Three-dimensional shape measuring device and method for switching its measurement mode.

Abstract

To provide a three-dimensional shape measuring device that can switch between three-dimensional shape measurement for a surface to be measured using a WLI method and three-dimensional shape measurement for the surface to be measured using a FV method without performing replacement of an objective lens, and a measuring mode switching method for the same.SOLUTION: A three-dimensional shape measuring device comprises: an interference unit that generates multiplexed light of measuring light returning from a surface to be measured and reference light returning from a reference surface; a holder that accommodates the interference unit and the reference surface, the holder formed of a material that is thermally deformed reversibly according to a change in temperature and changing a reference optical path length that is the optical path length of the reference light between the interference unit and the reference surface according to the change in temperature; a temperature adjustment unit that adjusts the temperature of the holder; and a temperature control unit that can control the temperature adjustment unit to selectively switch between a first measurement mode for matching the reference optical path length with a measured optical path length to generate an interference fringe in the multiplexed light, and a second measurement mode for making the reference optical path length different from the measured optical path length to prevent the generation of the interference fringe in the multiplexed light.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a three-dimensional shape measuring device for measuring the three-dimensional shape of a surface to be measured, and a method for switching the measurement mode thereof. [Background technology]

[0002] A method is known for optically measuring the three-dimensional shape of an object to be measured, such as the full-focus image of the surface to be measured, the surface shape, and the surface roughness shape, using a three-dimensional shape measuring device such as the white light interferometry (WLI) method described in Non-Patent Document 1 and Patent Document 1, or the focus variation (FV) method described in Non-Patent Document 2.

[0003] The WLI (Wide-Lens Resonance) three-dimensional shape measuring device comprises a microscope equipped with a light source and an interference unit, a drive mechanism, a camera, and a control device. The light source emits white light toward the interference unit. The interference unit splits a portion of the white light emitted from the light source as reference light, emits the remaining white light toward the surface to be measured, and emits the reference light toward the reference surface. The interference unit also emits interference light from the white light reflected from the surface to be measured and the reference light reflected from the reference surface toward the camera. The drive mechanism scans the interference unit or microscope along the scanning direction (vertical direction). While the interference unit is being scanned by the scanning mechanism, the camera continuously captures the interference light emitted from the interference unit and acquires multiple images including interference fringes. The control device measures the three-dimensional shape of the surface to be measured by comparing the brightness values ​​of each pixel at the same coordinate in each image and calculating the height information of the surface to be measured for each pixel.

[0004] The FV-type three-dimensional shape measuring device comprises a drive mechanism, a camera, and a control device. The drive mechanism scans the camera along the scanning direction. While being scanned by the drive mechanism, the camera continuously captures images of the surface to be measured, acquiring multiple images. The control device calculates the degree of focus for each pixel at the same coordinate in each image and measures the three-dimensional shape of the surface to be measured by detecting changes in the degree of focus for each pixel. [Prior art documents]

Patent Document

[0005]

Patent Document 1

Non-Patent Document

[0006]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] The WLI method has the advantages that the vertical resolution of the measured surface is high, and the disadvantages that the measurement time becomes long and it is not suitable for measuring the three-dimensional shape of an inclined surface. Therefore, the WLI method is suitable for measuring the surface roughness shape of the measured surface. On the other hand, the FV method has the advantages that the measurement time is short and it is more suitable for measuring the three-dimensional shape of an inclined surface than the white light interference method, and the disadvantage that the vertical resolution of the measured surface becomes low. Therefore, the FV method is suitable for measuring the shape of the measured surface.

[0008] Thus, the WLI method and the FV method have opposing advantages and disadvantages, resulting in a complementary relationship. For this reason, there is a demand for a single three-dimensional shape measuring device that can switch between the WLI method and the FV method depending on the type of surface to be measured and the measurement content.

[0009] In this case, the WLI method requires an interference objective lens, which consists of an objective lens, a beam splitter, and a reference surface (reference mirror), as an interference component. However, the image of the surface to be measured captured by the camera through this interference objective lens contains interference fringes. These interference fringes negatively affect the calculation of the three-dimensional shape of the surface to be measured using the FV method. Therefore, if the same objective lens is used for both the WLI and FV methods, the measurement accuracy of the three-dimensional shape of the surface measured using the FV method will decrease. As a result, in conventional three-dimensional shape measuring devices, the objective lens was switched to an interference objective lens when performing WLI measurements, and the objective lens was switched to a normal objective lens when performing FV measurements.

[0010] Therefore, conventional three-dimensional shape measuring devices require multiple types of objective lenses, and also necessitate an objective lens switching mechanism, which increases costs. Furthermore, attaching and detaching objective lenses may reduce the measurement accuracy of the three-dimensional shape of the surface being measured, for example, by changing the correction values ​​required for calculating the three-dimensional shape of the surface being measured.

[0011] This invention has been made in view of these circumstances, and aims to provide a three-dimensional shape measuring device and a method for switching the measurement mode thereof that can switch between three-dimensional shape measurement of a surface to be measured using the WLI method and three-dimensional shape measurement of a surface to be measured using the FV method without changing the objective lens. [Means for solving the problem]

[0012] A three-dimensional shape measuring apparatus for achieving the object of the present invention comprises: a light source unit that emits measurement light which is white light; an interference unit that splits a portion of the measurement light emitted from the light source unit as reference light, emits the measurement light onto the surface to be measured and emits the reference light onto the reference surface, and generates a combined wave of the measurement light returning from the surface to be measured and the reference light returning from the reference surface; a camera that images the combined wave of light generated by the interference unit; a scanning unit that, when the optical path length of the measurement light between the interference unit and the surface to be measured is defined as the measurement optical path length, scans the interference unit and the camera relative to the surface to be measured in a scanning direction in which the measurement optical path length changes; and during scanning by the scanning unit, the camera The system comprises: a measurement control unit that repeatedly images the combined wave light; a holder for housing the interference unit and the reference plane, which is made of a material that reversibly deforms with temperature changes and changes the reference optical path length, which is the optical path length of the reference light between the interference unit and the reference plane, with respect to temperature changes; a temperature adjustment unit that adjusts the temperature of the holder; and a temperature control unit that controls the temperature adjustment unit to make the reference optical path length match the measurement optical path length, thereby generating interference fringes in the combined wave light; and a second measurement mode that makes the reference optical path length different from the measurement optical path length, thereby suppressing the generation of interference fringes in the combined wave light.

[0013] This three-dimensional shape measuring device allows for selective switching between a first measurement mode and a second measurement mode by controlling the temperature of the holder.

[0014] In another aspect of the present invention, a three-dimensional shape measuring device is provided, in which, when the temperature control unit switches to a first measurement mode, the camera repeatedly captures multiplexed light during scanning by the scanning unit and outputs a plurality of first images including interference fringes, and the first shape calculation unit calculates the height information of the surface to be measured for each pixel based on the brightness value of each pixel at the same coordinate in the plurality of first images output from the camera to determine the three-dimensional shape of the surface to be measured. This makes it possible to measure the three-dimensional shape of the surface to be measured using the optical interference method.

[0015] In another aspect of the present invention, a three-dimensional shape measuring device is provided, in which, when the temperature control unit switches to a second measurement mode, the camera repeatedly captures multiplexed light during scanning by the scanning unit and outputs a plurality of second images in which the generation of interference fringes is suppressed, and a second shape calculation unit calculates the three-dimensional shape of the surface to be measured based on the result of calculating the change in focus in the scanning direction for each pixel at the same coordinate of the plurality of second images output from the camera. This makes it possible to measure the three-dimensional shape of the surface to be measured using the FV method.

