Spectrometry device and actuator

Abstract

Provided is a spectrometry device equipped with a drive mechanism capable of easily controlling the movement of a movable portion at a low and constant speed. An actuator is used as the drive mechanism, the actuator comprising: a conductor (231a) that extends in a first direction; a current supply unit that passes a current through the conductor; magnetic field sources (232a, 232b) that apply, to the conductor, a magnetic field in a direction having a directional component orthogonal to the first direction and a second direction (A) that is non-parallel to the first direction; a movable element (231) that moves in the second direction due to a Lorentz force generated by the current flowing through the conductor or a reaction to the Lorentz force; an elastic body (233) that resists the movement of the movable element; and a current control unit that controls the current supply unit such that the magnitude of the current flowing through the conductor changes with a predetermined rate of change over time that corresponds to the elastic characteristics of the elastic body.

Description

Spectral measurement device and actuator

[0001] The present invention relates to a spectral measurement device based on imaging-type two-dimensional Fourier spectroscopy and an actuator that can be used for a drive mechanism of a phase shifter thereof.

[0002] One of the methods for measuring the spectral characteristics of a sample is imaging-type two-dimensional Fourier spectroscopy. In this method, for example, as shown in Patent Document 1, non-directional light (measurement light) emitted from a sample surface is made into a parallel light beam by an objective lens, and then irradiated onto a phase shifter composed of a fixed mirror part and a movable mirror part that are parallel to each other and arranged side by side. The light is reflected by both mirror parts, condensed at the same point on the imaging surface by an imaging lens, and the intensity is measured by a photodetector. At this time, by moving the movable mirror part back and forth, the intensity distribution of interference light (interferogram) for each optical path length difference between the measurement light reflected by the fixed mirror part and the measurement light reflected by the movable mirror part can be obtained. By performing Fourier transform on this interferogram by a control unit, the spectral characteristics (spectral spectrum) of the measurement light can be obtained.

[0003] In the spectral measurement device having the above configuration, in order to obtain an interferogram even for visible light with a short wavelength, high movement accuracy is required for the drive mechanism (stage) of the movable mirror part. Therefore, conventionally, an expensive impact actuator or an ultrasonic motor has been used as the drive source for the stage.

[0004] International Publication No. 2020 / 175694

[0005] Aoyama Special Steel Co., Ltd. Servo Solution Site, "About Voice Coil Motors", [searched on February 21, 2025], Internet <URL:https: / / www.servo.jp / products / about_VCM.html>

[0006] Two-dimensional array sensors are used as photodetectors in spectroscopic measurement devices. Because the frame rate of two-dimensional array sensors is low, at most a few hundred Hz (typically 60 Hz), the movement of the stage must be controlled to be slow and constant in order to obtain an accurate spectral distribution. However, this requires a complex configuration. For example, when using the impact actuator described above as the drive source for the stage, a configuration is required in which the expansion and contraction of the piezoelectric element is detected by a capacitance sensor and the voltage applied to the piezoelectric element is feedback-controlled. Also, when using the ultrasonic motor described above as the drive source for the stage, a configuration is required in which the rotation speed of the motor is detected by an optical encoder and the motor's drive voltage is feedback-controlled.

[0007] The problem that this invention aims to solve is to provide a spectroscopic measuring device equipped with a drive mechanism that makes it easy to control the movement of a movable part at a low and constant speed.

[0008] To solve the above problems, the spectroscopic measuring apparatus according to the present invention comprises: a fixed reflective member having a fixed reflective surface; a movable reflective member having a movable reflective surface arranged parallel and side by side with the fixed reflective surface; a drive mechanism for moving the movable reflective member in the direction normal to the fixed reflective surface; a photodetector having a light-receiving surface on which a plurality of light-receiving elements are arranged; an introduction optical system for guiding measurement light so as to span the fixed reflective surface and the movable reflective surface; and an interference optical system for interfering the measurement light reflected by the fixed reflective surface and the measurement light reflected by the movable reflective surface on the light-receiving surface, wherein the drive mechanism comprises: a conductor that carries current in a direction having a directional component perpendicular to the direction normal to the fixed reflective surface and arranged in a magnetic field oriented nonparallel to the direction normal to the fixed reflective surface; a movable element that moves the movable reflective member in the direction normal to the fixed reflective surface by the Lorentz force or its reaction force generated by the current flowing through the conductor; and an elastic body that resists the movement of the movable reflective member. The system includes a current control unit that changes the magnitude of the current flowing through the conductor at a predetermined rate of change over time corresponding to the elastic properties of the elastic body.

[0009] To solve the above problems, the actuator according to the present invention comprises: a conductor extending in a first direction; a current supply unit for supplying current to the conductor; a magnetic field source for applying a magnetic field to the conductor having components perpendicular to the first direction and a second direction nonparallel to the first direction; a movable element that moves in the second direction due to the Lorentz force or its reaction generated by the current flowing through the conductor; an elastic body that resists the movement of the movable element; and a current control unit that controls the current supply unit so that the magnitude of the current flowing through the conductor changes at a predetermined rate of change over time according to the elastic properties of the elastic body.

[0010] In this invention, "side-by-side" means that the fixed reflective surface and the movable reflective surface are not in a state of overlapping. For example, when the fixed reflective surface and the movable reflective surface are planes parallel to each other in the vertical direction, a state in which the movable reflective surface is above or below the fixed reflective surface, or a state in which the movable reflective surface is to the left or right of the fixed reflective surface, is included in "side-by-side".

