JPH05264237A - Method and device for measuring surface of rotation - Google Patents

Abstract

PURPOSE:To provide a method and a device capable of accurately measuring the configuration and the profile irregularity of a surface of rotation. CONSTITUTION:Interference fringes are formed as to one cross section to be measured of a surface of rotation and are focused on first and second sensors 10, 15 by a focusing optical system 9 and an optical path dividing element 14. When scanning is performed along an axis of rotation by a translational block 13, movement of the measured cross section in the direction of the optical axis is measured as a flow of the stripes of the image of the interference fringes. The output of the first sensor 10 is stored on storage means 16. The stripes flowing on the image of the interference fringes detected by the second sensor 15 are counted by a counting means 18 and the displacement of the cross section in the direction of the optical axis is calculated. An equation of a bus in the direction of scanning is calculated by a bus calculation means 19 together with the displacement and the amount of movement of the translational block 13. Since the device is divided into the first and second sensors, processing is achieved at early stages and measuring can be done in a short time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for measuring the surface shape and surface accuracy of a rotating surface such as a toroidal surface, and in particular, forming an interference fringe on one measurement cross section of the rotating surface as a surface to be inspected. Scan the rotation surface along the rotation axis to form interference fringes one after another, and connect the interference fringes together to measure the surface accuracy and shape of the entire rotation surface in a short time. It is related to measurement technology.

[0002]

2. Description of the Related Art A rotating surface is a surface formed by generating an arbitrary curved line including a straight line as a generatrix and rotating the generatrix around a rotation axis. Typical examples are a toroidal surface and a cylindrical surface. is there. Then, as a technique capable of measuring the surface accuracy of the toroidal surface with high accuracy of a wavelength or less, the applicant of the present application discloses in Japanese Patent Application No. 2-126659 that the G main line of two main diameter lines orthogonal to each other on the toroidal surface. Radius line (bus bar) is short and R
A method for measuring a toroidal or toroidal surface (hereinafter referred to as "NTS") having a long main diameter line has been proposed.

[0003] Further, Japanese Patent Application No. 3-
No. 050104 proposes a method for measuring a barrel-shaped toroidal surface (BTS) or a saddle-shaped toroidal surface (KTS) having a long G main diameter line and a short R main diameter line. Figure 11 (a),
This will be explained below according to (b).

In FIG. 1, reference numeral 1 denotes a light source, which is a gas laser or semiconductor laser having high coherence. 2a,
2b is a beam expander for expanding a narrow light beam from the light source 1 to an appropriate size. 3 is a spatial filter, which cuts off unnecessary light such as ghost light and reflected light. An optical isolator 4 is a beam splitter 4a, λ /
It has four plates 4b and a reflecting surface 4c.

The light beams expanded by the beam expanders 2a and 2b reach the toroidal surface 7a as the surface to be inspected of the object 7 through the objective lens 6. This toroidal surface 7a
Of the G main radial lines AB and R main radial lines CD orthogonal to each other at the apex, is a rotation surface formed by rotating around the rotary shaft 12 with the G main radial line as the generatrix.

The final surface of the objective lens 6 is a reference surface 6a as a semi-transparent mirror, and the center of curvature thereof coincides with the rotation axis 12 described above. Further, the reference surface 6a or the toroidal surface 7a is arranged so as to be slightly shiftable and / or tiltable in the xz section. Then, a part of the light incident on the objective lens 6 is reflected by the reference surface 6a, and the rest is transmitted to irradiate the toroidal surface 7a, and is reflected from here.

Reference numeral 13 denotes a translation table for fixing the subject 7, which is driven by a linear motor, a linear air slider or the like (not shown) and can scan the toroidal surface 7a in parallel with the rotary shaft 12.

The coherent light beams reflected by the reference surface 6a and the toroidal surface 7a are returned and superposed on the incoming optical path, and the reference surface 6a.
12 and the toroidal surface 7a interfere with each other in one measurement section parallel to the R main diameter line which can be regarded as substantially parallel, and the focusing lens 9 forms an interference fringe image 11 as shown in FIG. 12 on the area sensor 10. ..