[0016] In another aspect of the present invention, a three-dimensional shape measuring device is provided, which includes a temperature measuring unit for measuring the temperature of a holder. A temperature control unit has pre-acquired a target temperature including a first temperature corresponding to a first measurement mode and a second temperature corresponding to a second measurement mode. The temperature control unit controls a temperature adjustment unit based on the measurement results of the temperature measuring unit and the target temperature to switch between the first measurement mode and the second measurement mode. This allows for selective switching between the first measurement mode and the second measurement mode by controlling the temperature of the holder.

[0017] In another aspect of the present invention, a three-dimensional shape measuring device has a temperature control unit that changes the temperature of a reference surface housing unit that houses a reference surface within a holder, and a temperature measuring unit that measures the temperature of the reference surface housing unit. This allows for selective switching between a first measurement mode and a second measurement mode by controlling the temperature of the holder.

[0018] In another aspect of the present invention, a three-dimensional shape measuring device is provided, comprising at least a heat insulating material covering the reference surface storage section, the temperature measuring section, and the temperature adjustment section. This allows the temperature of the reference surface storage section and its vicinity to be stabilized.

[0019] In another aspect of the present invention, the scanning unit moves at least the holder and the camera in the scanning direction. This allows the interference unit and the camera to scan the surface to be measured relative to the surface in the scanning direction.

[0020] In another aspect of the present invention, a three-dimensional shape measuring device is provided, comprising an objective lens that focuses measuring light onto the surface to be measured, an interference section positioned between the objective lens and the surface to be measured, and a reference surface positioned between the objective lens and the interference section. This allows for selective switching between a first measurement mode and a second measurement mode solely by controlling the temperature of the holder, even in a Mirau-type optical interferometer where a shutter cannot be inserted into the optical path of the reference light.

[0021] A method for switching the measurement mode of a three-dimensional shape measuring apparatus to achieve the object of the present invention comprises: a light source unit that emits measurement light which is white light; an interference unit that splits a portion of the measurement light emitted from the light source unit as reference light, emits the measurement light onto the surface to be measured and emits the reference light onto the reference surface, and generates a combined wave of the measurement light returning from the surface to be measured and the reference light returning from the reference surface; a camera that images the combined wave of light generated by the interference unit; and, when the optical path length of the measurement light between the interference unit and the surface to be measured is defined as the measurement optical path length, the interference unit and the camera are moved relative to the surface to be measured in the scanning direction in which the measurement optical path length changes. A method for switching the measurement mode of a three-dimensional shape measuring apparatus comprising a scanning unit for inspection, and a holder for housing an interference unit and a reference surface, the holder being made of a material that reversibly deforms with temperature changes, and which changes the reference optical path length, which is the optical path length of the reference light between the interference unit and the reference surface, according to a temperature change, selectively switching between a first measurement mode in which interference fringes are generated in the combined light by adjusting the temperature of the holder to match the reference optical path length to the measurement optical path length, and a second measurement mode in which the generation of interference fringes in the combined light is suppressed by making the reference optical path length different from the measurement optical path length. [Effects of the Invention]

[0022] This invention makes it possible to switch between three-dimensional shape measurement of a surface to be measured using the WLI method and three-dimensional shape measurement of a surface to be measured using the FV method without changing the objective lens. [Brief explanation of the drawing]

[0023] [Figure 1] This is a schematic diagram of a three-dimensional shape measuring device that measures the three-dimensional shape of a surface to be measured. [Figure 2]This is a functional block diagram of the control unit. [Figure 3] This figure compares the X-direction position of the reference surface when the reference surface housing is adjusted to temperature TWLI, and when the reference surface housing is adjusted to temperature TFV. [Figure 4] This is an explanatory diagram illustrating the temperature control of the reference surface housing according to the measurement mode by the temperature control unit. [Figure 5] This is an explanatory diagram illustrating the calculation of the three-dimensional shape of the surface to be measured by the first shape calculation unit. [Figure 6] This is an explanatory diagram illustrating the calculation of the three-dimensional shape of the surface to be measured by the second shape calculation unit. [Figure 7] This is a flowchart showing the flow of the measurement process for the three-dimensional shape of a surface to be measured using the three-dimensional shape measuring device of the first embodiment. [Figure 8] This is a magnified view of the interference objective lens and thermal insulation material of the white-light interference microscope of the three-dimensional shape measuring device of the second embodiment. [Figure 9] This is a magnified view of the interference objective lens of the white-light interference microscope of the three-dimensional shape measuring device of the third embodiment. [Modes for carrying out the invention]

[0024] [First Embodiment] Figure 1 is a schematic diagram of a three-dimensional shape measuring device 9 that measures the three-dimensional shape of a surface W to be measured. In the figure, among the mutually orthogonal XYZ directions, the XY direction is parallel to the horizontal direction, and the Z direction is parallel to the vertical direction.

[0025] As shown in Figure 1, the three-dimensional shape measuring device 9 can switch between measuring the three-dimensional shape of the surface W to be measured using the WLI method and measuring the three-dimensional shape of the surface W to be measured using the FV method. This three-dimensional shape measuring device 9 mainly comprises a white light interference microscope 10, a drive mechanism 12, a scale 14, a control device 16, and an operating unit 17.

[0026] The white light interference microscope 10 is a Michelson-type scanning white light interference microscope and has two measurement modes, including a WLI mode (corresponding to the first measurement mode of the present invention) that corresponds to three-dimensional shape measurement of the surface to be measured W using the WLI method, and an FV mode (corresponding to the second measurement mode of the present invention) that corresponds to three-dimensional shape measurement of the surface to be measured W using the FV method.

[0027] The white light interference microscope 10 comprises a light source unit 20, a beam splitter 22, an interference objective lens 24, a temperature control unit 26, a temperature sensor 28, a heat insulating material 30, an imaging lens 32, and a camera 34. The interference objective lens 24, beam splitter 22, imaging lens 32, and camera 34 are arranged in that order along the Z-direction upward from the measurement surface W. The light source unit 20 is positioned opposite the beam splitter 22 in the X-direction (or Y-direction).

[0028] The light source unit 20, under the control of the control device 16, emits a parallel beam of white light (low coherence light with little coherence) as measurement light L1 toward the beam splitter 22. The light source unit 20, although not shown in the figures, includes a light source capable of emitting measurement light L1, such as a light-emitting diode, semiconductor laser, halogen lamp, and high-intensity discharge lamp, and a collector lens that converts the measurement light L1 emitted from this light source into a parallel beam.

[0029] The beam splitter 22 is, for example, a half-mirror. The beam splitter 22 reflects a portion of the measurement light L1 incident from the light source 20 toward the interference objective lens 24 on the lower side in the Z direction. The beam splitter 22 also transmits a portion of the combined light L3, described later, incident from the interference objective lens 24 toward the upper side in the Z direction, and emits this combined light L3 toward the imaging lens 32.

[0030] The interference objective lens 24 is of the Michelson type and comprises an objective lens 24a, a beam splitter 24b, a reference surface 24c, and a holder 24d. The beam splitter 24b and the objective lens 24a are arranged in order along the Z-direction upward from the surface W to be measured, and the reference surface 24c is positioned opposite the beam splitter 24b in the X-direction (or Y-direction).

[0031] The objective lens 24a has a focusing function, and focuses the measurement light L1 incident from the beam splitter 22 onto the surface to be measured W through the beam splitter 24b.