[0011] In the spectroscopic measuring device and actuator according to the present invention, the interaction (Lorentz force or its reaction) between the current flowing through the conductor and the magnetic field passing through the conductor causes the movable reflector (movable element) to move in the direction normal to the fixed reflecting surface (second direction). At this time, the elastic body elastically deforms to resist the movement of the movable reflector (movable element), and this elastic force becomes the reaction force to the Lorentz force (or its reaction) that drives the movable reflector (movable element), so the movable reflector (movable element) is driven at a low speed. Furthermore, as will be described later, under low-speed driving, it can be approximated that all the power applied to the conductor is converted into the potential energy of the elastic body, so there is a certain relationship between the magnitude of the current flowing through the conductor and the elongation of the elastic body (displacement of the movable reflector or movable element). Therefore, the current control unit changes the magnitude of the current flowing through the conductor at a predetermined rate of change over time according to the elastic properties of the elastic body (details will be described later, but for example, if the elastic body is a linear elastic body, the current flowing through the conductor is changed linearly with respect to time). As a result, the movable reflector (movable element) is driven at a constant speed. Thus, the present invention has realized a drive mechanism suitable for a spectroscopic measuring device by finding that it is possible to drive at a low and constant speed by providing an elastic body.

[0012] According to the spectroscopic measuring device and actuator of the present invention, the movement of the movable element can be easily controlled at a low and constant speed without monitoring it with sensors or the like.

[0013] These are a top view and a side view of the spectroscopic measuring device according to the embodiment. This is a perspective view of the spectroscopic measuring device according to the embodiment. This is a diagram showing an example of the configuration of the drive mechanism according to the embodiment. This is a diagram showing an example of the configuration when elastic bodies are provided at multiple locations. This is a diagram showing an additional configuration of the drive mechanism according to the embodiment. This is a diagram showing an example of the configuration of the conductive part and the magnetic field application part according to the embodiment. This is an explanatory diagram of the operation of the spectroscopic measuring device according to the embodiment. This is a diagram showing the state when measurement light is incident on the movable reflective surface and the fixed reflective surface. This is an example of a diagram showing the characteristics of an elastic body. This is a schematic diagram showing the configuration of a test to evaluate the constant velocity of the drive mechanism according to the present invention. This is a graph showing the results of a test to evaluate the constant velocity of the drive mechanism according to the present invention.

[0014] Exemplary embodiments of the spectroscopic measuring device and actuator according to the present invention will be described with reference to the drawings.

[0015] [Configuration of the Spectroscopic Measurement Device] Figures 1 and 2 are schematic diagrams of the spectroscopic measurement device according to the embodiment (part of the housing of the spectroscopic measurement device is omitted in Figures 1 and 2). The spectroscopic measurement device 100 comprises a rectangular box-shaped housing 10, a phase shifter 20, an objective lens 31 and an imaging lens 32 housed inside it, a photodetector 40 mounted on the outside of the housing 10, a control device 50 (see Figure 7), and a power supply device 60 (see Figure 7).

[0016] The housing 10 consists of a rectangular plate-shaped base plate 11, four side walls 12-15, and a lid 16. The side walls 12-15 are detachably connected to each other, to the base plate 11, and to the lid 16, respectively, by screws (not shown).

[0017] The objective lens 31 is positioned on the base plate 11 such that its lens surface is parallel to the side wall 12. The imaging lens 32 is also positioned on the base plate 11 such that its lens surface is parallel to the side wall 13. The objective lens 31 and the imaging lens 32 are held between the base plate 11 and a lens holder 33 erected on the upper surface of the base plate 11. The lens holder 33 consists of an L-shaped member in top view and a pair of legs, the lower ends of which are fixed to the upper surface of the base plate 11. Recesses are formed on the upper surface of the base plate 11 at appropriate locations corresponding to the arrangement of the phase shifter 20, the objective lens 31, the imaging lens 32, and the lens holder 33. The objective lens 31 and the imaging lens 32 are positioned by inserting the lower ends of the objective lens 31, the imaging lens 32, and the legs of the lens holder 33 into these recesses. The configuration, which holds both the objective lens 31 and the imaging lens 32 with a single lens holder 33, allows the objective lens 31 and the imaging lens 32 to be brought close together.

[0018] An introduction port 70 for measuring light is provided in the side wall 12 at the portion facing the objective lens 31. The introduction port 70 has a cylindrical portion 71 that protrudes outward from the side wall 12, a condensing lens 72 fitted inside the cylindrical portion 71, and a conjugate plane grid 73 positioned between the condensing lens 72 and the objective lens 31 and on the conjugate plane of the objective lens 31. The conjugate plane grid 73 is held by a grid holder 74 erected on the upper surface of the base plate 11. The introduction optical system of the present invention is composed of the condensing lens 72, the conjugate plane grid 73, and the objective lens 31. Furthermore, an interference optical system is composed of the imaging lens 32.

[0019] A port 80 for the measurement light (reflected light) that has passed through the imaging lens 32 is provided in the part of the side wall 13 facing the imaging lens 32. A photodetector 40 is attached to the outer surface of the side wall 13 in the part where the port 80 is formed. The photodetector 40 is composed of a two-dimensional array sensor having a light-receiving surface on the imaging plane of the imaging lens 32, and has a plurality of light-receiving elements arranged in two dimensions on the light-receiving surface. The control device 50 includes a control unit 501 that controls the operation of the phase shifter 20, a calculation unit 502 that obtains an interferogram from the detection signal of the photodetector 40 and mathematically performs a Fourier transform on this interferogram to obtain spectral characteristics (spectrum), which are the relative intensity for each wavelength of the measurement light, a processing unit 503 that visualizes the calculation results of the calculation unit 502, a storage unit 504 that stores the processing results of the processing unit 503 and parameters related to the operation of the phase shifter 20, and a display unit 505 (display or printer, etc.) that outputs the processing results of the processing unit 503 and parameters related to the operation of the phase shifter 20. The power supply unit 60 supplies power to the drive mechanism 23, the photodetector 40, and the control device 50.

