Wavelength selection device, method for selecting wavelength, and measurement device

Abstract

To provide a wavelength selection device, a method for selecting a wavelength, and a survey device which can select a transmission wavelength without involving increase of the number of components or of the size.SOLUTION: A wavelength selection device includes: an EW element 2 having a transparent container 4 for sealing a first solution 5 transmitting a first wavelength and a second solution 6 transmitting a second wavelength different from the first wavelength; a power source unit 3 for applying a predetermined voltage to the EW element; and a control unit 10 for controlling the power source unit. The EW element moves at least one of the first solution and the second solution to the center part of the transparent container in response to an applied voltage so that light 7 in a wide bandwidth entering the EW element transmits through one of the first solution and the second solution alone.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a wavelength selection device, a wavelength selection method, and a surveying instrument that select a predetermined wavelength from light having a plurality of wavelengths and transmit the selected wavelength. [Background technology]

[0002] 2. Description of the Related Art In a light receiving optical system such as a camera, a wavelength selection filter is sometimes used so that only light of a specific wavelength is received in order to improve accuracy and suppress errors.

[0003] In addition, in order to reduce size and manufacturing costs, a single light receiving optical system may be made to perform multiple functions. In this case, since each function requires a different wavelength of light, the wavelength selection filter is required to have the function of switching the wavelength of light to be transmitted.

[0004] However, when multiple wavelength selection filters that transmit specific wavelengths are mechanically switched, there is a risk that this will lead to an increase in the number of parts and an increase in size. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2007-330558 A [Patent Document 2] JP 2018-146938 A Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention provides a wavelength selection device, a wavelength selection method, and a surveying instrument that are capable of selecting a transmission wavelength without increasing the number of parts or the size of the instrument. [Means for solving the problem]

[0007] The present invention relates to a wavelength selection device comprising an EW element having a transparent container that encloses a first solution that transmits a first wavelength and a second solution that transmits a second wavelength different from the first wavelength, a power supply unit capable of applying a predetermined voltage to the EW element, and a control unit that controls the power supply unit, wherein the EW element moves either the first solution or the second solution to the center of the transparent container in response to the applied voltage, and broadband light incident on the EW element is configured to transmit only either the first solution or the second solution.

[0008] The present invention also relates to a wavelength selection device further comprising a dual pass filter that is arranged coaxially with the EW element and transmits visible light and near infrared light.

[0009] The present invention also relates to a wavelength selection device configured so that the first solution transmits only visible light, and the second solution transmits only near-infrared light.

[0010] The present invention also relates to a wavelength selection device configured so that the first solution transmits light from visible light to near infrared light, and the second solution transmits only near infrared light.

[0011] The present invention also relates to a wavelength selection device configured so that the first solution transmits visible light and the second solution transmits near-infrared light.

[0012] The present invention also relates to a wavelength selection method in which a predetermined voltage is applied to an EW element having a transparent container that encloses a first solution that transmits a first wavelength and a second solution that transmits a second wavelength different from the first wavelength, and wideband light incident on the EW element is transmitted through only one of the first solution and the second solution.

[0013] Furthermore, the present invention relates to a surveying instrument comprising a distance measuring unit having a light emitting element that emits distance measuring light and a light receiving element that receives the reflected distance measuring light from the object to be measured, a detection unit having a detection light emitting unit that emits detection light of a different wavelength from the distance measuring light and a detection light receiving unit having a detection light receiving element that receives the reflected detection light reflected by the object to be measured, and a calculation control unit that calculates the distance to the object to be measured based on the reception result of the reflected distance measuring light at the receiving element, and calculates the direction of the object to be measured based on the reception result of the reflected detection light at the detection light receiving element, wherein the detection light receiving unit has the above-mentioned wavelength selecting device, and the wavelength selecting device is configured to select and transmit the reflected detection light and external light, and to have them received by the detection light receiving element. Effect of the Invention

[0014] According to the present invention, there is provided an EW element having a transparent container that encloses a first solution that transmits a first wavelength and a second solution that transmits a second wavelength different from the first wavelength, a power supply unit capable of applying a predetermined voltage to the EW element, and a control unit that controls the power supply unit, and the EW element is configured to move either the first solution or the second solution to the center of the transparent container in response to the applied voltage, and broadband light incident on the EW element is configured to transmit only either the first solution or the second solution. Therefore, there is no need to provide multiple wavelength selection filters or a mechanical switching mechanism for switching the wavelength selection filters in order to select the wavelength of the light to be transmitted, and it is possible to reduce the number of parts and make the device more compact.

[0015] Furthermore, according to the present invention, a predetermined voltage is applied to an EW element having a transparent container that encloses a first solution that transmits a first wavelength and a second solution that transmits a second wavelength different from the first wavelength, and wideband light incident on the EW element is transmitted through only one of the first solution and the second solution. This eliminates the need to provide multiple wavelength selection filters to select the wavelength of light to be transmitted or a mechanical switching mechanism to switch between the wavelength selection filters, thereby enabling a reduction in the number of parts and a reduction in size.