[0032] The beam splitter 24b corresponds to the interference section of the present invention, and for example, a half mirror is used. The beam splitter 24b splits a portion of the measurement light L1 incident from the objective lens 24a into reference light L2, transmits the remaining measurement light L1 to the surface to be measured W, and reflects the reference light L2 toward the reference surface 24c. In the figure, the symbol D1 indicates the measurement optical path length, which is the optical path length of the measurement light L1 between the beam splitter 24b and the surface to be measured W. The measurement light L1 that has passed through the beam splitter 24b is irradiated onto the surface to be measured W, and then reflected by the surface to be measured W and returns to the beam splitter 24b.

[0033] The reference surface 24c, for example, uses a reflective mirror to reflect the reference light L2 incident from the beam splitter 24b back towards the beam splitter 24b. The position of this reference surface 24c in the X direction can be manually adjusted by a position adjustment mechanism (not shown). This allows adjustment of the reference optical path length D2, which is the optical path length of the reference light L2 between the beam splitter 24b and the reference surface 24c. This reference optical path length D2 is adjusted to match (or nearly match) the measured optical path length D1 in WLI mode.

[0034] The beam splitter 24b generates a combined beam L3 from the measurement light L1 returning from the surface to be measured W and the reference light L2 returning from the reference surface 24c, and emits this combined beam L3 toward the objective lens 24a on the upper side in the Z direction. This combined beam L3 passes through the objective lens 24a and the beam splitter 22 and enters the imaging lens 32. As will be described in more detail later, the combined beam L3 is interference light containing interference fringes in WLI mode, and light with suppressed interference fringes in FV mode.

[0035] The holder 24d is made of a metal material such as brass, that is, a material that is reversibly thermally deformable. This holder 24d comprises a lens barrel 24d1 and a reference plane housing section 24d2. The lens barrel 24d1 is formed in a cylindrical shape extending in the Z direction and houses (holds) the objective lens 24a and the beam splitter 24b. The reference plane housing section 24d2 is formed in a cylindrical shape extending in the X direction from the holding position of the beam splitter 24b in the lens barrel 24d1 and houses the reference plane 24c. As previously described, the position of the reference plane 24c can be manually adjusted in the X direction by a position adjustment mechanism (not shown).

[0036] The temperature adjustment unit 26 is located near the reference plane housing 24d2 and, under the control of the control device 16 described later, adjusts the temperature at least between the beam splitter 24b and the reference plane 24c, i.e., the temperature of the reference plane housing 24d2. For example, a heater and a Peltier element can be used as this temperature adjustment unit 26.

[0037] As previously described, the reference surface housing 24d2 is made of brass and therefore undergoes reversible thermal deformation (expansion and contraction) in response to temperature changes. This allows the temperature adjustment unit 26 to change the temperature of the reference surface housing 24d2, thereby causing thermal deformation of the reference surface housing 24d2 and adjusting the X-direction position of the reference surface 24c accordingly. As a result, the reference optical path length D2 of the reference light L2 can be adjusted without relying on the previously described position adjustment mechanism. Therefore, the temperature adjustment unit 26 is used for switching between WLI mode and FV mode, as will be described in more detail later.

[0038] The temperature sensor 28 corresponds to the temperature measuring unit of the present invention. The temperature sensor 28 is located near the reference surface housing 24d2 and measures the temperature of at least the reference surface housing 24d2 (between the beam splitter 24b and the reference surface 24c) within the holder 24d, and outputs the temperature measurement result to the control device 16. The measurement result of this temperature sensor 28 is used by the control device 16 to control the temperature adjustment unit 26, i.e., to switch between WLI mode and FV mode.

[0039] The thermal insulation material 30 is provided to cover the entire interference objective lens 24, the temperature adjustment unit 26, and the temperature sensor 28. This prevents the temperature inside the thermal insulation material 30, particularly the temperature of the reference surface housing unit 24d2 and its vicinity, from changing due to external influences.

[0040] The imaging lens 32 images the multiplexed light L3 incident from the beam splitter 22 onto the imaging plane of the camera 34 (not shown in the figure). Specifically, the imaging lens 32 images a point on the focal plane of the objective lens 24a as an image point on the imaging plane of the camera 34.

[0041] Camera 34, although not shown in the illustration, is equipped with a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) type image sensor. Camera 34 captures the combined wave light L3 imaged on the image sensor's imaging surface using an imaging lens 32, and processes the resulting image signal of the combined wave light L3 to output an imaged image 36. The imaged image 36, as will be described in more detail later, is an image containing interference fringes in WLI mode and an image without interference fringes in FV mode.

[0042] The drive mechanism 12 corresponds to the scanning unit of the present invention. The drive mechanism 12 is composed of various actuators, such as a known linear motor or motor drive mechanism, and holds the white light interference microscope 10 so that it can move in the Z direction, which is the scanning direction. Under the control of the control device 16, the drive mechanism 12 scans the white light interference microscope 10 along the Z direction in both WLI mode and FV mode. This makes it possible to simultaneously change the measurement optical path length D1 required for WLI measurement and move the focus of the camera 34 required for FV measurement.

[0043] The drive mechanism 12 only needs to be capable of scanning the white light interference microscope 10 relative to the surface to be measured W in the Z direction. For example, it may scan the surface to be measured W (the support part that supports the surface to be measured W) in the Z direction.

[0044] Scale 14 is a position detection sensor that detects the Z-direction position of the white light interference microscope 10, and a linear scale is used, for example. This scale 14 repeatedly detects the Z-direction position of the white light interference microscope 10 and repeatedly outputs the position detection result to the control device 16.

[0045] The control device 16 comprehensively controls the switching of the measurement mode (WLI mode, FV mode) of the white light interference microscope 10 (three-dimensional shape measuring device 9) in response to input operations to the operation unit 17, the measurement operation of the three-dimensional shape of the surface to be measured W by the white light interference microscope 10 for each measurement mode, and the calculation of the three-dimensional shape of the surface to be measured W for each measurement mode. This control device 16 is equipped with an arithmetic circuit composed of various processors and memory. Various processors include CPUs (Central Processing Units), GPUs (Graphics Processing Units), ASICs (Application Specific Integrated Circuits), and programmable logic devices [e.g., SPLDs (Simple Programmable Logic Devices), CPLDs (Complex Programmable Logic Devices), and FPGAs (Field Programmable Gate Arrays)]. The various functions of the control device 16 may be implemented by a single processor, or by multiple processors of the same or different types.

[0046] Figure 2 is a functional block diagram of the control device 16. As shown in Figure 2, the control device 16 is connected to various parts of the white light interference microscope 10 (light source unit 20, temperature adjustment unit 26, temperature sensor 28, and camera 34), the drive mechanism 12, the scale 14, and the operation unit 17.

[0047] The control device 16 functions as a temperature control unit 100, a measurement control unit 102, a first shape calculation unit 104, and a second shape calculation unit 106 by executing a control program (not shown) read from a storage unit (not shown).

[0048] The temperature control unit 100 switches the measurement mode of the white light interference microscope 10 (WLI mode, FV mode) in response to the selection operation of the operation unit 17. Specifically, the temperature control unit 100 controls the temperature adjustment unit 26 to set the temperature of the reference plane storage unit 24d2 to a predetermined temperature T corresponding to the WLI mode. WLI(°C) and a predetermined temperature T corresponding to the FV mode FV (°C) and selectively switch. As a result, the temperature T WLI and the temperature T FV According to each, the reference surface storage portion 24d2 thermally expands, and the X-direction position of the reference surface 24c changes. As a result, the reference optical path length D2 is selectively switched between the length corresponding to the WLI mode and the length corresponding to the FV mode. Note that the temperature T WLI corresponds to the first temperature of the present invention, and the temperature T FV corresponds to the second temperature of the present invention.

