Displacement detection device

Abstract

Displacement detection device (200) comprising: a light source; a first beam splitter (103) designed to split the light emitted by the light source into a first beam and a second beam; a reflecting element (108) designed to reflect the first beam split by the first beam splitter (103); an objective lens (105) mounted in the displacement detection device (200) and designed to focus the second beam split by the first beam splitter (103) onto a surface to be measured; a first light receiving section (130) designed to receive interference light from the first beam reflected by the reflecting element (108) and the second beam reflected by the surface to be measured; a section (160) for outputting information about the relative position,a section (130) designed to output information about the relative position in the vertical direction of the surface to be measured based on the intensity of the interference light received by the first light receiving section; a second beam splitter (112) designed to couple out a portion of the second beam reflected by the surface to be measured; an astigmatism generator (110) designed to generate astigmatism in the second beam coupled out by the second beam splitter (112); a second light receiving section (140) designed to receive the second beam in which astigmatism has been generated by the astigmatism generator (110); and a section (150) for outputting information about the absolute position,which is designed to generate information about the absolute position in the vertical direction of the surface to be measured based on the intensity of the received light detected by the second light receiving section (140) and to output the generated information about the absolute position, wherein the light source comprises a first light source section (101a) and a second light source section (101b), each emitting light beams with different wavelengths, wherein the beam emitted by the first light source section (101a) is split by the first beam splitter (103) into the first beam and the second beam, and the beam emitted by the second light source section (101b) enters the surface to be measured through the first beam splitter (103) as the second beam, and the second beam splitter (112) couples out the beam emitted by the second light source section (101b) from the second beam.

Description

CROSS-REFERENCE TO RELATED REGISTRATIONS

[0001] The present invention contains an object relating to the Japanese patent application JP 2010-142291, filed with the Japanese Patent Office on June 23, 2010, the entire content of which is included here by reference to literature. BACKGROUND OF THE INVENTION: Field of invention:

[0002] The present invention relates to a displacement detection device for accurately detecting the displacement of a surface to be measured by a contactless sensor that uses light. Description of the related area:

[0003] Traditionally, displacement detection devices are widely used to measure the displacement and shape of a surface being measured.

[0004] Among these displacement detection devices, there is one that detects the displacement of the surface to be measured in a contactless manner using light. In such a device, for example, the light emitted by a light source is focused onto the surface to be measured by an objective lens. Furthermore, the light reflected from the surface is focused by an astigmatic optical element to create astigmatism, and this astigmatism is then directed onto a light-receiving element.

[0005] Based on the intensity of the light received by the light receiving element, a focal point error signal is generated using an astigmatism method, and a servo is operated to shift the objective lens so that the focal point of the concentrated light is located on the surface to be measured.

[0006] Furthermore, a linear scale is integrally attached to the objective lens via a connecting element in such a way that the linear scale, being locked in place with the displacement of the objective lens, also moves. The scale of the moving linear scale is read by a sensing head fixed at a fixed point, thereby detecting the displacement in the vertical direction of the surface being measured.

[0007] Since the linearity of the focal point error signal itself is poor in this displacement detection device, high detection accuracy cannot be achieved.

[0008] To solve this problem, a method for correcting the focal point error signal of the contactless sensor using a correction table has been proposed in the Japanese unexamined patent application publication No. H05-89480.

[0009] To improve the accuracy of displacement detection in the displacement detection device disclosed in Japanese unexamined patent application No. H05-89480, the NA (numerical aperture) of the objective lens is set large, thus reducing the diameter of the beam focused on the surface to be measured. For example, the detection accuracy of the linear scale is in the range of several nm to several hundred nm when the beam diameter formed on the surface to be measured is approximately 2 μm. SUMMARY OF THE INVENTION

[0010] However, in the displacement detection device disclosed in the Japanese unexamined patent application publication No. H05-89480, high resolution is achieved by reducing the beam diameter of the light projected onto the surface to be measured. Thus, the reflected light from the surface to be measured is susceptible to the influence of surface roughness, causing the projected light to scatter and thereby resulting in a measurement error.

[0011] Since the high resolution is achieved by reducing the beam diameter, there are also cases in which fine foreign bodies and / or the like adhering to the surface to be measured are detected, so that displacement information such as the displacement, shape and the like of the surface to be measured cannot always be obtained accurately.

[0012] Furthermore, a highly accurate positioning stage with a tilting mechanism is used in a current semiconductor manufacturing device, testing equipment, and the like. In such a highly accurate positioning stage, the measurement in the vertical direction must be performed at high speed while suppressing the heat generated by the sensor itself.

[0013] However, in earlier displacement detection devices, such as the displacement detection device disclosed in Japanese unexamined patent application publication No. H05-89480, the control must be designed such that the image of the beam is always located on the surface to be measured.

[0014] Thus, in the technique disclosed in the Japanese unexamined patent application publication No. H05-89480, the objective lens is moved up and down in the direction of its optical axis, driven, for example, by a drive mechanism such as an actuator using a magnet and a coil; however, due to the structure and mass of the actuator, there is a limitation on the mechanical response frequency of the up and down movement of the objective lens.

[0015] Furthermore, as the coil and the like are actuated, the objective lens is heated, causing the measuring position to drift.

[0016] For the reasons mentioned above, the operating conditions in conventional methods are limited.

[0017] In view of the problems mentioned above, it is an object of the present invention to create a displacement detection device that has broader operating conditions and can accurately detect the position in the vertical direction.

[0018] To solve the problems mentioned above, a displacement detection device in accordance with one aspect of the present invention comprises a light source, a first beam splitter designed to divide the light emitted by the light source into a first beam and a second beam, and a reflecting element designed to reflect the first beam divided by the first beam splitter.

[0019] Furthermore, the aforementioned displacement detection device includes an objective lens designed to concentrate the second beam, split by the first beam splitter, onto a surface to be measured, and a first light receiving section designed to receive interference light from the first beam reflected by the reflecting element and the second beam reflected by the surface to be measured.

[0020] Furthermore, the above-mentioned displacement detection device includes a section for outputting information about the relative position, which is designed to output information about the relative position in the vertical direction of the surface to be measured based on the intensity of the interference light received by the first light receiving section.

[0021] Furthermore, the above-mentioned displacement detection device includes a second beam splitter designed to couple out part of the second beam reflected by the surface to be measured, and an astigmatism generator designed to generate astigmatism in the second beam coupled out by the second beam splitter.

[0022] Furthermore, the above-mentioned displacement detection device includes a second light receiving section designed to receive the second beam in which astigmatism has been generated by the astigmatism generator, and a section for outputting information about the absolute position, designed to generate information about the absolute position in the vertical direction of the surface to be measured based on the intensity of the received light detected by the second light receiving section and to output the generated information about the absolute position.

[0023] In the displacement detection device according to the present invention, information about the relative position is obtained from the interference light of the light reflected from the surface to be measured and the light reflected from the reflecting component. In other words, the intensity of the interference light, which changes periodically in accordance with the height of the surface to be measured, is used as a scale.

[0024] Furthermore, in the displacement detection device, in accordance with the present invention, information about the absolute position is output based on the light reflected from the surface to be measured. Thus, the reference point and the reference position of the aforementioned scale formed by the interference light can be determined based on the information about the absolute position, so that the displacement of the surface to be measured can be accurately detected.

[0025] In the displacement detection device according to the present invention, the information about the relative position is obtained from the interference light of the reflected light from the surface to be measured and the reflected light from the reflecting component, and the information about the absolute position is obtained from the reflected light from the surface to be measured.

[0026] Thus, the displacement can be measured without using a scale conventionally manufactured using microfabrication. Furthermore, the scale does not need to be driven by the objective lens in a locked manner, as in conventional techniques.