[0020] Next, the configuration of the phase shifter 20 will be described with reference to Figures 1 to 6. As shown in Figures 1 and 2, the phase shifter 20 comprises a fixed reflective member 21, a movable reflective member 22, and a drive mechanism 23 for driving the movable reflective member 22. The fixed reflective member 21 is made of a rectangular parallelepiped metal block, and a reflective surface 21a (hereinafter also referred to as the fixed reflective surface 21a) is formed by mirror-finishing one of its surfaces. The movable reflective member 22 is made of a rectangular parallelepiped metal block, and a reflective surface 22a (hereinafter also referred to as the movable reflective surface 22a) is formed by mirror-finishing one of its surfaces. The movable reflective surface 22a has approximately the same size as the fixed reflective surface 21a and is arranged parallel and side by side with the fixed reflective surface 21a. "Side by side" means that the fixed reflective surface 21a and the movable reflective surface 22a are not in a state of overlapping. For example, when the fixed reflective surface 21a and the movable reflective surface 22a are planes parallel to each other in the vertical direction, the state in which the movable reflective surface 22a is aligned above or below the fixed reflective surface 21a, or the state in which the movable reflective surface 22a is aligned to the left or right of the fixed reflective surface 21a, is included in the "side-by-side" arrangement.

[0021] The drive mechanism 23 moves the movable reflective member 22 in the direction normal to the fixed reflective surface 21a (drive direction A), and includes a conductive part 231 having a conductor 231a, a current supply unit (not shown) that supplies current from the power supply unit 60 to the conductor 231a, a current control unit that controls the magnitude of the current, etc., a magnetic field application unit 232 that applies a magnetic field to the conductor 231a, and an elastic body 233 that can expand and contract in the direction normal to the fixed reflective surface 21a. Typically, the conductor 231a is a wire, and the conductive part 231 can be a coil formed by winding a wire on a coil bobbin. In this case, the winding direction of the wire corresponds to the first direction in the present invention, and the drive direction A corresponds to the second direction in the present invention. The first direction in the present invention can also be rephrased as the direction in which current flows through the conductor 231a. The magnetic field application unit 232 has a magnetic circuit, for example, in which a magnet 232b (which may be a permanent magnet or an electromagnet) is attached to a yoke 232a having an air gap. The magnetic circuit corresponds to the magnetic field source in this invention. In this case, by housing the conductive part 231 in the air gap of the magnetic field application part 232, the magnetic field application part 232 can apply a magnetic field to the conductor 231a. The elastic body 233 can be an elastic body of any shape and made of any material (for example, in addition to coil springs, springs of any shape such as plate-shaped or dish-shaped, or membrane-shaped or dome-shaped rubber), and its elastic properties (relationship between deformation and elastic force) can be linear or nonlinear. There are various variations in the arrangement of the elastic body 233, which will be described later.

[0022] The direction of the current flowing through the conductor 231a is non-parallel to the normal direction of the fixed reflective surface 21a, and the direction of the magnetic field applied to the conductor 231a has a component perpendicular to the normal direction of the fixed reflective surface 21a and the direction in which the conductor 231a carries the current. In other words, the normal direction of the fixed reflective surface 21a, the direction of the current flowing through the conductor 231a, and the direction of the magnetic field applied to the conductor 231a are not in the same plane. The current supply unit is typically a circuit connecting the power supply device 60 and the conductor 231a (it may also include the power supply device 60 itself). The current control unit can be the control unit 501, but a current control unit may be provided independently of the control unit 501.

[0023] The drive mechanism 23 can be, for example, a commercially available voice coil motor with a coil spring attached as an elastic body 233. Figure 3(a) shows a configuration of a voice coil motor suitable for the drive mechanism 23 (see Non-Patent Literature 1). As shown in this figure, the yoke 232a preferably has an annular air gap formed by nesting a cylindrical outer yoke and a columnar or cylindrical inner yoke coaxial with the outer yoke, and the magnet 232b is preferably mounted along the inner wall of the outer yoke so as to face the inner yoke. In this case, the conductive part 231 (coil) is housed along this annular air gap while passing the inner yoke through it.

[0024] Figures 3(b) to 3(e) show examples of the configuration of a drive mechanism 23, which is formed by attaching a coil spring as an elastic body 233 to the voice coil motor shown in Figure 3(a). In the configuration example shown in Figure 3(b), a fixed reflective member 21 is attached to the magnetic field application part 232 of a voice coil motor, which has a magnetic field application part 232 and a conductive part 231, respectively, which are the stator and the movable part (the movable part of the present invention), and a movable reflective member 22 is attached to one end of the coil bobbin of the conductive part 231. The other end of the coil bobbin of the conductive part 231 and the yoke 232a of the magnetic field application part 232 are connected by a coil spring. In this case, an inner yoke may be passed through the coil spring, or one or more coil springs may be provided at multiple locations around the inner yoke (see Figure 4). The advantages of providing multiple coil springs will be described later.

[0025] In the configuration example shown in Figure 3(c), the magnetic field application section 232 is the stator and the conductive section 231 is the movable section, which is the same as in the configuration example in Figure 3(b), but the mounting position of the coil spring is different. That is, in this configuration, one end of the coil spring is attached to the inside of the end of the coil bobbin of the conductive section 231 on the side to which the movable reflector member 22 is attached, and the other end is attached to the tip of the inner yoke. Of course, multiple coil springs can be used in this case as well.