[0049] FIG. 3 shows the X-direction position of the reference surface 24c when the reference surface storage portion 24d2 is adjusted to the temperature T WLI and the X-direction position of the reference surface 24c when the reference surface storage portion 24d2 is adjusted to the temperature T FV It is a figure which compared with the X-direction position of the reference surface 24c in the case of adjusting to.

[0050] As shown by reference numeral 3A in FIG. 3, the X-direction position of the reference surface 24c is manually adjusted by the above-described position adjustment mechanism (not shown) so as to coincide with the reference position A when the reference surface storage portion 24d2 is adjusted to the temperature T WLI The reference position A is the position of the reference surface 24c determined so that the reference optical path length D2 coincides with the measurement optical path length D1 in a state where the focal point of the interference objective lens 24 is aligned with the measurement surface W.

[0051] As described above, the reference surface storage portion 24d2 (holder 24d) is formed of a material that thermally expands reversibly. Therefore, the reference surface storage portion 24d2 is set to the temperature T WLIBy adjusting this, the X-direction position of the reference plane 24c is automatically adjusted to the reference position A. As a result, when the focus of the interference objective lens 24 is aligned with the surface to be measured W, the measurement optical path length D1 and the reference optical path length D2 coincide. Consequently, when the focus of the interference objective lens 24 is aligned with the surface to be measured W, the measurement light L1 returning from the surface to be measured W and the reference light L2 returning from the reference plane 24c strongly interfere in the beam splitter 24b, so that the combined light L3 generated by the beam splitter 24b becomes interference light containing interference fringes. Therefore, the captured image 36 (corresponding to the first image of the present invention) output from the camera 34 that captures this combined light L3 also contains interference fringes, making WLI method measurement possible.

[0052] As shown by reference numeral 3B in Figure 3, the temperature T FV The X-direction position of the reference surface 24c within the reference surface storage section 24d2 is set to coincide with the shift position B. The shift position B is the position of the reference surface 24c where, when the focus of the interference objective lens 24 is aligned with the surface to be measured W, the reference optical path length D2 is determined to be different from the measurement optical path length D1, and the generation of interference fringes in the combined light L3 is suppressed. Below, temperature T FV Here is an example of how to make that decision.

[0053] The depth of focus of the objective lens 24a is defined as "DOF (mm)", the linear thermal expansion coefficient of the reference plane housing 24d2 is defined as "α ( / °C)", and the temperature T FV and temperature T WLI Let "ΔT" be the difference between the two values, and the temperature T WLI Let the reference optical path length D2 be "d (mm)". Then, the temperature of the reference surface housing 24d2 is temperature T. WLI The change in the reference optical path length D2, ΔD2, when it changes by ΔT, is expressed by the following equation [Equation 1].

[0054] [Mathematics 1] ΔD2 = |BA| × 2 = ΔT × α × d

[0055] In order to suppress the generation of interference fringes so as not to affect FV method measurements, the change amount ΔD2 must be greater than N times the depth of focus (DOF) (where N is any natural number), as shown in equation [Equation 2] below. In other words, making the reference optical path length D2 different from the measured optical path length D1 in the present invention corresponds to changing the reference optical path length D2 by a change amount ΔD2 from a state in which it matches the measured optical path length D1.

[0056] [Math 2] ΔD2 = ΔT × α × d > |N × DOF|

[0057] In equation [Equation 2] above, for example, by setting N to 2 or greater, the generation of interference fringes can be suppressed so as not to affect the measurement using the FV method. Therefore, by rearranging equation [Equation 2] above, ΔT can be expressed as shown in equation [Equation 3] below.

[0058] [Math 3] ΔT = |T FV -T WLI |>|N×DOF / (α×d)|

[0059] In the above equation [Equation 3], "DOF", "α", and "d" are known values, and "N" can be set arbitrarily. For example, if the depth of focus of the objective lens 24a used in the white light interference microscope 10 has an NA (Numerical Aperture) of 0.7 is set to "DOF = 0.56 μm", and the linear thermal expansion coefficient of the reference plane housing 24d2 is set to "α = 20 × 10 -6 " and temperature T WLI If we assume that the reference optical path length D2 is "d=5mm" and N is 2, then the above equation [Equation 3] can be expressed as the following equation [Equation 4].

[0060] [Math 4] ΔT > 2 × (0.56 × 10) -3 )× / [(20×10 -6 ) × 5] = 11.2 (℃)

[0061] temperature T WLI For the temperature T that satisfies the above equation [Equation 4], FVBy setting this, the generation of interference fringes in the multiplexed light L3 can be suppressed.

[0062] As previously described, the reference surface housing 24d2 is made of a material that is reversibly thermally deformable, so the reference surface housing 24d2 is subjected to temperature T FV By adjusting this, the X-direction position of the reference plane 24c is automatically adjusted to shift position B. This suppresses the generation of interference fringes in the multiplexed light L3, and therefore also suppresses the generation of interference fringes in the captured image 36 (corresponding to the second image of this invention) output from the camera 34 that captured the multiplexed light L3. As a result, FV method measurement becomes possible.

[0063] Figure 4 is an explanatory diagram illustrating the temperature control of the reference surface housing 24d2 by the temperature control unit 100 according to the measurement mode. As shown in Figure 4, the temperature control unit 100 controls the temperature of the reference surface housing 24d2 to temperature T according to the measurement mode selected by the operation unit 17. WLI and temperature T FV It selectively switches between the two.

[0064] Specifically, the temperature control unit 100 determines that the reference surface housing unit 24d2 is at temperature T based on the measurement results of the temperature sensor 28. WLI (In WLI mode) or temperature T FV Feedback control is performed to control the temperature adjustment unit 26 so that it is adjusted (in FV mode). PID (Proportional-Integral-Differential) control is an example of this feedback control.

[0065] The temperature control unit 100 includes a temperature acquisition unit 100a, a target temperature storage unit 100b, a calculation processing unit 100c, and an output control unit 100d.

[0066] The temperature acquisition unit 100a is, for example, an interface connected to the temperature sensor 28, and each time the temperature measurement result is repeatedly output from the temperature sensor 28, it repeatedly acquires the temperature measurement result from the temperature sensor 28 and outputs the temperature measurement result to the calculation processing unit 100c. The target temperature storage unit 100b stores the temperature T WLI and temperature TFV The target temperature is stored in advance. The target temperature storage unit 100b may be located on a server on the internet.

[0067] The calculation processing unit 100c calculates the target temperature (temperature T) corresponding to the measurement mode (WLI mode, FV mode) selected on the operation unit 17. WLI , temperature T FV The target temperature is obtained from the target temperature storage unit 100b. Then, each time a new temperature measurement result is input from the temperature sensor 28, the calculation processing unit 100c calculates the difference between this temperature measurement result and the target temperature, and outputs this difference calculation result to the output control unit 100d.

[0068] The output control unit 100d controls the temperature of the temperature adjustment unit 26. The output control unit 100d stores, for example, a data table or calculation formula that defines the relationship between the difference calculation result from the calculation processing unit 100c and the amount of temperature adjustment by the temperature adjustment unit 26 necessary to adjust the temperature of the reference surface housing unit 24d2 to the target temperature. Based on the difference calculation result input from the calculation processing unit 100c, the output control unit 100d controls the temperature adjustment unit 26 by referring to the above-mentioned data table, etc., thereby adjusting the temperature of the reference surface housing unit 24d2 to the target temperature.

[0069] In this way, the temperature control unit 100 sets the temperature of the reference surface storage unit 24d2 to temperature T according to the measurement mode selected by the operation unit 17. WLI and temperature T FV By selectively switching between these two positions, the X-direction position of the reference plane 24c can be selectively switched between reference position A and shift position B. As a result, the temperature control unit 100 can selectively switch the measurement mode of the white light interference microscope 10 between WLI mode and FV mode.

