JP2011059174A - Lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To fix a length of a scanning range and a scanning speed in a lighting device. <P>SOLUTION: The lighting device, which illuminates an object area by causing light to scan the object area, includes: a light source (1) generating light; an optical system (17) which changeably adjusts an optical path of light from the light source; an electro-optical elements (9a and 9b) which have a refractive index distribution induced by application of a voltage and deflect the light from the optical system in accordance with the voltage in order to scan the object area; and a control part (15) which adjusts the voltage applied to the electro-optical elements in accordance with at least an incidence angle of light on the electro-optical elements. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a lighting device. The illumination device is used in, for example, an endoscope, a projector, a microscope, and the like.

  An endoscope optical system that scans an object by deflecting illumination light without mechanical drive by providing an electro-optic crystal (electro-optic element) at the tip is known (Patent Document 1).

An optical system of a scanning microscope that includes an electro-optic crystal behind a light source and can deflect illumination light with respect to an object without mechanical driving is known (Patent Document 2). In the optical system of this scanning microscope, the voltage applied to the electro-optic crystal is changed for each wavelength of illumination light, and the deflection direction can be made constant.
Special Table 2002-523162 JP 2008-158325 A

  However, when an electro-optic crystal is used for the scanning means, the light emission angle from the electro-optic crystal differs depending on the incident angle of light on the electro-optic crystal. For this reason, when the time rate of change of the applied voltage is the same, if the incident angle of the light to the electro-optic crystal is different, the length of the scanning range and the scanning speed are not constant.

  An object of the present invention is to make the length of a scanning range and the scanning speed constant in an illumination device.

  An illumination device that illuminates the target region by scanning the target region with light includes a light source that generates light, an optical system that adjusts an optical path of light from the light source, and a refractive index that is adjusted by applying a voltage. An electro-optic element whose distribution is induced, wherein the electro-optic element deflects light from the optical system in accordance with the voltage to scan the target area, and at least an incident angle of the light to the electro-optic element And a control unit that adjusts the voltage applied to the electro-optic element.

  According to the present invention, the length of the scanning range and the scanning speed can be made constant regardless of at least the incident angle of the light to the electro-optic element.

It is a schematic block diagram which shows the illuminating device which concerns on 1st embodiment. It is a figure explaining how the light ray bends in an electro-optic element. The case where the voltage applied to the voltage electrode is positive is shown. It is a figure explaining how a light ray bends in an electro-optic element. The case where the voltage applied to the voltage electrode is negative is shown. It is a figure which shows the incident angle and refraction angle of the light ray which injects into an electro-optical element. (A) It is a figure which shows the scanning range in case an incident angle is zero. (B) It is a figure which shows the scanning range in case an incident angle is not zero. (C) It is a graph which illustrates the applied voltage waveform when an incident angle is zero and when an incident angle is not zero. (A) It is a figure which shows the scanning range in case an incident position is a reference position. (B) It is a figure which shows the scanning range when an incident position is not a reference position. (C) It is a graph which illustrates the applied voltage waveform when an incident position is a reference position and when an incident position is not a reference position. (A) It is a figure which shows the scanning range in case light is red. (B) is a figure which shows the scanning range in case light is blue. (C) It is a graph which illustrates the applied voltage waveform when light is red and when light is blue. It is a schematic block diagram which shows the illuminating device which concerns on 2nd embodiment.

<First embodiment>
A first embodiment of a lighting device will be described with reference to FIG. In the first embodiment, the illumination device is provided in an endoscope or a projector. However, the present invention is applicable without being limited to this. For example, the illumination device may be provided in a microscope. The fiber bundle 7 is described using a perspective view.

  The illumination device includes a light source 1, an incident portion 3 (incident means), a fiber bundle 7, and a scanning portion 9 (scanning means). Thus, the illuminating device is composed of an optical scanning device.