[0027] Since the conventional drive mechanism is not required, the heat generated during operation can be reduced. Furthermore, since the drive mechanism is not needed, there is no issue with the response frequency, allowing for more flexible operating conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Fig. Figure 1 is a view schematically showing the configuration of a displacement detection device in accordance with a first embodiment of the present invention;

[0029] Fig. 2 is a block diagram that schematically shows the configuration of a section for outputting information about the relative position;

[0030] Fig. 3A to Fig. 3C are views that each show a spot of the light received by the second light-receiving section;

[0031] Fig. 4 is a graphical representation to explain a focal point error signal;

[0032] Fig. Figure 5 is a view schematically showing the configuration of a displacement detection device in accordance with a second embodiment of the present invention; and

[0033] Fig. Figure 6 is a view that schematically shows the configuration of a displacement detection device in accordance with a third embodiment of the present invention. DETAILED DESCRIPTION OF PREFERRED EXECUTION FORMS

[0034] The following will be based on Fig. 1 to Fig. 6. A displacement detection device in accordance with preferred embodiments of the present invention is described. However, it is noted that the present invention is not limited to these embodiments.

[0035] Furthermore, the various lenses described below can each be a single lens or a group of lenses.

[0036] If a single-mode semiconductor laser is used as the light source in the present invention, the measuring range can be extended, regardless of the embodiment, because a light beam with high coherence can be emitted. In this case, the temperature of the light source is preferably controlled to stabilize the wavelength of the emitted light.

[0037] Furthermore, if a multimode semiconductor laser is used as the light source, the spot pattern on the light-receiving surface of the light-receiving element is suppressed because the coherence of the light emitted by the multimode semiconductor laser is lower than that of the light emitted by the single-mode semiconductor laser. However, in this case, the measurement range becomes equal to the coherence length.

[0038] Furthermore, the light source is preferably detachably attached to the main body of the displacement detection device. With this arrangement, the light source can be easily replaced when it reaches the end of its service life or when the wavelength of the light source needs to be changed.

[0039] Furthermore, the light source can be an external light source that supplies light via an optical fiber or similar device. In this case, the light source, which is a heat source, can be moved externally. Additionally, because the light source is detachably attached to the optical fiber, it can be serviced at a location separate from the displacement detection device, thus improving processability.

[0040] Furthermore, the light from the light source can also be supplied from the outside through a gas chamber, a liquid chamber, a vacuum chamber, or the like. In this case, not only can the heat source be arranged separately from the main body of the device, but the component connected to the main body of the device, such as the optical fiber and / or the like, can also be eliminated, so that no vibration is transmitted to the main body of the device.

[0041] To reduce the influence of the wavelength variation of the light source caused by temperature fluctuations, an achromatic lens is preferably used as the objective lens to correct chromatic aberration. 1. First embodiment

[0042] Fig. Figure 1 is a view that schematically shows the configuration of a displacement detection device. 100in Überernstimurig with a first embodiment of the present invention. The displacement detection device 100 in accordance with the present embodiment, it contains a light source 1 , a first beam splitter 3 , which is used to divide the light from the light source 1 emitted light is designed into a first beam and a second beam, and a reflecting component 8 , which reflects the light passing through the first beam splitter 3 is designed with a split first beam.

[0043] Furthermore, the displacement detection device contains 100 a lens 5 , which concentrate the beam through the first beam splitter 3 split second beam onto a surface of an object to be measured 9 has been swept out, and a first light reception section 30, which is used to receive interference light from the reflecting component 8 reflected first ray and the one passing through the surface of the object to be measured 9 is designed for the reflected second beam.

[0044] Furthermore, the displacement detection device contains 100 a section 60 for outputting information about the relative position, for outputting the displacement of the surface of the object to be measured 9 in the vertical direction based on the intensity of the light received by the first light reception section 30 is designed to receive interference light.

[0045] Furthermore, the displacement detection device contains 100 a second beam splitter 20 , which is designed to extract part of the second beam reflected by the surface to be measured, and an astigmatism generator 10, which causes astigmatism in the image formed by the second beam splitter 20 is designed with a decoupled second beam.

[0046] Furthermore, the displacement detection device contains 100 a second light reception section 40 , which receives the second ray with the astigmatism generator in it 10 designed to prevent astigmatism, and a section 50 for outputting information about the absolute position, for generating information about the absolute position of the surface to be measured in the vertical direction based on the second light reception section 40 It is designed to measure the intensity of the received light and to output information about the absolute position.

[0047] The light source 1It can be configured, for example, by a semiconductor laser diode, a superluminescent diode, a luminescent diode, or the like. Since, as will be described later, the interference light from the light source is used to perform the measurement in the present invention, the measuring range is, incidentally, wider the higher the coherence length of the light from the light source.

[0048] The light source 1 The emitted light is passed through a lens. 2 such as a collimating lens or similar device, collimates the light to parallel light. Furthermore, the light passing through the lens is 2 collimated light through the first beam splitter (such as a polarizing beam splitter or the like) 3 divided into two beams.

[0049] For example, the light from the light source 1 s-polarized light through the first beam splitter 3reflected and p-polarized light through the first beam splitter 3 passed through.

[0050] The first beam, which emerges from the first beam splitter 3 The reflected s-polarized light is focused by a converging lens. 7 on the reflecting component (such as a mirror or the like) 8 concentrated. The light-reflecting thin film of the reflective component. 8 It is made of a metal such as gold or similar. Therefore, compared to a general reflective thin film made of a dielectric multiple layer, changes in the wavelength and properties of polarized light caused by changes in humidity can be suppressed, allowing for stable position detection.

[0051] The reflecting component 8 The reflected first ray passes through the converging lens.7 again on the first beam splitter 3 one. Incidentally, in the optical path between the first beam splitter 3 and the reflective structural element 8 a phase plate (such as a lambda quarter plate or the like) 6 arranged. Although the first ray is directed towards the reflecting component. 8 runs and from the reflective component 8 When the first beam returns, it passes through the phase plate twice. 6 transmitted so that its polarization direction is rotated by 90 degrees, so that the first ray is converted into p-polarized light.

[0052] Furthermore, the first beam, which has been converted into p-polarized light, is passed through the first beam splitter. 3 passed through and falls onto a converging lens 11 a.

[0053] On the other hand, the second beam, which comes from the beam splitter through the first beam,3 transmitted p-polarized light, through a phase plate (such as a lambda quarter plate or the like) 4 transmitted and thus circularly polarized light, which passes through the objective lens 5 to the surface of the object to be measured 9 The concentration increases with the NA value of the objective lens. 5 The higher the NA value, the higher the resolution; and the smaller the NA value of the objective lens. 5 The larger the area, the wider the measuring range of the surface to be measured.

[0054] Incidentally, it needs to go through the objective lens. 5 A concentrated second beam on the surface being measured does not produce an image.

[0055] By shifting the position of the image from the surface to be measured in such a way as to increase the spot diameter on the surface to be measured, the influence of measurement errors caused by the surface roughness of the surface to be measured, by foreign bodies adhering to the surface to be measured, and / or the like, can be reduced. Furthermore, in the technique disclosed in Japanese unexamined patent application publication no. H05-89480, the objective lens is actuated in such a way that it moves up and down following the surface to be measured, causing the light to produce an image on the surface to be measured. In contrast, the objective lens is 5 in the present embodiment in the displacement detection device 100 attached.

[0056] Thus, in the present embodiment, the position at which the lens passes through changes. 5An image of the second beam is to be generated, but not despite the unevenness of the surface to be measured. Therefore, the position at which the beam passes through the objective lens cannot be determined. 5 An image of the second beam is to be generated, serving as a reference point to obtain the absolute displacement of the surface to be measured.

[0057] The second beam incident on the surface to be measured is reflected and passes through the objective lens. 5 again onto the phase plate (such as a lambda quarter plate or the like) 4 One beam. The second beam is passed through the phase plate. 4 the circularly polarized light is converted into s-polarized light and passed through the first beam splitter. 3 reflected.

[0058] Furthermore, the beam splitter is 3 reflected second ray onto the converging lens 11 came up with it.

