JP3192461B2 - Optical measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical measuring device for measuring the surface shape of an object to be measured by using light such as a semiconductor laser.

[0002]

2. Description of the Related Art Conventionally, as a measuring device for non-contact measurement of a precisely finished surface shape of an object to be measured using a semiconductor laser beam, for example, Japanese Patent Application Laid-Open No. 1-2333 is disclosed.
Japanese Patent Application Laid-Open No. 07-07,072 is known. FIG. 4 is a configuration diagram of a conventional optical measuring device of this kind. In FIG. 4, reference numerals 1a and 1b denote a pair of semiconductor lasers arranged so that their optical axes are orthogonal to each other. Collimator lenses 2a and 2b are arranged on the front side of the semiconductor lasers 1a and 1b. The half mirror 3 transmits the laser beam from the semiconductor laser 1a and reflects the laser beam from the semiconductor laser 1b at right angles to irradiate the object 8 with the laser beam. On the side, a polarizing beam splitter 4 and a quarter-wave plate 5 are arranged. A condensing lens 6 is disposed on the side of the polarization beam splitter 4 for condensing reflected light of both laser beams reflected by the object 8 and bent by the polarization beam splitter 4 to the side. A position detecting element 7 such as a PSD for detecting the tangent angle of the surface of the object 8 to be measured from the spot position of the two reflected lights is disposed at the focal position of the condenser lens 6. Reference numeral 9 denotes a moving table on which the DUT 8 is placed.
0 is set.

In the conventional optical measuring device thus constructed, laser light alternately generated from each of the semiconductor lasers 1a and 1b at predetermined time intervals is output from the collimator lens 2 respectively.
a, 2b, a half mirror 3, a polarizing beam splitter 4, and a quarter-wave plate 5 to irradiate the object 8 to be measured. Then, the reflected lights of the two laser lights reflected on the surface of the device under test 8 pass through the quarter-wave plate 5 and the polarization beam splitter 4.
Is bent in the direction of the condenser lens 6, and is imaged on the position detecting element 7 by the condenser lens 6. At this time, since the signal output according to the position of the light spot imaged on the position detecting element 7 indicates the tangent angle of the surface of the device under test 8, the amount of change between the tangent angles due to both adjacent laser beams is determined. By performing the integration twice, the surface shape of the DUT 8 can be measured.

[0004]

In this type of optical device, the tangent angle of the surface of the object to be measured is determined by the position of the position where the reflected light from the object to be measured forms an image on the position detecting element through the condenser lens. It is calculated from the distance d from the center of the detection element and the focal length f between the position detection element and the condenser lens by an approximate expression of θ = d / 2f. Here, in the position detecting element, by substituting d for the resolution of the position detecting element as to how finely the deviation of the reflected light from the measured object from the center of the position detecting element can be detected, the surface of the measured object can be obtained. The resolution θ of the measurement angle, which indicates how finely the tangent angle of the can be detected, is expressed by the above equation. Since the resolution of the position detecting element is constant, the tangent angle can be measured with high accuracy by increasing the focal length f and increasing the resolution of the measurement angle. However, the measurable angle range is determined by the resolution of the measurement angle. Since it can be expressed by (detectable width of position detecting element / resolution of position detecting element) times, the higher the accuracy of measurement, the narrower the measurable angle range, and only a shape close to a plane with a small angle range can be measured. Therefore, in order to measure a workpiece having a large curvature and a wide angle range, there has been a problem that the measurement accuracy must be reduced.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the present invention will be described with reference to FIG. The present invention includes a traversable slide table 101 in the measuring direction relative to the detector 100, before with the measured object is placed
The slide table 101 is inclined with respect to the detection unit 100.
Install the turntable 102 that is installed as possible and
The entire measuring angle range of the object to be measured is measured by the position detecting element 117.
Sections divided into multiple measurement sections according to the settable angle range
Moving the dividing means 105 and the slide table 101
And the inside of each measurement section is sequentially detected by the detection unit 100.
Measurement control means 104 for measuring and the next adjacent measurement section
Measurable angle of the position detection element 117 when moving the measurement to
Slide so that the laser beam reflected in the degree range enters
Position system for controlling the table 101 and the rotary table 102
Control means 106 .

