the other end. Specifically, each partial electrode is connected to a high resistance wiring having a resistance value corresponding to the length at equal intervals, and a voltage is applied from the control circuit 23 between both ends of the high resistance wiring. Therefore, the voltage applied in steps changes along the first direction. Similarly, in the transparent electrode 34, two adjacent partial electrodes are connected by electrodes having the same electrical resistance. The control circuit 23 applies a voltage between the partial electrode 34-1 at one end and the partial electrode 34-n at the other end of the partial electrodes 34-1 to 34-n. Therefore, the voltage applied stepwise changes along the second direction.

Here, when a voltage V is applied between the transparent electrode 33 and the transparent electrode 34, that is, the liquid crystal layer 30, the direction in which the voltage is applied (that is, along the optical axis OA) according to the voltage V. The major axis direction of the liquid crystal molecules 37 is inclined in parallel with the direction). At this time, the direction in which the liquid crystal molecules 37 are oriented parallel to the polarization component (i.e., the extraordinary ray) when the refractive index of the liquid crystal molecules n _[psi and _(V) for, and _{n o ≦ n ψ (V)} ≦ n e . However, n _o polarization component (i.e., ordinary ray) perpendicular to the alignment direction of liquid crystal molecules is the refractive index with respect to, n _e is the refractive index for parallel polarization component in the longitudinal direction of the liquid crystal molecules.

ここで、φは第１の方向と液晶分子３７の配向方向とがなす角を表す。したがって、ΔVU及びΔVLが適切に調節されることで、光軸ＯＡに直交する面における、異常光線の偏向方向が所望の方向に設定され、かつ、常光線と異常光線間の偏向角が調整可能な範囲内で所望の角度に設定される。 Therefore, since the voltage applied to the liquid crystal layer 30 changes along the first direction by applying a voltage to the transparent electrode 33 as described above, the partial electrode 33-1 and the partial electrode 33-m Depending on the voltage between them, the refractive index for extraordinary rays changes along the first direction. Similarly, as the voltage is applied to the transparent electrode 34 as described above, the voltage applied to the liquid crystal layer 30 changes along the second direction, and thus the partial electrode 34-1 and the partial electrode 34-n. Depending on the voltage between them, the refractive index for extraordinary rays changes along the second direction. Therefore, the control circuit 23 adjusts the voltage between the partial electrode 33-1 and the partial electrode 33-m and the voltage between the partial electrode 34-1 and the partial electrode 34-n, so that the surface orthogonal to the optical axis OA. The refractive index of the liquid crystal layer 30 with respect to extraordinary rays can be changed along any direction. As a result, the extraordinary ray propagates in the liquid crystal layer 30 while being inclined from the optical axis OA along the direction of change in the refractive index of the liquid crystal layer 30. That is, the direction of change in the refractive index of the liquid crystal layer 30 is the deflection direction. Further, the deflection angle, which is the angle formed by the extraordinary ray with respect to the ordinary ray, is an angle corresponding to the magnitude of the refractive index gradient of the liquid crystal layer 30. That is, the extraordinary ray deflection direction A with respect to the first direction, the extraordinary ray deflection angle R with respect to the ordinary ray, the voltage ΔVU between the electrode 33-1 and the partial electrode 33-m, and the partial electrode 34-1 and the portion. The following equation holds between the voltage ΔVL between the electrodes 34-n.

Here, φ represents an angle formed by the first direction and the alignment direction of the liquid crystal molecules 37. Therefore, by appropriately adjusting ΔVU and ΔVL, the deflection direction of extraordinary rays can be set to a desired direction on the plane orthogonal to the optical axis OA, and the deflection angle between ordinary rays and extraordinary rays can be adjusted. The desired angle is set within a certain range.

  Furthermore, the minimum value of the voltage applied to one of the transparent electrode 33 and the transparent electrode 34 is applied to each transparent electrode so that the maximum value of the voltage applied to the other of the transparent electrode 33 and the transparent electrode 34 is higher. Voltage to be set. As a result, a voltage of a certain level or more is applied between the two transparent electrodes, and the liquid crystal molecules 37 included in the liquid crystal layer 30 can be driven.

