Optical device

Abstract

To provide an optical device which has a compact and lightweight optical system configuration, offers light propagation direction control accuracy in the order of microradians or less, has high environmental resistance and vibration resistance, can handle large-diameter beams and high-power light, and is low-cost, and to provide a light propagation direction controller.SOLUTION: An optical device 1 is provided, comprising a convex lens 10 acting as a focusing optical part with a focal point, and parallel flat plates 20 inserted between the convex lens 10 and the focal point to act as an optical element capable of shifting an apparent focal point in a direction perpendicular to an optical axis when viewed from a side of the convex lens 10.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an optical device used as a light propagation direction controller or selector for controlling the direction of light transmission or reception with high precision in a free space light transmitter or receiver. The present invention relates to an optical propagation direction controller having such an optical device. [Background technology]

[0002] In recent years, with the rapid development of laser applications such as LIDAR (Light Detection and Ranging), free-space optical communications, and optical 3D printers, there is a growing need for light propagation direction controllers that can fix or sweep the propagation direction of light such as laser beams at high speed and with high precision (with an error of less than a milliradian).

[0003] The main configurations of conventional light propagation direction controllers include those that control the angle of a mirror and those that shift the optical axis by shifting the lens position, etc. For the former, gimbal mirrors (see Non-Patent Document 1), galvanometer mirror systems (see Non-Patent Document 2), MEMS (Micro Electro Mechanical Systems) mirrors (see Non-Patent Document 3), etc. are commonly used. Furthermore, there are spatial light modulators that do not have mechanically moving parts and change the light propagation direction by spatially modulating the phase of light (see Non-Patent Document 4). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Y. Kaymak et al., "A Survey on Acquisition, Tracking, and Pointing Mechanisms for Mobile Free-Space Optical Communications," IEEE Communications Surveys and Tutorials 20, 1104-1123 (2018). [Non-Patent Document 2] H. Jigang et al., "Two Dimensional Laser Galvanometer Scanning Technology for Additive Manufacturing," International Journal of Materials, Mechanics and Manufacturing 6, 332-336 (2018). [Non-Patent Document 3] STS Holmstrom et al., "MEMS Laser Scanners: A Review," Journal of Microelectromechanical Systems 23, 259-275 (2014). [Non-Patent Document 4] Journal of the Japanese Society of Applied Physics, Optics, Vol. 36, p. 122 (2007). Summary of the Invention [Problem to be solved by the invention]

[0005] The present inventors are considering a laser wireless power supply from a lunar lander to a lunar exploration rover. This is a system in which a lunar lander equipped with a solar power generation panel in a sunlit area wirelessly supplies power to a lunar exploration rover in a permanent shadow area, which may be more than 1 km away, by using a laser beam (100 watts or more). The required accuracy of the laser beam propagation direction control is tens of microradians or less. In addition, as a general requirement for spacecraft, the optical propagation direction controller is strongly desired to be small and lightweight, environmentally resistant, and vibration resistant. Furthermore, in the case of laser transmission over 1 km, the beam diameter expands due to the diffraction effect of light, so the beam diameter on the light transmission side needs to be increased to more than 10 to tens of mm. If the above-mentioned conventional optical propagation direction controller is to be used in such a system, new problems such as the following arise.

[0006] (1) The accuracy of controlling the light propagation direction of gimbal mirrors and galvanometer mirror systems is largely determined by the performance of actuators such as motors, but it is difficult to achieve the required accuracy mentioned above with a lightweight and large diameter. In addition, the impact of vibration on the mirror is large because twice the angle change of the mirror controlled by the actuator is directly reflected in the change in the light propagation direction.

[0007] (2) Due to their small size, MEMS mirrors have difficulty handling large beams or high-power light.

[0008] (3) Spatial light modulators have low tolerance to environmental changes (temperature, etc.) and high power, and their use requires advanced optical phase monitoring / control technology.

[0009] (4) In general, a high-precision light propagation direction controller on the order of microradians tends to be expensive.

[0010] The present invention provides a configuration that solves these new problems, and its purpose is to provide an optical device and an optical propagation direction controller that have a small and lightweight optical system configuration, have a control accuracy of the light propagation direction of about microradians or less, have high environmental resistance and vibration resistance, can handle large-diameter beams and high-power light, and are low-cost. [Means for solving the problem]

[0011] In order to achieve the above-mentioned object, an optical device according to one embodiment of the present invention comprises a focusing optical component having a focal point, and an optical element inserted between the focusing optical component and the focal point, which can shift the apparent focus when viewed from the focusing optical component side in a direction perpendicular to the optical axis, and is characterized in that the propagation direction angle of light in a space on the side of the focusing optical component where the optical element is not present is changed according to the amount of shift.

[0012] (1) When a parallel plane plate is used as the optical element, the precision of the light propagation direction control and the sweep pitch can be adjusted simply by selecting the optical thickness (= thickness x refractive index) of the parallel plane plate and the lens focal length, making it possible to achieve a precision of direction control that is higher than the performance of the rotary actuator itself. At the same time, since it is less sensitive to the mechanical movement of the rotary actuator than the conventional method, vibration resistance is improved when controlling the light propagation direction with the same precision as the conventional method.

[0013] (2) Since the parallel plate is placed near the focal point of the light, it is possible to accommodate large diameter beams without significantly decreasing the accuracy of directional control or increasing the area of ​​optical elements such as the parallel plate. Furthermore, by using a parallel plate material with low absorption for the transmitted wavelength and applying anti-reflection treatment to both sides of the parallel plate, it is possible to ensure low light loss and resistance to high power light.

[0014] (3) High-precision control is possible simply by rotating optical elements such as parallel plane plates, and the influence of the surrounding environment such as temperature and humidity is generally small.

[0015] (4) By inserting multiple optical elements, such as parallel plane plates with different optical thicknesses, it is possible to achieve both high precision and wide-range control of the light propagation direction.

[0016] (5) By simply inserting an additional optical element such as a parallel plate into a conventional collimator or beam diameter converter, it is possible to easily provide a highly accurate directional control function without significantly increasing the size or weight of the optical system.

[0017] (6) It can be constructed by simply adding optical elements such as inexpensive plane-parallel plates.

[0018] In an optical device according to one embodiment of the present invention, the optical element has a transmissive parallel plane plate that can be rotated about an axis perpendicular to the optical axis or is fixed at a constant inclination angle and whose refractive index can be changed by external influences such as electromagnetic, thermal, or light.

[0019] In the optical device according to one aspect of the present invention, the light-collecting optical component is a collimator constituted by one or more lenses or one or more reflecting mirrors.

[0020] In the optical device according to one aspect of the present invention, the reflecting mirror is a reflecting telescope having a diameter of 50 mm or more.

[0021] In an optical device according to one embodiment of the present invention, the focusing optical component is a relay optical system or a beam diameter converter constituted by one or more lenses, one or more reflecting mirrors, or a combination of one or more lenses and one or more reflecting mirrors.

[0022] In an optical device according to one aspect of the present invention, the reflecting mirror is a reflecting telescope having a diameter of 50 mm or more.

[0023] In the optical device according to one aspect of the present invention, the parallel plane plate is capable of rotating about two axes perpendicular to each other.