[0059] Incidentally, the optical path length between the first beam splitter is 3 and the reflective structural element 8 preferably equal to the optical path length between the first beam splitter 3 and the position of the focal point through the objective lens 5 concentrated second beam (i.e., the optical path length between the first beam splitter) 3 and the reference point for measuring the absolute displacement).

[0060] Although the wavelength of the light source varies due to fluctuations in pressure, humidity, and temperature, in such an arrangement the influence exerted on the first beam can be made equal to the influence exerted on the second beam. Thus, the intensity of the interference light from the first and second beams, received by the first light-receiving section (the details of which will be described later), can be stabilized independently of the environment, allowing for a more accurate measurement.

[0061] The first ray and the second ray, which pass through the converging lens 11 Those that are allowed through are passed through the second beam splitter. 20 divided into two beams.

[0062] In the present embodiment, the second beam splitter 20 e.g. as a beam splitter 12 and a polarizing plate 21 configured.

[0063] The first beam and the one through the beam splitter 12 reflected second beam pale onto the light receiving section 30 a place where the rays are received.

[0064] Furthermore, the first beam and the beam splitter are 12 second beam transmitted through the polarizing plate 21 transmitted, whereby only the second ray, which reflects the light from the object being measured, passes through. 9 is, from the light reception section 40 is received.

[0065] The first light reception section 30 contains a semi-transparent mirror 31 and a polarization beam splitter 32 , wherein the first light-receiving section 30 to split the first beam and the second beam that are emitted by the beam splitter 12 are reflected, are designed in two beams, and the polarization beam splitter 32to further divide one of the two through the semi-transparent mirror 31 The beams are divided into two beams. Furthermore, the first light-receiving section contains 30 a first light-receiving element 33 and a second light-receiving element 34 , in order to divide each of the two by the polarization beam splitter 32 to receive split beams.

[0066] The first light reception section 30 also contains a phase plate (such as a lambda quarter plate or the like) 35 , which in the optical path of the other of the two through the semi-transparent mirror 31 is arranged in split beams, and includes a polarization beam splitter. 36 , which divides the phase plate 35 The transmitted beam is designed to be split into two beams. The first light-receiving section 30 It also contains a third light-receiving element. 37and a fourth light-receiving element 38 , in order to divide each of the two by the polarization beam splitter 36 to receive split beams.

[0067] The first ray and the second ray, which hit the semi-transparent mirror 31 Any ideas that come to mind will be shared.

[0068] The first ray and the second ray, which pass through the semi-transparent mirror 31 They are allowed to pass through and fall onto the polarization beam splitter. 32 One. The polarization beam splitter 32 is arranged at an angle, so that both the polarization direction of the first beam and the polarization direction of the second beam are aligned with respect to the plane of incidence of the polarization beam splitter. 32 are inclined at an angle of 45 degrees, with the polarization direction of the first beam and the polarization direction of the second beam differing by 90 degrees.

[0069] In such an arrangement, both the first beam and the second beam possess the p-polarized component and the s-polarized component with respect to the polarization beam splitter. 32 Thus, the first beam and the second beam, which pass through the polarization beam splitter, are 32 be allowed to pass through, e.g. to p-polarized light with the same polarization direction, so that the first beam and the second beam can interfere with each other.

[0070] Similarly, the first beam and the second beam, which pass through the polarization beam splitter, are 32 are reflected to s-polarized light with the same polarization direction with respect to the polarization beam splitter. 32 , so that the first beam and the second beam can interfere with each other.

[0071] The interference light of the first beam and the second beam, which pass through the polarization beam splitter 32The light is reflected by the first light-receiving element. 33 The interference light of the first beam and the second beam, which pass through the polarization beam splitter, is received. Furthermore, the interference light of the first beam and the second beam, which pass through the polarization beam splitter, is received. 32 be allowed through the second light-receiving element 34 received.

[0072] Furthermore, the phase of the process by which the first light-receiving element passes through differs. 33 photoelectrically converted signal and the phase of the signal received by the second light receiving element 34 photoelectrically converted signals 180 degrees apart.

[0073] In the first light-receiving element 33 and in the second light-receiving element 34 An interference signal expressed by "Acos(Kx + δ)" will be obtained. "A" represents the amplitude of the interference signal and "K" represents the wavenumber, expressed by "2Π / Λ", where "Λ" is the wavelength of the light source. 1 represented.

[0074] Furthermore, “x” represents the amount of change in the optical path length through the surface of the object being measured. 9 reflected second beam, whereby the optical path length of the second beam changes depending on the shape of the surface to be measured.

[0075] Since the reflective component 8 Since the optical path length of the first ray is fixed, it does not change. Thus, the first light-receiving element receives the light. 33 and the second light-receiving element 34 the interference light, in which bright and dark interference fringes of a cycle are generated each time the optical path length of the second beam changes by Λ / 2 depending on the shape of the surface to be measured.

[0076] On the other hand, the first ray and the second ray, which pass through the semi-transparent mirror, fall 31be reflected onto the phase plate (such as a lambda quarter plate or the like) 35 One. The first beam and the second beam, which are linearly polarized light beams whose polarization directions differ by 90 degrees, are separated by the phase plate. 35 transmitted and thus becoming circularly polarized light rays with opposite directions of rotation.

[0077] Furthermore, since the two circularly polarized light beams with opposite directions of rotation are located in the same optical path, they are superimposed and thereby become linearly polarized light, with this linearly polarized light being directed onto the polarization beam splitter. 36 comes to mind.

[0078] The s-polarized component of this linearly polarized light is separated by the polarization beam splitter. 36 reflected and passed through the third light-receiving element 37received. Furthermore, the p-polarized component is filtered by the polarization beam splitter. 36 passed through and through the fourth light-receiving element 38 received.

[0079] The polarization beam splitter 36 Incident linearly polarized light is generated by superimposing two circularly polarized light beams with opposite directions of rotation. Thus, the polarization direction of the superimposed linearly polarized light rotates when the optical path length of the second beam changes, thereby shifting the phase of the first beam and the phase of the second beam relative to each other.

[0080] If the optical path length of the second beam is changed by Λ / 2, the linearly polarized light rotates exactly 180 degrees. Thus, the third light receiving element receives 37 and the fourth light-receiving element 38the interference light, in which bright and dark interference fringes are produced each time the optical path length of the second beam changes by Λ / 2, with the third light receiving element 37 and through the fourth light-receiving element 38 The photoelectrically converted signal is expressed by “Acos(Kx + δ')”. “δ'” here represents an initial phase.

[0081] Furthermore, the phase of the light receiving element differs. 37 photoelectrically converted signal and the phase of the signal received by the fourth light receiving element 38 photoelectrically converted signals 180 degrees apart.

[0082] Incidentally, the polarization beam splitter 36 , which is used to divide the light received by the third light receiving element 37 and through the fourth light-receiving element 38 The received beams are designed to be at an angle of less than 45 degrees relative to the polarization beam splitter.32 arranged to divide the light received by the first light receiving element 33 and through the second light-receiving element 34 is designed to receive radiation.

[0083] Thus, the phase differs due to the third light-receiving element. 37 and through the fourth light-receiving element 38 received signals from the phase of the first light receiving element 33 and through the second light-receiving element 34 received signals by 90 degrees.

[0084] Thus, using the first light-receiving element 33 and through the second light-receiving element 34 received signals as a sine wave signal and using the signal received by the third light receiving element 37 and through the fourth light-receiving element 38 The received signals can be obtained as a cosine signal or a Lissajous signal.

[0085] The signals received by these light-receiving elements are processed by the section 60 calculated to output information about the relative position, counting the amount of displacement of the surface to be measured.

[0086] As in Fig. As shown in section 2, for example, 60 to output information about the relative position of the first light-receiving element 33 received signal and the signal received by the second light receiving element 34 received signals whose phases differ by 180 degrees are amplified by a differential amplifier 61a Differentially amplified, so that the DC component of the interference signal is canceled out.

