JP5489690B2 - Interference measurement device - Google Patents

Description

  The present invention relates to highly accurate shape measurement and wavefront aberration measurement, and in particular, interference for measuring the surface shape of a reduction projection optical lens for a semiconductor exposure apparatus, a mirror, etc. and the wavefront aberration of an optical system with high accuracy. The present invention relates to a measuring device.

  Conventionally, it is common to use interference measurement such as a Fizeau interferometer or a Twiman-Green interferometer as a method for measuring the shape of a spherical lens and mirror with high accuracy. Further, along with recent miniaturization and higher precision of semiconductor exposure apparatuses, shape accuracy of 1 nm to 0.1 nm is required for lenses and mirrors. However, since there is a measurement error due to air fluctuations in the measurement space in the interference measuring apparatus, it is difficult to perform highly accurate measurement as required. In view of this, an interferometer and an optical measurement system that performs measurement with high accuracy by reducing the influence of air fluctuation by using a reduced pressure environment such as a vacuum for an object to be measured are used.

  Thus, in order to make the measurement space of the interferometer into a reduced pressure environment such as a vacuum, the optical system and the object to be measured need only be housed in a vacuum chamber. However, suppression of vibration is also important in a highly accurate interference measuring apparatus, and in order to do this, a vibration isolator, in particular, an active vibration isolator is required to remove low-frequency vibration. However, since it is not preferable to vibrate the entire vacuum chamber connected to a vibration source such as a vacuum pump with an active vibration isolator, it is necessary to vibrate the interference optical system and the object to be measured from outside the vacuum chamber.

  In view of this, it is conceivable to use a bellows to separate the vacuum and the atmosphere and absorb the movement of the interferometer with the bellows. For this type of bellows, a metal bellows welded with metal is used in order to withstand atmospheric pressure. The bellows should have low rigidity in order to block vibration. Therefore, in the metal bellows, by increasing the number of steps of the bellows, the rigidity is lowered in the direction in which the bellows expands and contracts and the direction in which the bellows inclines. However, there is a limit to increasing the number of steps of the bellows to reduce the rigidity, and a high-precision interference measurement device is unsuitable for using a metal bellows because even a slight vibration affects the measurement accuracy.

  In order to further reduce the rigidity of the bellows, there has been proposed one that uses an elastic bellows instead of a metal bellows to prevent vibration transmission (see Patent Document 1), and this elastic bellows is used as an interference measuring device. It is possible to apply. Further, there has been proposed a structure in which a bellows is prevented from being deformed in the expansion / contraction direction by adding a support part to the outside of the bellows, and a bellows having sufficiently low rigidity can be used in the expansion / contraction direction (see Patent Document 2).

Japanese Patent Laid-Open No. 4-136944 Japanese Patent Laid-Open No. 11-125309

  However, in the above-described conventional configuration, when a low-rigid elastic bellows is used, when there is a pressure difference between the inside and outside of the elastic bellows, there is a problem that the elastic bellows is compressed or expanded in a radial direction perpendicular to the expansion and contraction direction. is there. When the elastic bellows is deformed in the radial direction in this way, there is a problem that rigidity is increased and vibration is transmitted to the interferometer via the elastic bellows.

  Therefore, the present invention suppresses the deformation of the elastic bellows in the radial direction, maintains the state where the elastic bellows has low rigidity, and demonstrates the original performance of the vibration isolator, enabling interference measurement with high accuracy. The object is to provide a measuring device.

The present invention relates to a laser light source, an interference optical system that irradiates the object to be measured with light from the laser light source, and causes interference between the reflected light from the object to be measured and the reference light, and interference fringes obtained by the interference optical system. An interference measuring apparatus comprising: an imaging unit configured to capture an image; a vacuum chamber in which the interference optical system and an object to be measured are disposed; and the interference optical device disposed inside the vacuum chamber in a non-contact state with the vacuum chamber. A support unit that supports the system and the object to be measured; a vibration isolator disposed outside the vacuum chamber; and a vibration isolator that is isolated by the vibration isolator and supports the support unit through an opening formed in the vacuum chamber. and support legs, wherein disposed between the vacuum chamber and the vibration damping device as an outer vacuum chamber enclosing said support leg, strike in undeformed state that holds the vacuum chamber airtightly An elastic bellows which is formed over preparative cylindrical, is disposed inside the elastic bellows, the inner diameter is larger than the diameter of the support leg, smaller than the inner diameter of the elastic bellows outer diameter undeformed state And a single regulating member that contacts the inner surface of the elastic bellows and regulates deformation of the elastic bellows inward in the radial direction.