[0006]

With the above arrangement, the entire measurement range of the object to be measured is defined.
Based on the measurable angle range by the interval dividing means 105,
Split and measure. First, the slide table 101 is measured.
The traverse is performed to the fixed start position, and the measurement is started. Suffered
The position of the light beam reflected by the object is determined by the position detecting element 11.
7 is detected. Next, the measurement control means 104
The slide table 101 measures a predetermined unit of measurement
Traversed in that direction, at which point a similar measurement is taken.
It is. In this way, each divided measurement section
When measurement is completed, measurement for the next adjacent measurement section
To perform position detection by the position control means 106.
The laser beam reflected within the measurable angle range of the
Slide table 101 and rotary table 1
By controlling 02, the surface shape of the measured object can be obtained.

As described above, the surface shape of a workpiece having a large curvature and a wide angle range can be measured with the resolution of the measurement angle that can be measured with high accuracy.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows an overall configuration diagram, and 11 shows
In the differential auto-collimation sensor section, a device under test 12 is provided below the differential auto-collimation sensor section 11.
Is mounted, and the rotary table 1 can be tilted around the Y axis in the figure.
3 and a slide table 14 which is rotatably mounted with the rotary table 13 and is movable in the X-axis direction in the figure. Here, the rotary table 13 and the slide table 14 are slid and turned by servo motors 17a and 17b, which will be described later, via ball screws and the like, respectively.

The differential auto-collimation sensor section 11
As shown in FIG. 2, a pair of semiconductor lasers 111a and 111b arranged in a direction in which the optical axes are orthogonal to each other, collimator lenses 112a and 112b arranged on the front surface of the semiconductor lasers 111a and 111b for emitting laser light, A half mirror 113 which transmits the laser beam from the semiconductor laser 111b and radiates the laser beam from the semiconductor laser 111b to the object to be measured 12 by bending the laser beam by 90 °, and a polarized beam arranged on the laser beam emission side of the half mirror 113 A splitter 114 and the polarization beam splitter 114
１ ／ wavelength plate 115 provided on the lower surface of
A condenser lens 116 for condensing the reflected light reflected via the polarizing beam splitter 114;
And a position detecting element 117 composed of a PSD or the like for detecting the tangent angle of the surface of the device under test 12 from the imaging position of the reflected light.

Since there is only one position detecting element 117, the laser beams of the semiconductor lasers 111a and 111b are generated alternately with a specified time difference. In FIG. 2, reference numeral 15 denotes a control device that has an arithmetic function of integrating the amount of change in the tangent angle detected in each tilt state twice in all measurement sections, and controls and manages the whole.

The control device 15 includes an AD converter 16 for converting a position signal output from the position detection element 117 of the differential autocollimation sensor unit 11 and corresponding to a tangent angle of the surface of the device under test 12 into a digital signal. Servo motors 17a and 17b which are connected to each other and drive-control the rotary table and the slide table 14 respectively are provided with a pulse generation circuit 18
a, 18b via amplifiers 19a, 19b, and a memory 20, an input device 21.

Next, the operation of the embodiment of the present invention configured as described above will be described with reference to the flowchart shown in FIG. First, the entire measurement angle range θ, the measurable angle range α, and the measurement unit amount β are input to the control device 15. Since the measurement is started from the end of the device under test 12, the device under test 12 is tilted so that the tangent angle θ ₁ = 0 at the end of the device under test 12, and the device under test 12 is traversed. Then, the irradiation position of the laser beam is adjusted to the end of the DUT 12. When the device under test 12 is tilted, the distance between the measuring device and the device under test 12 changes, but the focal position of the reflected light imaged from the condenser lens 116 onto the position detection element 117 is Since it is determined by the angle formed with respect to the center line passing through the center of the lens 116, the distance between the measuring device and the device under test 12 is not affected. here,
θ ₁ and θ ₂ represent tangent angles detected by a pair of optical laser beams as shown in FIG.

First, in step 200, the number of measurements N in the entire measurement angle range θ is calculated from the measurable angle range α. N is a whole number rounded up. The measurable angle range α is a value that satisfies α ₁ > α with respect to the maximum measurable angle range α _{1 in} order to allow a margin for measurement. Next, in step 201, the data number N ₁ of the divided measurement interval is set to 1.

Next, in step 202, the signals of the tangent angles θ ₁ and θ ₂ of the device under test 12 detected by the position detecting element 117 and converted into digital signals by the AD converter 16 are input to the control device. Next, in step 203, the amount of change Δθ between the tangent angles θ ₁ and θ ₂ is calculated. next,
In step 204, the change amount Δ of the tangent angles θ ₁ and θ ₂
is stored.