[0087] Furthermore, this signal is processed by an A / D converter. 62a A / D converted, with its signal amplitude, offset and phases being processed by a waveform correction processing section. 63to be corrected. In an incremental signal generator 64 This signal is calculated, for example, as an A-phase incremental signal.

[0088] A similar process is implemented in the third light-receiving element. 37 and in the fourth light-receiving element 38 received signal through a differential amplifier 61b differentially amplified and through an A / D converter 62b The signal is converted to analog-to-digital conversion. Furthermore, the signal amplitude, offset, and phase are corrected by the waveform correction processing section. 63 corrected and the signal is processed by the incremental signal generator 64 output as a B-phase incremental signal whose phase differs from that of the A-phase incremental signal.

[0089] Whether the two phases of the incremental signals obtained in the manner mentioned above are positive or negative is distinguished by a pulse discrimination circuit or the like (not shown in the drawing), which makes it possible to detect whether the amount of displacement of the surface to be measured in the height direction is in the positive or negative direction.

[0090] Furthermore, by counting the phase change per unit time of the incremental signal with a counter (not shown in the diagram), a measurement can be performed to see how many of the aforementioned cycles of intensity of the interference light of the first and second beams have changed. Thus, the amount of displacement of the surface being measured in the vertical direction can be determined by the processing described above.

[0091] Incidentally, the following can be found in the section 60The information output regarding the relative position of the present embodiment shall be either the two phases of the incremental signal mentioned above or a signal containing the magnitude and direction of the displacement calculated from the two phases of the incremental signals.

[0092] Subsequently, the other of the two is divided by the second beam splitter. 20 split beams, i.e., the one split by the beam splitter 12 Transmitted beam, described.

[0093] In the optical path of the first beam and the second beam, which pass through the beam splitter 12 The polarizing plate is allowed to pass through. 21 arranged so that only the second beam passes through. In such an arrangement, only the second beam (the reflected beam from the surface of the object being measured) is transmitted. 9is) decoupled and the offset light is removed.

[0094] Furthermore, the polarization plate 21 a chromium thin film or a dielectric multilayer thin film may be formed, which allows the polarization plate to also function as a beam splitter.

[0095] Since in this case the function of the beam splitter 12 and the function of the polarizing plate 21 Since the process can be carried out using a single component, the number of components can be reduced.

[0096] Furthermore, the polarization plate 21 transmitted second beam onto the second light receiving section 40 a.

[0097] Furthermore, in the section on the second light reception section 40 incident second ray through the astigmatism generator 10 Astigmatism is produced.

[0098] In the present embodiment, the optical path of the first beam and the second beam, which pass through the converging lens, is... 11 The beam splitter, inclined with respect to the optical axis of the beam, is concentrated. 12 provided that in the beam splitter 12 Astigmatism is produced by the transmitted beam.

[0099] Astigmatism can also be produced by providing a cylindrical lens; however, in the present embodiment, the beam splitter is preferably used. 12 to use, since the beam splitter 12 splits the beam into two beams in different directions while creating astigmatism, thus reducing the number of components.

[0100] As in Fig. 3A to Fig. As shown in 3C, the second light reception section contains 40 a fifth light-receiving element 41 , a sixth light-receiving element42 , a seventh light-receiving element 43 and an eighth light-receiving element 44 The shape of the spot formed on the second light-receiving section of the second beam depends on the position of the surface to be measured in the vertical direction.

[0101] For example, spot A1 of the second beam is located on the second light receiving section. 40 , as in Fig. Figure 3A shows an oval shape if the focal point of the second ray incident on the surface to be measured is located at a higher position than the surface to be measured.

[0102] Furthermore, spot A2 of the second beam is located on the second light receiving section. 40 , as in Fig. 3B shows a round shape if the focal point of the second beam shining onto the surface to be measured is located on the surface to be measured.

[0103] Furthermore, spot A3 of the second beam is located on the second light receiving section. 40 , as in Fig. 3C shows an oval shape if the focal point of the second beam shining onto the surface to be measured is located at a lower position than the surface to be measured, with the long axis direction of the oval spot A3 being rotated by 90 degrees compared to that of the oval spot A1.

[0104] Assuming that the output signals of the light receiving element 41 , of the light receiving element 42 , of the light receiving element 43 and the light receiving element 44 If A, B, C and D are in this order, a focal point error signal S can be formed FE (which indicates the displacement of the second beam incident on the surface to be measured from the position of the focal point) can be expressed by the following equation (1): S FE = (A + C) – (B + D) (1)

[0105] Fig. Figure 4 is a graphical representation showing the characteristic curve of the focal error signal obtained by equation (1). In equation 4, the horizontal axis represents the position of the surface to be measured in the vertical direction, and the vertical axis represents the focal error signal.

[0106] As shown, for example, by point B, the focal point error signal is zero when the focal point of the second beam shining onto the surface to be measured is located on the surface to be measured.

[0107] Since in the present embodiment the objective lens 5Since the focal point of the second beam, which is directed onto the surface to be measured, is fixed, the position of that point is kept constant. Therefore, the height of the surface being measured remains constant when the focal point error signal is zero, so that when the focal point error signal is zero, the position can be used as the reference point for detecting any displacement.

[0108] The arithmetic section for obtaining the focal point error signal can either be placed in the second light reception section. 40 be installed or in the section 50 It must be arranged to output information about the absolute position. Furthermore, the section 50 To output information about the absolute position at the focal point error signal, an A / D conversion is performed and the converted value is output.

[0109] Incidentally, in the optical path between the beam splitter 12 and the second light reception section 40A light-scattering body (e.g., frosted glass or the like) may be arranged. In such an arrangement, a cross-section perpendicular to the direction of the optical axis of the second ray, which leads to the second light-receiving section, may be formed. 40 This results in a uniform light intensity distribution. Therefore, the possibility of detecting fine defects, small foreign bodies, and / or the like on the surface being measured can be reduced, the influence of surface roughness can be minimized, and thus the average height of the surface can be measured.

[0110] If the aforementioned light-scattering body is set into vibrations at a frequency of 1 kHz, for example, in order to change the scattering direction, a spot pattern will also appear on the light-receiving elements. 41 , 42 , 43 and 44 averaged, thus reducing the spot contrast.

[0111] Furthermore, in the optical path of the second ray between the objective lens 5 and the second light reception section 40 An aperture diaphragm with a predetermined shape is arranged so that the light reflected from the surface to be measured and directed onto the objective lens 5 The incident light is again at a specific angle of incidence, and the incidence position is switched off. With such an arrangement, it is possible to prevent the diffracted light, caused by foreign particles adhering to the surface being measured and / or unevenness of the surface being measured, from passing through the second light receiving section. 40 is received as scattered light.

[0112] Furthermore, the light receiving elements of the first and second light receiving sections can also receive the interference light and / or the light with the astigmatism it contains using optical fibers. By using the optical fibers, the light receiving sections can be adjusted by the optical system of the displacement detection device. 100 They are arranged in separate layers.

[0113] Thus, by arranging the light-receiving elements near the section 50 to output information about the absolute location and the section 60 for the output of information, but the relative position of the telecommunications distance from the light receiving elements to the section 50 for the output of information about the absolute location and the section 60The output of information about the relative position can be reduced, thus increasing the response speed.

[0114] As described above, the displacement detection device 100 the light source 1 emitted light split into two beams, with the first beam hitting the reflecting component 8 one beam falls on the surface to be measured, and the second beam falls on the surface to be measured.

[0115] Furthermore, information about the absolute position is obtained by receiving the focal point error signal using the reflected light from the surface to be measured, and information about the relative position is obtained from the interference light of the reflected light from the reflecting component. 8 and the reflected light from the surface to be measured.

[0116] In conventional techniques, the position in the vertical direction is determined solely based on the focal point error signal. Therefore, a correction table must be used to compensate for the non-linearity of the focal point error signal.

