JPH0782533B2 - Shape measuring device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a shape measuring device for measuring the shape of a minute member such as a hand of a timepiece.

[Background of the Invention]

When the hands are attached to the timepiece during the manufacture and assembly of the timepiece, if the hands are bent, the hands will not contact each other or the hands will contact the glass, and the hands will not rotate smoothly.
Since problems such as time error and stoppage of the clock occur, it is necessary to measure the curved shape of the needle, especially for automatic assembly.

[Conventional technology]

Conventionally, as a method of measuring the shape of a minute member, a measured object is photographed by a TV camera, a video signal of a two-dimensional image is obtained, binarized at an appropriate threshold level, and it is determined according to the number of pixels of the TV camera. It is general that the pattern data is stored in a memory element and arithmetic processing is performed for shape recognition.

[Problems to be solved by the invention]

The pattern recognition method using the TV camera described above is used 2
-Dimensional TV camera currently has only a few hundred pixels on each side and poor resolution, and when the magnification of the TV camera is increased when the DUT is small, setting in the depth of focus direction is allowed. Since the range is narrowed, there are many problems in measurement such that the set position of the object to be measured cannot be changed. Further, there is a problem in that the cost of the apparatus becomes high, for example, when storing pattern data as a two-dimensional image, an extremely large number of memory elements are required, and an image processing unit for performing high-speed calculation is required. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional problems and enable the recognition of the shape of a minute member at a low cost with a simple device.

[Means for solving problems]

In order to achieve the above object, the present invention has the following configuration.

A light source, a first optical element group including a cylindrical lens for converting the shape and emission direction of a light beam from the light source, a first electromagnetically driven reflecting mirror, and a spherical lens, and light from the first optical element group. Beam to be measured, second optical element including Fourier transform lens for converting optical information and detection direction of light beam from the object, second electromagnetic drive reflection mirror and Fourier inverse transform lens A group, a photodetector for receiving a light beam from the second optical element group, a current supply source for supplying a current for controlling a reflection rotation angle of the first and second electromagnetically driven reflection mirrors, A data processing unit that converts the optical information obtained by the light detection unit into an electric signal to calculate the shape is provided.

At this time, the second electromagnetically driven reflecting mirror is arranged at the confocal position of the Fourier transform lens and the inverse Fourier transform lens, and has a low-pass type spatial filter configuration. Furthermore the first
The ratio of the current corresponding to the ratio of the focal lengths of the spherical lens and the Fourier transform lens included in the optical element group
And controlling the rotation angle of the second electromagnetically driven reflecting mirror.

[Action]

When the shape measurement is performed with the above configuration, a light beam from the light source is formed into an elliptical light beam by the first optical element group and is irradiated on the object to be measured. Since this elliptical light beam is a light beam having a substantially one-dimensional spread, the light beam is scanned by the first electromagnetically driven reflection mirror when measuring the object to be measured having a two-dimensional spread. . The light beam containing the optical information of the object to be measured reproduces the image by the object to be measured by the combination of the Fourier transform lens and the inverse Fourier transform lens included in the second optical element group. A spatial filter that cuts optical harmonic noise (higher-order diffracted light) is provided on the spectrum surface, but when the light beam is scanned, the light detection that receives the light beam from the second optical element group is performed. The second electromagnetically driven reflecting mirror also performs the operations of the above-described spatial filter and the reflecting mirror that controls the reflection of the light beam so that the position of incidence on the unit is always constant.

At this time, the spherical lens included in the first optical element group and the second lens
If the first and second electromagnetically driven reflecting mirrors are operated at a current ratio according to the ratio of the focal lengths of the Fourier transform lenses included in the optical element group, the light beam is always scanned at a fixed position. It becomes possible to detect the optical information of the object to be measured.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a shape measuring apparatus showing an embodiment of the present invention. 10 is a light source. It is advantageous to use a laser beam as a light source because the light intensity distribution is uniform and stable, parallel rays can be easily obtained, and the S / N ratio of optical information to be detected is good.