[0016] Furthermore, according to the present invention, there is provided a distance measurement unit having a light-emitting element that emits distance measurement light and a light-receiving element that receives the reflected distance measurement light from the object to be measured, a detection unit having a detection light irradiating unit that emits detection light of a different wavelength from the distance measurement light and a detection light receiving unit having a detection light receiving element that receives the reflected detection light reflected by the object to be measured, and a calculation control unit that calculates the distance to the object to be measured based on the reception result of the reflected distance measurement light to the receiving element, and calculates the direction of the object to be measured based on the reception result of the reflected detection light to the detection light receiving element, and the detection light receiving unit has the above-mentioned wavelength selection device, which is configured to select and transmit the reflected detection light and external light and cause them to be received by the detection light receiving element, so that the wavelength selection device can limit the light received by the detection light receiving element to visible light only, thereby providing the excellent effect of coloring the point cloud data measured by the distance measurement unit with high precision. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1A is a schematic diagram showing a wavelength selection device of the first embodiment, FIG. 1B is an EW element showing the case where a first solution is located at the center, and FIG. 1C is an explanatory diagram showing an EW element showing the case where a second solution is located at the center. [Diagram 2] 4 is a graph illustrating the transmittance characteristics of a first solution and a second solution. [Diagram 3] FIG. 1A is a schematic diagram showing a wavelength selection device according to a second embodiment, FIG. 1B is an EW element showing the case where the first solution is located at the center, and FIG. 1C is an explanatory diagram showing the EW element showing the case where the second solution is located at the center. [Figure 4] 13 is a graph illustrating the transmittance characteristics of a second solution and a dual pass filter. [Diagram 5] 11 is a graph illustrating the transmittance characteristics of a second solution after passing through a dual pass filter. [Figure 6] FIG. 10A is a schematic diagram showing a wavelength selection device according to a third embodiment, FIG. 10B is an EW element showing the case where the first solution is located at the center, and FIG. 10C is an explanatory diagram showing the EW element showing the case where the second solution is located at the center. [Figure 7] 1 is a graph illustrating transmittance characteristics of a first solution, a second solution, and a dual pass filter. [Figure 8] 4 is a graph illustrating the transmittance characteristics of a first solution and a second solution after passing through a dual pass filter. [Figure 9] FIG. 11 is a front sectional view showing a surveying instrument according to a fourth embodiment. [Figure 10] FIG. 13 is a perspective view showing a surveying instrument according to a fourth embodiment. [Figure 11] FIG. 2 is a configuration diagram showing a detection unit of the surveying instrument. [Figure 12] FIG. 13 is a configuration diagram showing a detection unit of a surveying instrument according to a fifth embodiment. [Figure 13] FIG. 13 is a configuration diagram showing a detection unit of a surveying instrument according to a sixth embodiment. [Figure 14] 13(A) is a configuration diagram showing the detection unit of a surveying instrument according to a seventh embodiment, and (B) is an explanatory diagram showing the relationship between the reflected image received by the detection light receiving element and the position of the object to be measured. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0019] First, a wavelength selecting device according to a first embodiment of the present invention will be described with reference to FIGS. 1(A) to 1(C) and 2. FIG.

[0020] In the first embodiment, the wavelength selection device 1 includes an electrowetting (EW) element 2, a power supply unit 3 for applying a predetermined voltage to the EW element 2, and a control unit 10 for controlling the power supply unit 3 so that the power supply unit 3 applies a predetermined amount of voltage.

[0021] The EW element 2 has, for example, a disk-shaped transparent container 4, and a first solution 5 and a second solution 6 sealed in the transparent container 4. The first solution 5 and the second solution 6 are a polar liquid and a non-polar liquid having different optical properties and are immiscible. The transparent container 4 may be in the shape of a rectangular plate.

[0022] 2 is a graph showing the transmittance characteristics of the first solution 5 and the second solution 6. In FIG. 2, a solid line A shows the transmittance characteristics of the first solution 5, and a dashed line B shows the transmittance characteristics of the second solution 6.

[0023] 2, the first solution 5 has an optical property of transmitting about 90% of a first wavelength, for example, visible light of 400 nm to 700 nm, and absorbing light of other wavelengths, while the second solution 6 has an optical property of transmitting about 90% of a second wavelength, for example, light of a wavelength around 850 nm, and absorbing light of other wavelengths.

[0024] Moreover, the first solution 5 and the second solution 6 are sealed in the transparent container 4 in a ratio of, for example, 1:1. When the control unit 10 causes the power supply unit 3 to apply a predetermined voltage (first voltage) to the EW element 2, the first solution 5 moves toward the center and the second solution 6 moves toward the outer periphery as shown in Fig. 1(B). When the control unit 10 causes the power supply unit 3 to apply a predetermined voltage (second voltage) different from the first voltage to the EW element 2, the second solution 6 moves toward the center and the first solution 5 moves toward the outer periphery as shown in Fig. 1(C).

[0025] When a predetermined voltage is applied, one of the first solution 5 and the second solution 6 becomes a circle at the center, and the other becomes annular surrounding the circle. The diameter of the circle at the center is larger than the beam diameter of the light 7 passing through the EW element 2. In other words, the light 7 incident on the EW element 2 is configured to be incident on only one of the first solution 5 and the second solution 6.

[0026] When the wavelength selection device 1 is used, the light 7 used is light having a plurality of wavelengths or broadband light such as white light.

[0027] When extracting the first wavelength, the power supply unit 3 applies a first voltage to the EW element 2, moves the first solution 5 to the center of the transparent container 4, and causes the light 7 to be incident on the first solution 5. As the light 7 passes through the first solution 5, light of wavelengths other than the first wavelength is absorbed, and only the light of the first wavelength is emitted from the EW element 2.

[0028] When extracting the second wavelength, the power supply unit 3 applies a second voltage to the EW element 2, moves the second solution 6 to the center of the transparent container 4, and causes the light 7 to be incident on the second solution 6. As the light 7 passes through the second solution, light of wavelengths other than the second wavelength is absorbed, and only the light of the second wavelength is emitted from the EW element 2.

[0029] Therefore, by switching the amount of voltage applied from the power supply unit 3 to the EW element 2, the wavelength of the light 7 emitted from the wavelength selection device 1 (the EW element 2) can be switched.

[0030] As described above, in the first embodiment, the EW element 2 is formed by sealing two solutions 5 and 6 having different transmittance characteristics in the transparent container 4, and by applying different voltages to the EW element 2, it is possible to select whether the first solution 5 or the second solution 6 is located at the center of the EW element 2.

[0031] Therefore, by simply placing the EW element 2 on the optical path of the light 7, which has multiple wavelengths or is broadband light, and switching the voltage applied to the EW element 2, the wavelength that passes through the EW element 2 can be selected and switched, eliminating the need to prepare two bandpass filters (wavelength selection filters) or a mechanical switching mechanism for switching between the two transmitted wavelengths, thereby reducing the number of parts and making the device more compact.

[0032] Next, a second embodiment of the present invention will be described with reference to Figures 3(A) to 3(C), 4, and 5. In Figures 3(A) to 3(C), the same elements as those in Figures 1(A) to 1(C) are given the same reference numerals, and their description will be omitted.

[0033] In the second embodiment, an EW element 9, a power supply unit 3 for applying a voltage to the EW element 9, a control unit 10, and a dual pass filter 11 are used as the wavelength selection device 8.

[0034] The EW element 9 is disposed on the optical path of the light 7, and has a disk-shaped transparent container 4, and a first solution 12 and a second solution 13 sealed in the transparent container 4.