[0117] In contrast, the displacement detection device 100 In the present embodiment, the interference light of the reflected light from the fixed reflecting component 8and the reflected light from the surface being measured. The intensity of the interference light changes periodically in accordance with the amount of displacement of the surface being measured. In other words, the linearity of the signal can be reliably maintained using the change in the intensity of the interference light as a scale. Since the period of change in the intensity of the interference light is determined by the wavelength of the light, the change in the intensity of the interference light can be used as an accurate and precise scale.

[0118] Furthermore, the reference point of the scale obtained from the change in the intensity of the interference light can be obtained from the focal point error signal, which is obtained from the reflected light from the surface to be measured.

[0119] Thus, in the present embodiment, the displacement can be accurately detected by counting the pulses (i.e., the phase information) generated by the section for outputting information about the relative position, e.g., using the position where the focal point error signal is zero as a reference.

[0120] Since the information about the absolute position (such as the focal point error signal or the like) is obtained as the reference for determining the absolute position in the present embodiment, the objective lens also requires 5 not to be moved up and down following the surface to be measured, as in conventional techniques.

[0121] Thus, the drive mechanism for moving the objective lens 5 This eliminates the problem and thus reduces heat generation. Furthermore, there are no operating conditions limited by the response speed of the drive mechanism.

[0122] Furthermore, the count value of the interference light in the section for outputting information about the relative position at any position of the focal point error signal can preferably be changed to any value.

[0123] Thus, even if the surface to be measured leaves the measuring range, the information about the original position can be counted immediately as soon as the surface to be measured is detected again.

[0124] Furthermore, the surface to be measured can also be moved up and down beforehand to obtain information about its absolute and relative positions. In this case, a linear correction to the signal shape near the zero crossings of the focal error signal can be performed by determining the difference between the absolute and relative position information and the correlation between these two values.

[0125] Furthermore, by obtaining the correlation between the information about the absolute location and the information about the relative location, and using the correlation as a correction value based solely on the location information of the section. 50To output information about the absolute position, which is obtained from the focal point error signal, the displacement itself is recorded in the event that the surface to be measured is out of sight and recording thus becomes impossible.

[0126] Since the displacement detection device 100 furthermore, it is corrected directly in the environment where the displacement detection device is located. 100 In practice, the relocation can be detected with greater accuracy based on the information obtained in this environment.

[0127] Furthermore, various measurement methods can be used in accordance with the environment. For example, displacement in an environment where the air temperature fluctuates significantly can be measured using methods other than those described in the section. 60 Information about the relative location is output using the information provided by the section 50Information about the absolute location is recorded.

[0128] Meanwhile, the relocation can be used instead of the one specified in the section. 50 Information about the absolute location is provided for the relocation using the information from the section 60 Information about the relative position is recorded when a quick response is required or the surface roughness of the surface to be measured is high.

[0129] Furthermore, the surface area of ​​the object to be measured is 9 preferably a mirror processing to reflect the light from the light source 1 exposed to emitted light, so that a signal with a higher S / R ratio can be obtained.

[0130] Furthermore, the object to be measured can be various objects, instead of being particularly limited. For example, the object to be measured could be... 9 A diffraction grating is used that reflects the light with the same wavelength as that from the light source. 1 emitted light is reflected.

[0131] In this case, the displacement detection device is preferably provided by the displacement detection device. 100 the present embodiment and is configured by a code ruler which uses a so-called “linear scale” to detect the position in the surface direction of a two-dimensional surface.

[0132] For example, if the diffraction grating is attached to a table, the displacement in the direction along the diffraction grating surface is measured by the code ruler, and the displacement in the direction perpendicular to the diffraction grating surface is measured by the displacement detection device. 100 measured in the present embodiment.

[0133] With such an arrangement, the displacement of the table in the three-dimensional direction can be detected, and thus the positioning of the table in equipment that requires precise three-dimensional position control, such as in micro-material processing equipment, can be carried out accurately.

[0134] In this case, a thin reflective film can be applied flat to the surface of the diffraction grating to reflect the light from the light source. 1 be educated.

[0135] The displacement detection device 100measures the reflected light from the reflective thin film to detect its displacement in the vertical direction.

[0136] Because of the diffraction grating in the area of ​​the light source 1 Since no diffracted light is produced by the emitted light, the displacement can be precisely measured. Furthermore, the linear scale measures diffracted light and similar phenomena using a light source that emits light which can be transmitted through the reflective thin film.

[0137] Furthermore, the reflective thin film can also be formed on the back side of the diffraction grating. In this case, the wavelength of the light emitted by the light source is reduced. 1 emitted light and the material of the diffraction grating are chosen so that the light emitted by the light source 1 The emitted light is transparent with respect to the material of the diffraction grating. With such an arrangement, it is possible to suppress the diffraction pattern in the light emitted by the light source.1 The incident light produces diffracted light.

[0138] Furthermore, the direction in which the diffracted light is generated can be controlled by directing the light emitted from the linear scale obliquely onto the diffraction grating, so that the diffracted light passes through the displacement detection device. 100 is not recorded. 2. Second embodiment

[0139] In the first embodiment, one light source is used. In a second embodiment, which will be described below, two light sources with different wavelengths are used.

[0140] Fig. Figure 5 is a view that schematically shows the configuration of a displacement detection device. 200 in accordance with the second embodiment of the present invention.

[0141] The displacement detection device 200in accordance with the present embodiment, a first light source is included. 101a and a first beam splitter 103 , which is used to divide the light emitted by the first light source 101a The emitted light is designed to be divided into a first beam and a second beam.

[0142] Furthermore, the displacement detection device contains 200 a reflective component 108 , which reflects the light passing through the first beam splitter 103 is designed with a split first beam.

[0143] Furthermore, the displacement detection device contains 200 a second light source 101b , which emit light with a different wavelength than the first light source 101a is designed, and a lens 105 , which are used to concentrate the second beam, which comes from the first light source 101a emitted and through the first beam splitter 103is divided, and a third beam originates from the second light source. 101b is sent out, towards the object to be measured 109 is designed.

[0144] Furthermore, the displacement detection device contains 200 a second beam splitter 112 and an astigmatism generator 110 , where the second beam splitter 112 designed to couple the third beam from the first beam, the second beam and the third beam, and the astigmatism generator 110 is designed to generate astigmatism in the decoupled third ray.

[0145] Furthermore, the displacement detection device contains 200 a first light reception section 130 , which is used to receive the interference light from the light-reflecting component 108designed to reflect the first beam and the second beam reflected by the surface to be measured, and a second light receiving section 140 , which receives the signal from the second beam splitter 112 is designed with a decoupled third beam.

[0146] Furthermore, the displacement detection device contains 200 a section 160 for outputting information about the relative position, which is used to output information about the relative position based on the first light reception section 130 is designed for the received signal, and a section 150 for outputting information about the absolute position, which is used to output information about the absolute position based on the second light reception section. 140 is designed for the included signal.

[0147] Similar to the first embodiment, the first light source can 101aand the second light source 101b It could be one of several light sources, such as a semiconductor laser diode, a superluminescent diode, a luminescent diode, and the like. However, the wavelength of the light emitted by the first light source... 101a emitted light and the wavelength of the light emitted by the second light source 101b emitted light differs from each other.

[0148] Preferably, p-polarized components and s-polarized components are in the array of components emitted by the first light source. 101a emitted light with respect to the first beam splitter (such as a polarizing beam splitter or the like) 103 They are the same.

[0149] Furthermore, the second light source 101b emitted light in relation to the first beam splitter 103 p-polarized light. Thus, the polarization direction of the light emitted by the second light source can be determined. 101bemitted light can be aligned by providing a polarizing plate (not shown in the drawing) or the like.

[0150] The one from the first light source 101a The emitted light is focused by a beam splitter (such as a wavelength-selective filter or the like). 113 reflected and falls onto a lens (such as a collimator lens or the like) 102 a.