[0026] The configurations shown in Figure 3(d) and Figure 3(e) differ from those shown in Figure 3(b) and Figure 3(c) in that the coil spring is mounted in the same position, but the conductive part 231 is fixed to the fixed reflective member 21 via the support base 235, and the movable reflective member 22 is attached to the magnetic field application part 232. In other words, in the configurations shown in Figure 3(d) and Figure 3(e), the conductive part 231 is the stator, and the magnetic field application part 232 is the movable part.

[0027] In this specification, the configuration shown in Figures 3(b) and 3(c), i.e., the configuration in which the conductive part 231 is the movable element in the present invention, is referred to as the moving coil type, and the configuration shown in Figures 3(d) and 3(e), i.e., the configuration in which the magnetic field application part 232 is the movable element in the present invention, is referred to as the moving magnet type. The moving coil type is advantageous for constant velocity control because the movable element is lightweight. The moving magnet type is advantageous because the wiring is fixed, resulting in less wear and tear.

[0028] In this embodiment, the statement that the conductive portion 231 (magnetic field application portion 232) is fixed to the fixed reflective member 21 includes cases where the fixed reflective member 21 is directly attached to the conductive portion 231 (magnetic field application portion 232), or where the position of the conductive portion 231 (magnetic field application portion 232) relative to the fixed reflective member 21 remains unchanged, such as when both are attached to the base plate 11 or support base 235.

[0029] The drive mechanism 23 can be equipped with various additional configurations to ensure that the direction of movement of the movable reflective member 22 is normal to the fixed reflective surface 21a. For example, as shown in Figure 5, in a moving magnet type drive mechanism 23, the conductive part 231 may be fixed to the fixed reflective member 21 via an adjustment screw 234 and a support base 235 that supports the adjustment screw 234. In this configuration, the position of the conductive part 231 can be finely adjusted in the direction normal to the fixed reflective surface 22a using the adjustment screw 234, or the orientation of the conductive part 231 can be finely adjusted to align with the direction normal to the fixed reflective surface 22a.

[0030] Furthermore, as also shown in Figure 5, the moving magnet type drive mechanism 23 may be configured to include a linear motion guide 236 having a guide rail 236a extending in the direction normal to the fixed reflective surface 22a, a guide unit 236b sliding on the guide rail 236a, and a mounting unit 236c to which the guide unit 236b, the magnetic field application unit 232, and the movable reflective member 22 are attached. With such a configuration, the drive mechanism 23 can more reliably move the movable reflective member 22 in the direction normal to the fixed reflective surface 21a. Of course, the adjustment screw 234 and the linear motion guide 235 can also be implemented in the moving coil type drive mechanism 23. The restricting means for restricting the direction of movement of the movable element is not limited to the adjustment screw 234 and the linear motion guide 235, but other known means can also be used.

[0031] Furthermore, the elastic body 233 does not necessarily need to connect the stator and the movable part of the voice coil motor; as shown in Figure 5, it can be provided between the guide rail 236a and the mounting unit 236c. In other words, the elastic body 233 can connect the fixed reflective member 21 or a portion fixed to the fixed reflective member 21 (fixed portion) and the movable reflective member or a portion that moves together with the movable reflective member 22 (movable portion). The movable portion may also be considered as the movable part in this invention.

[0032] By providing multiple coil springs at multiple locations on the drive mechanism 23, the elastic force is applied more uniformly to the movable part, making it possible to more reliably direct the movement direction of the movable reflective member 22 towards the normal direction of the fixed reflective surface 21a.

[0033] Note that the configuration of the conductive part 231 and the magnetic field application part 232 of the drive mechanism 23 according to the embodiment is not limited to that shown in Figure 3, and there are various variations. For example, as shown in Figure 6(a) (see Non-Patent Literature 1), the yoke 232a can have two layers of air gap, formed by combining a columnar or cylindrical center yoke and a pair of side yokes facing each other on either side of the center yoke. The magnets 232b are preferably mounted along the inner walls of each side yoke so as to face each other on either side of the center yoke. In this case, the conductive part 231 (coil) is housed along these two layers of air gap, passing through the center yoke. Alternatively, as shown in Figure 6(b) (see Non-Patent Literature 1), the yoke 232a can have one layer of air gap, formed by a pair of side yokes facing each other. In this case, it is preferable that the two magnets 232b, 232b are mounted along the inner wall of one side yoke in opposite directions, with the N pole and S pole facing each other on the other side yoke. In this case, the conductive part 231 (coil) is positioned within the air gap such that the direction of the current flowing through the conductive part 231 is opposite at the boundary between the two magnets 232b, 232b.

[0034] [Method for measuring spectral characteristics using a spectroscopic measuring device] The method for measuring the spectral characteristics of an object using the spectroscopic measuring device 100 configured above is called imaging-type two-dimensional Fourier spectroscopy. The method for measuring spectral characteristics using imaging-type two-dimensional Fourier spectroscopy will be described below with reference to Figures 7 and 8.

[0035] The drive mechanism 23 of the phase shifter 20 of the spectroscopic measuring device 100 is driven to move the movable reflective member 22 back and forth in the drive direction A in Figure 7. More specifically, the movable reflective member 22 is moved back and forth at a constant speed between a reference position where the movable reflective surface 22a and the fixed reflective surface 21a are on the same plane, and a variable position where the movable reflective surface 22a is in front of the fixed reflective surface 21a. The drive of the drive mechanism 23 is controlled by the control device 50. The detailed control method will be described later.

[0036] Next, multi-wavelength light emitted from the light source L is shone toward the object to be measured S, causing the light generated by the object to be measured S (reflected light, scattered light, transmitted light, etc.; hereinafter referred to as measurement light) to enter the inlet 70 of the spectroscopic measuring device 100. The measurement light that enters the inlet 70 passes through the focusing lens 72 and the objective lens 31, and then becomes parallel light and reaches the phase shifter 20. As shown in Figure 8, the measurement light that reaches the phase shifter 20 enters both reflective surfaces, straddling both the fixed reflective surface 21a and the movable reflective surface 22a, and is reflected by each reflective surface.