[0070] Returning to Figure 2, the measurement control unit 102 controls the drive mechanism 12, the light source unit 20, and the camera 34 to perform three-dimensional shape measurement of the surface to be measured W according to the measurement mode (WLI mode, FV mode) selected by the operation unit 17.

[0071] Specifically, the measurement control unit 102 starts the emission of measurement light L1 from the light source unit 20, and then controls the drive mechanism 12 to scan the white light interference microscope 10 in the Z direction. Furthermore, while the drive mechanism 12 is scanning the white light interference microscope 10 in the Z direction, the measurement control unit 102, based on the detection result of the Z-direction position of the white light interference microscope 10 by the scale 14, repeatedly causes the camera 34 to capture multiplexed light L3 and outputs the captured image 36 to the control device 16 each time the white light interference microscope 10 moves by a certain pitch in the Z direction. Note that the above-mentioned pitch in FV mode may be the same as the pitch in WLI mode, or it may be set to be wider than the pitch in WLI mode.

[0072] Furthermore, since the Z-direction position of camera 34 when imaging the multiplexed light L3 with camera 34 can be detected by scale 14, the pitch when scanning the white light interference microscope 10 in the Z-direction is not limited to a constant pitch but may be an unequal pitch (the same applies hereafter).

[0073] The captured images 36 for each pitch described above are input to the first shape calculation unit 104 in WLI mode and to the second shape calculation unit 106 in FV mode.

[0074] Figure 5 is an explanatory diagram illustrating the calculation of the three-dimensional shape of the surface to be measured W by the first shape calculation unit 104. The first shape calculation unit 104 calculates the three-dimensional shape of the surface to be measured W in WLI mode. The first shape calculation unit 104 acquires an image 36 input from the camera 34 via an image acquisition unit (interface) (not shown) each time the white light interference microscope 10 moves by a certain pitch.

[0075] Next, as shown in Figure 5, the first shape calculation unit 104 detects the brightness value of each pixel in each captured image 36 where interference fringes are generated. Then, the first shape calculation unit 104 compares the brightness values ​​(see symbol P1) of each pixel at the same coordinate in each captured image 36 (image sensor of the camera 34). Here, Figure 5 shows the relationship between the brightness value and the Z-direction position of any single pixel. The first shape calculation unit 104 calculates the height information of the surface W to be measured for each pixel at the same coordinate by determining the Z-direction position where the brightness value is maximized for each pixel at the same coordinate. This allows the three-dimensional shape of the surface W to be measured to be determined. Note that the calculation of the three-dimensional shape of the surface W to be measured in WLI mode is a known technique (see Patent Document 1 above), so a detailed explanation is omitted here.

[0076] Figure 6 is an explanatory diagram illustrating the calculation of the three-dimensional shape of the surface to be measured W by the second shape calculation unit 106. The second shape calculation unit 106 calculates the three-dimensional shape of the surface to be measured W in FV mode. The second shape calculation unit 106 acquires an image 36 input from the camera 34 via an image acquisition unit (not shown) each time the white light interference microscope 10 moves by a certain pitch.

[0077] Next, the second shape calculation unit 106 calculates the degree of focus (contrast value) for each pixel of each captured image 36 (image sensor of the camera 34) where interference fringes are suppressed. Then, as shown in Figure 6, the second shape calculation unit 106 compares the degree of focus (see symbol P2) for each pixel at the same coordinate in each captured image 36. Here, Figure 6 shows the relationship between the degree of focus and the Z-direction position for any one pixel. The second shape calculation unit 106 determines the Z-direction position where the degree of focus is maximized for each pixel at the same coordinate, thereby determining the focal position of the camera 34 relative to the surface to be measured W for each pixel at the same coordinate. This allows the three-dimensional shape of the surface to be measured W to be determined. Note that the calculation of the three-dimensional shape of the surface to be measured W in FV mode is also a known technique (see Patent Document 1 above), so a detailed explanation is omitted here.

[0078] [Operation of the First Embodiment] Figure 7 is a flowchart showing the flow of the measurement process for the three-dimensional shape of the surface to be measured W by the three-dimensional shape measuring device 9 of the first embodiment of the above configuration (corresponding to the measurement mode switching method of the present invention). It is assumed that the measurement control unit 102 starts emitting measurement light L1 from the light source unit 20, and the temperature sensor 28 starts measuring the temperature of the reference surface storage unit 24d2, and repeatedly outputs the temperature measurement result to the temperature acquisition unit 100a of the temperature control unit 100.

[0079] As shown in Figure 7, the operator determines the measurement mode of the white light interference microscope 10 to either WLI mode or FV mode depending on the type of surface W to be measured (flat surface, inclined surface) and the measurement content (surface roughness shape measurement, shape measurement), and performs the measurement mode selection operation by operating the control unit 17 (step S1). For example, when measuring the surface roughness shape of the surface W to be measured, the operator selects the WLI mode using the control unit 17, and when the surface W to be measured is inclined or when measuring the shape of the surface W to be measured, the operator selects the FV mode using the control unit 17.

[0080] When the WLI mode is selected, the calculation processing unit 100c of the temperature control unit 100 retrieves the target temperature T from the target temperature storage unit 100b. WLI The information is obtained. Next, each time a new temperature measurement result is input from the temperature sensor 28, the calculation processing unit 100c calculates this temperature measurement result and temperature T WLI The difference is calculated and this difference calculation result is output to the output control unit 100d. Then, the output control unit 100d controls the temperature adjustment unit 26 based on the difference calculation result to set the reference surface storage unit 24d2 to temperature T WLI Adjust to (Step S2A).

[0081] In this embodiment, the interference objective lens 24, temperature adjustment unit 26, and temperature sensor 28 are covered with a heat insulating material 30, so the temperature inside the heat insulating material 30, especially the reference plane housing unit 24d2 and its vicinity, is measured to temperature T WLI This can stabilize it.

[0082] The reference surface storage section 24d2 is at temperature T WLIWhen adjusted, the reference surface housing 24d2 undergoes thermal deformation so that the X-direction position of the reference surface 24c coincides with the reference position A, as shown by reference numeral 3A in Figure 3 described above. At this time, the insulating material 30 reduces the temperature of the reference surface housing 24d2 to T WLI Because it is stabilized in this way, the X-direction position of the reference surface 24c can be precisely adjusted to the reference position A.

[0083] By controlling the temperature of the reversibly thermally deformable reference surface housing 24d2 in this manner, the X-direction position of the reference surface 24c can be aligned to the reference position A with better reproducibility compared to manually adjusting the X-direction position of the reference surface 24c using a position adjustment mechanism (not shown). Furthermore, the X-direction position of the reference surface 24c can be adjusted at a lower cost than when a highly accurate automatic position adjustment mechanism with a resolution of several tens of nanometers is provided.

[0084] By aligning the X-direction position of the reference plane 24c with the reference position A, the reference optical path length D2 matches the measurement optical path length D1 when the focus of the interference objective lens 24 is aligned with the surface to be measured W. As a result, interference fringes are included in the combined light L3 generated by the beam splitter 24b. This allows the white light interference microscope 10 to be switched to WLI mode (step S3A).

[0085] On the other hand, when the FV mode is selected, the calculation processing unit 100c of the temperature control unit 100 retrieves the target temperature T from the target temperature storage unit 100b. FV The information is obtained. Subsequently, as in the case when WLI mode is selected, the difference calculation by the calculation processing unit 100c and the control of the temperature adjustment unit 26 by the output control unit 100d are performed, so that the temperature of the reference surface storage unit 24d2 reaches temperature T FV It is adjusted to (step S2B). Also, as previously described, since the interference objective lens 24 etc. are covered with the heat insulating material 30, the reference surface housing 24d2 and its vicinity are subjected to a temperature T FV This can stabilize it.