[0151] For example, this falls through the lens. 102 collimated light onto the beam splitter (such as a polarizing beam splitter or the like) 103 one where the light is split into the first ray, which consists of the s-polarized component, and the second ray, which consists of the p-polarized component.

[0152] The beam splitter 103 The reflected first ray is passed through a phase plate (such as a lambda quarter plate or the like).106 transmitted to become circularly polarized light, which is then converged by a lens 107 on the reflective component 108 comes to mind.

[0153] Furthermore, the reflecting component 108 reflected first ray through the converging lens 107 It passes through and falls onto the phase plate. 106 one, in order to become p-polarized light.

[0154] The first beam, which has been converted into p-polarized light, is split by the first beam splitter. 103 passed through and falls onto a converging lens 111 a.

[0155] On the other hand, the beam splitter 103 transmitted second beam through a phase plate (such as a lambda quarter plate or the like) 104 passed through and through the objective lens 105 to the surface of the object to be measured 109 concentrated.

[0156] The second beam, reflected by the object being measured, passes back through the objective lens. 105 onto the phase plate 104 a.

[0157] The second beam passes through the phase plate twice. 104 transmitted to become s-polarized light, with this s-polarized light passing through the first beam splitter 103 is reflected and onto the converging lens 111 comes to mind.

[0158] In the present embodiment, the first ray and the second ray, which point towards the converging lens, are 111 to stand out in their entirety, without being divided, through the first light reception section 130 received.

[0159] The second beam splitter (such as a wavelength-selective filter or the like) 112 is in the optical path through the converging lens 111arranged with concentrated light. The second beam splitter 112 The light is reflected with the same wavelength as that from the first light source. 101a emitted light and leaves the light with the same length as that from the second light source 101b emitted light through.

[0160] Thus, the first beam and the second beam are separated by the second beam splitter. 112 reflected and fall on the first light reception section 130 a.

[0161] The first light reception section 130 receives the interference light of the first beam and the second beam, with the first beam coming from the first light source 101a emitted and reflected by the component 108 is reflected and the second ray is from the first light source 101a emitted and reflected by the surface being measured.

[0162] The first light reception section 130can have the same configuration as the first light receiving section 30 exhibit the first embodiment.

[0163] The first beam and the second beam, which pass through the second beam splitter 112 The reflected images fall onto a semi-transparent mirror. 131 one, in order to be divided into two rays.

[0164] The first ray and the second ray, which pass through the semi-transparent mirror 131 The beams that have passed through fall onto a polarization beam splitter. 132 a.

[0165] The polarization beam splitter 132 is arranged at an angle, so that the plane of incidence of the polarization beam splitter 132The polarization beam splitter is inclined at an angle of 45 degrees with respect to both the polarization direction of the first beam and the polarization direction of the second beam. Thus, the p-polarized component and the s-polarized component are separated in both the first and second beams. 132 The s-polarized component and the p-polarized component are each generated by the polarization beam splitter. 132 The beam is split and coupled out, causing the first beam and the second beam to interfere with each other.

[0166] The interference light of the s-polarized component of the first beam and the s-polarized component of the second beam, which pass through the polarization beam splitter 132 The reflection is processed by a first light-receiving element. 133The interference light of the p-polarized component of the first beam and the p-polarized component of the second beam, which is separated by the polarization beam splitter, is received. 132 be allowed through a second light-receiving element 134 received.

[0167] Furthermore, the first ray and the second ray, which pass through the semi-transparent mirror, are 131 reflected by a phase plate (such as a lambda quarter plate or the like) 135 The light rays are transmitted through the light source and thus become circularly polarized rays with opposite directions of rotation. These two circularly polarized rays with opposite directions of rotation are then superimposed to form linearly polarized light whose polarization direction rotates.

[0168] The s-polarized component of this linearly polarized light is separated by a polarization beam splitter. 136 reflected and passed through a third light-receiving element 137 received. Furthermore, the p-polarized component is filtered by the polarization beam splitter. 136 passed through and by a fourth light-receiving element 138 received.

[0169] In the section 160 Information about the relative position is output by performing the same processing as that used in relation to the information provided by the four light-receiving elements. 133 , 134 , 137 , 138 received signals in the first embodiment (see Fig. 2) was described, information about the relative position such as two phases of the incremental signals was output.

[0170] On the other hand, the light from the second light source 101b third jet emitted by the jet combiner 113passed through. The one through the jet cleaner 113 The transmitted third ray is, for example, filtered through the lens. 102 collimates and falls onto the first beam splitter (such as a polarizing beam splitter or the like) 103 a.

[0171] Since the third beam is in relation to the first beam splitter 103 If the light is p-polarized, the third beam is splitterd by the first beam splitter. 103 passed through and through the objective lens 105 to the surface of the object to be measured 109 concentrated.

[0172] In the present embodiment, the objective lens 105The position of the focal point of the third beam is fixed and kept constant. The focal point does not need to be located on the surface being measured, but can also be located near it. By shifting the position of the image away from the surface being measured, the influence of measurement errors caused by surface roughness, foreign particles adhering to the surface, and / or the like can be reduced, thereby increasing the diameter of the spot.

[0173] The third beam, reflected by the surface being measured, passes through the objective lens. 105 again on the first beam splitter 103 a.

[0174] In the optical path between the first beam splitter 103 and the surface to be measured is the phase plate (such as a lambda quarter plate or the like) 104arranged. When the third beam travels to the surface to be measured and returns from it, it passes through the phase plate twice. 104 The light is transmitted to become p-polarized. Thus, the third beam passes through the first beam splitter. 103 reflected and falls onto the converging lens 111 a.

[0175] The one on the converging lens 111 The incident third beam is split by the second beam splitter (such as a wavelength-selective filter or the like). 112 passed through and through the second light reception section 140 received.

[0176] In the present embodiment, the astigmatism generator is also 110 through the converging lens 111 and through the second beam splitter 112 configured. The convergent light of the third beam is divided by the second beam splitter, which is arranged obliquely with respect to the optical axis. 112It passes through, thereby creating astigmatism.

[0177] Since the astigmatism generator 110 through the converging lens 111 and through the second beam splitter 112 When configured, astigmatism can be generated without using a cylindrical lens or similar device, thus reducing the number of components.

[0178] The second light reception section 140 contains similarity to the first embodiment (see Fig. 3A to Fig. 3C) four light receiving elements, wherein the section 150 A focal point error signal is generated to output information about the absolute position using the signals received by the light receiving elements.

[0179] In the present embodiment, the light emitted by the first light source falls within the range of the first light source. 101a emitted light onto the reflecting component 108and onto the surface to be measured, and the information about the relative position is obtained based on the interference light of the reflected light from the reflecting component. 108 and the reflected light from the surface being measured.

[0180] Furthermore, the light from the second light source is also affected. 101b The emitted light is directed onto the surface to be measured, and the information about the absolute position is generated based on the reflected light from the surface to be measured.

[0181] Thus, in the present embodiment it is also possible to determine a reference point (such as the position at which, for example, the zero crossing point of the focal point error signal is detected) and to determine the displacement from the reference point based on the information provided in section 160 To obtain information about the relative position generated for the output of information about the relative position.

[0182] Since the displacement in the vertical direction occurs without driving the objective lens 105 Since the measurement can be performed without a drive mechanism, no such mechanism is required. Therefore, there is neither heat generated by the drive mechanism nor a limitation on its response frequency. Consequently, the operating conditions can be relaxed, allowing the measurement to be performed in various environments.

[0183] Furthermore, in the present embodiment, the wavelength of the light used to acquire information about the relative position and the wavelength of the light used to acquire information about the absolute position are different from each other, with these light beams being divided by the second beam splitter (such as a wavelength-selective filter or the like). Since the output of the two light sources can be used to its maximum extent, displacement detection with a higher signal-to-noise ratio can be implemented.