Reference numeral 11 is a first optical element group, 110 is a cylindrical lens having a focal length f ₀ , 111 is a first electromagnetically driven reflecting mirror, and 112 is a spherical lens such as a plano-convex lens having a focal length of f ₁ . 12
Is an object to be measured, such as a clock hand. 13 is a second optical element group, 130 is a Fourier transform lens having a focal length of f ₂ , 131 is a second electromagnetically driven reflecting mirror, and 132 is a Fourier inverse transform lens having a focal length of f ₃ . Fourier transform lens 13 here
As the 0 and the Fourier inverse transform lens 132, a plano-convex lens may be used. Reference numeral 14 is a photodetection unit that detects the light emitted from the inverse Fourier transform lens 132. Since the light emitted from the inverse Fourier transform lens 132 has an elliptical beam shape that is one-dimensionally spread, the light detection unit 14 may be configured by a one-dimensional CCD line sensor. 15 is a current supply source. Current source
Reference numeral 15 supplies a current for controlling the rotation angle of reflection of the first electromagnetically driven reflective mirror 111 and the second electromagnetically driven reflective mirror 131. A data processing unit 16 converts the optical information obtained by the photodetection unit 14 into an electric signal to calculate the shape of the place corresponding to the scanning of the light beam and the entire shape, and at the same time, to supply the current 15 Control. The light beam 100 emitted from the optics 10 has a circular shape, and the combination of the cylindrical lens 110 and the spherical lens 112 forms an elliptical light beam that spreads in almost one dimension. At this time, the first electromagnetically driven reflection mirror 111 is arranged at the confocal position between the cylindrical lens 110 and the spherical lens 112. The first electromagnetically driven reflection mirror 111 is provided with a first current i from the current supply source 15.
₁ is applied, and the rotation angle of reflection is changed according to the magnitude of the current i ₁ . When the DUT 12 is a minute member, the transmitted light from the DUT 12 is affected by diffraction, and a Fraunhofer diffraction image is formed at the focal position of the inverse Fourier transform lens 130. This surface corresponds to the spectrum surface, but if the inverse Fourier transform lens 132 is arranged at the focal position behind the spectrum surface, the image of the DUT 12 will be reproduced again.

The spectrum plane is a position where the light beam is finely focused by the Fourier transform lens 130, but since the higher order diffracted light is included due to the above-mentioned diffraction phenomenon, it is focused as a fundamental wave by the spatial filter. It becomes necessary to pass only the light beam in the part where That is, a low pass type spatial filter is required. Further, since the spectral plane is a position which becomes a fixed point of scanning of the light beam as described later, the reflection of the light beam and the operation of the low pass type spatial filter described above may be combined. The second electromagnetically driven reflection mirror 131 performs the above-mentioned operation, and applies the second current i ₂ from the current supply source 15 to control the rotation angle of reflection depending on the magnitude of the current i _2. It is something to do.

FIG. 2 shows a configuration example of the second electromagnetically driven reflecting mirror. 20
Is a reflection mirror having a square shape, and 21 is a reflection surface of a substantially circular light beam, and has an area substantially equal to the center area of the light beam condensed by the Fourier transform lens 130 described above. A shaded portion of 22 is a portion that does not reflect the light beam and is a portion that is masked with, for example, black carbon or the like, and does not reflect high-order diffracted light other than the central portion. Reflector
21 makes it possible to combine the above-mentioned reflection of the light beam and the operation of the low-pass type spatial filter.

FIG. 3 shows a schematic view when the DUT 12 is irradiated with a light beam. The DUT 12 is assumed to be a clock hand. Reference numeral 30 is an elliptical light beam emitted from the first optical element group 11, and 31 is a fixed base on which the object to be measured 12 is installed.

It is preferable that the hands of the clock are not bent as described above,
If there is a bend, a gap is created between the object to be measured 12 and the fixed base 31, and when the light beam 30 is irradiated, the light detection unit 14 detects the transmission of light due to this gap, whereby the shape of the needle can be measured. . Light beam 30 for multi-point measurement at each needle location
Scan from position A to position B.

FIG. 4 shows an optical path diagram of the configuration of the above-described optical system when scanning a beam. Line 40 is the optical path for reflections at right angles and line 41 is the optical path for reflections other than right angles. The change amount l ₁ of the scan position at the position of the DUT 12 when the reflection angle when the current i ₁ is supplied to the first electromagnetically driven reflection mirror becomes θ ₁ is f ₁ θ with respect to the line 40 It is ₁ . (However, tan
θ ₁ ≈θ ₁ ) In this scan state, the deviation l ₂ of the incident position on the photodetector 14 by the inverse Fourier transform lens 132 is f ₃ θ ₂ = f ₁ · f with the incident angle θ ₂ with respect to the line 40. ₃ · θ ₁ / f ₂ .