[0024] In an optical device according to one embodiment of the present invention, the optical element comprises a first transmissive parallel plane plate which is rotatable about a first axis perpendicular to the optical axis as a rotation axis or which is fixed at a constant tilt angle and whose refractive index can be changed by external actions such as electromagnetism, heat, light, etc., and a second transmissive parallel plane plate which is rotatable about a second axis perpendicular to the optical axis and the first axis as a rotation axis or which is fixed at a constant tilt angle and whose refractive index can be changed by external actions such as electromagnetism, heat, light, etc.

[0025] In an optical device according to one embodiment of the present invention, the optical elements include two or more transmissive parallel plane plates, each of which can rotate independently or is fixed at a constant tilt angle and whose refractive index can be changed independently by external effects such as electromagnetism, heat, or light, and which have different optical thicknesses (= thickness x refractive index) when there is no external effect. The optical device according to an aspect of the present invention may further include a beam shaper arranged on the side of the focusing optical component opposite to the side on which the optical element is arranged. Effect of the Invention

[0026] According to the present invention, it is possible to realize a light propagation direction controller, selector, etc., which has a small and lightweight optical system configuration, has a control precision of light propagation direction of about microradians or less, has high environmental resistance and vibration resistance, and can handle large diameter beams and high power light, and is also low cost. [Brief description of the drawings]

[0027] [Figure 1] 1 is a diagram showing a configuration of an optical device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram for explaining in more detail the principle of the optical device shown in FIG. [Diagram 3] 2 is a graph showing an example of a calculation result of a light propagation direction angle in the optical device shown in FIG. 1. [Figure 4] 5 is a diagram showing a configuration of an optical device according to a second embodiment of the present invention. FIG. [Diagram 5] FIG. 13 is a diagram showing a configuration of an optical device according to a third embodiment of the present invention. [Figure 6] FIG. 13 is a diagram showing a configuration of an optical device according to a fourth embodiment of the present invention. [Figure 7] 7 is a diagram showing an example of a calculation result of the light propagation direction angle when each of the parallel plane plates having different thicknesses in the optical device shown in FIG. 6 is rotated independently. [Figure 8] FIG. 13 is a diagram showing a configuration of an optical device according to a fifth embodiment of the present invention. [Figure 9] FIG. 13 is a diagram showing a configuration of an optical device according to a sixth embodiment of the present invention. [Figure 10] FIG. 13 is a diagram showing a configuration of an optical device according to a seventh embodiment of the present invention. [Figure 11] FIG. 13 is a diagram showing a configuration of an optical device according to an eighth embodiment of the present invention. [Figure 12] FIG. 13 is a diagram showing a configuration of an optical device according to a ninth embodiment of the present invention. [Figure 13] FIG. 23 is a diagram showing a configuration of an optical device according to a tenth embodiment of the present invention. [Figure 14] FIG. 23 is a diagram showing a configuration of an optical device according to an eleventh embodiment of the present invention. [Figure 15] FIG. 23 is a diagram showing a configuration of an optical device according to a twelfth embodiment of the present invention. [Figure 16] FIG. 4 is a diagram showing a configuration of an optical device according to a modified example of the first embodiment of the present invention. [Figure 17] FIG. 1 is a diagram showing an embodiment in which an optical device according to the present invention is applied to a system for wireless laser power supply to a lunar rover; [Figure 18] 18 is a diagram showing an internal configuration of a laser transmitter shown in FIG. 17. [Figure 19] FIG. 1 is a diagram showing an embodiment in which an optical device according to the present invention is applied to a LIDAR / remote sensing system. [Figure 20] FIG. 20 is a diagram showing the internal configuration of the observation device shown in FIG. 19. [Figure 21] This is the result of an experiment to verify the accuracy of the beam direction controller according to the present invention, and shows the beam image transmitted 800 m when the adjustment knob of the two-axis holder holding the parallel plane plate was rotated a specified number of times. [Figure 22]This is an experimental result for verifying the accuracy of the beam direction controller according to the present invention, and shows the amount of change in the center of gravity position of the beam image transmitted 800 m away (in mm). [Diagram 23] This is an experimental result for verifying the accuracy of the beam direction controller according to the present invention, and shows the amount of change in the center of gravity position of the beam image transmitted 800 m (the light propagation direction angle as seen from the laser transmitter side) (in μrad). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0029] <First embodiment> FIG. 1 is a diagram showing a configuration of an optical device according to a first embodiment of the present invention. As shown in FIG. 1, the optical device 1 is a collimator that converts a diverging beam into parallel light, and includes a convex lens 10 and a transmission-type parallel plane plate 20 inserted between a laser light source 30 and the convex lens 10.

[0030] The convex lens 10, which functions as a focusing optical component, converts the laser light, which is divergent light output from the laser light source 30 arranged at the focal position of the convex lens 10, into parallel light.

[0031] The plane-parallel plate 20 is held rotatably. For example, the plane-parallel plate 20 is rotated in the direction of the symbol r in the figure and held at the position indicated by the dotted line.

[0032] The plane-parallel plate 20 is held by a holding mechanism (optical element holder) not shown, and may be rotated, for example, manually, or may be rotatably held by a rotation drive mechanism (kinematic mount for optical elements or a rotation stage) not shown, and may be rotated under the control of a predetermined control system (a system having a stepping motor or a piezoelectric drive device) not shown.

[0033] Such an optical device 1 constitutes a light propagation direction controller, selector, or the like, which is made up of a Fourier transform optical system having a conversion function between a light spatial distribution and a light propagation angle distribution.

[0034] For example, in this optical device 1, when the plane-parallel plate 20 is rotated in the direction of the symbol r in the figure to the position indicated by the dotted line, the apparent focus (the emission end image of the laser light source 30) when viewed from the convex lens 10 side shifts in a direction perpendicular to the optical axis. This controls the propagation direction of light on the opposite side of the focus (the emission end image of the laser light source 30) across the convex lens 10. That is, in the optical device 1 according to the present invention, the propagation direction of light on the opposite side of the convex lens 10 can be controlled by changing the angle of the plane-parallel plate 20 with respect to the optical axis.

[0035] FIG. 2 is a diagram for explaining in more detail the principle of the optical device 1 configured as above. In FIG. 2, the focal length of the convex lens 10, which is a focusing optical component, is f, and the refractive index of the parallel plane plate 20 is n 1 The inclination angle θ of the parallel plane plate 20 in this case 0 The light propagation direction angle φ with respect to is expressed by the following mathematical formula 1. In Fig. 2, d is the thickness of the parallel plane plate 20, and Δx is the parallel shift amount of the light beam in the direction perpendicular to the optical axis (=the shift amount of the apparent focal position).

number

[0036] In this formula, f is 100 mm, n 1 When the calculation is performed assuming that the thickness d is 1.5, the result is as shown in FIG. 3. The graph in FIG. 3 shows the relationship between the inclination angle θ 0 The graph shows the light propagation direction angle φ with respect to θ, and is a calculation result showing the dependence of the directional control performance on the thickness d. As is clear from this graph, 0Since the change in φ is about three orders of magnitude smaller than that of θ, the control accuracy of the light propagation direction is improved by about three orders of magnitude. For example, when transmitting power wirelessly from a laser to a lunar exploration rover equipped with a light receiving panel with an aperture diameter of about 300 mm, a directional control accuracy of at least 50 μrad (a deviation of 50 mm at a distance of 1 km) is required. If d = 1.5 mm, then θ 0 This means that a rotation accuracy of about 10 mrad is sufficient.