  FIG. 5 is a diagram showing the relationship between the voltage applied between the partial electrodes at both ends of each transparent electrode, the voltage applied to one transparent electrode, and the voltage applied to the other transparent electrode. As shown in FIG. 5, in this example, it is assumed that the voltage VUmax applied to the partial electrode 33-m is higher than the voltage VUmin applied to the partial electrode 33-1 of the transparent electrode 33. Similarly, it is assumed that the voltage VLmax applied to the partial electrode 34-n is higher than the voltage VLmin applied to the partial electrode 34-1 of the transparent electrode 34. Furthermore, the voltage VUmin is higher than the voltage VLmax, and each voltage is set so that the difference (VUmin−VLmax) is larger than the voltage offset Lmin between the transparent electrode 33 and the transparent electrode 34.

  In the graph shown in FIG. 5, the horizontal axis represents voltage, and the vertical axis represents the refractive index with respect to extraordinary rays. A curve 500 represents the relationship between the voltage applied to the liquid crystal layer 30 and the refractive index with respect to extraordinary rays.

As shown in FIG. 5, the voltage ΔVU and the voltage ΔVL are adjusted so that the voltage ΔVU and the voltage ΔVL are included in the voltage range Vrange in which the refractive index change is linear with respect to the voltage change. That is, the voltage ΔVU and the voltage ΔVL are adjusted within a range in which the condition represented by the following expression is satisfied.

ただし、αは正の定数であり、VUmin-VLmax+2α=Lminとなる。 Furthermore, if the midpoint of Vrange is Vc, VUmin and VLmax are preferably set so as to satisfy the following conditions.

However, α is a positive constant, and VUmin−VLmax + 2α = Lmin.

  The control circuit 23 includes, for example, one or a plurality of processors, a nonvolatile semiconductor memory and a volatile semiconductor memory, and a drive circuit for driving the first liquid crystal element 21 and the second liquid crystal element 22. Have. Then, the control circuit 23 variably controls the polarization direction and the deflection angle of the extraordinary ray by controlling the voltage distribution applied to the respective liquid crystal layers of the first liquid crystal element 21 and the second liquid crystal element 22.

  In the present embodiment, when the ordinary ray and the extraordinary ray pass through the sample 10, the control circuit 23 matches the direction in which the ordinary ray and the extraordinary ray are aligned on the plane orthogonal to the optical axis OA, and the deflection direction. In addition, each of the first liquid crystal element 21 and the second liquid crystal element 22 has a liquid crystal layer so that the extraordinary ray is emitted from the beam splitting element 2-1 at an angle corresponding to the shear amount between the ordinary ray and the extraordinary ray. Control the applied voltage distribution. Note that the amount of shear and the angle formed by the optical axis OA and the extraordinary ray at the front focal position of the condenser lens 3 correspond to each other one-to-one. That is, as the shear amount increases, the angle formed between the ordinary ray and the extraordinary ray at the front focal position of the condenser lens 3 also increases.

  FIG. 6A is a diagram for explaining the relationship between the positional relationship between the liquid crystal elements of the light beam splitting element 2-1 and the condenser lens 3, and the inclination of the extraordinary ray with respect to the optical axis OA and the shear amount. FIG. 6B is a diagram showing an example of a table representing the relationship between the focal length of the condenser lens 3, the deflection angle of the extraordinary ray by each liquid crystal element, and the shear amount.