When the translation table 13 is scanned along the rotation axis 12, the measurement cross section moves and interference fringe images are formed one after another.
By connecting these, the surface shape and surface accuracy of the entire toroidal surface 7a can be measured. Further, the above-mentioned device is not limited to the BTS, and can measure all the rotating surfaces such as all toroidal surfaces and cylindrical surfaces. Further, in this case, it should be noted that even if the rotation axis is a three-dimensionally curved rotation surface, the translation table may scan in accordance with the bending of the rotation axis, so that it is applicable.

FIG. 13 is a diagram showing the positional relationship between the toroidal surface and the reference surface. In the figure, O indicates the center of curvature of the G main radial line AB (bus line) of the surface to be inspected or the toroidal surface 7a. Of the reference surfaces 6a ₁ and 6a ₂ , one reference surface 6a ₁ is located at the center of the surface 7a to be detected, and the other reference surface 6a ₂ is the center of the surface 7a to be detected by scanning the translation table 13. It shows a state in which it has been moved downward from the position by h. During this time, the coherent light irradiates the reference surface 6a and the test surface 7a so that the coherent light is always focused on the rotating shaft 12.

When the reference surface comes to the position of 6a ₁ as shown in FIG. 13, the reference wave reflected at the center of the reference surface 6a ₁
The test wave reflected from the measurement section 7a _{1 at} the center of the test surface 7a is reflected and superimposed as shown by the arrow to form an interference fringe.

Next, when the reference surface 6a is moved to the position of 6a ₂ by scanning, the reference wave and the test wave which are reflected at a right angle to both the reference surface 6a ₂ and the test surface 7a interfere with each other. The test wave reflected in the direction of and the reference wave interfere with each other. At this time, the measurement cross section 7a ₂ is Δ in the direction of the rotation axis 12.
The h shift and the interference fringe image are formed with a Δh ′ shift from the center of the reference surface 6a ₂ . 14, the reference surface is an interference fringe image 11 ₁ when in 6a _1, the reference surface is an indication the interference fringe image 11 ₂ when there is a movement in the 6a _2.

On the other hand, the measurement cross sections 7a ₁ and 7a ₂ are shown in FIG.
When the surface shape of the rotating surface is measured as shown in (4) by Δd in the optical axis direction, it is necessary to obtain Δd for the scanning amount h + Δh and specify the shape of the busbar by an equation or the like. Here, the value of h can be read from the linear encoder provided on the translation table 13, and Δh can be obtained by calculation or drawing from the value of h if the bus bar is known. When the bus bar is unknown, Δh ′ is obtained by actual measurement, and the following equation Δh ′ = f sin θ (f is the focal length of the reference lens 6) (1) Δh = (r ₀ −Δd) sin θ (2) ∴ Δh can be obtained from Δh = Δh ′ (r ₀ −Δd) / f (3) if the displacement amount Δd in the optical axis direction is known. In addition, here, the radius of curvature r of the R main radius line
₀ can be measured by a known method such as cat's eye interferometry.

The displacement amount Δd in the optical axis direction can be obtained as follows. When the measurement cross section moves in the optical axis direction, the interference fringe image on the sensor has a stripe pattern flowing in any of the x directions in FIG. Therefore, if an observation point is set on the interference fringe image 11 and the number of fringes passing through the observation point is counted, the wavelength of the coherent light is known, and the displacement amount Δd can be obtained. For that purpose, the output change of the element of the sensor 10 corresponding to the observation point may be counted. Then, by substituting the obtained Δd into the above equation (3), Δh can be obtained and the busbar can be obtained.

[0015]

However, in the above measuring apparatus, since the sensor for taking the data of the interference fringe image and the sensor for taking the intensity signal of the observation point are the same, it takes a long time for the measurement. There was a problem that it passed.
The present invention has been made to solve this problem, and an object of the present invention is to provide a method and apparatus capable of accurately measuring the surface shape and surface accuracy of a rotating surface in a short time.

[0016]

In order to achieve the above object, the measuring method of the present invention irradiates coherent light from the same light source on a surface to be inspected and a reference surface which is a reference, and reflects from both surfaces. A step of forming an interference fringe on one measurement cross section of the surface to be inspected by superimposing the reference wave and the wave to be inspected, and forming the interference fringe continuously by scanning the surface to be inspected along the rotation axis of the rotating surface. And a step of dividing the superposed reference wave and the test wave into two optical paths,
The step of forming the interference fringe image on the first and second sensors in each optical path, the step of storing the data of each interference fringe image formed on the first sensor, and the step of forming the interference fringe image on the second sensor. A step of measuring intensity signals at at least two designated observation points having a phase difference of approximately nπ / 2 (n is a natural number), the number of inversions of the intensity signals of the interference fringes detected at these observation points, and the interference fringes. The step of calculating the shape of the surface to be inspected in the scanning direction from the moving direction of the object, and the step of measuring the shape and accuracy of the entire surface from the interference fringe data stored in the first sensor and the shape calculated via the second sensor. It is characterized by a configuration consisting of.