[0037] In the optical device 1 according to the present invention, not only the one-dimensional direction control but also two-dimensional direction control may be performed. Two-dimensional direction control can be realized, for example, by inserting two parallel plane plates 20 between the laser light source 30 and the convex lens 10 and rotating each of them about an axis (x-axis) perpendicular to the optical axis (z-axis) and perpendicular to the paper surface and an axis (y-axis) parallel to the paper surface, or by rotating one parallel plane plate about two axes, the x-axis and the y-axis. Two-dimensional direction control can also be achieved by a combination of rotation about an arbitrary axis (r-axis) perpendicular to the optical axis (z-axis) and rotation about the optical axis (z-axis) itself as the central axis.

[0038] As can be seen from Equation 1, instead of the optical device 1, the refractive index n 1In the case of the optical device 1' using the parallel plane plate 20' whose refractive index can be changed, it is possible to control the light propagation direction angle φ while fixing the parallel plane plate 20' at a certain inclination angle without rotating it. In this case, there is no mechanical driving part, and resistance to mechanical vibration and wear is improved. Examples of the material that can change the refractive index include optical crystals that utilize the electro-optic effect in LN (lithium niobate) crystal, KDP (potassium dihydrogen phosphate) crystal, BBO (beta barium borate) crystal, KTN (potassium tantalate niobate) crystal, etc., and it is considered that high-speed directional control at least on the order of kHz or more is possible by using these as the parallel plane plate 20'. Note that the material of the parallel plane plate 20' is not limited to these, and any material that can change the refractive index is acceptable. Furthermore, by using two parallel plane plates 20' whose refractive index can be changed and controlling the light propagation direction angle φ on axes (for example, vertical and horizontal) that are perpendicular to each other, two-dimensional directional control is also possible.

[0039] 1 and 2 may be replaced with an optical sensor, and the light traveling direction may be reversed. In this case, the light receiving device may be capable of selecting the light arrival angle with high accuracy.

[0040] <Second embodiment> FIG. 4 is a diagram showing a configuration of an optical device according to a second embodiment of the present invention.

[0041] As shown in FIG. 4, the optical device 2 is a relay optical system or a Keplerian beam diameter converter, and has a first convex lens 11, a first transmissive parallel plane plate 21, a second transmissive parallel plane plate 22, and a second convex lens 12.

[0042] The first convex lens 11 focuses the laser light, which is parallel light, within the optical device 2. The second convex lens 12 converts the laser light, which is divergent light, into parallel light within the optical device 2. This allows the optical device 2 to function as a relay optical system or a beam diameter converter.

[0043] The first plane-parallel plate 21 is inserted between the first convex lens 11 and the focal points of the first and second convex lenses 11, 12. The second plane-parallel plate 22 is inserted between the focal points of the first and second convex lenses 11, 12 and the second convex lens 12. The first and second plane-parallel plates 21, 22 are held rotatably in the direction of the symbol r in the figure.

[0044] In the optical device 2 configured in this manner, while functioning as a relay optical system or a beam diameter converter, the propagation direction of the laser light after passing through the convex lens 12 can be controlled by controlling the rotation of the first and second parallel plane plates 21, 22 in the r direction.

[0045] In this optical device 2, the first and second plane-parallel plates 21 and 22 are inserted on both sides of the focal point, but it is also possible to insert one plane-parallel plate on only one side.

[0046] In addition, when using plane-parallel plates 21 and 22 whose refractive index can be changed by applying electricity, magnetism, heat, light, or the like, it is possible to control the light propagation direction angle φ while fixing the plane-parallel plates 21 and 22 at a constant inclination angle without rotating them. In this case, there is no mechanical drive unit, and resistance to mechanical vibration and wear is also improved.

[0047] It is also possible to use an optical device in which the light traveling direction in Fig. 4 is reversed. In this case, the light receiving device can select the light arrival angle with high accuracy.

[0048] <Third embodiment> FIG. 5 is a diagram showing a configuration of an optical device according to a third embodiment of the present invention.

[0049] As shown in FIG. 5, the optical device 3 is a Galilean beam diameter converter, and includes one concave lens 13, one convex lens 14, and a transmission type parallel plane plate 23.

[0050] The concave lens 13 diverges the parallel laser light within the optical device 3. The convex lens 14 converts the diverging laser light into parallel light within the optical device 3. This allows the optical device 3 to function as a beam diameter converter.

[0051] The plane-parallel plate 23 is inserted between the convex lens 14 and the focal point of the convex lens 14 (which is outside the optical device 3) and between the concave lens 13 and the convex lens 14. The plane-parallel plate 23 is held so as to be rotatable in the direction indicated by the symbol r in the drawing.

[0052] In the optical device 3 configured in this manner, the propagation direction of the laser light after passing through the convex lens 14 can be controlled by rotating the plane-parallel plate 23 in the r direction while exerting the function of a beam diameter converter. In addition, compared to the second embodiment shown in Fig. 4, the focal points of the concave lens 13 and the convex lens 14 are outside the optical device 3, so that the optical device 3 can be made smaller in size.

[0053] In addition, when using a plane-parallel plate 23 whose refractive index can be changed by applying electricity, magnetism, heat, light, or the like, it is possible to control the light propagation direction angle φ while fixing the plane-parallel plate 23 at a constant inclination angle without rotating it. In this case, there is no mechanical drive unit, and resistance to mechanical vibration and wear is also improved.

[0054] It is also possible to use an optical device in which the light traveling direction in Fig. 5 is reversed. In this case, the light receiving device can select the light arrival angle with high accuracy.

[0055] <Fourth embodiment> FIG. 6 is a diagram showing a configuration of an optical device according to a fourth embodiment of the present invention.

[0056] As shown in FIG. 6, while the optical device 1 shown in FIG. 1 has one parallel plane plate 20, the optical device 4 has three transmission type parallel plane plates 24, 25, and 26 having different thicknesses.

[0057] The parallel plane plates 24, 25, and 26 are inserted between the convex lens 10 and the laser light source 30. The parallel plane plates 24, 25, and 26 are each held so as to be independently rotatable in the direction indicated by the symbol r in the drawing.

[0058] In the optical device 4 configured in this manner, the propagation direction of the laser light can be changed with different accuracy and pitch by independently rotating and controlling the plane-parallel plates 24, 25, and 26 in the r direction while exhibiting the function of a collimator. Note that the number of plane-parallel plates is not limited to three, and any number of plates can be used, and the degree of freedom in accuracy and pitch increases according to the number of plates.

[0059] The graph in FIG. 7 shows the relationship between the inclination angle θ of each of the parallel plane plates when the thicknesses d of the parallel plane plates 24, 25, and 26 are significantly different from each other. 0 7 shows an example of a calculation result showing the light propagation direction angle φ after passing through the convex lens 10 with respect to the light propagation direction angle φ after passing through the convex lens 10. Here, the focal length of the convex lens 10 is 100 mm, and the refractive index is 1.5. As can be seen from this graph, when three parallel plane plates with significantly different thicknesses are inserted, the directional control accuracy and pitch of each parallel plane plate can have a difference of several times to about 10 times or more. Since the total control angle in this embodiment is the sum of the control angles of the parallel plane plates 24, 25, and 26, by inserting multiple parallel plane plates with significantly different thicknesses, it is possible to simultaneously perform both coarse adjustment and fine adjustment, and to collectively mount functions that are difficult to implement in existing devices. In the calculation of FIG. 7, all three plates are set to the same refractive index, but the control accuracy and pitch of each parallel plane plate can be changed by changing the value of each refractive index in the same way.