  As shown in FIG. 6A, the extraordinary ray 601 is emitted at an angle θ1 with respect to the optical axis OA when the liquid crystal element 21 gives a deflection angle θ1 that is the first deflection angle. The extraordinary ray 601 is directed by the liquid crystal element 22 to the opposite side with respect to when it is emitted from the liquid crystal element 21. At that time, the liquid crystal element 22 gives a deflection angle of (θ1 + θ2) to the extraordinary ray 601 in the direction opposite to the deflection angle θ1 by the liquid crystal element 21. As a result, the extraordinary ray 601 exits the liquid crystal element 22 so as to be inclined with respect to the optical axis OA (that is, the ordinary ray) at θ 2 that is the second deflection angle. Thereafter, the extraordinary ray 601 intersects the optical axis OA at the front focal position of the condenser lens 3 at a position advanced by the distance y1 along the optical axis OA. Thereafter, the extraordinary ray 601 is collimated with respect to the optical axis OA by the condenser lens 3 having a focal length f and reaches the sample 10.

  As shown in FIG. 6B, the table 600 shows, for each row, the deflection angle given to the extraordinary ray by each liquid crystal element with respect to the shear amount. In the table 600, the deflection angle is represented as the inclination of the traveling direction of the wavefront of the extraordinary ray relative to the optical axis OA. In the table 600, in order from the left, the deflection angle of extraordinary rays by the first liquid crystal element 21 (ie, θ1), the deflection angle of extraordinary rays by the second liquid crystal element 22 (ie, θ1 + θ2), and the second liquid crystal. The extraordinary ray tilt angle θ2 with respect to the optical axis OA when emitted from the element 22, the focal length f of the condenser lens 3, the shear amount, and the distance y1 from the second liquid crystal element 22 to the front focal position of the condenser lens 3 are shown. . As shown in the table 600, if the distance y1 is constant, the deflection angle given to each extraordinary ray by each liquid crystal element increases as the shear amount increases. If the shear amount is constant, the deflection angle that each liquid crystal element gives to the extraordinary ray increases as the distance y1 increases. Further, the deflection angle (θ1 + θ2) given to the extraordinary ray by the second liquid crystal element 22 in order for the extraordinary ray to intersect the optical axis OA at the front focal position of the condenser lens 3 is determined by the first liquid crystal element 21. It is larger than the deflection angle θ1 given to the extraordinary ray and in the opposite direction.

  The control circuit 23 sets the voltages ΔVU and ΔVL applied across the two transparent electrodes of each liquid crystal element according to the deflection direction and the shear amount in accordance with the relationship shown in the equation (1) and the above table. . For example, for each focal length of the condenser lens 3, a reference table showing a relationship between the deflection direction and the shear amount and the voltages ΔVU and ΔVL applied between the two transparent electrodes of each liquid crystal element is provided by the control circuit 23. It is stored in advance in a semiconductor memory. For example, the control circuit 23 receives a reference table corresponding to the focal length based on the focal length of the condenser lens 3 that is input from an external device (not shown) and received via a communication interface (not shown). By selecting and referring to the selected reference table, both ends of the two transparent electrodes of each liquid crystal element corresponding to the deflection direction and the shear amount input from an external device and received via a communication interface (not shown) The voltages ΔVU and ΔVL applied between them are determined. The control circuit 23 controls the drive circuit so that the determined voltages ΔVU and ΔVL are obtained.

  Further, the control circuit 23 can make the background of the observed image of the sample 10 brighter or darker by adjusting the magnitude of the voltage applied to the liquid crystal layer 30. For example, when the phase difference between the ordinary ray and the extraordinary ray, which does not depend on the sample 10, is 2 kπ (where k is an integer), the ordinary ray and the extraordinary ray are emphasized by interference in the background portion. Becomes brighter. Conversely, when the phase difference between the ordinary ray and the extraordinary ray, which does not depend on the sample 10, is (2k + 1) π, the ordinary ray and the extraordinary ray are weakened by the interference in the background portion, so the background is dark. Become. Then, by appropriately adjusting a voltage applied to the liquid crystal layer 30, for example, {(VUmin + VUmax) / 2− (VLmax + VLmin) / 2}, the phase modulation amount between the ordinary ray and the extraordinary ray changes. Therefore, the control circuit 23 can adjust the brightness of the background of the image of the sample 10 by adjusting this voltage.