[0086] The reference surface storage section 24d2 is at temperature T FVWhen adjusted, the reference surface housing 24d2 undergoes thermal deformation so that the X-direction position of the reference surface 24c coincides with the shift position B, as shown by reference numeral 3B in Figure 3 described above. At this time, the reference surface housing 24d2 is heated by the insulating material 30 to a temperature T FV Because it is stabilized in this way, the X-direction position of the reference surface 24c can be precisely adjusted to the shift position B. As a result, the X-direction position of the reference surface 24c can be aligned to the shift position B with better reproducibility compared to manually adjusting the X-direction position of the reference surface 24c, and furthermore, it is possible to achieve lower costs than when using a high-precision automatic position adjustment mechanism.

[0087] By aligning the X-direction position of the reference plane 24c with the shift position B, the reference optical path length D2 becomes different from the measurement optical path length D1 when the focus of the interference objective lens 24 is aligned with the surface to be measured W. As a result, the generation of interference fringes in the multiplexed light L3 generated by the beam splitter 24b is suppressed. Consequently, the white light interference microscope 10 is switched to FV mode (step S3B).

[0088] Once the measurement mode of the white light interference microscope 10 has been switched, the measurement control unit 102 controls the drive mechanism 12 to start scanning the white light interference microscope 10 in the Z direction (step S4). Then, based on the detection result of the Z-direction position of the white light interference microscope 10 by the scale 14, the measurement control unit 102 repeatedly causes the camera 34 to capture multiplexed light L3 each time the white light interference microscope 10 moves by a certain pitch in the Z direction (steps S5, NO in step S6, step S7). When the measurement mode is WLI mode, the camera 34 sequentially inputs the captured image 36 in which interference fringes are generated to the first shape calculation unit 104. On the other hand, when the measurement mode is FV mode, the camera 34 sequentially inputs the captured image 36 in which the generation of interference fringes is suppressed to the second shape calculation unit 106.

[0089] Furthermore, in FV mode, the pitch can be widened compared to WLI mode, thus shortening the measurement time. Conversely, in WLI mode, the pitch is narrower than in FV mode, resulting in higher vertical resolution for measuring the three-dimensional shape of the surface W being measured.

[0090] When scanning by the white light interference microscope 10 is completed (YES in step S6), the first shape calculation unit 104 or the second shape calculation unit 106 is activated according to the measurement mode (step S8).

[0091] When the measurement mode is WLI mode, the first shape calculation unit 104 detects the brightness value for each pixel of each captured image 36 where interference fringes are generated, and determines the Z-direction position where the brightness value is maximized for each pixel at the same coordinate in each captured image 36, thereby calculating the height information of the surface to be measured W for each pixel at the same coordinate. As a result, the first shape calculation unit 104 calculates the three-dimensional shape of the surface to be measured W (step S9A).

[0092] On the other hand, when the measurement mode is FV mode, the second shape calculation unit 106 calculates the degree of focus for each pixel of each captured image 36 in which interference fringes are suppressed, and determines the Z-direction position where the degree of focus is maximized for each pixel at the same coordinate in each captured image 36, thereby determining the focal position of the camera 34 with respect to the surface to be measured W for each pixel at the same coordinate. As a result, the second shape calculation unit 106 calculates the three-dimensional shape of the surface to be measured W (step S9B).

[0093] As described above, in this embodiment, the X-direction position of the reference surface 24c can be reproducibly moved between the reference position A and the shift position B by controlling the temperature of the reversibly thermally deformable reference surface housing 24d2. This makes it possible to switch the measurement mode of the white interference microscope 10 without changing the interference objective lens 24 or manually adjusting the X-direction position of the reference surface 24c. As a result, it becomes unnecessary to prepare multiple types of interference objective lenses 24 according to the type of measurement mode, to prepare a switching mechanism for the interference objective lens 24, or to provide a high-precision reference surface 24c position adjustment mechanism, thus enabling cost reduction. Furthermore, the problem of reduced measurement accuracy of the three-dimensional shape of the surface W to be measured due to the attachment and detachment of the interference objective lens 24 is prevented.

[0094] [Second Embodiment] Figure 8 is an enlarged view of the interference objective lens 24 and the heat insulating material 30A of the white light interference microscope 10 of the three-dimensional shape measuring device 9 of the second embodiment.

[0095] In the first embodiment described above, the entire interference objective lens 24, the temperature adjustment unit 26, and the temperature sensor 28 are covered by the heat insulating material 30. However, as shown in Figure 8, in the second embodiment, only the reference plane housing unit 24d2, the temperature adjustment unit 26, and the temperature sensor 28 are covered by the heat insulating material 30A. The second embodiment has basically the same configuration as the first embodiment, except that it is equipped with a different heat insulating material 30A than the heat insulating material 30 of the first embodiment. Therefore, components that are functionally or structurally identical to those in the first embodiment are denoted by the same reference numerals and their descriptions are omitted.

[0096] In this way, by covering the reference surface storage section 24d2, the temperature adjustment section 26, and the temperature sensor 28 with the heat insulating material 30A, the reference surface storage section 24d2 and its vicinity can be heated to the target temperature (temperature T) as in the first embodiment described above. WLI , temperature T FVThis allows for stabilization. Furthermore, the generation of aberrations in the objective lens 24a due to heat generated in the temperature control unit 26 can be minimized, enabling three-dimensional shape measurement of the surface W to be measured that is resistant to temperature changes. As a result, even higher accuracy and reliability of three-dimensional shape measurement of the surface W to be measured becomes possible.

[0097] [Third Embodiment] Figure 9 is a magnified view of the interference objective lens 200 of the white light interference microscope 10 of the three-dimensional shape measuring device 9 of the third embodiment.

[0098] In each of the above embodiments, the white light interference microscope 10 is equipped with a Michelson-type interference objective lens 24. However, as shown in Figure 9, in the third embodiment, the white light interference microscope 10 is equipped with a Mirau-type interference objective lens 200. The third embodiment has basically the same configuration as the above embodiments, except that it is equipped with an interference objective lens 200 that is different from the interference objective lens 24 of the above embodiments. Therefore, components that are functionally or structurally identical to those in the above embodiments are denoted by the same reference numerals and their descriptions are omitted.

[0099] The Mirau-type interference objective lens 200 comprises an objective lens 200a, a beam splitter 200b, a reference plane 200c, and a holder 200d. The beam splitter 200b, the reference plane 200c, and the objective lens 200a are arranged in order along the Z-direction upward from the surface W under measurement. That is, the reference plane 200c is positioned between the objective lens 200a and the beam splitter 200b.

[0100] The objective lens 200a has a focusing function, and focuses the measurement light L1 incident from the beam splitter 22 (see Figure 1) onto the surface to be measured W through the beam splitter 200b.

[0101] The beam splitter 200b corresponds to the interference section of the present invention, splitting a portion of the measurement light L1 incident from the objective lens 200a into reference light L2, transmitting the remaining measurement light L1 downward in the Z direction to the surface to be measured W, and reflecting the reference light L2 toward the reference surface 24c on the upper side in the Z direction.

[0102] The reference surface 200c, for example, uses a reflective mirror to reflect the reference light L2 incident from the beam splitter 200b on the lower Z-direction side toward the beam splitter 200b. The position of this reference surface 200c in the Z-direction can be manually adjusted by a position adjustment mechanism (not shown). This allows adjustment of the reference optical path length D2 between the beam splitter 200b and the reference surface 200c. In WLI mode, this reference optical path length D2 is adjusted to match the measurement optical path length D1 between the beam splitter 200b and the surface under measurement W.