[0060] In the optical device 4 according to this embodiment, not only can the propagation direction of the laser light be changed with different precision and pitch as described above, but also the number of parallel plane plates can be increased to two or more to change the inclination angle θ 0 By reducing the maximum value of the angle θ 0 At the same time, it is also possible to reduce astigmatism, which increases in proportion to the square of

[0061] In addition, when using the plane-parallel plates 24, 25, and 26 whose refractive index can be changed by applying electricity, magnetism, heat, light, or the like, it is possible to control the light propagation direction angle φ while fixing the plane-parallel plates 24, 25, and 26 at a constant inclination angle without rotating them. In this case, there is no mechanical drive unit, and resistance to mechanical vibration and wear is also improved.

[0062] 6 may be replaced with an optical sensor, and the light traveling direction may be reversed, resulting in a light receiving device that can select the light arrival angle with high accuracy.

[0063] <Fifth embodiment> FIG. 8 is a diagram showing a configuration of an optical device according to a fifth embodiment of the present invention. As shown in FIG. 8, the optical device 101 is a collimator that converts a diverging beam into parallel light, and includes a concave mirror 110 and a transmission-type parallel plane plate 120 inserted between a laser light source 130 and the concave mirror 110.

[0064] The concave mirror 110 converts the laser light, which is divergent light output from a laser light source 130 arranged at the focal position of the concave mirror 110, into parallel light.

[0065] The plane-parallel plate 120 is held rotatably. For example, the plane-parallel plate 120 is rotated in the direction of the symbol r in the figure.

[0066] The plane-parallel plate 120 is held by a holding mechanism (optical element holder) not shown, and may be rotated, for example, manually, or may be rotatably held by a rotation drive mechanism (kinematic mount for optical elements or a rotation stage) not shown, and may be rotated under the control of a predetermined control system (a system having a stepping motor or a piezoelectric drive device) not shown.

[0067] Such an optical device 101 constitutes an optical propagation direction controller, selector, or the like, which is made up of a Fourier transform optical system having a conversion function between optical spatial distribution and optical propagation angle distribution.

[0068] For example, in this optical device 101, when the parallel plane plate 120 is rotated in the direction of the symbol r in the figure, the apparent focus of the concave mirror 110 (the image of the laser light source 130 at the emission end) when viewed from the concave mirror 110 side is shifted in a direction perpendicular to the optical axis connecting the laser light source 130 and the concave mirror 110. This controls the propagation direction of light in a direction intersecting the optical axis connecting the laser light source 130 and the concave mirror 110 via the concave mirror 110. That is, in the optical device 101 according to the present invention, by changing the angle of the parallel plane plate 120 with respect to the optical axis, it is possible to control the optical propagation direction of the laser light output from the optical device 101 after passing through the concave mirror 110. Note that in this embodiment, a reflective concave mirror is used instead of a lens of a transmissive refractive type that generally has a refractive index dispersion, so that the optical axis is largely bent and the difficulty of optical alignment generally tends to increase, but there is a possibility that it can be applied to a wider wavelength range. In addition, because it is a reflective type, heat generation due to light absorption is unlikely to occur, and even if heat is generated, it is easy to cool.

[0069] In addition, when using a plane-parallel plate 120 whose refractive index can be changed by applying electricity, magnetism, heat, light, or the like, it is possible to control the light propagation direction angle φ while fixing the plane-parallel plate 120 at a constant angle without rotating it. In this case, there is no mechanical drive unit, and resistance to mechanical vibration and wear is also improved.

[0070] 8 may be replaced with an optical sensor, and the light traveling direction may be reversed, resulting in a light receiving device that can select the light arrival angle with high accuracy.

[0071] Sixth embodiment FIG. 9 is a diagram showing a configuration of an optical device according to a sixth embodiment of the present invention. As shown in FIG. 9, the optical device 102 is a collimator using a large-aperture Cassegrain reflecting telescope that converts a diverging beam into parallel light, and has a pair of concave mirrors 111 and convex mirrors 112, and a transmissive parallel plane plate 121 inserted between the laser light source 130 and the concave mirror 111 and convex mirror 112.

[0072] The pair of concave mirrors 111 and convex mirrors 112 converts into parallel light the laser light, which is divergent light output from a laser light source 130 arranged at the focal position of the pair of concave mirrors 111 and convex mirrors 112. By using a Cassegrain reflecting telescope as in this embodiment, it is possible to handle large diameter beams of about 50 mm or more, which are generally difficult to handle with transmissive refractive lenses.

[0073] The plane-parallel plate 121 is held rotatably. For example, the plane-parallel plate 121 is rotated in the direction of the symbol r in the figure.

[0074] The plane-parallel plate 121 is held by a holding mechanism (optical element holder) not shown, and may be rotated manually, for example, or may be rotatably held by a rotation drive mechanism (kinematic mount for optical elements or a rotation stage) not shown, and may be rotated under the control of a predetermined control system (a system having a stepping motor or a piezoelectric drive device) not shown.

[0075] Such an optical device 102 constitutes a light propagation direction controller, selector, or the like, which is made up of a Fourier transform optical system having a conversion function between a light spatial distribution and a light propagation angle distribution.

[0076] For example, in this optical device 102, when the plane-parallel plate 121 is rotated in the direction of the symbol r in the figure, the apparent focal point (the image of the emission end of the laser light source 130) when viewed from the pair of concave mirrors 111 and convex mirror 112 side is shifted in a direction perpendicular to the optical axis connecting the laser light source 130 and the pair of concave mirrors 111 and convex mirror 112. This controls the propagation direction of light on the opposite side of the focal point (the emission end of the laser light source 130) across the pair of concave mirrors 111 and convex mirror 112. That is, in the optical device 102 according to the present invention, the propagation direction of light on the opposite side of the pair of concave mirrors 111 and convex mirror 112 can be controlled by changing the angle of the plane-parallel plate 121 with respect to the optical axis. In Figure 9, a Cassegrain reflecting telescope is used as an example of an optical mechanism (focusing optical component) that can handle large diameter beams of about 50 mm or more, which are generally difficult to handle with transmissive refractive lenses. However, this is not limited to this, and other types of reflecting telescopes may also be used.

[0077] In addition, when using a plane-parallel plate 121 whose refractive index can be changed by applying electricity, magnetism, heat, light, or the like, it is possible to control the light propagation direction angle φ while fixing the plane-parallel plate 121 at a constant inclination angle without rotating it. In this case, there is no mechanical drive unit, and resistance to mechanical vibration and wear is also improved.

[0078] 9 may be replaced with an optical sensor, and the light traveling direction may be reversed, resulting in a light receiving device that can select the light arrival angle with high accuracy.

[0079] Seventh embodiment FIG. 10 is a diagram showing a configuration of an optical device according to a seventh embodiment of the present invention.

[0080] As shown in FIG. 10, the optical device 103 is a Keplerian reflective relay optical system or beam diameter converter, and has a first concave mirror 113, a first transmissive parallel plane plate 122, a second transmissive parallel plane plate 123, and a second concave mirror 114.

[0081] The first concave mirror 113 focuses the laser light, which is parallel light, within the optical device 103. The second concave mirror 114 converts the laser light, which is divergent light within the optical device 103, into parallel light. This allows the optical device 103 to function as a relay optical system or a beam diameter converter.