  The drive voltage applied from the drive circuit to the two transparent electrodes of each liquid crystal element may be, for example, an AC voltage that has been subjected to pulse height modulation (PHM) or pulse width modulation (PWM). Further, the drive circuit may speed up the response of each liquid crystal element by driving the voltage applied to the two transparent electrodes of each liquid crystal element by overdrive.

  Regarding the light beam splitting element 2-2, each liquid crystal element is arranged so that the second liquid crystal element 22 is positioned on the sample 10 side and the first liquid crystal element 21 is positioned on the imaging unit 5 side. Thus, the control circuit 23 transmits the sample 10 and is condensed by the objective lens 4 by performing the same control as the voltage distribution control for the liquid crystal layer of each liquid crystal element of the light beam splitting element 2-1. Ordinary rays and extraordinary rays can be combined into one light beam.

  As described above, the light beam splitting element according to an embodiment of the present invention has two liquid crystal elements arranged along the optical axis, and each liquid crystal element is arranged along a direction orthogonal to each other. A liquid crystal layer sandwiched between two transparent electrodes having a plurality of partial electrodes. Therefore, this light beam splitting element adjusts the voltage applied between the partial electrodes at both ends of each of the two transparent electrodes in each liquid crystal element, so that the deflection direction of the extraordinary ray with respect to the ordinary ray and the ordinary ray It is possible to control the deflection angle of the extraordinary ray with respect to. For this reason, in the differential interference microscope apparatus, by using this light beam splitting element instead of the Nomarski prism, the shear amount or the alignment direction of the two light beams when passing through the sample can be adjusted without performing a mechanical operation. Is possible.

  According to the modification, each control element 23 may drive each liquid crystal element included in the plurality of light beam splitting elements. The control circuit 23 may also be used as a controller of the microscope apparatus 100.

  According to still another modification, the light beam splitting element may include three or more liquid crystal elements arranged side by side along the optical axis. Also in this case, each liquid crystal element can have the same configuration as the liquid crystal element according to the above embodiment. In this case, the light beam splitting element can make the adjustment range of the deflection angle wider. Further, the control circuit may adjust the voltage applied to each liquid crystal element of the light beam splitting element so that the ordinary light beam and the extraordinary light beam emitted from the light beam splitting device are parallel to each other.

  According to still another modification, one of the two transparent electrodes of each liquid crystal element included in the light beam splitting element has a plurality of partial electrodes formed in a matrix, and the other is a single transparent electrode that is an active region. You may form so that the whole may be covered. In this case, the partial electrodes may be insulated from each other and the partial electrodes may be connected to the control circuit so that the control circuit can control the voltage applied to each partial electrode independently. Also in this case, the control circuit may determine the voltage in each of the first direction and the second direction and the voltage between the two transparent electrodes, as in the above embodiment.

  Moreover, the light beam splitting element according to the above-described embodiment or modification may be used in an apparatus other than a microscope.

  As described above, those skilled in the art can make various modifications in accordance with the embodiment to be implemented within the scope of the present invention.

DESCRIPTION OF SYMBOLS 100 Microscope apparatus 1 Light source 2-1 and 2-2 Beam splitting element 3 Condenser lens 4 Objective lens 5 Imaging part 10 Sample 21 1st liquid crystal element 22 2nd liquid crystal element 23 Control circuit 30 Liquid crystal layer 31, 32 Transparent substrate 33 , 34 Transparent electrode 33-1 to 33-m, 34-1 to 34-n Partial electrode 35, 36 Alignment film 37 Liquid crystal molecule 38 Seal member

Claims (6)