  The light source 1 emits red (R) light (wavelength λr), green (G) light (wavelength λg), and blue (B) light (wavelength λb) as light of the three primary colors. The light source 1 may be one that emits light of the three primary colors by including a white light source and an RGB filter. Alternatively, the light source 1 may be one that emits light of the three primary colors by including red (R), green (G), and blue (B) light emitting diodes or laser diodes. Further, in order to facilitate the deflection operation of the electro-optical element described later, the light from the light source 1 may be appropriately polarized by a polarizing plate. The light source 1 is not limited to the three primary colors, and may emit a desired number of light of a desired color.

  The incident unit 3 selectively causes light from the light source 1 to enter one of a plurality of fibers on one end face (proximal end) of the fiber bundle 7. In the present embodiment, the incident portion 3 includes first and second galvanometer mirrors 3a and 3b that perform deflection operations in directions perpendicular to each other. The galvanometer mirrors 3a and 3b are controlled by a controller 15 described later via an actuator (not shown).

  The fiber bundle 7 is composed of a plurality of n optical fibers that are bundled. Each optical fiber transmits light incident on one end face (proximal end) of the fiber bundle 7 and emits it from the other end face (distal end) of the fiber bundle. Note that n is, for example, several to thousands.

  A lens group 5 including one or more lenses is appropriately provided between the incident portion 3 and the fiber bundle 7. The focal point of the lens group 5 is adjusted so that the light emitted from the incident portion 3 enters one optical fiber of the fiber bundle 7. A lens group 11 including one or more lenses or the like is also provided between the fiber bundle 7 and the scanning unit 9 as appropriate. The lens group 11 makes the light from the optical fiber substantially parallel and enters the scanning unit 9. The light from the scanning unit 9 is focused on a scanning target region (scanning target surface) 100 that is a scanning target by a lens group 13 including one or more lenses. The scanning range is expanded by the lens group 13 at a predetermined magnification.

  The incident portion 3, the lens group 5, the lens group 11, and the fiber bundle 7 constitute an optical system 17 that adjusts the optical path of light from the light source 1 so as to be changeable. The optical system 17 can adjust the optical path of the light from the light source so that it can be changed, and can generate off-axis light deviating from the optical axes of the lens groups 5 and 11.

  The scanning unit 9 periodically scans the scanning target region 100 with the emitted light emitted from the distal end of the fiber bundle 7. While light is incident on one fiber of the fiber bundle 7, scanning with one period or an integral multiple of the period is performed. The scanning position (scanning point) in the scanning target area 100 moves sequentially. In FIG. 1, a first scanning position (P1) and a second scanning position (P2) are shown as an example.

  The scanning unit 9 includes two electro-optic elements 9a and 9b that perform deflection operations in directions perpendicular to each other. The electro-optic elements 9a and 9b are composed of an electro-optic crystal. In order to facilitate the deflection operation by the voltage of the electro-optic element 9b, a λ / 2 plate may be provided between the two electro-optic elements 9a and 9b to change the polarization direction of the light.

  The controller (control unit) 15 controls the deflection operation in the Y-axis direction in the XY plane by applying a voltage Vy in the Y-axis direction to the electrode of the electro-optic element 9a. The controller 15 controls the deflection operation in the Z-axis direction in the X-Z plane by applying a voltage Vz in the Z-axis direction to the electrode of the electro-optic element 9b. The X axis indicates the coordinate in the optical axis direction. When the controller 15 changes the voltages Vy and Vz, the scanning position can be moved two-dimensionally in the YZ plane. The controller 15 has two voltage generators for the voltages Vy and Vz.

  The controller (control unit) 15 includes a central processing unit (CPU) and a memory. The controller 15 also controls the light source 1, the incident part 3, and the like.

  When the optical scanning device of FIG. 1 is mounted on an endoscope, reflected light from a scanning position is detected by a detector (not shown), and an image of a scanning target surface can be displayed on a monitor or the like. When mounted on a projector, the optical scanning device of FIG. 1 can display a predetermined image on a scanning target surface such as a screen.