[0037] The light reflected from the fixed reflective surface 21a when the measurement light is incident on it (fixed reflected light) and the light reflected from the movable reflective surface 22a when the measurement light is incident on it (movable reflected light) both pass through the imaging lens 32 and then focus onto the light-receiving surface of the photodetector 40 to form interference light. Multiple light-receiving elements are arranged on the light-receiving surface of the photodetector 40, and each light-receiving element generates a detection signal corresponding to the intensity of the interference light of the measurement light emitted from a bright spot of the object to be measured S. The detection signals from each light-receiving element are output from the photodetector 40 to the control device 50 for processing.

[0038] Since the light emitted from the object S to be measured contains light of various wavelengths, the intensity of the interference light changes by moving the movable reflective surface 22a and changing the difference in optical path length between the fixed reflected light and the movable reflected light. Therefore, when the detection signal from the photodetector 40 is processed in the control device 50, an interferogram showing the change in the intensity of the interference light is obtained, and the spectral characteristics (spectrum) of the measured light are obtained by mathematically performing a Fourier transform on this interferogram. In the spectroscopic measurement device 100 according to this embodiment, since multiple photodetectors are arranged in two dimensions on the light-receiving surface of the photodetector 40, the spectral characteristics of the measured light emitted from the object S to be measured can be measured in two dimensions.

[0039] [Control Method for the Drive Mechanism] The control method for the drive mechanism 23 will be explained below. For the sake of explanation, the drive mechanism 23 will be assumed to be a moving coil type (i.e., the magnetic field application part 232 is the stator and the conductive part 231 is the movable part), but a moving magnet type can also be controlled in the same way.

[0040] In the drive mechanism 23, the current control unit flows a current through the conductor 231a in a direction nonparallel to the normal direction of the fixed reflective surface 21a, and the magnetic field application unit 232 applies a magnetic field to the conductor 231a having a component perpendicular to the normal direction of the fixed reflective surface 21a and the direction in which the current flows through the conductor 231a. When the current flows through the conductor 231a, the movable element begins to move due to the Lorentz force directed in the normal direction of the fixed reflective surface 21a. The direction of movement of the movable element can be switched by changing the direction in which the current flows.

[0041] Because driving using the Lorentz force provides a very fast response, the above-mentioned driving method has been used exclusively for the purpose of rapidly reciprocating a movable part (voice coil motor). On the other hand, in the field of spectroscopic measurement equipment technology, two-dimensional array sensors are used as photodetectors, and their frame rate is low, at most a few hundred Hz (typically 60 Hz). Therefore, in order to obtain an accurate spectral distribution, the movement of the stage must be controlled at a slow and constant speed. For these reasons, in the field of spectroscopic measurement equipment, actuators with a driving method using the Lorentz force, especially voice coil motors, were not considered suitable for use, despite having sufficient stroke (about 1 mm) for the phase shifter.

[0042] Therefore, in the drive mechanism 23 according to this embodiment, the stator and the movable element are connected by an elastic body (typically an elastic body that can expand and contract in the direction normal to the fixed reflective surface 21a) that resists the movement of the movable reflective member 22 (movable element). With this configuration, when the movable element is driven in the direction normal to the fixed reflective surface 21a, an elastic force acts on the movable element in proportion to its displacement. This elastic force is in the opposite direction to the Lorentz force and acts as a reaction force to the Lorentz force, so the movable element is driven at a low speed. The moving speed of the movable element can be set to about 300 mm / h (approximately 0.1 mm / s) by adjusting the magnitude of the current in the current control unit. This is a sufficiently low speed for driving the phase shifter of the spectroscopic measuring device.

[0043] When current flows through the conductor 231a, the power is stored as the kinetic energy of the mover and the potential energy of the elastic body. At this time, if the mover is lightweight and driven at a low speed, its kinetic energy can be ignored. The conditions for ignoring the kinetic energy of the mover will be described later. When all the power when current flows through the conductor 231a is converted into the potential energy of the elastic body, when the elastic body is a linear elastic body, the relationships of the following formulas (1) and (2) can be obtained.

[0044]

[0045] Formulas (1) and (2) mean that the magnitude of the current (that is, the power) and the displacement of the mover are in a proportional relationship. Therefore, in the current control unit, by increasing the magnitude of the current (power) flowing through the conductor 231a linearly with respect to time, the displacement of the mover can be controlled linearly with respect to time, that is, the mover can be controlled at a constant speed. As will be described later, the fluctuation of the speed of the mover can be suppressed to about ±1%. This is sufficient as the constant speed of driving the phase shifter of the spectroscopic measurement device.

[0046] When the characteristics of the elastic body are non-linear, if the relationship between the deformation amount and the elastic force of the elastic body is measured in advance, the relationship between the magnitude of the current (power) flowing through the conductor 231a and the displacement of the mover can be calculated in the same manner as in the linear case. That is, when the elastic characteristics of the elastic body are represented by the following formula (3), the following formula (4) is obtained as the relationship between the magnitude of the current (power) flowing through the conductor 231a and the displacement of the mover (see also Fig. 9).

[0047]

[0048] Therefore, even when the elastic characteristics of the elastic body are non-linear, if the relationship of formula (4) is known, by changing the magnitude of the current (power) flowing through the conductor 231a with time based on that relationship, the displacement of the mover can be controlled linearly with respect to time, that is, the mover can be controlled at a constant speed.