[0103] The beam splitter 200b generates a combined beam L3 from the measurement light L1 returning from the surface to be measured W and the reference light L2 returning from the reference surface 200c, and emits this combined beam L3 toward the objective lens 200a on the upper side in the Z direction. After this combined beam L3 enters the beam splitter 22 from the objective lens 200a, it is imaged by the camera 34 via the imaging lens 32, as in the embodiments described above.

[0104] The holder 200d, like the holder 24d in each of the above embodiments, is formed in a cylindrical shape extending in the Z direction from a reversibly heat-deformable material such as brass, and houses (holds) the objective lens 200a, the beam splitter 200b, and the reference plane 200c. The portion (region) within this holder 200d that houses the beam splitter 200b and the reference plane 200c becomes the reference plane housing section 200d1.

[0105] In the third embodiment, the temperature adjustment unit 26 is located near the reference plane housing unit 200d1 and, under the control of the temperature control unit 100 described above, adjusts the temperature at least between the beam splitter 200b and the reference plane 200c, i.e., the temperature of the reference plane housing unit 200d1. By changing the temperature of the reference plane housing unit 200d1, the reference plane housing unit 200d1 is thermally deformed, and the Z-direction position of the reference plane 200c can be adjusted according to this thermal deformation. As a result, the Z-direction position of the reference plane 200c can be adjusted to a reference position A (not shown) where the reference optical path length D2 coincides with the measured optical path length D1, and a shift position B (not shown) where the reference optical path length D2 does not coincide with the measured optical path length D1. Therefore, as in each of the above embodiments, the reference optical path length D2 can be adjusted, and the measurement mode of the white light interference microscope 10 can be selectively switched between WLI mode and FV mode.

[0106] The temperature sensor 28 is located near the reference surface housing 200d1 and measures the temperature of at least the reference surface housing 200d1 within the holder 200d, and outputs the temperature measurement result to the temperature control unit 100 (see Figure 4). As a result, similar to the embodiments described above, the temperature control unit 100 determines, based on the measurement result of the temperature sensor 28, that the reference surface housing 24d2 reaches the target temperature (temperature T WLI , temperature T FV Feedback control can be performed to control the temperature adjustment unit 26 so that it is adjusted to the specified value.

[0107] In the third embodiment, the heat insulating material 30 is provided so as to cover the interference objective lens 200, the temperature adjustment unit 26, and the temperature sensor 28. This allows the reference surface housing unit 200d1 and its vicinity to reach the target temperature (temperature T WLI , temperature T FV This can be stabilized. Furthermore, similar to the second embodiment shown in Figure 8 described above, the heat insulating material 30A may be used to cover only the reference surface storage section 200d1, the temperature adjustment section 26, and the temperature sensor 28.

[0108] As described above, in the third embodiment as well, the Z-direction position of the reference surface 200c can be reproducibly moved between the reference position A and the shift position B by controlling the temperature of the reference surface housing section 200d1 (holder 200d) of the Mirau-type interference objective lens 200, so that the measurement mode of the white light interference microscope 10 can be switched, as in the above embodiments. As a result, the same effects as in the above embodiments can be obtained.

[0109] As a method for switching the measurement mode of the white light interference microscope 10, for example, if a Michelson-type interference objective lens 24 is used, the measurement mode can be switched between FV mode and WLI mode by inserting and removing a shutter in the optical path of the reference light L2. However, in the case of a Mirau-type interference objective lens 200, if a shutter is inserted in the optical path of the reference light L2, the measurement light L1 is also blocked by the shutter, making it impossible to perform measurement in FV mode. Therefore, when a Mirau-type interference objective lens 200 is provided, as in the white light interference microscope 10 of the third embodiment, it is effective to switch the measurement mode by controlling the temperature of the reference plane storage unit 200d1 (holder 200d).

[0110] [others] In the above embodiments, the example described was that the white light interference microscope 10 is equipped with a Michelson-type interference objective lens 24 or a Mirau-type interference objective lens 200. However, various known interference objective lenses, such as the Linik type, may also be provided. Furthermore, each part of the interference objective lens 24 (objective lenses 24a, 200a, beam splitters 24b, 200b, and reference planes 24c, 200c) may be provided separately.

[0111] In each of the above embodiments, the white interference microscope 10 is scanned in the Z direction by the drive mechanism 12, but the object to be scanned is not particularly limited as long as at least the interference objective lenses 24, 200 and the camera 34 can be scanned in the Z direction.

[0112] [Note] As can be seen from the descriptions of the embodiments detailed above, this specification includes disclosures of a variety of technical ideas, including the inventions shown below.

[0113] [Additional note 1] A light source unit that emits white light for measurement, An interference unit that splits a portion of the measurement light emitted from the light source unit into reference light, emits the measurement light onto the surface to be measured and emits the reference light onto the reference surface, and generates a combined wave of the measurement light returning from the surface to be measured and the reference light returning from the reference surface, A camera that captures the multiplexed light generated by the interference unit, When the optical path length of the measurement light between the interference unit and the surface to be measured is defined as the measurement optical path length, the scanning unit scans the interference unit and the camera relative to the surface to be measured in the scanning direction in which the measurement optical path length changes, During scanning by the scanning unit, a measurement control unit causes the camera to repeatedly capture the multiplexed light, A holder for housing the interference portion and the reference surface, formed of a material that reversibly deforms with temperature changes, and which changes the reference optical path length, which is the optical path length of the reference light between the interference portion and the reference surface, in accordance with the temperature changes. A temperature adjustment unit for adjusting the temperature of the holder, A temperature control unit that can selectively switch between a first measurement mode, which generates interference fringes in the multiplexed light by controlling the temperature adjustment unit to match the reference optical path length to the measurement optical path length, and a second measurement mode, which suppresses the generation of interference fringes in the multiplexed light by making the reference optical path length different from the measurement optical path length. A three-dimensional shape measuring device equipped with the following features.

[0114] [Additional note 2] When the temperature control unit switches to the first measurement mode, the camera repeatedly captures the multiplexed light during scanning by the scanning unit and outputs a plurality of first images including the interference fringes. The three-dimensional shape measuring device according to Appendix 1, further comprising a first shape calculation unit that calculates height information of the surface to be measured for each pixel based on the brightness values ​​of each pixel at the same coordinate of a plurality of first images output from the camera, thereby determining the three-dimensional shape of the surface to be measured.

[0115] [Additional note 3] When the temperature control unit switches to the second measurement mode, the camera repeatedly captures the multiplexed light during scanning by the scanning unit and outputs a plurality of second images in which the generation of interference fringes is suppressed. A three-dimensional shape measuring device according to appendix 1 or 2, comprising a second shape calculation unit that calculates the three-dimensional shape of the surface to be measured based on the result of calculating the change in the degree of focus in the scanning direction for each pixel at the same coordinate of a plurality of second images output from the camera.

[0116] [Additional note 4] The holder is equipped with a temperature measuring unit for measuring the temperature of the holder, The temperature control unit has previously acquired a target temperature that includes a first temperature corresponding to the first measurement mode and a second temperature corresponding to the second measurement mode. The three-dimensional shape measuring apparatus according to any one of the appendices 1 to 3, wherein the temperature control unit controls the temperature adjustment unit based on the measurement result of the temperature measuring unit and the target temperature to switch between the first measurement mode and the second measurement mode.

[0117] [Additional note 5] The temperature adjustment unit changes the temperature of the reference surface housing portion that houses the reference surface within the holder, The three-dimensional shape measuring device according to Appendix 4, wherein the temperature measuring unit measures the temperature of the reference surface storage unit.