[0035] In the second embodiment, the first solution 12 has an optical property of transmitting light having a wavelength ranging from visible light to near infrared light, for example, light having a wavelength of 400 nm to 1100 nm, and the second solution 13 has an optical property of transmitting at least about 90% of light having a wavelength transmitted by the dual pass filter 11, for example, light having a wavelength of 800 nm to 900 nm, and absorbing light having wavelengths other than those, as shown by the dashed line B in FIG.

[0036] The dual pass filter 11 is disposed on the optical path of the light 7, and is configured so that the light 7 transmitted through the dual pass filter 11 is incident on the EW element 9. The dual pass filter 11 is configured to transmit light of two wavelength bands, for example, visible light of 400 nm to 700 nm as a first wavelength, and light of 850 nm as a second wavelength, as shown by the solid line A in Fig. 4.

[0037] When the control unit 10 causes the power supply unit 3 to apply a predetermined voltage (first voltage) to the EW element 9, the first solution 12 moves toward the center of the transparent container 4 and becomes circular, as shown in Fig. 3(B). When the power supply unit 3 applies a predetermined voltage (second voltage) to the EW element 9, the second solution 13 moves toward the center of the transparent container 4 and becomes circular, as shown in Fig. 3(C).

[0038] Therefore, when a first voltage is applied to the EW element 9, the light 7 passes through the dual pass filter 11 and the first solution 12, which transmits all wavelengths. On the other hand, when a second voltage is applied to the EW element 9, the light 7 passes through the dual pass filter 11 and the second solution 13, which transmits approximately 90% of light with wavelengths of 800 nm or more. In other words, the light 7 passes through only one of the first solution 12 and the second solution 13.

[0039] When extracting light of a first wavelength and a second wavelength from the light 7, which is broadband light such as white light, a first voltage is applied to the power supply unit 3, the first solution 12 is moved to the center of the transparent container 4, and the light 7 transmitted through the dual pass filter 11 is made incident on the first solution 12. Since the first solution 12 has optical properties that allow all wavelengths to be transmitted, the light 7, which has been converted into light of two wavelengths, the first wavelength and the second wavelength, by the dual pass filter 11, is emitted from the EW element 9, as shown by the solid line A in FIG.

[0040] When extracting only the light of the second wavelength from the light 7, a second voltage is applied to the power supply unit 3, the second solution 13 is moved to the center of the transparent container 4, and the light 7 transmitted through the dual pass filter 11 is made to enter the second solution 13. Since the second solution 13 has an optical property of transmitting only the second wavelength, the light of the first wavelength out of the light 7 is absorbed, and only the light of the second wavelength is emitted from the EW element 9, as shown by the dashed dotted line C in FIG.

[0041] Therefore, by controlling the control unit 10 to switch the amount of voltage that the power supply unit 3 applies to the EW element 9, the wavelength of the light 7 emitted from the wavelength selection device 8 (the EW element 9) can be switched.

[0042] Since the second solution 13 has a transmittance of about 90% for the second wavelength, the amount of the light 7 transmitted through the second solution 13 is about 90% of the amount of the light 7 of the second wavelength that is incident on the second solution 13.

[0043] In the second embodiment, the wavelength selection device 8 has the dual pass filter 11 arranged coaxially with the EW element 9, and the light 7 transmitted through the dual pass filter 11 is incident on the EW element 9, forming a double structure (multiple structure).

[0044] Therefore, the transmittance of the light 7 does not need to depend on the absorption characteristics (physical properties) of the solutions 12 and 13, and the transmittance can be designed using a multilayer film, thereby improving the design freedom of the transmittance characteristics of the wavelength selection device 8 compared to the wavelength selection device of the first embodiment.

[0045] Furthermore, by using the dual pass filter 11 in the wavelength selection device 8, the gradient of the rise and fall of the filter transmittance can be designed to be steep, and the reflectance of the transmission blocking band can be designed to be sufficiently large, thereby improving the signal-to-noise ratio.

[0046] Furthermore, when the bands of the first and second wavelengths used in wavelength switching are separated, the use of the dual pass filter 11 can make the gradient of the rise and fall of the transmitted wavelength band steep even if the gradient of the transmittance of the EW element 9 is not steep.

[0047] In addition, by making the gradient of the rise and fall of the transmittance of the wavelength selection device 8 steep and making the transmission wavelength band visible light, the color of the visible light extracted by the wavelength selection device 8 can be improved.

[0048] Furthermore, in the second embodiment as well, there is no need to prepare two bandpass filters or a switching mechanism for switching between two wavelengths, and the number of parts can be reduced and the wavelength selection device 8 can be made smaller.

[0049] Next, a third embodiment of the present invention will be described with reference to Figures 6(A) to 6(C), 7, and 8. In Figures 6(A) to 6(C), the same components as those in Figures 1(A) to 1(C) are given the same reference numerals, and the description thereof will be omitted.

[0050] In the third embodiment, the wavelength selection device 14 includes an EW element 15, a power supply unit 3 for applying a voltage to the EW element 15, a control unit 10 for controlling the power supply unit 3, and a dual pass filter 11.

[0051] The EW element 15 is disposed on the optical path of the light 7, and has a disk-shaped transparent container 4, and a first solution 16 and a second solution 17 sealed in the transparent container 4.

[0052] In the third embodiment, the first solution 16 has an optical characteristic of transmitting about 90% of light having a wavelength of 400 nm to 600 nm, transmitting about 50% of light having a wavelength of 650 nm, and absorbing light having other wavelengths, as shown by the dashed line A in Fig. 7. The second solution 17 has an optical characteristic of transmitting about 90% of light having a wavelength of 800 nm or more, and absorbing light having other wavelengths, as shown by the dashed line B in Fig. 7. Furthermore, the dual pass filter 11 has an optical characteristic of transmitting a first wavelength (400 nm to 700 nm) and a second wavelength (near 850 nm), and blocking light having other wavelengths, as shown by the solid line C in Fig. 7.

[0053] When the power supply unit 3 applies a predetermined voltage (first voltage) to the EW element 15, the first solution 16 moves toward the center of the transparent container 4 and becomes circular, as shown in Fig. 6(B). When the power supply unit 3 applies a predetermined voltage (second voltage) to the EW element 15, the second solution 17 moves toward the center of the transparent container 4 and becomes circular, as shown in Fig. 6(C).