Alternatively, the position of the interference fringe image detected by the first sensor is transmitted to the second sensor to position the second sensor, or the second sensor outputs the intensity signals of the plurality of observation points. It is configured to perform parallel processing, or the first
The sensor may be an area sensor, the data of the interference fringe images of a plurality of lines may be stored, and the center position of the interference fringe image may be detected from the phase of the interference fringe data of each line.

Further, the measuring apparatus of the present invention irradiates the coherent light from the same light source on the surface to be inspected and the reference surface as a reference, and superimposes the reference wave and the wave to be inspected reflected from both surfaces. A device for forming interference fringes on one measurement cross section of the surface to be inspected, a translation table for supporting the object to be scanned along the rotation axis of the rotating surface and issuing a scanning amount signal, the superimposed reference wave and object wave to be detected. And an optical path splitting means for splitting the optical path into two optical paths, first and second sensors for forming an interference fringe image in each optical path, means for storing data of the interference fringe image from the first sensor, and second The sensor detects the intensity signals of the interference fringes at at least two or more observation points on the sensor where the phase difference of the interference fringes is approximately nπ / 2 (n is a natural number) and inverts the intensity signal at each observation point. Observing point output counting means for counting the number, and observing point output counting means A bus bar calculating means for calculating the shape of the rotating surface in the scanning direction from the movement amount signal of the translation table, the interference fringe data of the interference fringe data storing means, and the bus bar shape of the bus bar calculating means, and the surface shape of the entire rotating surface and It is characterized by a configuration including a calculation means for calculating the surface accuracy.

Alternatively, there is provided a moving means for transmitting the position of the interference fringe image detected by the first sensor to the second sensor and positioning the second sensor, or the second sensor is provided with the plurality of observations. A configuration that is a sensor that can output point signal outputs in parallel, or that the first sensor is an area sensor, and an interference fringe image of a plurality of lines is formed between the first sensor and the interference fringe data storage means. It is desirable to adopt a configuration in which line detection means for storing data and detecting the center position of the interference fringe image from the phase of the interference fringe data in each line is provided.

[0020]

The coherent light is applied to the test surface and the reference surface, the reference wave and the test wave are superposed and interfered with each other, and split into two optical paths by the optical path splitting element, and then combined on the first and second sensors. Make them image. When the surface to be inspected is scanned along the rotation axis by the translation table, the distance between the measurement section and the reference surface in the optical axis direction changes, and a striped pattern of interference fringe images flows. The first sensor measures the image forming position of the interference fringe image and the surface accuracy information in the direction along the measurement cross section. The second sensor counts the number of fringes flowing through each of the multiple observation points whose fringe phases are nπ / 2 apart on the interference fringe image, and shifts the number of fringes and the wavelength of the coherent light in the optical axis direction. The amount is calculated, and the equation of the generatrix in the scanning direction is calculated together with the movement amount of the translation table. By combining the data from the first and second sensors, the shape and surface accuracy of the entire rotating surface can be measured. Further, since the sensor is divided into the first and second sensors, the processing time is shortened and the measurement can be performed in a short time.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a block diagram of an apparatus of the present invention. In FIG. 1, the one surrounded by a dotted line is the same interference optical system as shown in FIG. 11, the inside shows only a focusing lens 9, and the others are omitted. is doing. The other part surrounded by a dotted line shows the CPU of the computer.

Reference numeral 14 denotes an optical path splitting element which splits the light from the focusing lens 9 into two directions and is composed of a beam splitter having a semitransparent mirror 14a. A second sensor 15 is a CCD line sensor, and an interference fringe image 11 is formed on the first sensor and the second sensor. An interference fringe data storage means 16 stores the interference fringe image data from the first sensor 10 in a RAM, a floppy disk or the like.

Reference numeral 17 is a moving means for moving the second sensor 15 to a position where an interference fringe image is formed. Reference numeral 18 is an observation point output counting means, which counts the output of the element corresponding to the observation point of the interference fringe image and obtains the displacement amount Δd of the measurement cross section in the optical axis direction from the wavelength of the coherent light.