[0049] Below, we consider the conditions under which the kinetic energy of the movable part can be ignored. For a linear elastic body, the potential energy of the elastic body is expressed by equation (1), so the allowable deviation (error) in the velocity of the movable part can be considered as the error in the potential energy of the elastic body. If the kinetic energy of the movable part is sufficiently smaller than the error in the potential energy of the elastic body, it can be considered to be negligible. In other words, the condition under which the kinetic energy of the movable part can be ignored is expressed by the following equation (5).

[0050]

[0051] When manufacturing a spectroscopic measuring device according to an embodiment, if the required speed of the movable element is known, it is necessary to select an elastic body such that the kinetic energy can be ignored at that required speed. If the elastic body is a linear elastic body, the spring constant must satisfy the following equation (6).

[0052]

[0053] The drive speed of the movable element is preferably 0.1 mm / s or less, and the speed error is preferably within 1%. Therefore, the spring constant is preferably satisfied by the following equation (7).

[0054]

[0055] Typically, the mass of the movable part is approximately 30g, and the maximum elongation of the elastic body is approximately 3mm. Therefore, for the movable part's speed to be 0.1mm / s and its tolerance to be 1%, the spring constant must be 50g / s. 2 (5.0 x 10 -5The spring constant should be sufficiently larger than (N / mm). Since most elastic materials satisfy this condition, basically any elastic material can be used under the above conditions. To increase the spring constant, for example, the winding diameter of the coil spring can be reduced. Also, when using a coil spring with a small winding diameter, it is preferable to provide multiple coil springs at multiple locations on the drive mechanism 23 in order to ensure that the elastic force is applied uniformly to the movable element. However, although a larger spring constant is preferable for low-speed driving, if it is too large, power consumption will increase, so a spring constant of about 2.0 N / mm to 3.0 N / mm is preferable. Even if the mass of the movable element, the maximum elongation of the elastic material, the speed of the movable element, and their tolerances differ from those above, an elastic material with an appropriate spring constant can be selected based on equation (5).

[0056] Furthermore, given a spring constant, the range of speeds in which the kinetic energy of the movable element can be ignored is expressed by the following equation (8). In other words, for speeds that satisfy the following equation (8), the relationship in equation (2) holds, and by linearly changing the magnitude of the current, the movable element can be driven at a constant speed.

[0057]

[0058] For example, if the mass of the movable part is 30g, the minimum extension of the coil spring is 2mm, the spring constant is 2.0N / mm, and the tolerance of the speed is 1%, then the speed of the movable part is approximately 2.7 × 10⁻⁶. 3 It is sufficient if it is significantly smaller than mm / s. Since the required speed of the spectroscopic measuring device according to this embodiment is typically 0.1 mm / s, the kinetic energy of the movable element can always be ignored within the speed range handled by the spectroscopic measuring device, and constant velocity control is possible based on that speed.

[0059] If the elastic properties of an elastic material are nonlinear, for example, by linearly approximating the elastic properties of the elastic material when the elongation is between 2 mm and 3 mm (corresponding to a movable element displacement of 0 mm to 1 mm), an appropriate elastic material can be selected in the same manner as described above.

[0060] As explained above, in this embodiment, the magnitude of the current (power) flowing through the conductor 231a corresponds to the displacement (position) of the movable element (one-to-one correspondence in the case of a linear elastic body). Therefore, the movement of the movable element can be easily controlled at a low and constant speed without the need for the complex configuration of detecting the operation of the drive mechanism with a capacitive sensor or optical encoder and performing feedback control, which has been required in the past.

[0061] Furthermore, while conventional impact actuators and ultrasonic motors used in spectroscopic measuring devices are typically palm-sized, the actuator according to this embodiment can be made to approximately 10mm x 10mm x 5mm by using a voice coil motor. In addition, while impact actuators are sold for several million yen and ultrasonic motors for several hundred thousand yen, the voice coil motor according to this embodiment can be made to approximately several thousand yen. Therefore, by using a voice coil motor, the spectroscopic measuring device according to this embodiment can be supplied at a small size (about the size of an eraser) and at a low cost (approximately several thousand yen), and is expected to achieve commercial success in the field of spectroscopic measuring device technology.

[0062] It should be noted that the actuator according to this embodiment, having a conductive part 231 and a magnetic field application part 232, may be mistakenly thought to be similar to a conventional solenoid at first glance. However, a solenoid is a mechanism that, while current is flowing through the coil, attracts the movable core into the coil using the magnetic field generated by the coil, and when the current is cut off, returns the movable core to its original position using the elastic force of a spring. Therefore, a solenoid moves the movable core instantaneously between a starting point and an ending point. On the other hand, the actuator according to this embodiment moves the movable element at a low and constant speed, and is completely different from a solenoid.

[0063] [Evaluation of Constant Velocity of the Drive Mechanism] A test was conducted to evaluate the constant velocity of the drive mechanism according to the present invention. The procedure and results of the test are described below.

[0064] In this test, a drive mechanism was fabricated by combining a voice coil motor (AVM12-6.4-0.5, diameter 9.2 mm, coil mass 30 g, stroke 1 mm) and a coil spring (KSSC5091, free length 3.0 mm, outer diameter 1.85 mm, wire diameter 0.25 mm, number of turns 5.5, material SUS304WPB, spring constant 2.44 N / mm), and the displacement of the coil was measured when the magnitude of the current was changed linearly with respect to time. Figure 10 is a schematic diagram of the apparatus configuration for this test. A Keyence SI-F100 (capable of measuring up to 1000 μm, resolution 0.01 μm) was used for measurement.