[0054] When a first voltage is applied to the EW element 15, the light 7 passes through the dual pass filter 11 and enters the first solution 16. The dual pass filter 11 has an optical characteristic of transmitting only light having a first wavelength, which is visible light, and a second wavelength, which is near-infrared light, from the broadband light 7, and the first solution 16 has an optical characteristic of transmitting only wavelengths less than 650 nm. Therefore, the broadband light 7 is blocked by the dual pass filter 11 except for the first and second wavelengths, and the first solution 16 absorbs the second wavelength. That is, as shown by a solid line A in FIG. 8, only light having a first wavelength (400 nm to 700 nm) is transmitted from the broadband light 7.

[0055] On the other hand, when a second voltage is applied to the EW element 15, the light 7 passes through the dual pass filter 11 and enters the second solution 17. Since the second solution 17 has an optical characteristic of transmitting only wavelengths of 800 nm or more, the dual pass filter 11 blocks light other than the first and second wavelengths of the light 7, and the second solution 17 further absorbs the light of the first wavelength. That is, as shown by the dashed line B in FIG. 8, only light of the second wavelength (near 850 nm) is transmitted from the broadband light 7.

[0056] Therefore, when the light 7 having only a first wavelength is emitted from the EW element 15, a first voltage is applied to the EW element 15 by the power supply unit 3, and when the light 7 having only a second wavelength is emitted from the EW element 15, a second voltage is applied to the EW element 15 by the power supply unit 3. That is, by switching the amount of voltage applied from the power supply unit 3 to the EW element 15, it is possible to select the wavelength of the light 7 that passes through the wavelength selection device 8 (the EW element 15) and is emitted.

[0057] Since the first solution 16 has a transmittance of about 90% for the first wavelength, the amount of the light 7 transmitted through the first solution 16 is about 90% of the amount of light incident on the first solution 16. Similarly, since the second solution 17 has a transmittance of about 90% for the second wavelength, the amount of the light 7 transmitted through the second solution 17 is about 90% of the amount of light incident on the second solution 17.

[0058] In the third embodiment, the wavelength selection device 14 has a double structure (multiple structure) in which the EW element 15 and the dual pass filter 11 are arranged coaxially, so that the rising and falling gradients of the filter transmittance can be designed to be steep, the S / N ratio can be improved, and the color of visible light can be improved.

[0059] Furthermore, since the first solution 16 and the second solution 17 each have the optical property of absorbing one of the two wavelengths transmitted through the dual pass filter 11, by switching the amount of voltage applied to the EW element 15 and selecting the solution into which the light 7 is incident, it is possible to reliably emit the light 7 having only one wavelength.

[0060] Furthermore, in the third embodiment as well, there is no need to prepare two bandpass filters or a switching mechanism for selecting two wavelengths, and the number of parts can be reduced and the wavelength selection device 14 can be made smaller.

[0061] The wavelength selecting devices 1, 8, 14 according to the first to third embodiments described above are applied to, for example, a camera provided in a surveying instrument or detection of a measurement object (prism). Hereinafter, a fourth embodiment of the present invention will be described with reference to Figs. 9 and 10. In the fourth embodiment, the wavelength selecting device 1 according to the first embodiment is applied to a surveying instrument. Note that, for example, a retroreflective prism is used as the measurement object measured by the surveying instrument.

[0062] The surveying instrument 21 is, for example, a laser scanner, and is composed of a leveling unit 22 attached to a tripod (not shown), and a surveying instrument main body 23 attached to the leveling unit 22.

[0063] The leveling unit 22 has a leveling screw 30, which is used to level the surveying device main body 23 horizontally.

[0064] The surveying device main body 23 is equipped with (contains) a fixed section 24, a support section 25, a horizontal rotation shaft 26, a horizontal rotation bearing 27, a horizontal rotation motor 28 as a horizontal rotation drive section, a horizontal angle encoder 29 as a horizontal angle detection section, a vertical rotation shaft 31, a vertical rotation bearing 32, a vertical rotation motor 33 as a vertical rotation drive section, a vertical angle encoder 34 as a vertical angle detection section, a scanning mirror 35, an operation panel 36 serving both as an operation section and a display section, a calculation control section 37, a memory section 38, a distance measurement section 39, a detection section 41, etc. As the calculation control section 37, a CPU specialized for this device or a general-purpose CPU is used.

[0065] The horizontal rotation bearing 27 is fixed to the fixed portion 24. The horizontal rotation shaft 26 has a vertical axis 26a, and the horizontal rotation shaft 26 is rotatably supported by the horizontal rotation bearing 27. In addition, the base stand portion 25 is supported by the horizontal rotation shaft 26, and the base stand portion 25 rotates integrally with the horizontal rotation shaft 26 in the horizontal direction.

[0066] The horizontal rotation motor 28 is provided between the horizontal rotation bearing 27 and the base frame portion 25, and the horizontal rotation motor 28 is controlled by the arithmetic and control unit 37. The arithmetic and control unit 37 causes the horizontal rotation motor 28 to rotate the base frame portion 25 about the axis 26a.

[0067] The relative rotation angle of the support part 25 with respect to the fixed part 24 is detected by the horizontal angle encoder 29. A detection signal from the horizontal angle encoder 29 is input to the calculation control part 37, which calculates horizontal angle data. The calculation control part 37 performs feedback control of the horizontal rotation motor 28 based on the horizontal angle data.

[0068] Further, the vertical rotation shaft 31 having a horizontal axis 31a is provided on the base part 25. The vertical rotation shaft 31 is rotatable via the vertical rotation bearing 32. The intersection of the axis 26a and the axis 31a is the emission position of the distance measuring light, and is the origin of the coordinate system of the surveying device main body 23.

[0069] A recess 42 is formed in the base portion 25. One end of the vertical rotation shaft 31 extends into the recess 42, and the scanning mirror 35 is fixed to the one end, and the scanning mirror 35 is stored in the recess 42. In addition, the vertical angle encoder 34 is provided on the other end of the vertical rotation shaft 31.

[0070] A window 43 is provided at a position facing the scanning mirror 35 and is made of a transparent material such as glass, and rotates together with the scanning mirror 35. The window 43 is inclined at a predetermined angle with respect to a distance measurement optical axis 49 (described later), and is provided with an anti-reflection coating.