  2 and 3 are diagrams for explaining how a light beam bends in an electro-optic element (electro-optic crystal). For simplicity, FIGS. 2 and 3 describe only the electro-optic element 9a for Y-axis scanning, but the same applies to the electro-optic element 9b for Z-axis scanning. The Y axis indicates coordinates in the direction from the ground electrode to the non-ground electrode (voltage electrode). The light incident surface of the electro-optic element 9a is a YZ plane. It is assumed that Y = 0 at the end of the electro-optic element 9a on the ground electrode 20b side, and the coordinate Y increases from the ground electrode 20b toward the voltage electrode 20a.

  An applied voltage V from the power source is applied to the electro-optical element 9a via the electrodes (voltage electrode 20a and ground electrode 20b). FIG. 2A shows a case where the applied voltage V applied to the electro-optic element 9a is positive. FIG. 3A shows a case where the applied voltage V is negative. When the applied voltage V is positive, the voltage electrode 20a is a positive electrode and the ground electrode 20b is a negative electrode. When the applied voltage V is negative, the voltage electrode 20a is a negative electrode and the ground electrode 20b is a positive electrode.

  By applying a voltage to the electro-optical element 9a, a refractive index distribution (refractive index distribution) is generated, and light incident on the electro-optical element 9a is bent and emitted from the electro-optical element 9a. Further, the refractive index distribution changes depending on the applied voltage. For this reason, by changing the voltage applied to the electro-optical element 9a, the angle of the light beam emitted from the electro-optical element 9a changes. Moreover, the spot of the light irradiated to a target object can be moved by changing an applied voltage.

  When the applied voltage is constant, the emission angle θ varies depending on the incident angle α, the incident position y, and the wavelength λ. Therefore, it is necessary to make the length of the scanning range and the scanning speed constant irrespective of the incident angle of light to the electro-optic element 9a, the incident position of light, or the wavelength of light.

  Hereinafter, for the sake of simplicity, a description will be given of a case where the refractive index distribution n (Y) in the electro-optic element 9a is expressed by a linear expression of the coordinate Y as in the following Expression (1). Since the coefficient A depends on the voltage V, the refractive index distribution changes depending on the voltage V.

For example, an electric field is generated in the electro-optical element 9a (for example, KTa _1-x Nb _x O ₃ ) by injecting a current to incline the electric field in the direction of the applied voltage, thereby obtaining a large gradient in refractive index. (See JP 2008-158325 A, JP 2007-310104 A, etc.). In this case, the coefficient A is expressed by the following formula (2).

Here, n ₀ is the refractive index when the applied voltage is zero, S _ij is the secondary electro-optic constant, and d is the thickness of the crystal in the electric field direction (distance between the electrodes). The coefficient A is proportional to the square of the applied voltage. FIG. 2B shows a refractive index change (refractive index gradient) when the applied voltage V applied to the electro-optic element 9a is positive. FIG. 3B shows the refractive index change when the applied voltage V is negative.

  When wavelength dependency is taken into consideration, the refractive index n is expressed by the following formula (3).

  Thus, since the refractive index depends on the Y coordinate due to the voltage applied to the electro-optical element 9a, the optical path in the electro-optical element 9a is bent by the applied voltage. Further, as the magnitude of the applied voltage V is larger, the optical path in the electro-optic element 9a is bent more greatly. Therefore, the scanning position tan θ is determined according to the applied voltage V, and the length of the scanning range is determined according to the change range of the applied voltage V. As described above, θ is an emission angle. In addition, since the actual scanning position in the scanning target region 100 is uniquely determined by tan θ, the scanning position is represented by tan θ in the present embodiment.

  When another optical system is disposed between the electro-optical element 9a and the scanning target region, θ is an emission angle from the optical system disposed closest to the scanning target region. This also applies to the following drawings.