The present invention also provides a laser light source, an interference optical system that irradiates the object to be measured with light from the laser light source, and interferes with reflected light from the object to be measured and reference light, and interference obtained by the interference optical system. In an interference measuring apparatus including an imaging unit that images a fringe, a vacuum chamber in which the interference optical system and an object to be measured are arranged, a non-contact state with the vacuum chamber, and the inner side of the vacuum chamber, A support unit that supports the interference optical system and the object to be measured; a vibration isolator disposed outside the vacuum chamber; and the support unit that is vibration-isolated by the vibration isolator and formed through the opening formed in the vacuum chamber. a support leg for supporting the disposed between the vacuum chamber and the support portion as an inner vacuum chamber enclosing said support legs, undeformed state for holding the vacuum chamber airtightly An elastic bellows which is formed in a straight tubular, the disposed outside the elastic bellows, the inner diameter is set larger than the outer diameter of the elastic bellows undeformed state, the contact with the outer surface of the elastic bellows And a single regulating member that regulates deformation of the elastic bellows toward the outside in the radial direction.

  According to the present invention, since the deformation of the elastic bellows due to the pressure difference is suppressed by the regulating member, the rigidity of the elastic bellows can be kept low, and the elastic bellows effectively absorbs vibration transmitted from the vacuum chamber. be able to. Therefore, since the original performance of the vibration isolator can be exhibited, highly accurate interference measurement can be performed in the vacuum chamber.

It is explanatory drawing of the interference measuring apparatus which concerns on 1st Embodiment of this invention, (a) is a figure which shows schematic structure of an interference measuring apparatus, (b) is a figure which shows an elastic bellows. It is a figure for demonstrating a control member, (a) is a perspective view of a control member, (b) is a figure which shows the state by which the elastic bellows is controlled by the control member. It is explanatory drawing of the interference measuring device which concerns on 2nd Embodiment of this invention, (a) is a figure which shows schematic structure of an interference measuring device, (b) is a figure which shows the state by which the elastic bellows is controlled by the control member. It is.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is an explanatory diagram of an interference measuring apparatus according to the first embodiment of the present invention. An interference measuring apparatus 100 shown in FIG. 1A includes an interferometer 101. The interferometer 101 will be described as being a Fizeau interferometer, but is not limited thereto, and other types of interferometers such as a Twiman-Green interferometer and a Michelson interferometer may be used.

  The interferometer 101 includes an interferometer body 102, a mirror 103, a reference spherical lens 104 which is an interference optical system, a piezo driving device 105, and the like. The interferometer body 102 includes a laser light source 102A and a CCD camera 102B that is an imaging unit. The mirror 103 bends the parallel light from the laser light source 102A of the interferometer body 102 by 90 °. The reference spherical lens 104 is a lens that converts parallel light into a spherical wave and reflects a part of the light as reference light. The piezo drive device 105 changes the reference spherical lens 104 by ½ wavelength in the optical axis direction. A workpiece to be measured W that is a workpiece to be measured is disposed opposite to the reference spherical lens 104. The workpiece W to be measured is supported by a stage (not shown). The workpiece W to be measured is a lens or a mirror.