[0071] The base portion 25 is provided with the detection unit 41. As shown in Fig. 10, the detection unit 41 is provided adjacent to the recess 42, and opens, for example, on the front side of the surveying instrument 21. When the base portion 25 is horizontal, the optical axis of the detection unit 41 extends in a direction that is horizontal and perpendicular to a plane including the axis 26a and the axis 31a. Detection light is irradiated along a detection optical axis 59 (described later).

[0072] The vertical rotation motor 33 is provided on the vertical rotation shaft 31, and the vertical rotation motor 33 is controlled by the arithmetic and control unit 37. The arithmetic and control unit 37 rotates the vertical rotation shaft 31 by the vertical rotation motor 33, and the scanning mirror 35 is rotated around the axis 31a.

[0073] The rotation angle of the scanning mirror 35 is detected by the vertical angle encoder 34, and a detection signal is input to the arithmetic and control unit 37. The arithmetic and control unit 37 calculates vertical angle data of the scanning mirror 35 based on the detection signal, and performs feedback control on the vertical rotation motor 33 based on the vertical angle data.

[0074] The horizontal angle data, vertical angle data, and measurement results calculated by the arithmetic control unit 37 are stored in the memory unit 38. As the memory unit 38, various storage means such as a HDD as a magnetic storage device, a CD or DVD as an optical storage device, a memory card as a semiconductor storage device, a USB memory, etc. The memory unit 38 may be detachable from the base unit 25, or may be capable of transmitting data to an external storage device or an external data processing device via a communication means (not shown).

[0075] The storage unit 38 stores various programs such as a sequence program for controlling the distance measurement operation, a calculation program for calculating distance by the distance measurement operation, a calculation program for calculating an angle based on horizontal angle data and vertical angle data, a calculation program for calculating three-dimensional coordinates of a desired measurement point based on distance and angle, a program for controlling the detection unit 41, a detection program for detecting a measurement object based on reflected detection light, a tracking program for tracking a measurement object, etc. In addition, various programs are executed by the calculation control unit 37, thereby performing various processes.

[0076] The operation panel 36 is, for example, a touch panel, and serves as both an operation section for issuing distance measurement instructions and changing measurement conditions, such as the measurement point interval, and a display section for displaying distance measurement results, images, and the like.

[0077] The distance measurement unit 39 has a distance measurement light emitting unit 44, a distance measurement light receiving unit 45, a tracking light emitting unit 46, and a tracking light receiving unit 47, and each of them is controlled by the arithmetic control unit 37. The distance measurement light emitting unit 44 and the distance measurement light receiving unit 45 constitute a distance measurement unit, and the tracking light emitting unit 46 and the tracking light receiving unit 47 constitute a tracking unit.

[0078] The distance measurement light emitting unit 44 has a light emitting element 48, which emits distance measurement light along the distance measurement optical axis 49, and the distance measurement light is incident on the scanning mirror 35. The distance measurement light is deflected at a right angle by the scanning mirror 35, passes through the window portion 43, and is irradiated onto the measurement object. As the scanning mirror 35 rotates around the axis 31a, the distance measurement light is rotated (scanned) within a plane that is perpendicular to the axis 31a and includes the axis 26a.

[0079] Incidentally, since the window portion 43 is inclined at a predetermined angle with respect to the distance measurement optical axis 49, the distance measurement light reflected by the window portion 43 (reflected distance measurement light) is prevented from entering the distance measurement light receiving portion 45. Moreover, the emission position of the distance measurement light in the scanning mirror 35, i.e., the reflection position of the distance measurement light, is the mechanical center of the surveying instrument 21, and the mechanical center is located on the intersection of the axis 26a and the axis 31a.

[0080] The distance measuring light reflected by the object to be measured passes through the window 43 along the light receiving optical axis 51 and enters the scanning mirror 35. The reflected distance measuring light is also reflected at a right angle by the scanning mirror 35 and received by the light receiving element 52 of the distance measuring light receiving unit 45.

[0081] The calculation control unit 37 executes distance measurement for each pulse of the distance measurement light based on the time difference between when the light emitting element 48 emits the distance measurement light and when the light receiving element 52 receives the reflected distance measurement light (i.e., the round trip time of the pulsed light) and the speed of light, and calculates the distance to the measurement object. The timing of emitting the distance measurement light, i.e., the pulse interval, can be changed via the operation panel 36. Also, based on the distance measurement result and the horizontal angle data and vertical angle data obtained by the horizontal angle encoder 29 and the vertical angle encoder 34, the three-dimensional coordinates of the measurement object (the irradiation point of the distance measurement light) can be calculated.

[0082] Moreover, by rotating the base unit 25 and the scanning mirror 35 at a constant speed while emitting the distance measuring light at a predetermined pulse interval, the vertical rotation of the scanning mirror 35 and the horizontal rotation of the base unit 25 cooperate to perform two-dimensional scanning with the distance measuring light. Moreover, by detecting the vertical angle and the horizontal angle for each pulse light by the vertical angle encoder 34 and the horizontal angle encoder 29, vertical angle data and horizontal angle data can be obtained. From the vertical angle data, horizontal angle data and distance measuring data, the three-dimensional coordinates of the measurement object and three-dimensional point cloud data corresponding to the measurement object can be obtained.

[0083] In parallel with the distance measurement operation, a tracking light having a wavelength different from the distance measurement light is emitted from the tracking light emitting element 53 of the tracking light emitting unit 46 at a predetermined spread angle along a tracking optical axis 54 and enters the scanning mirror 35 approximately coaxially with the distance measurement light. The tracking light is deflected at a right angle by the scanning mirror 35 and is irradiated onto the measurement object approximately coaxially with the distance measurement light. Here, approximately coaxial means that the optical axes are parallel and the distance between the optical axes is within the allowable error range from 0.

[0084] The tracking light reflected by the measurement object (reflected tracking light) passes through the window 43 along the tracking light receiving optical axis 55 and enters the scanning mirror 35. The reflected tracking light is reflected at a right angle by the scanning mirror 35 and received by the tracking light receiving element 56 of the tracking light receiving unit 47.

[0085] The tracking light receiving element 56 is a CCD or CMOS sensor which is a collection of pixels, and each pixel is configured to be able to specify its position on the tracking light receiving element 56. For example, each pixel has pixel coordinates with the center of the tracking light receiving element 56 as the origin, and its position on the tracking light receiving element 56 is specified by the pixel coordinates.