  For example, the waveform (time dependency) of the applied voltage V is a sawtooth wave (see FIG. 5C). Here, the absolute values of the minimum value Vmin and the maximum value Vmax of the applied voltage waveform are equal, but the present invention is not limited to this. The length Ra of the scanning range is proportional to the difference between the scanning position tan θ (V = Vmax) corresponding to the minimum value Vmin of the applied voltage and the scanning position tan θ (V = Vmin) corresponding to the maximum value Vmax of the applied voltage. Therefore, in this embodiment, for the sake of simplicity, the length of the scanning range is defined as Ra = tan θ (V = Vmax) −tan θ (V = Vmin).

  The exit angle θ is expressed by the following formula (4) depending on the incident angle α corresponding to the refraction angle β on a one-to-one basis and the incident position y.

  Here, L is the length of the electro-optic element (crystal) in the optical axis direction. As shown in FIG. 4, β is a refraction angle, and the relationship of Expression (5) is established between the incident angle α and the refraction angle β. The incident angle α and the refraction angle β are positive when light is incident in the direction from the voltage electrode 20a side to the ground electrode 20b side.

  The controller 15 sets a maximum in accordance with at least one of the incident angle, the incident position, and the wavelength so that the length Ra {= tan θ (V = Vmax) −tan θ (V = Vmin)} of the scanning range becomes a constant value. Adjust voltage Vmax (maximum voltage value) and minimum voltage Vmin (minimum voltage value). Thereby, the length Ra of the scanning range becomes a constant value regardless of the incident angle α, the incident position y, and the wavelength λ. The period and frequency of the applied voltage waveform are constant regardless of the incident angle, wavelength, and incident position. Further, the controller 15 may be configured to adjust the Vmax and Vmin of the applied voltage waveform so that the length Ra of the scanning range becomes constant in consideration of the influence of the aberration of the lens group 13 and the like.

  Simultaneously with the adjustment of Vmax and Vmin, the voltage change rate with time is adjusted according to the incident angle, the incident position, and the wavelength. Thereby, the scanning speed can be made constant regardless of the incident angle, the incident position, and the wavelength. The time change rate of the voltage is given by (Vmax−Vmin) / DT according to Vmin to Vmax, where DT is the time required for the voltage to change from Vmin to Vmax. In the case of a sawtooth wave, DT is approximately equal to the period.

  It is difficult to analytically obtain the maximum voltage Vmax and the minimum voltage Vmin such that the length Ra of the scanning range is constant with respect to the incident angle α, the incident position y, and the wavelength λ based on the formula (4). It is. For this reason, the maximum voltage Vmax and the minimum voltage Vmin that make the length of the scanning range constant may be obtained in advance for each of the incident angle α, the incident position y, and the wavelength λ through experiments and simulations. For example, as shown in Table 1, the controller 15 stores a lookup table (reference table) for determining the maximum voltage Vmax and the minimum voltage Vmin for each of the incident angle α, the incident position y, and the wavelength λ in the memory. Good. The controller 15 refers to the lookup table and sets the maximum voltage Vmax and the minimum voltage Vmin according to the incident angle α, the incident position y, and the wavelength λ.

  In the present embodiment, the incident angle α and the incident position y are obtained from the operation amount of the incident unit 3 by the controller 15. In this embodiment, since the incident angle α and the incident position y are determined by the incident optical fiber selected by the galvanometer mirrors 3a and 3b, the incident angle α and the incident position y are the angles γa and gal of the galvanometer mirrors 3a and 3b. It is associated with γb (that is, the operation amount). As shown in Table 2, the controller 15 may store a lookup table for obtaining the incident angle α and the incident position y from the angles γa and γb of the galvanometer mirrors 3a and 3b in the memory. The controller 15 can acquire the incident angle α and the incident position y according to the angles γa and γb with reference to the lookup table.