From the above relationship, θ ₁ / θ ₂ = f ₂ / f ₁ is obtained, so that the second electromagnetically driven reflecting mirror 131 applies a current proportional to f ₁ · θ ₁ / f ₂ by the current supply source 15. _{If the} reflection angle is corrected so that ₂ = 0, the light detection unit 14 can always detect the light beam at a fixed point, regardless of the size of the light beam scan.

FIG. 5 shows an example of a calculation waveform diagram based on the curved shape of the hands of the timepiece.

The vertical axis is the binarized voltage, and the horizontal axis is the address address corresponding to the pixel position of the CCD line sensor.

Reference numeral 50 denotes light transmission through the gap between the fixed table 31 and the object 12 to be measured shown in FIG.
When a CCD line sensor is used for the light detection unit 14, photoelectric conversion is performed to output a video signal, and the data processing unit 16 performs A / D conversion of the video signal to determine the threshold level and binarize it. The number of bits between each of the transmissive portion 50 and the light non-transmissive portion 51 is calculated, and converted into dimensions to calculate the shape.

A CCD line sensor with a pixel number of about 4000 bits has been put into practical use, and has a very high resolution. Also, a memory of approximately 4K words is sufficient for measurement data. From the viewpoint of the optical system, the image of the object to be measured can be reproduced at a magnification according to the ratio of the focal lengths of the Fourier transform lens 130 and the inverse Fourier transform lens 132, and the position of the object to be measured is unlikely to be affected by fluctuations in the object position of the object to be measured 12. Easy to set up.

〔The invention's effect〕

As is clear from the above embodiments, according to the present invention, it is possible to always detect a light beam having a good S / N ratio at a fixed position even when scanning the light beam, and realize an inexpensive and highly accurate shape measuring device. Is possible.

[Brief description of drawings]

FIG. 1 is a block diagram of a shape measuring apparatus showing an embodiment of the present invention, FIG. 2 is an explanatory view of a second electromagnetically driven reflecting mirror, and FIG.
The figure is a schematic explanatory diagram when irradiating the measured object with a light beam,
FIG. 4 is an optical path diagram for explaining scanning of the light beam of the optical system of the shape measuring device, and FIG. 5 is a waveform diagram showing an example of the measurement result of the shape of the needle by the shape measuring device. 10 ... Light source, 11 ... First optical element group, 12 ... Object to be measured, 13 ... Second optical element group, 14 ... Photodetection section, 15 ... Current supply source, 16 ... Data Processing unit, 111 ... First electromagnetically driven reflective mirror, 130 ... Fourier transform lens, 131 ... Second electromagnetically driven reflective mirror, 132 ... Fourier inverse transform lens.

Claims (1)

[Claims] 1. A light source, a cylindrical lens and a spherical lens for converting the shape and emission direction of a light beam from the light source, and a first electromagnetically driven reflection mirror arranged at a confocal position of both lenses. A first optical element group, an object to be measured irradiated with the light beam from the first optical element group, a Fourier transform lens for converting optical information and a detection direction of the light beam from the object to be measured, Second optical element group including an electromagnetically driven reflection mirror No. 2 and a Fourier inverse transform lens, a photodetector for receiving a light beam from the second optical element group, and the first and second electromagnetically driven reflection elements A current supply source that supplies a current that controls the reflection rotation angle of the mirror, and a data processing unit that converts the optical information obtained by the photodetection unit into an electric signal to calculate the shape, The electromagnetically driven reflective mirror of A low-pass type spatial filter that is arranged at the confocal position of the Fourier transform lens and the inverse Fourier transform lens included in the optical element group, and reflects light only in the central part of the incident light beam. The first electromagnetically driven reflective mirror and the second electromagnetically driven reflection mirror are provided at a current ratio corresponding to a ratio of focal lengths of the spherical lens included in the first optical element group and the Fourier transform lens included in the second optical element group.
2. A shape measuring device characterized by controlling the electromagnetically driven reflection mirror.