[0082] The first plane-parallel plate 122 is inserted between the first concave mirror 113 and the focal points of the first and second concave mirrors 113, 114. The second plane-parallel plate 123 is inserted between the focal points of the first and second concave mirrors 113, 114 and the second concave mirror 114. The first and second plane-parallel plates 122, 123 are held rotatably in the direction of the symbol r in the figure.

[0083] In the optical device 103 configured in this manner, the first and second plane-parallel plates 122, 123 can be rotated in the r direction to control the propagation direction of light after passing through the concave mirror 114 while functioning as a relay optical system or a beam diameter converter. In this embodiment, a reflective concave mirror is used instead of a transmissive refractive lens that generally has a refractive index dispersion, so that the optical axis is greatly bent and the difficulty of optical alignment generally tends to increase, but there is a possibility that it can be applied to a wider wavelength range. In addition, because it is a reflective type, it is less likely to generate heat due to light absorption, and even if heat is generated, it is easy to cool.

[0084] In this optical device 103, the first and second plane-parallel plates 122, 123 are inserted on both sides of the focal point, but it is also possible to insert one plane-parallel plate on only one of the focal points.

[0085] In addition, when using the plane-parallel plates 122 and 123 whose refractive index can be changed by applying electricity, magnetism, heat, light, or the like, it is possible to control the light propagation direction angle φ while fixing the plane-parallel plates 122 and 123 at a constant inclination angle without rotating them. In this case, there is no mechanical drive unit, and resistance to mechanical vibration and wear is also improved.

[0086] It is also possible to use an optical device in which the light traveling direction in Fig. 10 is reversed. In this case, the light receiving device can select the light arrival angle with high accuracy.

[0087] <Eighth embodiment> FIG. 11 is a diagram showing a configuration of an optical device according to an eighth embodiment of the present invention.

[0088] As shown in FIG. 11, the optical device 104 is a Galilean reflection type beam diameter converter, and includes one convex mirror 115, one concave mirror 116, and a transmission type parallel plane plate 124.

[0089] The convex mirror 115 diverges the parallel laser light within the optical device 104. The concave mirror 116 converts the diverging laser light into parallel light within the optical device 104. This allows the optical device 104 to function as a beam diameter converter.

[0090] The plane-parallel plate 124 is inserted between the concave mirror 116 and the focal point of the concave mirror 116 (which is outside the optical device 104) and between the concave mirror 116 and the convex mirror 115. The plane-parallel plate 124 is held so as to be rotatable in the direction indicated by the symbol r in the drawing.

[0091] In the optical device 104 configured in this manner, the propagation direction of light after passing through the concave mirror 116 can be controlled by rotating the plane parallel plate 124 in the r direction while exerting the function of a beam diameter converter. In this embodiment, a reflective concave mirror is used instead of a transmissive refractive lens that generally has a refractive index dispersion. Although the optical axis is largely bent and the difficulty of optical alignment generally tends to increase, the optical device 104 may be applicable to a wider wavelength range. In addition, since the optical device 104 is of the reflective type, it is less likely to generate heat due to light absorption, and even if it does generate heat, it is easy to cool it. Furthermore, compared to the seventh embodiment, the focal points of the convex mirror 115 and the concave mirror 116 are outside the optical device 104, so the size of the optical device 104 can generally be reduced.

[0092] In addition, when using a plane-parallel plate 124 whose refractive index can be changed by applying electricity, magnetism, heat, light, or the like, it is possible to control the light propagation direction angle φ while fixing the plane-parallel plate 124 at a constant inclination angle without rotating it. In this case, there is no mechanical drive unit, and resistance to mechanical vibration and wear is also improved.

[0093] It is also possible to use an optical device in which the light traveling direction in Fig. 11 is reversed. In this case, the light receiving device can select the light arrival angle with high accuracy.

[0094] <Ninth embodiment> FIG. 12 is a diagram showing a configuration of an optical device according to a ninth embodiment of the present invention.

[0095] As shown in FIG. 12, the optical device 105 is a Keplerian mixed transmission / reflection type relay optical system or beam diameter converter, and has a convex lens 117, a transmission type first parallel plane plate 125, a transmission type second parallel plane plate 126, and a concave mirror 118.

[0096] The convex lens 117 focuses the laser light, which is parallel light, inside the optical device 105. The concave mirror 118 converts the laser light, which is divergent light inside the optical device 105, into parallel light. This allows the optical device 105 to function as a relay optical system or a beam diameter converter.

[0097] The first plane-parallel plate 125 is inserted between the convex lens 117 and the focal points of the convex lens 117 and the concave mirror 118. The second plane-parallel plate 126 is inserted between the focal points of the convex lens 117 and the concave mirror 118 and the concave mirror 118. The first and second plane-parallel plates 125, 126 are held rotatably in the direction of the symbol r in the figure.

[0098] In the optical device 105 configured in this manner, the propagation direction of light after passing through the concave mirror 118 can be controlled by rotating the first and second plane-parallel plates 125 and 126 in the r direction while exerting the function of a relay optical system or a beam diameter converter. As in this embodiment, it is possible to use transmissive refractive lenses and reflecting mirrors, each of which has its own advantages and disadvantages, as elements for focusing or diverging light and to use them in combination, depending on the requirements and restrictions of the system to which the present invention is applied (for example, the layout inside the laser transmitter housing, the laser wavelength / bandwidth, temperature control performance, etc.). Of course, the convex lens 117 may be replaced with a concave mirror, and the concave mirror 118 may be replaced with a convex lens.

[0099] In this optical device 105, the first and second plane-parallel plates 125, 126 are inserted on both sides of the focal point, but it is also possible to insert one plane-parallel plate on only one of the focal points.

[0100] In addition, when using the plane-parallel plates 125 and 126 whose refractive index can be changed by applying electricity, magnetism, heat, light, or the like, it is possible to control the light propagation direction angle φ while fixing the plane-parallel plates 125 and 126 at a constant inclination angle without rotating them. In this case, there is no mechanical drive unit, and resistance to mechanical vibration and wear is also improved.

[0101] It is also possible to use an optical device in which the light traveling direction in Fig. 12 is reversed. In this case, the light receiving device can select the light arrival angle with high accuracy.

[0102] <Tenth embodiment> FIG. 13 is a diagram showing a configuration of an optical device according to a tenth embodiment of the present invention.

[0103] As shown in FIG. 13, the optical device 106 is a Galilean type mixed transmission / reflection type beam diameter converter, and includes one concave lens 119, one concave mirror 131, and a transmission type parallel plane plate 127.

[0104] The concave lens 119 diverges the parallel laser light within the optical device 106. The concave mirror 131 converts the divergent laser light into parallel light within the optical device 106. This allows the optical device 106 to function as a beam diameter converter.

[0105] The plane-parallel plate 127 is inserted between the concave mirror 131 and the focal point of the concave mirror 131 (which is outside the optical device 106), and between the concave mirror 131 and the concave lens 119. The plane-parallel plate 127 is held so as to be rotatable in the direction indicated by the symbol r in the drawing.

[0106] In the optical device 106 configured in this manner, the propagation direction of the light after passing through the concave mirror 131 can be controlled by rotating the plane parallel plate 127 in the r direction while exerting the function of the beam diameter converter. As in this embodiment, it is possible to use a transmissive refractive lens and a reflecting mirror, each of which has its own advantages and disadvantages, as an element for focusing or diverging light and to use them in combination according to the requirements and limitations of the system to which the present invention is applied (for example, the layout inside the laser transmitter housing, the laser wavelength / bandwidth, temperature control performance, etc.). Of course, the concave lens 119 may be replaced with a convex mirror, and the concave mirror 131 may be replaced with a convex lens. Compared to the ninth embodiment, the focal points of the concave lens 119 and the concave mirror 131 are outside the optical device 106, so that the size of the optical device 106 can generally be reduced.