  If necessary, a detector that detects the angle (that is, the operation amount) of the galvanometer mirrors 3a and 3b can be provided.

  The controller 15 may store a lookup table for directly obtaining Vmax and Vmin from the angles γa and γb of the galvanometer mirrors 3a and 3b in the memory. In this case, the controller 15 can directly obtain Vmax and Vmin from the angles γa and γb of the galvanometer mirrors 3a and 3b with reference to the lookup table.

-Dependence of applied voltage on incident angle-
Next, the dependency of the applied voltage on the incident angle and its adjustment will be described. Here, a case where the wavelength λ and the incident position y are the same and only the incident angle α is different will be described.

  5A and 5B show how the length of the scanning range changes according to the incident angle α when the applied voltage waveform (sawtooth wave here) is the same as in the prior art. Indicate. FIG. 5A shows the scanning range when the incident angle α is zero (when α = β = 0). FIG. 5B shows a scanning range when the incident angle α is not zero (α, β ≠ 0). The exit angle θ is expressed as the following formula (6) with respect to the refraction angle β that is uniquely determined from the incident angle α.

Here, n1 is the refractive index at the incident position.

  When the waveform of the applied voltage is the same, the width at which the emission angle θ varies due to the change in the applied voltage increases as the incident angle α increases.

  Therefore, the maximum voltage Vmax and the minimum voltage Vmin are adjusted according to the incident angle α so that the length Ra of the scanning range is a constant value K regardless of the incident angle. That is, Vmax and Vmin are set so that the following formula (7) is established for an arbitrary incident angle α1.

The period and frequency of the applied voltage waveform are constant regardless of the incident angle α. Vmax0 is the maximum applied voltage when α = 0, and Vmin0 is the minimum applied voltage when α = 0.

  FIG. 5C illustrates an applied voltage waveform when the incident angle α is zero (α = 0) and when the incident angle α is not zero (α = α1 ≠ 0). Here, the applied voltage waveform is a sawtooth wave having the same absolute value (magnitude) of Vmax and Vmin, but is not limited thereto. The amplitude (Vmax−Vmin) of the applied voltage waveform is adjusted so as to decrease as the incident angle α increases. Thereby, the length Ra of the scanning range is the same regardless of the incident angle α. As shown in FIG. 5C, when the incident angle α is not zero, the amplitude (Vmax−Vmin) of the applied voltage waveform is adjusted to be smaller than when the incident angle α is zero. At the same time, the time change rate of the voltage is adjusted according to the incident angle α. Thereby, the scanning speed can be made constant regardless of the incident angle α. The time change rate of the voltage is given by (Vmax−Vmin) / DT according to Vmin to Vmax, where DT is the time required for the voltage to change from Vmin to Vmax. In the case of a sawtooth wave, DT is approximately equal to the period.

  Thus, the applied voltage can be set according to the incident angle α so that the length of the scanning range and the scanning speed are constant.

-Dependence of applied voltage on incident position-
Next, the dependency of the applied voltage on the incident position and its adjustment will be described. Here, a case where the wavelength λ and the incident angle α are the same and only the incident position y is different will be described. For simplicity, the case where the incident angle α is zero is treated here.

  6A and 6B show how the length of the scanning range changes according to the incident position y when the waveform of the applied voltage (sawtooth wave here) is the same as in the prior art. Indicate. FIG. 6A shows the scanning range when the incident position y is at the center position in the thickness direction of the optical crystal as the reference position y0 (y = y0 = −d / 2). FIG. 6B shows the scanning range when the incident position y is not the reference position (y ≠ y0).

  The exit angle θ is expressed by the following formula (8) with respect to the incident position y.