[0118] [Additional note 6] The three-dimensional shape measuring device according to Appendix 5, comprising at least an insulating material covering the reference surface storage section, the temperature measuring section, and the temperature adjustment section.

[0119] [Additional note 7] The three-dimensional shape measuring apparatus according to any one of the appendices 1 to 6, wherein the scanning unit moves at least the holder and the camera in the scanning direction.

[0120] [Additional note 8] The system includes an objective lens that focuses the measurement light onto the surface to be measured, The interference portion is positioned between the objective lens and the surface to be measured. The three-dimensional shape measuring apparatus according to any one of the appendices 1 to 7, wherein the reference surface is positioned between the objective lens and the interference portion.

[0121] [Additional note 9] A light source unit that emits white light for measurement, An interference unit that splits a portion of the measurement light emitted from the light source unit into reference light, emits the measurement light onto the surface to be measured and emits the reference light onto the reference surface, and generates a combined wave of the measurement light returning from the surface to be measured and the reference light returning from the reference surface, A camera that captures the multiplexed light generated by the interference unit, When the optical path length of the measurement light between the interference unit and the surface to be measured is defined as the measurement optical path length, the scanning unit scans the interference unit and the camera relative to the surface to be measured in the scanning direction in which the measurement optical path length changes, A holder for housing the interference portion and the reference surface, formed of a material that reversibly deforms with temperature changes, and which changes the reference optical path length, which is the optical path length of the reference light between the interference portion and the reference surface, in accordance with the temperature changes. In a method for switching the measurement mode of a three-dimensional shape measuring device equipped with, A method for switching the measurement mode of a three-dimensional shape measuring device, comprising: a first measurement mode in which interference fringes are generated in the combined light by adjusting the temperature of the holder to match the reference optical path length to the measurement optical path length; and a second measurement mode in which the generation of interference fringes in the combined light is suppressed by making the reference optical path length different from the measurement optical path length. [Explanation of Symbols]

[0122] 9 Three-dimensional shape measuring device 10 White light interference microscope 12 Drive mechanism 1 / 14 scale 16 Control device 17 Control section 20 Light source section 22 Beam Splitter 24 Interferometric objective lenses 24a objective lens 24b Beam Splitter 24c reference plane 24d holder 24d1 lens barrel 24d2 Reference surface storage compartment 26 Temperature adjustment section 28 Temperature Sensor 30 Insulation 30A insulation 32 imaging lenses 34 Cameras 36 Acquired Images 100 Temperature control unit 100a Temperature acquisition part 100b Target temperature storage section 100c Calculation Processing Unit 100d Output Control Unit 102 Measurement Control Unit 104 1st shape calculation section 106 2nd shape calculation section 200 Interferometric objective lens 200a objective lens 200b Beam Splitter 200c reference plane 200d holder 200d1 Reference surface storage section A Reference position B Shift position D1 Measurement optical path length D2 Reference optical path length L1 Measurement light L2 Reference Light L3 combined light T FV temperature T WLI temperature W Surface to be measured ΔD2 Change

Claims

1. A light source unit that emits white light for measurement, An interference unit that splits a portion of the measurement light emitted from the light source unit into reference light, emits the measurement light onto the surface to be measured and emits the reference light onto the reference surface, and generates a combined wave of the measurement light returning from the surface to be measured and the reference light returning from the reference surface, A camera that captures the multiplexed light generated by the interference unit, When the optical path length of the measurement light between the interference unit and the surface to be measured is defined as the measurement optical path length, the scanning unit scans the interference unit and the camera relative to the surface to be measured in the scanning direction in which the measurement optical path length changes, During scanning by the scanning unit, a measurement control unit causes the camera to repeatedly capture the multiplexed light, A holder for housing the interference portion and the reference surface, formed of a material that reversibly deforms with temperature changes, and which changes the reference optical path length, which is the optical path length of the reference light between the interference portion and the reference surface, in accordance with the temperature changes. A temperature adjustment unit for adjusting the temperature of the holder, A temperature control unit that can selectively switch between a first measurement mode, which generates interference fringes in the multiplexed light by controlling the temperature adjustment unit to match the reference optical path length to the measurement optical path length, and a second measurement mode, which suppresses the generation of interference fringes in the multiplexed light by making the reference optical path length different from the measurement optical path length. A three-dimensional shape measuring device equipped with the following features.

2. When the temperature control unit switches to the first measurement mode, the camera repeatedly captures the multiplexed light during scanning by the scanning unit and outputs a plurality of first images including the interference fringes. The three-dimensional shape measuring device according to claim 1, further comprising a first shape calculation unit that calculates height information of the surface to be measured for each pixel based on the brightness values ​​of each pixel at the same coordinate of a plurality of first images output from the camera, thereby determining the three-dimensional shape of the surface to be measured.

3. When the temperature control unit switches to the second measurement mode, the camera repeatedly captures the multiplexed light during scanning by the scanning unit and outputs a plurality of second images in which the generation of interference fringes is suppressed. A three-dimensional shape measuring device according to claim 1 or 2, further comprising a second shape calculation unit that calculates the three-dimensional shape of the surface to be measured based on the result of calculating the change in focus in the scanning direction for each pixel at the same coordinate of a plurality of second images output from the camera.

4. The holder is equipped with a temperature measuring unit for measuring the temperature of the holder, The temperature control unit has previously acquired a target temperature that includes a first temperature corresponding to the first measurement mode and a second temperature corresponding to the second measurement mode. The three-dimensional shape measuring apparatus according to claim 1 or 2, wherein the temperature control unit controls the temperature adjustment unit based on the measurement result of the temperature measuring unit and the target temperature to switch between the first measurement mode and the second measurement mode.

5. The temperature adjustment unit changes the temperature of the reference surface housing portion that houses the reference surface within the holder, The three-dimensional shape measuring device according to claim 4, wherein the temperature measuring unit measures the temperature of the reference surface storage unit.

6. The three-dimensional shape measuring device according to claim 5, comprising at least an insulating material covering the reference surface storage section, the temperature measuring section, and the temperature adjustment section.

7. The three-dimensional shape measuring apparatus according to claim 1 or 2, wherein the scanning unit moves at least the holder and the camera in the scanning direction.

8. The system includes an objective lens that focuses the measurement light onto the surface to be measured, The interference portion is positioned between the objective lens and the surface to be measured. The three-dimensional shape measuring apparatus according to claim 1 or 2, wherein the reference surface is arranged between the objective lens and the interference portion.

9. A light source unit that emits white light for measurement, An interference unit that splits a portion of the measurement light emitted from the light source unit into reference light, emits the measurement light onto the surface to be measured and emits the reference light onto the reference surface, and generates a combined wave of the measurement light returning from the surface to be measured and the reference light returning from the reference surface, A camera that captures the multiplexed light generated by the interference unit, When the optical path length of the measurement light between the interference unit and the surface to be measured is defined as the measurement optical path length, the scanning unit scans the interference unit and the camera relative to the surface to be measured in the scanning direction in which the measurement optical path length changes, A holder for housing the interference portion and the reference surface, formed of a material that reversibly deforms with temperature changes, and which changes the reference optical path length, which is the optical path length of the reference light between the interference portion and the reference surface, in accordance with the temperature changes. In a method for switching the measurement mode of a three-dimensional shape measuring device equipped with, A method for switching the measurement mode of a three-dimensional shape measuring device, comprising: a first measurement mode in which interference fringes are generated in the combined light by adjusting the temperature of the holder to match the reference optical path length to the measurement optical path length; and a second measurement mode in which the generation of interference fringes in the combined light is suppressed by making the reference optical path length different from the measurement optical path length.

Images