[0107] In addition, when using a plane-parallel plate 127 whose refractive index can be changed by applying electricity, magnetism, heat, light, or the like, it is possible to control the light propagation direction angle φ while fixing the plane-parallel plate 127 at a constant inclination angle without rotating it. In this case, there is no mechanical drive unit, and resistance to mechanical vibration and wear is improved.

[0108] It is also possible to use an optical device in which the light traveling direction in Fig. 13 is reversed. In this case, the light receiving device can select the light arrival angle with high accuracy.

[0109] <Eleventh embodiment> FIG. 14 is a diagram showing a configuration of an optical device according to an eleventh embodiment of the present invention.

[0110] As shown in FIG. 14, the optical device 107 is a Keplerian mixed transmission / reflection type relay optical system or beam diameter converter, and includes a convex lens 132, a pair of concave mirrors 133 and convex mirrors 134 which are Cassegrain type reflecting telescopes, and a transmission type parallel plane plate 128.

[0111] The convex lens 132 focuses the laser light, which is parallel light, inside the optical device 107. A pair of concave mirrors 133 and convex mirrors 134 convert the laser light, which is divergent light inside the optical device 107, into parallel light. This allows the optical device 107 to function as a relay optical system or a beam diameter converter. By using a Cassegrain reflecting telescope as in this embodiment, it is possible to handle large diameter beams of about 50 mm or more, which are generally difficult to handle with transmissive refractive lenses.

[0112] The parallel plane plate 128 is inserted between the convex lens 132 and the focal point of the convex lens 132. The parallel plane plate 128 is supported so as to be rotatable in the direction of the symbol r in the drawing.

[0113] In the optical device 107 configured in this manner, the propagation direction of light after passing through the concave mirror 133 can be controlled by rotating the plane-parallel plate 128 in the r direction while exerting the function of a relay optical system or a beam diameter converter. Note that, in Fig. 14, a Cassegrain reflecting telescope is given as an example of an optical mechanism (light-collecting optical component) capable of handling a large-diameter beam of about 50 mm or more, which is generally difficult to handle with a transmissive refractive lens, but the present invention is not limited to this, and other types of reflecting telescopes may be used.

[0114] In addition, when using a plane-parallel plate 128 whose refractive index can be changed by applying electricity, magnetism, heat, light, or the like, it is possible to control the light propagation direction angle φ while fixing the plane-parallel plate 128 at a constant inclination angle without rotating it. In this case, there is no mechanical drive unit, and resistance to mechanical vibration and wear is also improved.

[0115] It is also possible to use an optical device in which the light traveling direction in Fig. 14 is reversed. In this case, the light receiving device can select the light arrival angle with high accuracy.

[0116] <Twelfth embodiment> FIG. 15 is a diagram showing a configuration of an optical device according to a twelfth embodiment of the present invention.

[0117] As shown in FIG. 15, the optical device 108 is a Galilean-type mixed transmission / reflection type beam diameter converter, and includes a concave lens 135, a pair of concave mirrors 136 and convex mirrors 137 which are Cassegrain-type reflecting telescopes, and a transmission type parallel plane plate 129.

[0118] The concave lens 135 diverges the parallel laser light within the optical device 108. A pair of concave mirrors 136 and convex mirrors 137 convert the diverging laser light within the optical device 108 into parallel light. This allows the optical device 108 to function as a beam diameter converter. By using a Cassegrain reflecting telescope as in this embodiment, it is possible to handle large diameter beams of about 50 mm or more, which are generally difficult to handle with transmissive refractive lenses.

[0119] The plane-parallel plate 129 is inserted between the pair of concave mirrors 136 and convex mirror 137 and the focal points of the pair of concave mirrors 136 and convex mirror 137 (which are located outside the optical device 108), and between the convex mirror 137 and the concave lens 135. The plane-parallel plate 129 is held rotatably in the direction indicated by the symbol r in the drawing.

[0120] In the optical device 108 configured in this manner, the propagation direction of light after passing through the concave mirror 136 can be controlled by rotating the plane-parallel plate 129 in the r direction while exerting the function of a beam diameter converter. In FIG. 15, a Cassegrain reflecting telescope is given as an example of an optical mechanism (light-collecting optical component) capable of handling a large-diameter beam of about 50 mm or more, which is generally difficult to handle with a transmissive refractive lens, but the present invention is not limited to this and other types of reflecting telescopes may be used. Furthermore, compared to the eleventh embodiment, the focal points of the concave lens 135 and the pair of concave mirrors 136 and convex mirror 137 are outside the optical device 108, so that the size of the optical device 108 can generally be reduced.

[0121] In addition, when using a plane-parallel plate 129 whose refractive index can be changed by applying electricity, magnetism, heat, light, or the like, it is possible to control the light propagation direction angle φ while fixing the plane-parallel plate 129 at a constant inclination angle without rotating it. In this case, there is no mechanical drive unit, and resistance to mechanical vibration and wear is also improved.

[0122] It is also possible to use an optical device in which the light traveling direction in Fig. 15 is reversed. In this case, the light receiving device can select the light arrival angle with high accuracy.

[0123] <Application example to a system that wirelessly supplies laser power to a lunar rover> FIG. 17 is a diagram showing an embodiment in which the optical device according to the present invention is applied to a system for wireless laser power supply to a lunar rover.

[0124] As shown in FIG. 17, a laser wireless power supply system 170 includes a lunar lander 172 arranged in a sunlit region 171 on the lunar surface, and a lunar rover 174 traveling in a permanently shadowed region 173 on the lunar surface.

[0125] The lunar lander 172 has a power generation system (not shown) using solar power generation panels 175, and a laser transmitter 176 using the optical device according to the present invention. The lunar rover 174 has a laser receiving photoelectric conversion panel 177 that receives the laser light sent from the laser transmitter 176 and converts it into electricity. Taking into account weight and size restrictions, the light receiving surface of the laser receiving photoelectric conversion panel 177 is assumed to be small, for example, about 30 cm in diameter.

[0126] FIG. 18 is a diagram showing the internal configuration of the laser transmitter 176.

[0127] As shown in FIG. 18, the laser transmitter 176 includes a laser light source 178, an optical device 33 having, for example, the concave lens 13, the convex lens 14, and the transmission type parallel plane plate 23 shown in FIG. 5, a variable beam diameter converter 191, and a beam shaper 192. The parallel plane plate 23 is configured to be able to adjust the light transmission direction two-dimensionally under the control of, for example, a control system not shown. The two-dimensional light propagation direction control can be realized by, for example, rotating one parallel plane plate 23 about two axes, the x-axis and the y-axis. The beam shaper 192 is disposed at the rear side of the optical device 33, and the laser light emitted from the optical device 33 is emitted to the lunar rover 174 side through the beam shaper 192. In an optical system equipped with a device for precisely controlling the wavefront of the laser light, such as a beam shaper, it is generally difficult to control the propagation direction of the wavefront-controlled light with high precision using conventional technology. In other words, when the light propagation direction controller is inserted before the beam shaper, the entire optical system in the latter stage, including the beam shaper, which is typically sensitive to the light input conditions, must be adjusted according to the direction control, while when the light propagation direction controller is inserted in the latter stage, there is a risk of the controlled wavefront being destroyed. On the other hand, by using the configuration according to the present invention, which requires only the insertion of a parallel plane plate, it is possible to easily avoid these problems. As shown in Figures 1 and 2, at the focal position on the right side of the lens 10, the beam center position does not change even if the light propagation direction is deflected, but by placing the beam shaper 192 at a position corresponding to this, it is possible to suppress the change in the light input conditions to the beam shaper 192, that is, the deterioration of the wavefront control performance.