  When the applied voltage waveform is a sawtooth wave in which the absolute values of Vmax and Vmin are equal, the width at which the emission angle θ fluctuates due to a change in the applied voltage is maximized at the reference position, and the incident position y is shifted to the voltage electrode 20a side. It decreases as much. When the incident position y is not at the reference position (y ≠ y0), the fluctuation range of the exit angle θ is smaller than that when the incident position y is the reference position.

  Therefore, the maximum voltage Vmax and the minimum voltage Vmin are adjusted according to the incident position y so that the length Ra of the scanning range is a constant value K regardless of the incident position. That is, the following formula (9) is established for an arbitrary incident position y1.

  Here, Vmax0 is the maximum applied voltage when y = y0, and Vmin0 is the minimum applied voltage when y = y0. The period and frequency of the applied voltage waveform are constant regardless of the incident position y.

  FIG. 6C illustrates an applied voltage waveform when the incident position y is the reference position (when y = y0) and when the incident position y is not the reference position (when y ≠ y0). Here, the applied voltage waveform is a sawtooth wave having the same absolute value (magnitude) of Vmax and Vmin, but is not limited thereto. The amplitude (Vmax−Vmin) of the applied voltage waveform is adjusted so as to increase as the incident position approaches the electrode side. At the same time, the time change rate of the voltage is adjusted according to the incident position y. Thereby, the scanning speed can be made constant regardless of the incident position y.

  Thus, the applied voltage can be set according to the incident position y so that the length of the scanning range and the scanning speed are constant.

-Dependence of applied voltage on wavelength-
Next, the dependency of the applied voltage on the wavelength and the adjustment thereof will be described. Here, a case where the incident angle α and the incident position y are the same and only the wavelength λ is different will be described. For simplicity, the case where the incident angle α is zero and the incident position y is the reference position will be described.

  FIGS. 7A and 7B show how the length of the scanning range changes according to the wavelength λ when the waveform of the applied voltage (sawtooth wave here) is the same as in the prior art. Indicates. FIG. 7A shows the scanning range when the wavelength λ is the reference wavelength (red wavelength) λr (λ = λr). FIG. 7B shows the scanning range when the wavelength λ is the blue wavelength λb (λ = λb).

  The emission angle θ is expressed by the following formula (10) with respect to the wavelength λ.

  The range in which the emission angle θ varies with the change in applied voltage increases as the wavelength λ decreases. For example, when the wavelength λ is a blue wavelength (λb), the fluctuation range of the emission angle θ due to the applied voltage is larger than that when the wavelength λ is a red wavelength (λr). This is because in the electro-optic element, the shorter the wavelength, the greater the refractive index.

  Therefore, the maximum voltage Vmax and the minimum voltage Vmin are adjusted according to the wavelength λ so that the length Ra of the scanning range is a constant value K regardless of the wavelength λ. That is, the following formula (11) is established for an arbitrary wavelength λ1.

  The period and frequency of the applied voltage waveform are constant regardless of the wavelength λ. Vmax0 is the maximum applied voltage when λ = λr, and Vmin0 is the minimum applied voltage when λ = λr.

  FIG. 7C illustrates an applied voltage waveform when the wavelength λ is the red wavelength λr (λ = λr) and when the wavelength λ is the blue wavelength λb (λ = λb). Here, the applied voltage waveform is a sawtooth wave having the same absolute value (magnitude) of Vmax and Vmin, but is not limited thereto. The amplitude (Vmax−Vmin) of the applied voltage waveform is adjusted so as to increase as the wavelength λ increases. At the same time, the time change rate of the voltage is adjusted according to the wavelength λ. Thereby, the scanning speed can be made constant regardless of the wavelength λ.

  Thus, the applied voltage can be set according to the wavelength λ so that the length of the scanning range and the scanning speed are constant.

  In the above embodiment, the applied voltage may not be adjusted according to the incident position. Moreover, it is good also as a structure which does not adjust an applied voltage according to a wavelength. This is because the contribution of the refraction angle β is particularly large in Equation (4). However, the maximum voltage Vmax and the minimum voltage Vmin are adjusted according to at least the incident angle α.