  Laser light, which is parallel light emitted from the laser light source 102A of the interferometer main body 102, is bent in the 90 ° direction by the mirror 103 inclined at 45 °. Part of the laser light incident on the reference spherical lens 104 is reflected by the reference spherical surface in the reference spherical lens 104, and the rest is transmitted as a spherical wave. The transmitted laser light is irradiated and reflected on the workpiece W to be measured, and the reflected light again follows the same optical path, and the reference spherical lens 104 interferes with the reflected light to generate interference fringes due to the interference light. . The interference fringes due to the interference light are imaged by the CCD camera 102B, and the image data is taken into the host computer 106.

  The host computer 106 analyzes the interference fringes and calculates the shape of the workpiece W to be measured. At this time, the reference spherical lens 104 is moved by ½ wavelength by the piezo driving device 105, and the image data of a plurality of interference fringes are captured and calculated in the meantime to improve the measurement accuracy.

  By the way, in this interference measurement, if there is an air fluctuation between the reference spherical lens 104 and the workpiece W to be measured, the optical path length of the laser light changes, causing a measurement error. Vibration also causes measurement errors. Therefore, in the first embodiment, the interference measuring apparatus 100 includes a vacuum chamber 108 that is depressurized by the vacuum pump 107, and the reference spherical lens 104 and the workpiece W to be measured are arranged inside the vacuum chamber 108. Has been. Since the reference spherical lens 104 and the workpiece W to be measured are arranged inside the decompressed vacuum chamber 108, interference fringes formed by causing the reference spherical lens 104 to interfere with the reflected light of the workpiece W to be measured and the reference light. It is possible to avoid an error due to air fluctuations from being superimposed on. The vacuum chamber 108 is supported on the floor F via legs 109.

  The vibration of the vacuum pump 107 is transmitted to the vacuum chamber 108, and the vibration of the floor F is transmitted via the legs 109. On the other hand, the reference spherical lens 104 and the workpiece W to be measured arranged inside the vacuum chamber 108 are supported by an active vibration isolator 110 arranged outside the vacuum chamber 108. The vibration isolator 110 is disposed on the floor F below the vacuum chamber 108. Thus, vibrations from the floor F and the vacuum chamber 108 are not transmitted to the reference spherical lens 104 and the workpiece W to be measured.

  More specifically, a box-shaped metal support 111 that supports the reference spherical lens 104 and the workpiece W to be measured is provided inside the vacuum chamber 108. The support portion 111 includes a bottom plate 111A and a top plate 111B. The bottom plate 111A is provided with a stage (not shown) on which the workpiece W to be measured is placed. Therefore, the workpiece W to be measured is supported by the support portion 111 via a stage or the like (not shown). An opening 111a through which light passes is formed at a position facing the reference spherical lens 104 of the top plate 111B.

  In the lower part of the vacuum chamber 108, an opening 108a facing the vibration isolator 110 is formed. Then, the rod-like support leg 112 that has been vibration-isolated by the vibration isolator 110 extends from the vibration isolator 110 to the bottom plate 111A of the support portion 111 through the opening 108a and is connected to the bottom plate 111A. The base end of the support leg 112 is supported in a non-contact manner by an electromagnetic motor 110a (for example, a Lorentz type magnetic levitation motor) of the vibration isolator 110. With the above configuration, the reference spherical lens 104 and the workpiece W to be measured arranged inside the vacuum chamber 108 are supported in a non-contact state with respect to the vacuum chamber 108 by the support legs 112, the support portions 111, and the like. Then, the reference spherical lens 104 and the workpiece W to be measured are vibration-isolated to the vibration isolator 110 via the support leg 112, the support portion 111, and the like.

  By the way, since an opening 108a is formed in the lower portion of the vacuum chamber 108, the interference measuring apparatus 100 is an elastic bellows that keeps the vacuum chamber 108 in an airtight state in order to maintain the degree of vacuum inside the vacuum chamber 108. 113 is provided.

  The elastic bellows 113 is made of rubber. Therefore, the rigidity in the axial direction (Z direction) and the direction orthogonal to the axial direction (XY direction) is lower than that of the metal bellows, and vibration can be effectively absorbed. The elastic bellows 113 is disposed between the vacuum chamber 108 and the vibration isolator 110 so as to surround the support leg 112 outside the vacuum chamber 108. As shown in FIG. 1B, the elastic bellows 113 is formed of a straight cylindrical member in an undeformed state. As described above, the elastic bellows 113 is formed of a straight cylindrical member in a non-deformed state. Therefore, the rigidity is lower in the direction perpendicular to the axial direction of the elastic bellows 113 than when the bellows is formed. Vibration can be absorbed.