[0065] Figure 11 shows graphs illustrating the results of this test. These graphs plot elapsed time on the horizontal axis and coil displacement on the vertical axis. Figure 11(a) shows the measured values, and Figure 11(b) shows the measured values ​​with an approximation curve superimposed. It can be seen that the coil displacement is proportional to the elapsed time. The slope (velocity) at this time is approximately 0.056 mm / s, and the relative error (ratio of measured value to approximation value to the value of the approximation curve) is a maximum of 1.84% and a minimum of -1.80%, indicating sufficient low-speed and constant-speed operation. From the above, it has been shown that by linearly changing the magnitude of the current with respect to time, the coil can be driven at a corresponding low and constant speed.

[0066] It is said that applying voltage generates a back electromotive force in the coil, but this is not a problem if the current is controlled to increase gradually (linearly), as in this test. Although the results are not shown in the figures, when the actuator according to this embodiment was driven with a constant current power supply, it was not possible to drive the movable element at a constant speed. Therefore, it is considered important to change the magnitude of the current at a predetermined rate of change over time according to the elastic properties of the elastic body (for a linearly elastic body, change it linearly as shown in this test).

[0067] Furthermore, as long as the drive is at a low speed, the inertia of the movable part can be ignored and is not expected to affect the constant velocity.

[0068] [Embodiments] It will be apparent to those skilled in the art that the exemplary embodiments described above are specific examples of the following embodiments.

[0069] (Section 1) A spectroscopic measuring apparatus according to one aspect of the present invention comprises: a fixed reflective member having a fixed reflective surface; a movable reflective member having a movable reflective surface arranged parallel and side by side with the fixed reflective surface; a drive mechanism for moving the movable reflective member in the direction normal to the fixed reflective surface; a photodetector having a light-receiving surface on which a plurality of light-receiving elements are arranged; an introduction optical system for guiding measurement light so as to span the fixed reflective surface and the movable reflective surface; and an interference optical system for interfering the measurement light reflected by the fixed reflective surface and the measurement light reflected by the movable reflective surface on the light-receiving surface, wherein the drive mechanism comprises: a conductor that carries current in a direction having a directional component perpendicular to the direction normal to the fixed reflective surface and arranged in a magnetic field oriented nonparallel to the direction normal to the fixed reflective surface; a movable element that moves the movable reflective member in the direction normal to the fixed reflective surface by the Lorentz force or its reaction force generated by the current flowing through the conductor; and an elastic body that resists the movement of the movable reflective member. The system includes a current control unit that changes the magnitude of the current flowing through the conductor at a predetermined rate of change over time corresponding to the elastic properties of the elastic body.

[0070] (Paragraph 2) The spectroscopic measuring device according to Paragraph 2 is the spectroscopic measuring device according to Paragraph 1, wherein the drive mechanism further comprises a magnetic field source for applying the magnetic field.

[0071] (Section 10) An actuator according to one aspect of the present invention comprises: a conductor extending in a first direction; a current supply unit for supplying current to the conductor; a magnetic field source for applying a magnetic field to the conductor having components perpendicular to the first direction and a second direction not parallel to the first direction; a movable element that moves in the second direction due to a Lorentz force or its reaction generated by the current flowing through the conductor; an elastic body that resists the movement of the movable element; and a current control unit that controls the current supply unit so that the magnitude of the current flowing through the conductor changes at a predetermined rate of change over time according to the elastic properties of the elastic body.

[0072] In the spectroscopic measuring apparatus described in paragraphs 1 and 2 and the actuator described in paragraph 10, the interaction between the current flowing through the conductor and the magnetic field passing through the conductor (Lorentz force or its reaction force) moves the movable reflector (movable element) in the direction normal to the fixed reflecting surface (second direction). At this time, the elastic body elastically deforms to resist the movement of the movable reflector (movable element), and this elastic force becomes the reaction force to the Lorentz force (or its reaction force) that drives the movable reflector (movable element), so the movable reflector (movable element) is driven at a low speed. Furthermore, as already mentioned, under low-speed driving, it can be approximated that all the power applied to the conductor is converted into the potential energy of the elastic body, so there is a certain relationship between the magnitude of the current flowing through the conductor and the elongation of the elastic body (displacement of the movable reflector or movable element). Therefore, the current control unit changes the magnitude of the current flowing through the conductor at a predetermined rate of change over time according to the elastic properties of the elastic body (for example, if the elastic body is a linear elastic body, the current flowing through the conductor is changed linearly with respect to time). As a result, the movable reflector (movable element) is driven at a constant speed. Thus, the present invention has realized a drive mechanism suitable for a spectroscopic measuring device by finding that it is possible to drive at a low and constant speed by providing an elastic body. With the spectroscopic measuring device according to paragraphs 1 and 2 and the actuator according to paragraph 10, the movement of the movable element can be easily controlled at a low and constant speed without monitoring it with sensors or the like.

[0073] (Clause 3) The spectroscopic measuring device according to paragraph 3 is the spectroscopic measuring device according to paragraph 1 or claim 2, wherein the conductor is provided on the movable element.

[0074] According to the spectroscopic measuring device described in paragraph 3, the movable element can be made lightweight.

[0075] (Paragraph 4) The spectroscopic measuring device according to Paragraph 4 is the spectroscopic measuring device according to Paragraph 2, wherein the magnetic field source is provided on the movable element.

[0076] According to the spectroscopic measuring device described in paragraph 4, the wiring is fixed in place, resulting in less wear and tear.

[0077] (Article 5) The spectroscopic measuring device according to Article 5 is the spectroscopic measuring device according to any of Articles 1 to 4, wherein the elastic body is a linear elastic body, and the current control unit changes the magnitude of the current flowing through the conductor linearly with respect to time.