Since the voltage applied to the electro-optic element is adjusted according to the incident angle of the action effect light, the length of the scanning range and the scanning speed can be made constant regardless of the incident angle. Since the voltage applied to the electro-optic element is adjusted according to the incident position of light, the length of the scanning range and the scanning speed can be made constant regardless of the incident position. Since the voltage applied to the electro-optic element is adjusted according to the wavelength of light, the length of the scanning range and the scanning speed can be made constant regardless of the wavelength. The length of the scanning range can be made constant by adjusting the maximum value and the minimum value of the voltage. The scanning speed can be made constant by adjusting the time change rate of the voltage. A current is injected by applying a voltage to generate electric charge therein, thereby inducing a gradient of refractive index in the electro-optic element.

<Second embodiment>
As shown in FIG. 8, in the second embodiment, the incident unit 3 is configured by a digital mirror device (DMD) 30. Each of the plurality of micromirrors constituting the DMD 30 reflects a part of the light from the light source 1 in response to an instruction from the controller 15 to generate a light beam incident on the electro-optic element. The controller 15 sequentially selects micromirrors.

  In this case, the incident angle α and the incident position y are obtained from the number of the micromirror selected by the controller 15. Since the incident angle α and the incident position y are determined by the position of the selected micromirror, the incident angle α and the incident position y are associated with the number of the micromirror. As shown in Table 3, the controller 15 may store a lookup table (reference table) for obtaining the incident angle α and the incident position y from the micromirror number in the memory. The controller 15 refers to the lookup table and sets the maximum voltage Vmax and the minimum voltage Vmin according to the incident angle α, the incident position y, and the wavelength λ. Simultaneously with the adjustment of Vmax and Vmin, the voltage change rate with time is adjusted according to the incident angle, the incident position, and the wavelength.

  The controller 15 may store a lookup table for obtaining Vmax and Vmin directly from the micromirror number in the memory. In this case, the controller 15 can directly obtain Vmax and Vmin from the number of the selected micromirror with reference to this lookup table.

  In the second embodiment, the same effects as in the first embodiment can be obtained.

  The present invention is not limited to the first and second embodiments described above, and it is obvious that various modifications can be made within the scope of the technical idea. For example, in the first and second embodiments described above, an example in which the incident angle α and the incident position y are changed and light is incident on the electro-optical element has been described. However, only the incident angle α may be changed by changing the configuration of the lens group 11 or the like.

DESCRIPTION OF SYMBOLS 1 Light source 3 Incident part 3a, 3b Galvano mirror 5, 11, 13 Lens group 7 Fiber bundle 9 Scan part 9a, 9b Electro-optic element 15 Controller 17 Optical system 20a Voltage pole 20b Ground pole 100 Scan object area | region

Claims (6)

In an illumination device that illuminates the target area by scanning the target area with light,
A light source that generates light;
An optical system that adjusts an optical path of light from the light source in a changeable manner;
An electro-optic element in which a refractive index distribution is induced by application of a voltage, and deflects light from the optical system in accordance with the voltage in order to scan the target region;
And a controller that adjusts the voltage to be applied to the electro-optic element in accordance with at least an incident angle of light to the electro-optic element.   2. The illumination device according to claim 1, wherein the control unit adjusts the voltage applied to the electro-optical element in accordance with a light incident position on the electro-optical element.   The lighting device according to claim 1, wherein the control unit adjusts the voltage applied to the electro-optic element according to a wavelength of light.   The lighting device according to any one of claims 1 to 3, wherein the control unit adjusts a time change rate of the voltage.   The lighting device according to claim 1, wherein the control unit adjusts the maximum value and the minimum value of the voltage.   6. The refractive index gradient is induced in the electro-optical element by injecting a current by applying the voltage and generating an electric charge therein. 6. Lighting equipment.

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