The liquid crystal layer includes liquid crystal molecules aligned along a predetermined alignment direction, and linearly polarized light transmitted through the liquid crystal layer is converted into a first light flux and a second light according to a voltage distribution applied to the liquid crystal layer. And a first liquid crystal element for deflecting the second light beam with respect to the first light beam at a first deflection angle along a set deflection direction, and aligning along the alignment direction The second liquid crystal layer includes the liquid crystal layer including the liquid crystal molecules, and transmits the second light beam transmitted through the liquid crystal layer with respect to the first light flux transmitted through the liquid crystal layer according to a voltage distribution applied to the liquid crystal layer. A second liquid crystal element that deflects the luminous flux at a second deflection angle;
Voltage distribution applied to the liquid crystal layer of the first liquid crystal element and voltage applied to the liquid crystal layer of the second liquid crystal element according to the deflection direction, the first deflection angle, and the second deflection angle. A control unit for controlling the distribution;
A light beam splitting element.   The control unit applies the first light flux and the second light flux to the liquid crystal layer of the first liquid crystal element such that the first light flux and the second light flux intersect at a predetermined distance from the second liquid crystal element. The light beam splitting element according to claim 1, wherein the light beam splitting element controls a voltage distribution and a voltage distribution applied to the liquid crystal layer of the second liquid crystal element. The first liquid crystal element has a first transparent electrode and a second transparent electrode facing each other with the liquid crystal layer interposed therebetween,
The first transparent electrode has a plurality of partial electrodes arranged along a first direction, and the adjacent partial electrodes of the plurality of partial electrodes are connected via a resistor,
The second transparent electrode has a plurality of partial electrodes arranged along a second direction orthogonal to the first direction, and the adjacent partial electrodes of the plurality of partial electrodes are resistors. Connected through
The control section includes one end of the plurality of partial electrodes included in the first transparent electrode and one end of the plurality of partial electrodes included in the second transparent electrode. The light beam splitting element according to claim 1, wherein a voltage corresponding to the deflection direction and the first deflection angle is applied between the partial electrode and the other partial electrode.   The control unit is configured so that the second deflection angle is opposite to the first deflection angle, and the second deflection angle is larger than the first deflection angle. The light beam splitting element according to claim 2, wherein a voltage distribution applied to the liquid crystal layer of the liquid crystal element and a voltage distribution applied to the liquid crystal layer of the second liquid crystal element are controlled.   The control unit applies a voltage distribution applied to the liquid crystal layer of the first liquid crystal element and the second distribution so that a refractive index with respect to the linearly polarized light component parallel to the alignment direction changes along the deflection direction. The light beam splitting element according to claim 4, wherein a voltage distribution applied to the liquid crystal layer of the liquid crystal element is controlled. A light source that emits linearly polarized light;
The linearly polarized light is divided into a first light beam and a second light beam arranged along a set deflection direction, and the second light beam is inclined with respect to the first light beam according to a set shear amount. A beam splitting element;
A lens that directs the first light flux and the second light flux toward the sample at intervals according to the shear amount;
An imaging unit that images the sample with one luminous flux that is a combination of the first luminous flux and the second luminous flux that have passed through the sample;
The beam splitting element is
The liquid crystal layer includes liquid crystal molecules aligned along a predetermined alignment direction, and the linearly polarized light transmitted through the liquid crystal layer is converted into the first light flux according to a voltage distribution applied to the liquid crystal layer. A first liquid crystal element that divides the second luminous flux into the second luminous flux and deflects the second luminous flux with respect to the first luminous flux along the deflection direction at a first deflection angle corresponding to the shear amount; The liquid crystal layer includes liquid crystal molecules that are aligned along the alignment direction, and the liquid crystal is applied to the first light flux that passes through the liquid crystal layer according to a voltage distribution applied to the liquid crystal layer. The second light beam transmitted through the layer is deflected at a second deflection angle corresponding to the shear amount, thereby causing the first light beam and the second light beam to intersect at the front focal position of the lens. Liquid crystal element,
Voltage distribution applied to the liquid crystal layer of the first liquid crystal element and voltage applied to the liquid crystal layer of the second liquid crystal element according to the deflection direction, the first deflection angle, and the second deflection angle. A control unit for controlling the distribution;
A microscope apparatus.

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