Numeral 19 is a busbar calculating means for determining the busbar equation from the above Δd and the translation amount h of the translation platform 13. Reference numeral 20 denotes a surface shape / accuracy calculating means, which calculates the surface shape from the equation of the busbar and the accuracy of each measurement section.

Reference numeral 21 denotes a display unit which displays the measured surface shape and surface accuracy of the surface to be inspected, and is composed of, for example, a display or a printer. Of these, the interference fringe data storage means 1
6, a CPU or the like of a host computer is applied to each of the observation point output counting means 18, the busbar calculating means 19, and the surface shape / accuracy calculating means 20.

The operation of the present invention will be described with reference to the flowcharts of FIGS. 1 and 2 and FIGS. 3 to 7. The light beam on which the reference wave emitted from the focusing lens 9 and the test wave are superimposed is
The optical path splitting element 14 splits the optical path into two optical paths, one of which passes through the semi-transparent mirror 14a and forms an interference fringe image 11 on the first sensor 10 which is the same CCD area sensor as the conventional sensor. The other is reflected by the semi-transparent mirror 14a and forms an interference fringe image 11 on the second sensor 15.

From this state, the subject is moved in parallel by an appropriate distance. Along with this, the cross section to be measured moves in the optical axis direction, and the striped pattern of the interference fringe image 11 flows in any of the x axis directions shown in FIG. 3, and simultaneously moves in the y axis direction (# 1).
After the translational movement by a predetermined amount, the position coordinates of the translational table 13 at that time, that is, the translational movement amount h is read (# 2). Next, the data of the interference fringe image after the translational movement is set to the first sensor 10
The read interference fringe data is input from each line to the interference fringe data storage means 16 (# 3). The interference fringe data storage means 16 detects the line with the highest output fluctuation (PV value) of each line (# 4) and stores the data of that line (# 5).

As shown in FIG. 3, an interference fringe image 1 before translational movement
1, the two observation points P that are shifted by approximately π / 2 in the phase of the interference fringe
₁ and P ₂ are determined, and the outputs I ₁ and I ₂ of the elements corresponding to the observation points P ₁ and P ₂ on the second sensor 15 are taken out as shown in FIG. Then, when the light is translated on the translation stage, the distance on the optical axis of the measurement cross section changes, so that a stripe pattern of interference fringes flows and the outputs I ₁ and I _{2 of the} element change. As shown in FIG. 5, the vertical axis represents signal intensity I and the horizontal axis represents time t.
I ₁ and I ₂ corresponding to ₁ and P ₂ draw a sine curve with a phase shift of π / 2.

As shown in FIG. 6, the vertical axis indicates the observation point P.₂Strength of
Degree signal I₂And the observation point P on the horizontal axis ₁Intensity signal I₁To
A point P (I₁，
I₂) Is plotted. When the measurement cross section approaches in the optical axis direction
If point P is clockwise in that case, counterclockwise when going away.
Since it becomes a rotation, the moving direction of the measurement section can be easily identified.
Will be. Also, in FIG.
If the rotation is calculated, Δd of the surface to be inspected, that is, the amount of displacement and
And the direction of displacement can be known. Observe the above operations
This is performed by the point output counting means 18 (# 6).

In # 5, the line with the highest PV value is detected, but a signal indicating the position of this line is input to the moving means 17, and the position of the second sensor is controlled accordingly (# 7). ), So that an interference fringe image is always formed on the second sensor 15.

The above steps # 1 to # 7 are repeated until the measurement of the entire rotating surface is completed (# 8). After this,
The value of Δd from the observation point output counting means 18 and the value of the translation amount h from the translation table 13 are input to the busbar computing means 19, and Δh 'is calculated to obtain the shape of the busbar.

Further, the shape of the busbar is input to the surface shape / accuracy calculating means 20, combined with the interference fringe data from the interference fringe data storage means 16, and subjected to, for example, FFT processing, to obtain the surface shape of the entire rotating surface or The surface accuracy is calculated and displayed on the display unit 21. The FFT processing is described in the above-mentioned Japanese Patent Application No. 2-126659.