[0086] The calculation control unit 37 calculates the position deviation between the center of the tracking light receiving element 56 and the light receiving position of the reflected tracking light relative to the tracking light receiving element 56, and is configured to drive the horizontal rotation motor 28 and the vertical rotation motor 33 based on the position deviation so that the center of the tracking light receiving element 56 coincides with the light receiving position, thereby tracking the object to be measured.

[0087] Next, a case where the wavelength selecting device 1 according to the first embodiment is applied to the detection unit 41 for detecting a prism will be described with reference to Fig. 11. The detection unit 41 is controlled by the arithmetic and control unit 37. In addition, the control unit 10 (see Fig. 1) of the wavelength selecting device 1 is also controlled by the arithmetic and control unit 37.

[0088] The detection unit 41 has a detection light emitting unit 57 and a detection light receiving unit 58. The detection light emitting unit 57 has the detection light axis 59. The detection light emitting unit 57 also has, in order from the light emitting side, a detection light emitting element 61, an irradiation system lens 62, a beam splitter 63, and a protective glass 64.

[0089] The detection light emitting element 61 is, for example, an LED or laser light source that emits near-infrared light of a wavelength different from the distance measuring light and the reflected distance measuring light, for example, near-infrared light of about 850 nm, as detection light 65. The illumination system lens 62 is configured to diverge the detection light 65 emitted from the detection light emitting element 61 at a predetermined divergence angle. The divergence angle of the detection light 65 is larger than the divergence angle of the tracking light, and is appropriately set between, for example, 3.5° and 35°.

[0090] The beam splitter 63 has optical properties of transmitting 50% of the incident light and reflecting 50%. The protective glass 64 is coated with an AR (Anti Reflection) coating so that the detection light 65 emitted from the detection light emitting element 61 is not reflected by the protective glass 64.

[0091] The detection light receiving unit 58 has a detection light receiving optical axis 66. The detection light receiving unit 58 has, in order from the light receiving side, a detection light receiving element 67 provided on the detection light receiving optical axis 66, a wavelength selecting device 1 (EW element 2), a light receiving system lens group 68 composed of a plurality of lenses, the beam splitter 63, and the protective glass 64 provided on the reflected optical axis of the beam splitter 63. Note that the power supply unit 3 (see FIG. 1(A)) for applying a voltage to the EW element 2 is omitted from the illustration in FIG.

[0092] The angle of view of the detection light receiving unit 58 by the light receiving system lens group 68 is larger than the angle of view of the tracking light receiving unit 47. Moreover, the angle of view of the detection light receiving unit 58 is appropriately selected from a range of 3° to 30° so as to be smaller than the spread angle of the detection light irradiating unit 57. In this embodiment, the detection light receiving optical axis 66 and the detection light receiving optical axis 66 reflected by the beam splitter 63 are collectively referred to as the detection light receiving optical axis 66.

[0093] The detection light receiving element 67 is a CCD or CMOS sensor which is a collection of pixels, and the position of each pixel can be specified on the detection light receiving element 67. For example, each pixel has pixel coordinates with the center of the detection light receiving element 67 as the origin, and the position on the detection light receiving element 67 is specified by the pixel coordinates.

[0094] The detection light 65 emitted from the detection light emitting element 61 is diverged by the illumination system lens 62 to a predetermined spread angle, and then passes through the beam splitter 63 and the protective glass 64, and is irradiated onto the object to be measured. When the surveying instrument main body 23 is leveled horizontally, the detection optical axis 59 is horizontal.

[0095] The detection light 65 (reflected detection light 69) reflected by the measurement object or the like passes through the protective glass 64 and enters the beam splitter 63. A part of the reflected detection light 69 that enters the beam splitter 63 is reflected at a right angle by the beam splitter 63, passes through the light receiving system lens group 68 and the EW element 2, and is received by the detection light receiving element 67, and a detection image is acquired.

[0096] The calculation control unit 37 detects a measurement object such as a prism based on the detection image or the received amount of the reflected detection light 69, calculates the position deviation between the center of the detection light receiving element 67 and the receiving position of the reflected detection light 69, and calculates the direction of the measurement object based on the position deviation.

[0097] In addition, based on the calculated direction of the object to be measured, the calculation control unit 37 drives the horizontal rotation motor 28 to rotate the support unit 25 horizontally so that the object to be measured is positioned on the tracking optical axis 54, and drives the vertical rotation motor 33 to rotate the scanning mirror 35 vertically.

[0098] When the object to be measured is located within the irradiation range (angle of view) of the tracking light and the reflected tracking light from the object to be measured is received by the tracking light receiving element 56, the calculation control unit 37 starts tracking the object to be measured using the tracking light emitting unit 46 and the tracking light receiving unit 47.

[0099] Here, when a first voltage is applied from the power supply unit 3 to the EW element 2, only visible light having a first wavelength, i.e., a wavelength band of 400 nm to 700 nm, passes through the EW element 2, and light in other wavelength bands is absorbed by the EW element 2. Therefore, the reflected detection light 69 is absorbed by the first solution 5 of the EW element 2, and only external light incident coaxially or approximately coaxially with the reflected detection light 69 passes through the EW element 2 and is received by the detection light receiving element 67. That is, the detection light receiving unit 58 can be used as a camera for collimating a measurement object or coloring point cloud data.

[0100] Furthermore, when a second voltage is applied from the power supply unit 3 to the EW element 2, only near-infrared light of a second wavelength, i.e., near 850 nm, passes through the EW element 2, and light in other wavelength bands is absorbed by the EW element 2. Therefore, external light incident coaxially or approximately coaxially with the reflected detection light 69 is absorbed by the second solution 6 of the EW element 2, and only the reflected detection light 69 passes through the EW element 2 and is received by the detection light receiving element 67. That is, the EW element 2 functions as an external light removal filter, and the detection light receiving unit 58 can be used to detect the measurement object (prism).

[0101] Furthermore, the detection unit 41 is capable of acquiring an image acquired with the detection light 65 irradiated and an image acquired with the detection light 65 not irradiated. By calculating the difference between the two images, light other than the reflected detection light, such as external light, can be completely removed, making it possible to detect a measurement object having retroreflective properties, such as a prism, with high accuracy.