When internal vacuum (vacuum) condition in the vacuum chamber 108, the elastic bellows 113, the pressure difference between the internal pressure of the atmospheric pressure and the vacuum chamber 108, compressed radially inward (arrow r ₁ direction) (crushed) modified Force acts. Therefore, in the first embodiment, the interference measuring apparatus 100 is disposed inside the elastic bellows 113, and contacts the inner surface of the elastic bellows 113 when the elastic bellows 113 is compressed and deformed so as to be radially inward of the elastic bellows 113. A restricting member 114 for restricting the deformation is provided.

  The regulating member 114 is formed of a rigid body such as metal, and as shown in FIGS. 2A and 2B, a ring member 114a formed in a ring shape having a larger diameter than the support leg 112, and a ring And a plurality of bar members 114b extending in the axial direction (Z direction) from the member 114a. The proximal end of the rod member 114b is fixed to the ring member 114a, and the distal end is fixed to the vibration isolator 110 (case). The regulating member 114 may not be a metal as long as it can withstand deformation of the elastic bellows 113 due to atmospheric pressure. Further, the configuration of the regulating member 114 may be any configuration as long as it can withstand the deformation of the elastic bellows 113 caused by atmospheric pressure. For example, the ring member 114a may be omitted.

  The inner diameter of the restricting member 114 is set larger than the diameter of the support leg 112. Further, the length of the restricting member 114 in the axial direction is set to be longer than half of the length of the elastic bellows 113 in the axial direction. Therefore, when the vacuum pump 107 is operated and the inside of the vacuum chamber 108 is depressurized, the elastic bellows 113 is elastically deformed by being compressed radially inward, but the inner surface of the elastic bellows 113 comes into contact with the regulating member 114 and the elastic bellows 113 is deformed. Deformation is regulated. Further, the outer diameter of the restricting member 114 is set to be equal to or smaller than the inner diameter of the elastic bellows 113 in a non-deformable state and equal to or larger than the inner diameter at the maximum deformation that can keep the rigidity of the elastic bellows 113 low. As described above, the deformation amount of the elastic bellows 113 is limited by the restriction member 114.

  Therefore, in the first embodiment, even if the elastic bellows 113 is deformed inward in the radial direction, the deformation is restricted by the restricting member 114. Therefore, the elastic bellows 113 is not deformed by the pressure difference between the atmospheric pressure and the pressure in the vacuum chamber 108. Deformation is suppressed. Therefore, the rigidity of the elastic bellows 113 can be kept low, and the vibration transmitted from the vacuum chamber 108 can be effectively absorbed by the elastic bellows 113. Therefore, since the original performance of the vibration isolator 110 can be exhibited, highly accurate interference measurement can be performed in the vacuum chamber 108.

  Even if the elastic bellows 113 is deformed radially inward, the elastic bellows 113 is regulated by the regulating member 114, and the elastic bellows 113 can be prevented from coming into contact with the support leg 112 that is a vibration isolation object. Therefore, since the elastic bellows 113 does not press the support leg 112, the original performance of the vibration isolator 110 can be effectively exhibited, and highly accurate interference measurement can be performed in the vacuum chamber 108.

  Here, the interferometer body 102 may be disposed inside the vacuum chamber 108, but in this embodiment, the interferometer body 102 is disposed outside the vacuum chamber 108 so that the operation of the interferometer body 102 is stabilized. Specifically, the interference measurement apparatus 100 includes a support base 121 that is disposed above the vacuum chamber 108 and on which the interferometer body 102 and the mirror 103 are placed. In the upper part of the vacuum chamber 108, an opening 108b facing the support base 121 is formed. The lower part of the support base 121 and the top plate 111B of the support part 111 are connected by the upper support leg 122, and the support base 121 is removed from the vibration isolator 110 via the support leg 112, the support part 111, and the upper support leg 122. Shake. That is, the interferometer main body 102 and the mirror 103 arranged outside the vacuum chamber 108 are also vibration-isolated by the vibration isolator 110, and as a result, the entire interferometer 101 is vibration-isolated by the vibration isolator 110.