In the above measurement, the observation points are P ₁ , P
_{The number of} observation points is 2 and the interval is π / 2. However, if the number of observation points is set to 0, π / 2, π, 3π / 2 ... Be the way. Also, it is not necessary to set the intervals between the observation points to be exactly π / 2 intervals,
It's easy to see what's good.

If the line connecting the central portions of the interference fringe images 11 measures the shape along the α cross section in FIG. 7, the observation points P ₁ and P ₂ shown in FIG. The shape along the β cross section will be measured. However, as long as it is a surface of revolution, the same applies to determining the equation of the generatrix of the surface of revolution in any case.

In the above embodiment, the position of the second sensor 15 is controlled by the output from the interference fringe data storage means 16. However, when the generatrix of the rotating surface is a straight line, the interference fringe image is in the y-axis direction. May not move to the
May be unnecessary. Further, since the position of the second sensor may be manually operated, the moving means 17 is not essential.

FIG. 8 is a block diagram showing another embodiment of the present invention. In the above-described embodiment, only one line having the highest PV value is read from the first sensor, but the PV value of a line different from the actual line may be higher due to the influence of stray light or the like. is there. This embodiment prevents such drawbacks.

FIG. 9 shows a state in which the interference fringe image 11 is formed on the first sensor 10. However, since the surface 7a to be inspected is an aspherical surface, the fringe pattern does not become a straight line, and FIG. As shown, it is convex upward or, conversely, it is convex downward (not shown). That is, the initial phase of the interference fringe is either most advanced in the central part or, conversely, most delayed.

Therefore, as indicated by reference numerals 1 to 7 in the figure, among a number of lines forming the first sensor, a line having the highest PV value with respect to the interference fringe 11 and a plurality of lines on both sides thereof are considered. The data about the line is stored in the interference fringe data storage means 16. Then, by calculating the initial phase of the interference fringes for each line and plotting the initial phase of each line in a graph as shown in FIG. 10, it is easy to determine which line the phase is most advanced or delayed. Therefore, the central line of the interference fringe image can be extracted without being affected by stray light or the like.

The line detecting means 22 shown in FIG. 8 takes the interference fringe data for a plurality of lines, calculates the phase, and detects the line at the center of the interference fringes. Figure 9,
In the tenth embodiment, since the line 4 corresponds, the information on this line is input to the interference fringe data storage means.
The interference fringe data storage means 16 is the same as in the above-mentioned embodiment.
The moving means 17 is instructed to move the second sensor to the position corresponding to the line 4. Further, the interference fringe data of the 4th line is output to the surface shape / accuracy calculating means 20. The subsequent steps are the same as those in the above-mentioned embodiment.

In the above embodiment, the second sensor has a C
Although the CD line sensor is used, the CCD line sensor detects the output of each element one by one in a time series, so that it takes a long time for detection. Therefore, if the number of photodiodes corresponding to the number of observation points is arranged, parallel processing can be performed, so that the detection time can be shortened.

[0041]

As described above, according to the present invention, when measuring the surface shape of the rotating surface, an interference fringe image for one measurement section is formed on two sensors, and the first sensor is used. Since the interference fringe data is stored and the surface shape in the scanning direction is measured by the second sensor, the surface shape and surface accuracy of the rotating surface can be measured accurately and at high speed.

Further, by measuring the output of a plurality of lines by the line detecting means, the center position of the interference fringe can be known without being affected by stray light or the like. Furthermore, if the second sensor is configured to move according to the detection position from the interference fringe data storage means, it is possible to easily measure even a rotating surface having a complicated shape.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a rotating surface measuring device according to the present invention.

2 is a flow chart showing the operation of the apparatus of FIG.

FIG. 3 is an xy plane view showing an interference fringe image formed on a second sensor.

FIG. 4 is a diagram showing an interference fringe image on a CCD line sensor as a second sensor.

FIG. 5 is a graph showing the intensity change at the observation point on the interference fringe image, (a) is a diagram showing the intensity I ₁ at the observation point P ₁ ,
(b) is a diagram showing the intensity I ₂ of the observation point P ₂ .

FIG. 6 is a diagram illustrating a method of detecting a moving direction of a measurement cross section from intensities I ₁ and I _{2 of} observation points.

FIG. 7 is a perspective view showing a busbar measured by observation points P ₁ and P ₂ on a barrel-shaped toroidal surface.

FIG. 8 is a block diagram showing a main part of the second embodiment.

FIG. 9 is a diagram showing an interference fringe image formed on the first sensor.