[0184] Furthermore, the first light source can 101a and the second light source 101b They emit light alternately. In this case, information about the relative position and information about the absolute position are received alternately, and the displacement can be detected by synchronizing the information.

[0185] By causing the light sources to emit light alternately, stray light (i.e., light generated inside the enclosure where the light from the first light source originates) can be reduced. 101a to the second light reception section 140 where the light from the second light source falls and / or where it falls 101b on the first light reception section 130 (occurs) can be further reduced so that position detection can be performed with higher accuracy. 3. Third embodiment

[0186] In the present embodiment, the information about the absolute position of the displacement is obtained from the astigmatism of the reflected light from the surface to be measured, and the information about the relative position is obtained from the interference light of the reflected light from the surface to be measured and the reflected light from a specific solid reference surface such as the reflecting component or the like.

[0187] If the focal point error signal is obtained using the astigmatism method, the light must be focused onto the surface to be measured at a specific level. However, if the change cycle of the interference light intensity is measured, the light does not need to be focused onto the surface.

[0188] In the present embodiment, two light sources are used, with the light beams emitted by each light source being assigned to measure astigmatism and interference light, respectively. Furthermore, the light beams emitted by the two light sources are focused onto the surface to be measured with different spot diameters.

[0189] In such an arrangement, the light used to obtain the focal point error signal can be concentrated at a certain level on the surface to be measured, while the light used to measure the interference light can be incident on the surface to be measured with a larger spot diameter than the light used to obtain the focal point error signal.

[0190] This allows the measurement of relative position to be performed in a wider area while maintaining high measurement accuracy.

[0191] Fig. Figure 6 is a view that schematically shows the configuration of a displacement detection device. 300 in accordance with a third embodiment of the present invention.

[0192] The displacement detection device 300 in accordance with the present embodiment, a first light source is included. 201a and a first beam splitter 203 , which is used to divide the light emitted by the first light source 201a The emitted light is designed to be divided into a first beam and a second beam.

[0193] Furthermore, the displacement detection device contains 300 a reflective component 208 , which reflects the light passing through the first beam splitter 203 is designed with a split first beam.

[0194] Furthermore, the displacement detection device contains 300 a second light source 201b, which emit light with a different wavelength than the first light source 201a is designed, and a lens 205 , which are used to concentrate the second beam, which comes from the first light source 201a emitted and through the first beam splitter 203 is divided, and a third beam originates from the second light source. 201b is sent out, towards the object to be measured 209 is designed.

[0195] Furthermore, the displacement detection device contains 300 a second beam splitter 212 and an astigmatism generator 210 , where the second beam splitter 212 designed to couple the third beam from the first beam, the second beam and the third beam, and the astigmatism generator 210 is designed to generate astigmatism in the decoupled third ray.

[0196] Furthermore, the displacement detection device contains 300 a first light reception section 230 , which receives the interference light from the reflecting component 208 designed to reflect the first beam and the second beam reflected by the surface to be measured, and a second light receiving section 240 , which receives the signal from the second beam splitter 212 is designed with a decoupled third beam.

[0197] Furthermore, the displacement detection device contains 300 a section 260 for outputting information about the relative position, which is used to output information about the relative position based on the first light reception section 230 is designed for the received signal, and a section 250for outputting information about the absolute position, which is used to output information about the absolute position based on the second light reception section. 240 is designed for the received signal.

[0198] Similar to the first and second embodiments, the first light source 201a and the second light source 201b It could be one of several light sources, such as a semiconductor laser diode, a superluminescent diode, a luminescent diode, and the like. However, the wavelength of the light emitted by the first light source... 201a emitted light and the wavelength of the light emitted by the second light source 201b emitted light differs from each other.

[0199] Preferably, the area supplied by the first light source is 201aemitted light the p-polarized components and the s-polarized components with respect to the first beam splitter (such as a polarizing beam splitter or the like) 203 They are the same.

[0200] Furthermore, the second light source 201b emitted light in relation to the first beam splitter 203 p-polarized light. Furthermore, only p-polarized light can be extracted using a polarizing plate.

[0201] The one from the first light source 201a The emitted light is focused by a beam splitter. 213 reflected and falls on the first beam splitter (such as a polarizing beam splitter or the like) 203 one. The second beam splitter 213 The light is reflected with the same wavelength as that from the first light source. 201a emitted light and leaves the light with the same length as that from the second light source201b emitted light through.

[0202] The one from the first light source 201a emitted and directed onto the first beam splitter 203 The incident light is split into the first beam, which consists of an s-polarized component, and the second beam, which consists of a p-polarized component.

[0203] The beam splitter 203 The reflected first ray is, for example, focused by a lens. 207 collimated to parallel light and falls onto the reflecting component 208 one. Furthermore, the light is reflected by the reflective component. 208 reflected and through the lens 207 passed through to become convergent light, with this convergent light then being directed back onto the first beam splitter 203 comes to mind.

[0204] In the optical path between the first beam splitter 203 and the reflective structural element 208is a phase plate (such as a lambda quarter plate or the like) 206 arranged so that the first beam splitter 203 The first incident beam is re-polarized to p-polarized light. Thus, the first beam is split by the first beam splitter. 203 passed through and falls onto a lens 211 a.

[0205] The first beam splitter 203 The transmitted second ray passes through the objective lens. 205 collimated, for example to become parallel light, whereby this parallel light is directed onto the surface of the object to be measured. 209 The second beam, reflected by the surface being measured, passes through the objective lens. 205 converted to convergent light and falls on the first beam splitter 203 a.

[0206] In the optical path between the first beam splitter 203 and the object to be measured 209is a phase plate (such as a lambda quarter plate or the like) 204 arranged so that the first beam splitter 203 The incoming second beam is again polarized to s-type light. Thus, the second beam is split by the first beam splitter. 203 reflected and falls onto the lens 211 a.

[0207] On the other hand, the light from the second light source 201b emitted third beam, e.g., through a collimating lens 202 collimated to parallel light by the beam merging device (such as a wavelength-selective filter or the like) 213 passed through and falls onto the first beam splitter 203 a.

[0208] Since the third beam is in relation to the first beam splitter 203 If the light is p-polarized, the third beam is splitterd by the first beam splitter. 203 passed through and through the objective lens 205The beam is focused onto the surface to be measured. Furthermore, the third beam reflected by the surface being measured is directed through the objective lens. 205 transmitted to become parallel light, and falls on the first beam splitter 203 a.

[0209] Since during the above-mentioned process the third beam passes twice through the phase plate (such as a lambda quarter plate or the like) 204 When the third beam is passed through and its polarization direction is thereby rotated by 90 degrees, it passes through the first beam splitter. 203 reflected. Furthermore, the reflected third ray falls on the lens. 211 a.

[0210] In the present embodiment, the light emitted by the first light source falls within the range of the first light source. 201a emitted light as divergent light onto the objective lens 205 and onto the lens 207one, so that these lenses can also be used, for example, as collimator lenses to collimate the light from the first light source. 201a emitted light can be used.

[0211] In this arrangement, the first beam and the second beam can be directed onto the surface to be measured and onto the reflecting component. 208 with a larger spot diameter than that which is projected onto the surface to be measured by the light from the second light source 201b the emitted third beam is generated, and it enters the room.

[0212] Incidentally, the light from the first light source can 201a and the light from the second light source 201b the surface to be measured can be measured using various known optical systems with different spot diameters, instead of being limited to the optical system described here as an example.

[0213] Furthermore, in the present embodiment, similar to the second embodiment (see Fig. 5) the first ray and the second ray that converge on the lens 211 The light enters the system and is received in its entirety by the first light reception section without being divided.

[0214] The first ray and the second ray, which hit the lens 211 The incident wavelengths are filtered, for example, by the second beam splitter (such as a wavelength-selective filter or the like). 212 collimated and reflected.

[0215] The first beam and the second beam, which pass through the second beam splitter 212 They are reflected through a lens 214 on the first light reception section 230 concentrated.