[0128] In the laser wireless power supply system 170 configured as above, the parallel plane plate 23 is adjusted in response to a signal from a subsystem (not shown) that detects the deviation of the laser arrival position, so that the laser light emitted from the laser transmitter 176 of the lunar lander 172 can be accurately irradiated to the laser receiving photoelectric conversion panel 177 of the lunar rover 174, which may be about 1 km away, with a position deviation of about several centimeters or less. As a result, the laser wireless power supply system 170 can reliably wirelessly supply power from the lunar lander 172 to the lunar rover 174 with almost no optical loss. In particular, the laser wireless power supply system 170 can homogenize the intensity distribution of the transmitted beam by disposing the beam shaper 192 on the rear side of the optical device 33. Also, since it is not necessary to provide a configuration for homogenizing the intensity distribution of the beam on the lunar rover 174 side, the weight of the lunar rover 174, which is the power receiving side, can be reduced, and the power consumption of the lunar rover 174 can be reduced.

[0129] <Application example to LIDAR / remote sensing system> FIG. 19 is a diagram showing an embodiment in which the optical device according to the present invention is applied to a LIDAR / remote sensing system.

[0130] As shown in FIG. 19, a lidar / remote sensing system 180 includes, for example, a movable observation vehicle 181 and an observation instrument 182 mounted on the observation vehicle 181.

[0131] FIG. 20 is a diagram showing the configuration of an observation device 182 in which an optical device according to the present invention is implemented.

[0132] As shown in FIG. 20, the observation instrument 182 includes a laser light source 183 that irradiates a single-color, multiple-color, or white laser light toward an object to be observed 186 located at a distance of, for example, several hundred meters to several kilometers as shown in FIG. 19, a photodetector or spectroscope 184 that measures reflected and scattered light from the object to be observed 186, an optical device 102 having a pair of concave mirrors 111 and convex mirrors 112, which are, for example, Cassegrain reflecting telescopes shown in FIG. 9, and a parallel plane plate 121 arranged at the entrance of the photodetector or spectroscope 184, and an aperture 185 interposed between the photodetector or spectroscope 184 and the optical device 102. The parallel plane plate 121 is configured to be able to precisely select the light receiving direction two-dimensionally under the control of, for example, a control system not shown. The two-dimensional direction control can be realized by, for example, a combination of rotation about an arbitrary axis (r-axis) perpendicular to the optical axis (z-axis) and rotation about the optical axis (z-axis) itself as the central axis. It is believed possible to obtain a two-dimensional map of the surface and inner surface condition of the object under observation 186 by irradiating the laser light onto a relatively wide area of ​​the surface of the object under observation 186, and then receiving, measuring and analyzing the reflected and scattered light therefrom with a photodetector or spectroscope 184 while selecting and sweeping the reflected and scattered light two-dimensionally with the optical device 102. Here, the aperture 185 is used to select and limit the light receiving direction more accurately.

[0133] Incidentally, the laser light from the laser light source 183 in Fig. 20 may also be controlled two-dimensionally in the form shown in Fig. 18. That is, a specific position on the unobserved object 186 may be selectively irradiated, or the selected area may be swept at high speed. In that case, the optical device 102 receives reflected and scattered light from the selected irradiation area in synchronization with the sweep, or receives light from a wide light receiving direction range all at once.

[0134] <Experimental Results> In the optical device 3 shown in Fig. 5, we designed and constructed a laser beam transmission system in which the focal length of the concave lens 13 was -75 mm and the focal length of the convex lens 14 was 100 mm, and attached the parallel plane plate 23 (thickness: 1 mm, refractive index: approximately 1.5) to an angle adjuster with the product name "KC2-TM" (manufactured by Thorlabs), and conducted an experiment to verify the accuracy of the laser beam propagation direction controller. The knob of the "KC2-TM" is threaded with 100 TPI (Threads per inch), allowing for angle adjustment of 3.36 mrad per knob rotation. Five rotations of the knob result in an angle change of 16.8 mrad.

[0135] In this experimental system, the output power of the laser light source was set to about 250 mW, and the beam image after 800 m transmission was observed. Figure 21 shows the beam image at the destination of 800 m transmission when the laser light propagation direction was swept up and down / left and right from the center position by manually operating the "KC2-TM" (knob ±5,10 rotations). Furthermore, Figure 22 shows the amount of change in the beam center position at the destination of 800 m transmission, and Figure 23 shows the corresponding amount of change in the light propagation direction angle as seen from the light transmitting side equipped with the optical device 3. Note that Figures 22 and 23 show multiple measurement data points superimposed.

[0136] These experimental results demonstrated that the beam center direction can be controlled with an accuracy of at least ±10 μrad, including reproducibility, which corresponds to a beam center position deviation of ±10 mm at a distance of 1 km.

[0137] In addition, it was confirmed that the time fluctuation of the beam center position in this measurement was less than a few μrad by measuring it multiple times with the direction controller fixed. This value is dominated by slight fluctuations in the atmosphere of the transmission path and noise in the measurement system, and due to the high earthquake resistance that is a feature of this invention, it is considered that the contribution of vibration of the light transmitter is almost zero.

[0138] <Other> The present invention is not limited to the above-described embodiments, and various modifications and applications are possible within the scope of the technical idea of ​​the present invention, and the scope of implementation of such modifications and applications also belongs to the technical scope of the present invention. [Explanation of symbols]

[0139] 1, 1', 2, 3, 4, 101, 102, 103, 104, 105, 106, 107, 108: Optical device 10: Convex lens 11: First convex lens 12: Second convex lens 13: Concave lens 14: Convex lens 20: Parallel plane plate 20': Parallel plane plate 21: First parallel plane plate 22: Second parallel plane plate 23: Parallel plane plate 24: Parallel plane plate 25: Parallel plane plate 26: Parallel plane plate 33:Optical device 110: Concave mirror 111: Concave mirror 112: Convex mirror 113: First concave mirror 114: Second concave mirror 115: Convex mirror 116: Concave mirror 117: Convex lens 118: Concave mirror 119: Concave lens 120: Parallel plane plate 121: Parallel plane plate 122: First parallel plane plate 123: Second parallel plate 124: Parallel plane plate 125: First parallel plane plate 126: Second parallel plate 127: Parallel plane plate 128: Parallel plane plate 129: Parallel plane plate 131: Concave mirror 132: Convex lens 133: Concave mirror 134: Convex mirror 135: Concave lens 136: Concave mirror 137: Convex mirror 161: Refractive index control section 170: Laser wireless power supply system 171: Sunlit area on the moon 172: Lunar Lander 173: Permanent shadow area on the moon 174: Lunar Rover 175: Solar panels 176: Laser transmitter 177: Photoelectric conversion panel for laser reception 178: Laser light source 180: Lidar / Remote Sensing System 181: Observation vehicle 182: Observation equipment 183: Laser light source 184: Photodetector or spectrometer 185: Aperture 186: Observed object 191: Variable beam diameter converter 192: Beam shaper