FIG. 10 is a graph showing initial phases for a plurality of lines.

FIG. 11 is a diagram showing a toroidal surface measuring device of a BTS in the example of the prior application, (a) is a yz surface view, and (b) is an xz surface view.

FIG. 12 is a diagram showing interference fringes formed on an area sensor.

FIG. 13 is a yz plane view for explaining the positional relationship between a toroidal surface as a test surface and a reference surface.

FIG. 14 is a diagram illustrating a state in which an interference fringe image moves on a first sensor by scanning.

[Explanation of symbols]

 1 Light Source 6a Reference Surface 7a Test Surface 13 Translational Stage 9 Focusing Optical System 10 First Sensor 12 Rotation Axis 13 Translational Stage 14 Optical Path Splitting Element 15 Second Sensor 16 Interference Pattern Data Storage Means 17 Moving Means 18 Observation Point Output Counting Means 19 Busbar calculating means 20 Surface shape / accuracy calculating means 22 Line detecting means

Claims (8)

[Claims] 1. A measurement cross section of a surface to be inspected by irradiating the surface to be inspected and a reference surface serving as a reference with coherent light from the same light source, and superimposing the reference wave and the wave to be detected reflected from both surfaces. The step of forming interference fringes, the step of scanning the surface to be inspected along the rotation axis of the rotating surface to form the interference fringes continuously, and the superposed reference wave and the wave to be inspected are divided into two optical paths. , A step of forming an interference fringe image on the first and second sensors in each optical path, a step of storing data of each interference fringe image formed on the first sensor, and an interference fringe image by the second sensor. Measuring intensity signals at at least two designated observation points with a phase difference of approximately nπ / 2 (n is a natural number), and the number of inversions and interference of the intensity signals of the interference fringes detected at these observation points. Calculating the shape of the surface to be inspected in the scanning direction from the moving direction of the stripes; Method of measuring the rotational surface, characterized in that comprising the step of measuring the stored interference pattern data and shape from the entire surface shape and accuracy calculated via the second sensor in. 2. The method for measuring a rotating surface according to claim 1, wherein the position of the interference fringe image detected by the first sensor is transmitted to the second sensor to position the second sensor. 3. The second sensor processes the intensity signals of the plurality of observation points in parallel by the second sensor.
Alternatively, the method for measuring the rotating surface according to the item 2. 4. The first sensor is an area sensor,
4. The rotating surface according to claim 1, wherein data of interference fringe images for a plurality of lines are stored, and a center position of the interference fringe images is detected from a phase of the interference fringe data in each line. Measuring method. 5. A measurement cross section of a surface to be inspected by irradiating the surface to be inspected and a reference surface serving as a reference with coherent light from the same light source, and superimposing the reference wave and the wave to be detected reflected from both surfaces. A device for forming interference fringes, a translation stage that supports the subject and scans along the rotation axis of the rotating surface, and outputs a scanning amount signal; and an optical path that divides the superimposed reference wave and test wave into two optical paths. Splitting means, first and second sensors for forming an interference fringe image in each optical path, means for storing data of the interference fringe image from the first sensor, and position of the interference fringe in the second sensor Phase difference is almost n / 2
(N is a natural number) Observation point output counting means for detecting intensity signals of interference fringes at at least two or more observation points on a sensor apart from each other, and counting the number of inversions of the intensity signal at each observation point, and the observation point. A bus bar calculating means for calculating the shape of the rotating surface in the scanning direction from the output counting means and the movement amount signal of the translation table, the interference fringe data of the interference fringe data storage means, and the bus bar shape of the bus bar computing means, and the entire rotating surface. And a calculation means for calculating the surface shape and surface accuracy of the rotating surface measuring apparatus. 6. The rotating surface according to claim 5, further comprising moving means for transmitting the position of the interference fringe image detected by the first sensor to the second sensor and positioning the second sensor. measuring device. 7. The rotating surface measuring device according to claim 5, wherein the second sensor is a sensor capable of outputting signal outputs from the plurality of observation points in parallel. 8. The first sensor comprises an area sensor, and data of interference fringe images for a plurality of lines is stored between the first sensor and the interference fringe data storage means to thereby obtain an interference fringe in each line. 8. The rotating surface measuring device according to claim 5, further comprising line detection means for detecting the center position of the interference fringe image from the phase of the data.