[0102] As described above, in the fourth embodiment, the wavelength that passes through the EW element 2 can be selected by switching the amount of voltage applied to the EW element 2. Therefore, simply by switching the amount of voltage applied to the EW element 2, it is possible to select whether the detection light receiving unit 58 is used for prism detection or as a camera.

[0103] Therefore, there is no need to provide a plurality of bandpass filters or a filter switching mechanism for switching the transmission wavelength, and the number of parts can be reduced and the size can be reduced.

[0104] Furthermore, since the wavelength selection device 1 can cause the detection light receiving element 67 to receive only visible light, a fine image can be obtained and point cloud data can be colored with high accuracy.

[0105] Furthermore, since a mechanism can be omitted from the detection light receiving portion 58, mechanical failures can be suppressed.

[0106] Furthermore, since it is not necessary to insert a bandpass filter onto the detection optical axis 59 every time the transmission wavelength is switched, the bandpass filters are not inserted at a relative inclination, and a decrease in position detection accuracy can be prevented.

[0107] Furthermore, the angle of view of the detection light receiving section 58 is larger than that of the tracking light receiving section 47, and the detection section 41 is configured to detect the measurement object as a preliminary step to tracking. Therefore, the measurement object is easier to detect than when the measurement object is detected only by the tracking light, so the time until detection can be shortened, and the operation time can be shortened and the operation efficiency can be improved.

[0108] Next, a fifth embodiment of the present invention will be described with reference to Fig. 12. In Fig. 12, the same components as those in Fig. 11 are designated by the same reference numerals in Fig. 3(A) to Fig. 3(C) and will not be described.

[0109] In the fifth embodiment, the wavelength selection device 8 according to the second embodiment is used as the detection unit 41 of the surveying instrument 21 (see FIG. 10). The detection light receiving element 67 is configured so that the RGB sensitivity is approximately the same in the wavelength range of 800 nm to 900 nm. The other configurations are the same as those in the fourth embodiment.

[0110] In the fifth embodiment, the reflected detection light 69 is reflected by the beam splitter 63 and transmitted through the light receiving lens group 68. In the process of passing through the dual pass filter 11, only the first and second wavelengths, i.e., only the reflected detection light 69 and external light in the visible light region, are transmitted and enter the EW element 9.

[0111] Also in the fifth embodiment, by switching the amount of voltage applied to the EW element 9, it is possible to select whether the reflected detection light 69 transmitted through the dual pass filter 11 is incident on and transmitted through the first solution 12 or the second solution 13. In other words, it is possible to select whether two types of light, the reflected detection light 69 and visible light, are emitted from the EW element 9, or whether only the reflected detection light 69 is emitted.

[0112] In the fifth embodiment, the wavelength selection device 8 is not configured to be capable of extracting only visible light, but the detection light receiving element 67 is configured so that the RGB sensitivity is approximately equal at the second wavelength.

[0113] Therefore, even if the EW element 9 emits both visible light of a first wavelength and the reflected detection light 69 of a second wavelength, the effect of the reflected detection light 69 on color is negligible, so that the device can be used as a camera.

[0114] That is, also in the fifth embodiment, simply by switching the amount of voltage applied to the EW element 9, it is possible to select whether the detection light receiving portion 58 is used for prism detection or as a camera.

[0115] Furthermore, by using the wavelength selection device 8, the filter gradient of the transmission wavelength can be made steep, so that the signal-to-noise ratio can be improved.

[0116] Next, a sixth embodiment of the present invention will be described with reference to Fig. 13. In Fig. 13, the same components as those in Fig. 11 are designated by the same reference numerals in Fig. 3(A) to Fig. 3(C) and Fig. 11, and the description thereof will be omitted.

[0117] In the sixth embodiment, the wavelength selection device 14 according to the third embodiment is used as a detection unit 41 of a surveying instrument 21 (see FIG. 10). The other configurations are the same as those of the fourth embodiment.

[0118] In the sixth embodiment, the reflected detection light 69 is reflected by the beam splitter 63 and transmitted through the light receiving lens group 68. In the process of passing through the dual pass filter 11, only the first and second wavelengths, i.e., the reflected detection light 69 and external light in the visible light region, are transmitted, and the reflected detection light 69 is incident on the EW element 15.

[0119] Also in the sixth embodiment, by switching the amount of voltage applied to the EW element 15, it is possible to select whether the reflected detection light 69 transmitted through the dual pass filter 11 is incident on and transmitted through the first solution 16 or the second solution 17. In other words, it is possible to select whether only visible light or only the reflected detection light 69 is emitted from the EW element 15.

[0120] Therefore, the detection light receiving unit 58 can be used as a camera that obtains images using only visible light, and can also be used as a detection unit that detects the measurement object (prism) using only the reflected detection light 69.

[0121] In the sixth embodiment, only one of the first wavelength and the second wavelength transmitted through the dual pass filter 11 can be emitted from the EW element 15, so that the filter gradient of the transmitted wavelength can be made steeper, thereby improving the S / N ratio.

[0122] In the fourth to sixth embodiments, the wavelength selection devices 1, 8, 14 are disposed between the detection light receiving element 67 and the light receiving lens group 68, but the location is not limited to this. For example, the wavelength selection devices 1, 8, 14 may be disposed between the light receiving lens group 68 and the beam splitter 63, or between the beam splitter 63 and the protective glass 64. In other words, the wavelength selection devices 1, 8, 14 may be disposed anywhere on the optical path of the reflected detection light 69.

[0123] Next, a seventh embodiment of the present invention will be described with reference to Figures 14(A) and 14(B). In Figures 14(A) and 14(B), the same reference numerals are used for the same parts as in Figure 11, and the description thereof will be omitted.

[0124] In the seventh embodiment, the detection unit 41 has a first detection light irradiating unit 71 , a second detection light irradiating unit 72 , and a detection light receiving unit 73 .

[0125] The first detection light irradiating section 71 has a first detection optical axis 74, and a first detection light emitting element 75, a first irradiation system lens 76, and a first protective glass 77, which are provided on the first detection optical axis 74 in this order from the light emitting side. The first detection light emitting element 75 irradiates first detection light 78 along the first detection optical axis 74.