  The interference measuring apparatus 100 is arranged between the vacuum chamber 108 and the support base 121 so as to surround the upper support leg 122 outside the vacuum chamber 108 and has the same structure as that of the elastic bellows 113. It has. The upper elastic bellows 123 keeps the vacuum chamber 108 airtight. Further, the interference measuring apparatus 100 is arranged inside the upper elastic bellows 123 and has the same configuration as the restriction member 114 that contacts the inner surface of the upper elastic bellows 123 and restricts the deformation of the upper elastic bellows 123 in the radial direction. An upper regulating member 124 is provided.

  Therefore, even if the upper elastic bellows 123 is deformed inward in the radial direction, the upper restricting member 124 restricts the deformation, so that the deformation of the upper elastic bellows 123 due to the pressure difference between the atmospheric pressure and the pressure in the vacuum chamber 108 is suppressed. The Accordingly, the rigidity of the upper elastic bellows 123 can be kept low, and the vibration transmitted from the vacuum chamber 108 can be effectively absorbed by the upper elastic bellows 123. Therefore, since the original performance of the vibration isolator 110 can be exhibited, highly accurate interference measurement can be performed in the vacuum chamber 108.

  Even if the upper elastic bellows 123 is deformed inward in the radial direction, the upper elastic bellows 123 is restricted by the upper restricting member 124, and the upper elastic bellows 123 is prevented from coming into contact with the upper support leg 122 that is the object of vibration isolation. can do. Therefore, since the upper elastic bellows 123 does not press the upper support leg 122, the original performance of the vibration isolator 110 can be effectively exhibited, and highly accurate interference measurement can be performed in the vacuum chamber 108. .

  In the support base 121 and the vacuum chamber 108, openings 121c and 108c are provided at positions corresponding to the optical path between the mirror 103 and the reference spherical lens 104. An optical window (not shown) through which light passes is installed in the opening 121c of the support base 121, and similarly, an elastic bellows 125 and a regulating member 126 are provided. If an optical window is provided in the opening 108c of the vacuum chamber 108, the elastic bellows 125 and the regulating member 126 can be omitted.

[Second Embodiment]
Next, an interference measuring apparatus 100A according to a second embodiment of the present invention will be described with reference to FIG. In FIG. 3, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  Since the opening 108a is formed in the lower part of the vacuum chamber 108, the interference measuring apparatus 100A includes an elastic bellows 113A that holds the vacuum chamber 108 in an airtight state in order to maintain the degree of vacuum inside the vacuum chamber 108. ing.

  The elastic bellows 113A is made of rubber. Therefore, the rigidity in the axial direction (Z direction) and the direction orthogonal to the axial direction (XY direction) is lower than that of the metal bellows, and vibration can be effectively absorbed. The elastic bellows 113 </ b> A is disposed between the vacuum chamber 108 and the support portion 111 so as to surround the support leg 112 inside the vacuum chamber 108. The elastic bellows 113A is formed of a straight cylindrical member in an undeformed state. As described above, the elastic bellows 113A is formed of a straight cylindrical member in a non-deformed state. Therefore, the rigidity is lower in the direction perpendicular to the axial direction of the elastic bellows 113A than when the bellows is formed. Vibration can be absorbed.

When internal vacuum (vacuum) condition in the vacuum chamber 108, the elastic bellows 113A, the pressure difference between the internal pressure of the atmospheric pressure and the vacuum chamber 108, the deformation force that expands outward in the radial direction (arrow r ₂ direction) acts To do. Therefore, in the second embodiment, the interference measuring apparatus 100A is disposed outside the elastic bellows 113A, and when the elastic bellows 113A is deformed, it contacts the outer surface of the elastic bellows 113A and deforms the elastic bellows 113A outward in the radial direction. 114A is provided.