Claims

1. A focusing optical component having a focus with a focal length f; a transmission-type parallel plane plate having a thickness d and a refractive index n 1 that is inserted between the focal point of the focusing optical component and the focusing optical component and can be rotated on an axis perpendicular or parallel to the optical axis, the parallel plane plate being capable of moving the light beam after passing through the parallel plane plate parallel to the light beam before passing through the parallel plane plate by the rotation, and shifting the apparent focus as seen from the focusing optical component side in a direction perpendicular to the optical axis; Equipped with the focusing optical component converts the divergent light beam emitted from or passing through the focus into a parallel light beam having a diameter of 10 or more mm in a space on the side where the parallel plane plate is not present, and changes the emission angle φ of the parallel light beam from the focusing optical component by a Fourier transform action of the focusing optical component in accordance with the shift amount of the apparent focus, The focal length f of the focusing optical component, the thickness d of the parallel plane plate, and the refractive index n 1 are expressed by the following formula: is selected so that the delivery angle φ changes on the order of microradians or less with respect to a change in the inclination angle θ 0 of the parallel plane plate on the order of milliradians or more, Even if the parallel plane plate is rotated, a point where the position and shape of the converted parallel light beam do not change exists at a position that is a focal length f away from the focusing optical component in a space on the side where the parallel plane plate is not present. optical equipment.

2. A focusing optical component having a focus with a focal length f; a transmission-type parallel plane plate having a thickness d, which is inserted between the focal point of the focusing optical component and the focusing optical component at an inclination angle θ 0 with respect to the optical axis and has a refractive index n 1 that changes due to an external action, and which is capable of moving the light beam after passing through the parallel plane plate parallel to the light beam before passing through the parallel plane plate due to the change in refractive index, and shifting the apparent focus as seen from the focusing optical component side in a direction perpendicular to the optical axis; Equipped with the focusing optical component converts a divergent light beam emitted from or passing through the focus into a parallel light beam having a diameter of 10 or more mm in a space on the side where the parallel plane plate is not present, and changes a sending angle φ of the parallel light beam from the focusing optical component by a Fourier transform action of the focusing optical component in accordance with an amount of shift of the apparent focus, The focal length f of the focusing optical component, the thickness d of the parallel plane plate, and the inclination angle θ 0 are expressed by the following formula: is selected so that the sending angle φ changes on the order of a microradian or less with respect to the change in the refractive index n 1 of the parallel plane plate based on Even if the refractive index is changed, a point where the position and shape of the converted parallel light beam do not change exists at a position that is a focal length f away from the focusing optical component in the space on the side where the parallel plane plate is not present. optical equipment.

3. A focusing optical component having a diameter of more than 10 mm and a focal length f; a transmission-type parallel plane plate having a thickness d and a refractive index n 1 that is inserted between the focal point of the focusing optical component and the focusing optical component and can be rotated on an axis perpendicular or parallel to the optical axis, the parallel plane plate being capable of moving the light beam after passing through the parallel plane plate parallel to the light beam before passing through the parallel plane plate by the rotation, and shifting the apparent focus as seen from the focusing optical component side in a direction perpendicular to the optical axis; Equipped with the focusing optical component is disposed at a position such that a parallel light beam coming from a space on the side where the parallel plane plate is not present is focused on a sensor of a photodetector or a spectrometer; an arrival angle φ of the parallel light beam is selected by a Fourier transform action of the focusing optical component in accordance with an amount of shift of the apparent focus caused by the rotation of the parallel plane plate; The focal length f of the focusing optical component, the thickness d of the parallel plane plate, and the refractive index n 1 are expressed by the following formula: is selected so that the arrival angle φ changes on the order of a microradian or less with respect to a change in the tilt angle θ 0 of the parallel plane plate on the order of a milliradian or more, A point where the position and shape of the selected parallel light beam do not change even when the parallel plane plate is rotated is present at a position spaced apart from the focusing optical component by a focal length f on the side where the parallel plane plate is not present. optical equipment.

4. A focusing optical component having a diameter of more than 10 mm and a focal length f; a transmission-type parallel plane plate having a thickness d, which is inserted between the focal point of the focusing optical component and the focusing optical component at an inclination angle θ 0 with respect to the optical axis and has a refractive index n 1 that changes due to an external action, and which is capable of moving the light beam after passing through the parallel plane plate parallel to the light beam before passing through the parallel plane plate due to the change in refractive index, and shifting the apparent focus as seen from the focusing optical component side in a direction perpendicular to the optical axis; Equipped with the focusing optical component is disposed at a position such that a parallel light beam arriving from a space on a side of the focusing optical component where the parallel plane plate is not present is focused on a sensor of a photodetector or a spectroscope; an arrival angle φ of the parallel light beam is selected by a Fourier transform action of the focusing optical component in response to an apparent focal shift amount caused by a change in a refractive index n 1 of the parallel plane plate due to an external action on the parallel plane plate; The focal length f of the focusing optical component, the thickness d of the parallel plane plate, and the inclination angle θ 0 are expressed by the following formula: is selected so that the arrival angle φ changes on the order of a microradian or less with respect to the change in the refractive index n 1 of the parallel plane plate based on A point where the position and shape of the selected parallel light beam do not change even if the refractive index is changed exists at a position separated by a focal length f from the focusing optical component in a space on the side where the parallel plane plate is not present. optical equipment.

5. The focusing optical component is a collimator composed of one or more lenses or one or more reflecting mirrors.

5. An optical device according to any one of the preceding claims.

6. The reflector is a reflecting telescope having a diameter of 50 mm or more.

6. The optical device according to claim 5.

7. The focusing optical component may include one or more lenses, one or more reflecting mirrors, Or it is a relay optical system or a beam diameter converter that is composed of a combination of one or more lenses and one or more reflecting mirrors.

5. An optical device according to any one of the preceding claims.

8. The reflector is a reflecting telescope having a diameter of 50 mm or more.

8. The optical device according to claim 7.

9. The parallel plane plate can rotate about two axes perpendicular to each other.

4. An optical device according to claim 1 or 3.

10. The parallel plane plate includes a first parallel plane plate of a transmission type that is rotatable about a first axis perpendicular to the optical axis; a second parallel plane plate of a transmission type that can be rotated about a second axis perpendicular to the optical axis and the first axis as a rotation axis; 4. An optical device according to claim 1 or 3.

11. The parallel plane plate includes a first parallel plane plate of a transmission type, which is fixedly disposed at a predetermined inclination angle with respect to a first axis perpendicular to the optical axis and has a variable refractive index, and a second parallel plane plate of a transmission type, which is fixedly disposed at a predetermined inclination angle with respect to a second axis perpendicular to the optical axis and the first axis and has a variable refractive index.

5. An optical device according to claim 2 or 4.

12. The parallel plane plate includes two or more transmission type parallel plane plates each of which can be rotated independently about the optical axis.

4. An optical device according to claim 1 or 3.

13. the parallel plane plates are fixedly disposed at a predetermined inclination angle with respect to the optical axis, and include two or more transmissive parallel plane plates having a variable refractive index; 5. An optical device according to claim 2 or 4.

14. The position and shape of the parallel light beam do not change, It is characterized by the inclusion of an optical element that is sensitive to the beam incidence position.

14. Optical device according to any one of the preceding claims.

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