[0126] The second detection light irradiating section 72 has a second detection optical axis 79, and a second detection light emitting element 81, a second irradiation system lens 82, and a second protective glass 83, which are provided on the second detection optical axis 79 in this order from the light emitting side. The second detection light emitting element 81 irradiates second detection light 84 along the second detection optical axis 79. The first detection light 78 and the second detection light 84 are near-infrared light having the same wavelength as in the other embodiments, and have the same spread angle.

[0127] The detection light receiving section 73 has a detection light receiving optical axis 85, a detection light receiving element 86 provided on the detection light receiving optical axis 85 in this order from the light receiving side, the wavelength selecting device 1 (EW element 2) according to the first embodiment, a light receiving system lens group 87, and a protective glass 88. The configuration of the detection light receiving element 86 is the same as that of the detection light receiving element 67 in the other embodiments, and therefore a description thereof will be omitted.

[0128] Moreover, the first detection light emitting unit 71 and the second detection light emitting unit 72 are provided at symmetrical positions with the detection light receiving unit 73 in between. That is, the first detection optical axis 74 and the second detection optical axis 79 are symmetrical with respect to the detection light receiving optical axis 85, and the first detection optical axis 74, the second detection optical axis 79, and the detection light receiving optical axis 85 are positioned on the same plane.

[0129] When the first detection light 78 is irradiated from the first detection light emitting unit 71 at a predetermined spread angle and the second detection light 84 is irradiated from the second detection light emitting unit 72 at a predetermined spread angle, the reflected first detection light reflected by a measurement object such as a prism is received by the detection light receiving element 86, and a first reflected image 89 is formed. Also, the reflected second detection light reflected by the measurement object is received by the detection light receiving element 86, and a second reflected image 91 is formed.

[0130] Since the first detection optical axis 74 is not coaxial with the detection light receiving optical axis 85, the position of the first reflected image 89 on the detection light receiving element 86 does not match the position of the object to be measured. Similarly, since the second detection optical axis 79 is not coaxial with the detection light receiving optical axis 85, the position of the second reflected image 91 on the detection light receiving element 86 does not match the position of the object to be measured.

[0131] On the other hand, since the first detection optical axis 74, the second detection optical axis 79, and the detection light receiving optical axis 85 are located on the same plane, and the first detection optical axis 74 and the second detection optical axis 79 are arranged symmetrically with respect to the detection light receiving optical axis 85, the center of the straight line connecting the center of the first reflection image 89 and the center of the second reflection image 91 can be calculated as the position 92 of the object to be measured.

[0132] In the seventh embodiment, the first detection light emitting portion 71, the second detection light emitting portion 72, and the detection light receiving portion 73 are arranged so that the first detection light axis 74, the second detection light axis 79, and the detection light receiving light axis 85 are non-coaxial and parallel.

[0133] Therefore, the amount of light of the first detection light 78 and the second detection light 84 can be increased without being attenuated by deflecting optical components such as a beam splitter in the optical system, so that the reach of the first detection light 78 and the second detection light 84 can be extended, thereby expanding the detection range of the object to be measured and shortening the detection time.

[0134] Furthermore, since the detection light receiving unit 73 has the wavelength selection device 1 (the EW element 2), by switching the amount of voltage applied to the EW element 2, the detection light receiving element 86 can receive only the first reflected detection light and the second reflected detection light, or only external light excluding the first reflected detection light and the second reflected detection light, and the use can be selected between use for detecting a measured object and use as a camera.

[0135] In the seventh embodiment, the wavelength selection device 1 according to the first embodiment is provided in the detection light receiving unit 73, but similar to the fifth and sixth embodiments, the wavelength selection device 8 according to the second embodiment or the wavelength selection device 14 according to the third embodiment may be provided in place of the wavelength selection device 1.

[0136] Furthermore, in the seventh embodiment, it goes without saying that the wavelength selection device 1 may be provided between the light receiving lens group 87 and the protective glass 88, rather than between the light receiving lens group 87 and the detection light receiving element 86. [Explanation of symbols]

[0137] 1 Wavelength selection device 2. EW element 3 Power supply section 4 Transparent container 5. First solution 6. Second Solution 7 light 8 Wavelength selection device 9 EW elements 11 Dual Pass Filter 12 First Solution 13 Second Solution 14 Wavelength selection device 15 EW element 16 First Solution 17 Second Solution 21 Surveying equipment 41 Detection unit

Claims

1. A wavelength selection device comprising: an EW element having a transparent container that encloses a first solution that transmits a first wavelength and a second solution that transmits a second wavelength different from the first wavelength; a power supply unit capable of applying a predetermined voltage to the EW element; and a control unit that controls the power supply unit, wherein the EW element moves either the first solution or the second solution to the center of the transparent container in response to the applied voltage, and broadband light incident on the EW element is transmitted through only either the first solution or the second solution.

2. 2. The wavelength selection device according to claim 1, further comprising a dual pass filter arranged coaxially with the EW element and transmitting visible light and near infrared light.

3. 2. The wavelength selection device according to claim 1, wherein the first solution is configured to transmit only visible light, and the second solution is configured to transmit only near infrared light.

4. 3. The wavelength selection device according to claim 2, wherein the first solution is configured to transmit light from visible light to near infrared light, and the second solution is configured to transmit only near infrared light.

5. 3. The wavelength selection device according to claim 2, wherein the first solution is configured to transmit visible light and the second solution is configured to transmit near infrared light.

6. A wavelength selection method comprising: applying a predetermined voltage to an EW element having a transparent container that encloses a first solution that transmits a first wavelength and a second solution that transmits a second wavelength different from the first wavelength; and causing only one of the first solution and the second solution to transmit broadband light incident on the EW element.

7. A surveying instrument comprising: a distance measuring unit having a light emitting element that emits distance measuring light and a light receiving element that receives the reflected distance measuring light from the object to be measured; a detection unit having a detection light irradiating unit that emits detection light of a different wavelength from the distance measuring light and a detection light receiving unit having a detection light receiving element that receives the reflected detection light reflected by the object to be measured; and a calculation control unit that calculates the distance to the object to be measured based on the reception result of the reflected distance measuring light to the receiving element, and calculates the direction of the object to be measured based on the reception result of the reflected detection light to the detection light receiving element, wherein the detection light receiving unit has a wavelength selecting device described in any one of claims 1 to 5, and the wavelength selecting device is configured to select and transmit the reflected detection light and external light, and to have them received by the detection light receiving element.

Images