  The inner diameter of the restricting member 114 </ b> A is set larger than the diameter of the support leg 112. Further, the length of the restricting member 114A in the axial direction (Z direction) is set to be longer than half of the length of the elastic bellows 113A in the axial direction (Z direction). Therefore, when the vacuum pump 107 is operated and the inside of the vacuum chamber 108 is decompressed, the elastic bellows 113A is elastically deformed to expand radially outward, but the outer surface of the elastic bellows 113A comes into contact with the regulating member 114A and the elastic bellows 113A Deformation is regulated. The inner diameter of the restricting member 114A is set to be equal to or larger than the outer diameter of the non-deformed elastic bellows 113A and equal to or smaller than the outer diameter at the maximum deformation that can keep the elastic bellows 113A in a low rigidity state. Thus, the deformation amount of the elastic bellows 113A is limited by the restricting member 114A.

  Therefore, in the second embodiment, even if the elastic bellows 113A is deformed radially outward, the deformation is restricted by the restricting member 114A. Therefore, the elastic bellows 113A is not deformed by the pressure difference between the atmospheric pressure and the pressure in the vacuum chamber 108. Deformation is suppressed. Therefore, the rigidity of the elastic bellows 113A can be kept low, and the vibration transmitted from the vacuum chamber 108 can be effectively absorbed by the elastic bellows 113A. Therefore, since the original performance of the vibration isolator 110 can be exhibited, highly accurate interference measurement can be performed in the vacuum chamber 108.

  Here, the interference measuring apparatus 100A has an upper elastic bellows having the same configuration as that of the elastic bellows 113A disposed between the vacuum chamber 108 and the support 111 so as to surround the upper support leg 122 inside the vacuum chamber 108. 123A. The vacuum chamber 108 is kept airtight by the upper elastic bellows 123A. Further, the interference measuring apparatus 100A is arranged outside the upper elastic bellows 123A, and has the same configuration as the restriction member 114A that contacts the outer surface of the upper elastic bellows 123A and restricts the deformation of the upper elastic bellows 123A to the radially outer side. An upper regulating member 124A is provided.

  Therefore, even if the upper elastic bellows 123A is deformed radially outward, the upper restricting member 124A restricts the deformation, so that the deformation of the upper elastic bellows 123A due to the pressure difference between the atmospheric pressure and the pressure in the vacuum chamber 108 is suppressed. The Accordingly, the rigidity of the upper elastic bellows 123A can be kept low, and the vibration transmitted from the vacuum chamber 108 can be effectively absorbed by the upper elastic bellows 123A. Therefore, since the original performance of the vibration isolator 110 can be exhibited, highly accurate interference measurement can be performed in the vacuum chamber 108.

  In the support base 121 and the vacuum chamber 108, openings 121c and 108c are provided at positions corresponding to the optical path between the mirror 103 and the reference spherical lens 104. The opening 108c of the vacuum chamber 108 is provided with an optical window (not shown) through which light is transmitted. In the case where an optical window (not shown) is installed in the opening 121c of the support base 121, similarly, an elastic bellows and a regulating member may be provided.

  Although the present invention has been described based on the above embodiment, the present invention is not limited to this. In the above embodiment, the opening 108 a is formed in the lower part of the vacuum chamber 108, and the support leg 112 extending from the vibration isolator 110 is connected to the support 111 through the opening 108 a to isolate the interference optical system and the object to be measured. However, the present invention is not limited to this. That is, the position of the opening formed in the vacuum chamber is not limited to the lower part, and can be arbitrarily formed, for example, at the upper part or the side part of the vacuum chamber. Similarly to the above-described embodiment, a support leg extending from the vibration isolator through the formed opening may be connected to the support to dampen the interference optical system and the object to be measured. Also in this case, the elastic bellows is disposed so as to surround the support leg and holds the vacuum chamber in an airtight manner, and the regulating member may be provided corresponding to the elastic bellows.