Next, in step 205, the object to be measured 12 is traversed by moving the object to be measured 12 by traversing the slide table 14. Next, in step 206, it is determined whether the traversal of the measurable angle range α has been completed. In this case, when the entire measurement range of the device under test 12 is divided by the control device 15 in advance, the divided position is calculated at coordinates on the ideal curved surface of the device under test 12, so that the coordinate position Until the traverse is completed, it is determined. If the traversing has not been performed in the measurable angle range α, the process returns to step 202 and the measurement is performed.

If it is determined in step 206 that the traversal of the measurable angle range α has been completed, in step 207, the tangent angle θ ₁ of the last measurement point in the measurement section is stored. Next, in step 208, the rotary table 13 is turned to tilt the DUT 12 by a predetermined amount α. Next, in step 209, the tangent angle γ of the final measurement point in a state where the DUT 12 is inclined by the predetermined amount α from the stored tangent angle θ ₁ of the final measurement point, that is, γ is obtained by γ = θ ₁ −α. Ask.

Next, in step 210, θ ₁ = γ
The object to be measured 12 is traversed to the measurement point where. Next, in step 211, it is determined whether or not θ ₁ = γ at the position where the DUT 12 is traversed. θ ₁
If not, the flow returns to step 210 to traverse the DUT 12 again.

[0018] In step 211, if it is determined that the theta ₁ = gamma, the process proceeds to step 212, in order to measure the next measurement interval, the data number N ₁ is incremented by one.
Next, in step 213, determines whether data number N ₁ is greater than the number of measurements N. If N ₁ <N, the process returns to step 202 and the measurement is performed.

At step 213, if N ₁ > N,
In step 214, the tangent angle variation Δθ is integrated twice in all the measurement sections to obtain the surface shape of the DUT 12 and the measurement is completed. In this way, since the entire measurement range is divided for the object to be measured and the surface shape is measured, the surface shape of the object to be measured having a large angle range can be measured with high accuracy.

In the above embodiment, the tangent angle of the surface of the object to be measured is detected by a pair of laser beams, and the change in the tangent angle is integrated twice to determine the surface shape. Accordingly, the present invention may be applied to a method of detecting the tangent angle of the surface of the object to be measured, integrating the tangent angle, and obtaining the surface shape of the object to be measured.

[0021]

As described above, according to the present invention,
And traversable slide table in the measuring direction relative to the detector unit, the slide together with the object to be measured is placed
It was attached to the table so that it could be tilted with respect to the detector.
A rotary table is installed, and the light beam reflected from the object
The position of the system is detected by the position detection element,
When the measurement within the measurement section of
Position control means to make measurements
Laser light reflected within the measurable angle range of the
Control the slide table and rotary table to enter
Therefore, the surface shape of a workpiece having a large curvature and a wide angle range can be continuously measured with a measurement angle resolution that can be measured with high precision.

[Brief description of the drawings]

FIG. 1 shows a claim correspondence diagram of the present invention.

FIG. 2 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 3 is a flowchart showing the operation of the embodiment of the present invention.

FIG. 4 is a configuration diagram of a conventional optical measurement device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Differential autocollimation sensor part 111a, 111b Semiconductor laser 112a, 112b Collimator lens 113 Half mirror 114 Beam splitter 115 Quarter-wave plate 116 Condensing lens 117 Position detecting element 12 Object to be measured 13 Rotary table 14 Slide table 15 Controller 16 AD converter 17a, 17b Servo motor 18a, 18b Pulse generation circuit 19a, 19b Amplifier 20 Memory 21 Input device

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kazuhiro Moritoku 1-1, Asahi-cho, Kariya-shi, Aichi Pref. JP-A-60-140314 (JP, A) JP-A-63-243708 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01B 11/24

Claims (1)

(57) [Claims] 1. A detection unit for irradiating a laser beam from a laser light source to an object to be measured and detecting a laser beam reflected by the object to be measured by a position detecting element to obtain a shape of the object to be measured.
In the optical measuring device was example, measured relative to the detecting unit
And traversable slide table in a direction, the object to be measured
Is placed on the slide table and the detection is performed.
With a rotary table that can be tilted with respect to the
And the entire measurement angle range of the object to be measured is determined by the position detection element.
Divided into multiple measurement sections according to the measurable angle range of the
Moving the slide table,
Measurement to measure sequentially within each measurement section by the detection unit
Move the measurement to the control means and the next adjacent measurement section
Reflected in the measurable angle range of the position detecting element.
Slide table and rotary table so that the
An optical measuring device, comprising: a position control means for controlling a cable .