[0078] According to the spectroscopic measuring device described in paragraph 5, the magnitude of the current flowing through the conductor and the displacement of the movable element correspond one-to-one, and complex current control is not required, making it even easier to control the position of the movable element.

[0079] (Paragraph 6) The spectroscopic measuring device according to Paragraph 6 is a spectroscopic measuring device according to any of Paragraphs 1 to 5, wherein the drive mechanism further includes a restricting means for restricting the direction of movement of the movable reflective member.

[0080] According to the spectroscopic measuring device described in paragraph 6, the movable reflective member can be moved more reliably in the direction normal to the fixed reflective surface.

[0081] (Paragraph 7) The spectroscopic measuring device relating to Paragraph 7 is a spectroscopic measuring device relating to any of Paragraphs 1 to 6, wherein the elastic body is provided at multiple locations of the drive mechanism.

[0082] According to the spectroscopic measuring device described in paragraph 7, since the elastic force is applied more uniformly to the movable part, the direction of movement of the movable reflective member can be more reliably aligned with the normal direction of the fixed reflective surface. Furthermore, for example, when using a coil spring as the elastic body, if multiple coil springs are provided, the winding diameter of the coil springs will inevitably be smaller compared to using a single coil spring, thus allowing for a larger spring constant.

[0083] (Clause 8) The spectroscopic measuring device according to Clause 8, in the spectroscopic measuring device according to Clause 5, satisfies the following equation (7) between the mass m of the movable element and the displacement x of the movable element.

[0084] (Paragraph 9) The spectroscopic measuring device relating to Paragraph 9 is a spectroscopic measuring device relating to any of Paragraphs 1 to 8, wherein the predetermined rate of change over time is such that the movable element is driven at a predetermined speed of 0.1 mm / s or less, and the error of said speed is within 1%.

[0085] The spectroscopic measuring apparatus described in paragraphs 8 and 9 provides a spectroscopic measuring apparatus in which the speed at which the phase shifter is driven is sufficiently low.

[0086] 100...Spectroscopic measuring device 10...Housing 11...Base plate 12-15...Side wall 16...Lid 20...Phase shifter 21...Fixed reflective member 21a...Fixed reflective surface 22...Movable reflective member 22a...Movable reflective surface 23...Drive mechanism 231...Conductive part 231a...Conductor 232...Magnet application part 232a...Yoke 232b...Magnet 233...Elastic body 234...Adjustment screw 235...Support base 236...Linear motion guide 236a...Guide rail 236b...Guide unit 236c...Mounting unit 31...Objective lens 32...Imaging lens 33...Lens holder 40...Photodetector 50...Control device 501...Control unit 502...Calculation unit 503...Processing unit 504...Storage unit 505...Display unit 60...Power supply unit 70...Inlet 71...Cylindrical section 72...Concentrating lens 73...Conjugate surface grid 74...Grid holder 80...Outlet A...Drive direction

Claims

1. A fixed reflective member having a fixed reflective surface; a movable reflective member having a movable reflective surface arranged parallel and side-by-side with the fixed reflective surface; a drive mechanism for moving the movable reflective member in the direction normal to the fixed reflective surface; a photodetector having a light-receiving surface on which a plurality of light-receiving elements are arranged; an introduction optical system for guiding measurement light so as to span the fixed reflective surface and the movable reflective surface; an interference optical system for interfering the measurement light reflected by the fixed reflective surface and the measurement light reflected by the movable reflective surface on the light-receiving surface, wherein the drive mechanism comprises a conductor that carries current in a direction having a directional component perpendicular to the direction normal to the fixed reflective surface and positioned in a magnetic field oriented nonparallel to the direction normal to the fixed reflective surface; a movable element that moves the movable reflective member in the direction normal to the fixed reflective surface by the Lorentz force or its reaction force generated by the current flowing through the conductor; and an elastic body that resists the movement of the movable reflective member. A spectroscopic measuring device comprising a current control unit that changes the magnitude of the current flowing through the conductor at a predetermined rate of change over time according to the elastic properties of the elastic body.

2. The spectroscopic measuring apparatus according to claim 1, wherein the drive mechanism further comprises a magnetic field source for applying the magnetic field.

3. The spectroscopic measuring apparatus according to claim 1, wherein the conductor is provided on the movable element.

4. The spectroscopic measuring apparatus according to claim 2, wherein the magnetic field source is provided on the movable element.

5. The spectroscopic measuring apparatus according to claim 1, wherein the elastic body is a linear elastic body, and the current control unit changes the magnitude of the current flowing through the conductor linearly with respect to time.

6. The spectroscopic measuring apparatus according to claim 1, wherein the drive mechanism further comprises a restricting means for restricting the direction of movement of the movable reflective member.

7. The spectroscopic measuring apparatus according to claim 1, wherein the elastic body is provided at multiple locations of the drive mechanism.

8. The spectroscopic measuring apparatus according to claim 5, wherein the spring constant k of the linear elastic body satisfies the following equation (7) between the mass m of the movable element and the displacement x of the movable element.

9. The spectroscopic measuring apparatus according to claim 1, wherein the predetermined rate of change over time is such that the movable element is driven at a predetermined speed of 0.1 mm / s or less, and the speed error is within 1%.

10. An actuator comprising: a conductor extending in a first direction; a current supply unit for supplying current to the conductor; a magnetic field source for applying a magnetic field to the conductor having components perpendicular to the first direction and a second direction nonparallel to the first direction; a movable element that moves in the second direction due to a Lorentz force or its reaction force generated by the current flowing through the conductor; an elastic body that resists the movement of the movable element; and a current control unit that controls the current supply unit so that the magnitude of the current flowing through the conductor changes at a predetermined rate of change over time according to the elastic properties of the elastic body.

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