100, 100A Interferometry apparatus 101 Interferometer 102 Interferometer body 102A Laser light source 102B CCD camera (imaging unit)
104 Reference spherical lens (interference optical system)
107 vacuum pump 108 vacuum chamber 108a opening 110 vibration isolator 111 support 112 support leg 113, 113A elastic bellows 114, 114A regulating member 121 support base 122 upper support leg 123, 123A upper elastic bellows 124, 124A upper regulating member W Measurement work (object to be measured)

Claims (5)

A laser light source, an interference optical system that irradiates the object to be measured with light from the laser light source, and causes interference between the reflected light from the object to be measured and the reference light, and an imaging unit that captures interference fringes obtained by the interference optical system In an interference measurement device comprising:
A vacuum chamber in which the interference optical system and the object to be measured are arranged;
A support part that is disposed inside the vacuum chamber in a non-contact state with the vacuum chamber and supports the interference optical system and an object to be measured;
A vibration isolator disposed outside the vacuum chamber;
A support leg that is isolated by the vibration isolator and supports the support through an opening formed in the vacuum chamber;
It is arranged between the vacuum chamber and the vibration isolator so as to surround the support leg outside the vacuum chamber, and is formed in a straight cylindrical shape in an undeformed state to hold the vacuum chamber airtight. With an elastic bellows,
The elastic bellows is disposed inside the elastic bellows, has an inner diameter larger than the diameter of the support leg, and an outer diameter smaller than an inner diameter of the elastic bellows in an undeformed state, and contacts the inner surface of the elastic bellows. An interference measuring device comprising: one restricting member that restricts deformation inward in the radial direction. A laser light source, an interference optical system that irradiates the object to be measured with light from the laser light source, and causes interference between the reflected light from the object to be measured and the reference light, and an imaging unit that captures interference fringes obtained by the interference optical system In an interference measurement device comprising:
A vacuum chamber in which the interference optical system and the object to be measured are arranged;
A support part that is disposed inside the vacuum chamber in a non-contact state with the vacuum chamber and supports the interference optical system and an object to be measured;
A vibration isolator disposed outside the vacuum chamber;
A support leg that is isolated by the vibration isolator and supports the support through an opening formed in the vacuum chamber;
It is arranged between the vacuum chamber and the support portion so as to surround the support leg inside the vacuum chamber, and is formed in a straight cylindrical shape in an undeformed state that holds the vacuum chamber in an airtight manner. An elastic bellows,
Is arranged outside of the elastic bellows, the inner diameter is set larger than the outer diameter of the elastic bellows undeformed state, one that contacts the outer surface of the elastic bellows to restrict the deformation in the radial direction outside of the elastic bellows interference measuring apparatus characterized by comprising a regulating member, a. A support table disposed above the vacuum chamber and on which the laser light source and the imaging unit are placed;
An upper support leg that connects the support and the support through an opening formed in the upper part of the vacuum chamber;
An upper elastic bellows that is disposed outside the vacuum chamber and between the vacuum chamber and the support so as to surround the upper support leg, and holds the vacuum chamber in an airtight manner;
2. An upper regulating member disposed inside the upper elastic bellows and contacting an inner surface of the upper elastic bellows to regulate deformation of the upper elastic bellows in the radial direction. Or the interference measuring apparatus of 2. A support table disposed above the vacuum chamber and on which the laser light source and the imaging unit are placed;
An upper support leg that connects the support and the support through an opening formed in the upper part of the vacuum chamber;
An upper elastic bellows which is disposed between the vacuum chamber and the support portion so as to surround the upper support leg inside the vacuum chamber, and holds the vacuum chamber in an airtight manner;
2. An upper regulating member disposed outside the upper elastic bellows and configured to contact the outer surface of the upper elastic bellows and restrict deformation of the upper elastic bellows in the radial direction. Or the interference measuring apparatus of 2. The upper elastic bellows, interference measuring apparatus according to claim 3 or 4, characterized in that it is formed in a straight tubular in undeformed state.

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