[0216] Furthermore, the first light reception section 230 In the present embodiment, the same configuration as the first light-receiving section 30the first embodiment (see Fig. 1) exhibit.

[0217] The first light reception section 230 measures the interference light of the first beam and the second beam.

[0218] The first beam and the second beam, which pass through the second beam splitter 212 They are reflected and fall onto a semi-transparent mirror. 231 one, in order to be divided into two beams, each containing the first beam and the second beam.

[0219] The first ray and the second ray, which pass through the semi-transparent mirror 231 They are allowed to pass through and fall onto a polarization beam splitter. 232 a.

[0220] The polarization beam splitter 232 is arranged at an angle, so that the plane of incidence of the polarization beam splitter 132The polarization beam splitter is inclined at an angle of 45 degrees both with respect to the polarization direction of the first beam and with respect to the polarization direction of the second beam. Thus, in both the first and second beams, the p-polarized and s-polarized components are polarized relative to the polarization beam splitter. 132 generated so that the first beam and the second beam can interfere with each other.

[0221] The interference light of the s-polarized component of the first beam and the s-polarized component of the second beam, which pass through the polarization beam splitter 232 The reflection is processed by a first light-receiving element. 233 Furthermore, the interference light of the first beam and the second beam, which consist of the p-polarized light passed through the polarization beam splitter, is received. 232 is transmitted through a second light-receiving element 234received.

[0222] Furthermore, the first ray and the second ray, which pass through the semi-transparent mirror, are 231 reflected by a phase plate (such as a lambda quarter plate or the like) 235 The light is transmitted through the surface and thus becomes circularly polarized light rays with opposite directions of rotation. The two circularly polarized light rays with opposite directions of rotation are superimposed to become linearly polarized light, whose polarization direction rotates in accordance with the displacement of the surface being measured.

[0223] The s-polarized component of this linearly polarized light is separated by a polarization beam splitter. 236 reflected and passed through a third light-receiving element 237 received. Furthermore, the p-polarized component is filtered by the polarization beam splitter. 236transmitted and through a fourth light-receiving element 238 received.

[0224] Furthermore, similar to the second embodiment (see Fig. 2) the section 260 to output information about the relative position, the information about the relative position is obtained based on the information provided by the first light-receiving elements. 233 , 234 , 237 , 238 It receives signals and outputs information about the relative position.

[0225] On the other hand, the lens 211 incident third beam through the second beam splitter (such as a wavelength-selective filter or the like) 212 passed through and through the second light reception section 240 received.

[0226] In the present embodiment, the astigmatism generator is also 210 through the converging lens 211 and through the lens in relation to the optical axis of the converging lens211 obliquely arranged second beam splitter 212 configured. With this arrangement, astigmatism can be created without using a cylindrical lens or the like, thus reducing the number of components.

[0227] Similar to the first embodiment (see Fig. 3A to Fig. 3C) contains the second light reception section 240 four light-receiving elements, wherein the section 250 to output information about the absolute position using the signals received by the light receiving elements, generates the information about the absolute position (such as the focal point error signal or the like) and outputs the generated information about the absolute position.

[0228] In this embodiment, information about the absolute position is obtained from the light reflected by the surface to be measured, and information about the relative position is obtained from the interference light of the light reflected by the surface to be measured and the light reflected by the fixed reflecting component.

[0229] Thus, the reference position can be determined based on information about the absolute position, such as the focal point error signal or the like, and the displacement relative to the reference position can be obtained based on information about the relative position.

[0230] Since information about the absolute position and information about the relative position can be obtained without the objective lens 205To eliminate the need for an up-and-down motion, the drive mechanism in conventional technology can be removed. As a result, heat generation can be reduced and the limitations on operating conditions caused by the response frequency can be eased.

[0231] Furthermore, in the present embodiment, the spot diameter of the light incident on the surface to be measured, for example, can be set larger than the spot diameter of the light for obtaining information about the absolute position, in order to obtain information about the relative position. Thus, the measurement range of the information about the relative position can be extended.

[0232] Incidentally, in the second and third embodiments, the count value of the interference light in the section for outputting information about the relative position in any position of the focal point error signal can also preferably be changed to any value.

[0233] Thus, even if the surface to be measured leaves the measuring range, the information can be immediately counted in its original position as soon as the surface to be measured is detected again.

[0234] Furthermore, the present embodiment is the same as the first embodiment in that the surface to be measured can be moved up and down beforehand in order to perform a measurement in order to obtain the information about the absolute position and the information about the relative position beforehand and to obtain a correction value.

[0235] By correcting the information about the absolute position with the correction value, the displacement can be counted based on the absolute value information obtained from the focal point error signal, even in the case where the surface to be measured is out of sight and thus detection becomes impossible.

[0236] Furthermore, the surface of the object to be measured is preferably subjected to mirror processing so that it reflects the light emitted by the light source, so that a signal with a higher S / R ratio can be obtained.

[0237] Furthermore, in the second and third embodiments, the object to be measured can be different objects instead of being particularly limited. Thus, three-dimensional displacement can be captured when a diffraction grating is used as the object to be measured.

[0238] In this case, a reflective thin film can be used to reflect the light from the light source. 1 either formed flat on the surface of the diffraction grating or formed on the back side of the diffraction grating.

[0239] Furthermore, the light-reflecting thin film of the reflecting component is preferably made of a metal such as gold or the like, similar to the first embodiment. This allows changes in wavelength and polarized light properties caused by changes in humidity to be suppressed, thus ensuring stable position detection.

[0240] Furthermore, a light-scattering body (e.g., frosted glass or the like) can be arranged in the optical path between the second beam splitter and the second light-receiving section.

[0241] Furthermore, an aperture diaphragm with a predetermined shape can be arranged in the optical path of the third beam between the objective lens and the second light receiving section, so that the light reflected from the surface to be measured and incident again on the objective lens at a specific angle of incidence and at a specific angle of incidence is interrupted.

[0242] Furthermore, the light receiving elements of the first light receiving section and the second light receiving section can also receive the interference light and / or the light in which astigmatism is generated using optical fibers.

[0243] The preferred embodiments of the displacement detection device in accordance with the present invention have been described above. Of course, the present invention is not limited to the embodiments described above, and various modifications and adaptations can be made without deviating from the inventive concept and scope of protection of the present invention. QUOTES INCLUDED IN THE DESCRIPTION

[0244] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0245] JP 2010-142291

[0001] JP 05-89480 [0008, 0009, 0010, 0013, 0014, 0055]

Claims

[1] Displacement detection device comprising: a light source; a first beam splitter designed to divide the light emitted by the light source into a first beam and a second beam; a reflective component designed to reflect the first beam split by the first beam splitter; an objective lens designed to concentrate the second beam, split by the first beam splitter, onto a surface to be measured; a first light receiving section designed to receive interference light from the first beam reflected by the reflecting component and the second beam reflected by the surface to be measured; a section for outputting information about the relative position, which is designed to output information about the relative position in the vertical direction of the surface to be measured based on the intensity of the interference light received by the first light reception section; a second beam splitter designed to couple out part of the second beam reflected by the surface to be measured; an astigmatism generator designed to generate astigmatism in the second beam coupled out by the second beam splitter; a second light-receiving section designed to receive the second beam in which the astigmatism has been generated by the astigmatism generator; and a section for outputting information about the absolute position, which is designed to generate information about the absolute position in the vertical direction of the surface to be measured based on the intensity of the received light detected by the second light reception section and to output the generated information about the absolute position. [2] Displacement detection device according to claim 1, wherein the light source comprises a first light source section and a second light source section, each emitting light beams with different wavelengths, wherein the beam emitted by the first light source section is split by the first beam splitter into the first beam and the second beam, and the beam emitted by the second light source section is incident on the surface to be measured by the second beam splitter as the second beam, and the second beam splitter couples out the beam emitted by the second light source section from the second beam.

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