JPH07208939A - Measuring equipment using laser - Google Patents

Abstract

PURPOSE:To obtain a measuring equipment using a laser which can transform a parallel laser beam having a nonuniform light intensity distribution into a parallel laser beam having a uniform light intensity distribution by a simple constitution and method and can measure with a high resolution the dimensions of a substance to be measured. CONSTITUTION:An optical filter 15 for a laser beam whereby the light intensity distribution of the laser beam after passing through the filter is made uniform, is prepared. This optical filter 15 for the laser beam is disposed in the measuring equipment 10 using a laser which has a means for transforming the laser beam from a laser light source 14 into a parallel beam and a means for positioning a substance to be measured within the effective use width of the parallel laser beam and measuring the dimensions of the substance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser-based measuring device used as a non-contact outer shape (diameter) measuring device or sensor using a parallel laser beam.

[0002]

2. Description of the Related Art The cross-sectional beam shape of a laser beam varies from 1 mm or less to 30 mm due to differences in the resonator structure and the like.
There are a wide variety of types, including prismatic ones, which are selected according to the purpose used for measurement and detection. For example, when a pattern obtained by projecting a laser beam on a screen is viewed, a circular pattern, which is a basic mode, or a multimode having a complicated shape such as an elliptical shape or a donut shape is formed. Generally, the above-mentioned beam-shaped light intensity distribution forms a two-dimensional asymmetric Gaussian distribution as shown in FIG. Such a laser beam is applied to various devices by bending, expanding, narrowing, shaking, or modulating the laser beam output from the laser oscillator.

An apparatus for converting a laser beam into a band-shaped parallel laser beam, positioning an object to be measured such as a wire rod or a bar within the area of the parallel laser beam, and measuring the outer shape and diameter of the object to be measured without contact. Is known. As a method of converting a laser beam into a parallel laser beam, for example, a galvanometer scanner, a polygon scanner, an acousto-optic effect means, etc. and an fθ lens are used to shake the laser beam to form a parallel laser beam and measure an object to be measured. A scanning type measuring device may be used. Further, there is a beam expansion type measuring device for measuring an object to be measured by expanding a laser beam using a cylindrical lens, a collimator lens or the like to form a parallel laser beam.

A typical example thereof is shown in FIG. In the conventional laser-based measuring device 1, the laser beam emitted from the laser light source unit 2 by the above-described method is collimated by the light projecting lens 3 to form a parallel laser beam. The DUT 4 is positioned within the widthwise area of the parallel laser beam. The beam other than the shadow blocked by the DUT 4 is focused on the light receiving element section 6 by the light receiving lens 5. The light receiving element portion 6 receives the light amount of this beam, and sends a signal based on this to the controller 7. The signal is calculated by the signal processing unit provided inside the controller 7, and the size of the object to be measured is displayed on the display unit to inform the user.

[0005]

Such a measuring apparatus is affected by the optical intensity distribution of the laser beam itself for the above-mentioned reason, as well as the optical element, lens, aperture, etc. used. The light intensity distribution of the laser beam formed through them is further deviated as shown in FIG. That is, the unevenness of the light amount change becomes large, and the difference in the light intensity between the central portion and the end portion in the width direction becomes large within the measurement region (effective measurement width). Even when the same object to be measured is measured, if the measurement position changes, the measurement result by the light receiver in the device will differ. That is, as shown in FIGS. 4 to 6, the area of the distribution due to the shadow due to the difference in the measurement position of the measured object,
That is, there is a drawback that the size of the object to be measured cannot be accurately measured because the light intensity changes. In order to reduce such unevenness of light intensity change, it is necessary to always use the vicinity of the central portion in the width direction of the parallel laser beam, which has a relatively small difference in light intensity distribution, and to reduce the maximum width of the measured object. There was a limit.

By the way, in order to form a uniform parallel laser beam, the beam width is expanded by increasing the focal length of the lens, and only the beam near the center where the light intensity distribution is relatively uniform is used. There is known a method of forming a parallel laser beam having a uniform light intensity by cutting an area with an aperture or a shielding plate. However, the light intensity of the collimated laser beam formed is weak, and therefore S
The N ratio is lowered and the resolution of the minimum measurement width of the measured object is deteriorated. Therefore, the width of the parallel laser beam cannot be expanded and the effective width is limited.

In the apparatus having the above-mentioned structure, there is no apparatus in which the effective width of the parallel laser beam is 100 mm or more, and in any case, the apparatus having the width of 50 to 60 mm is the maximum.
Moreover, the size of the effective measured object is limited to a size considerably smaller than the maximum effective utilization width. The present invention has been made in view of the above problems, an optical element, a lens,
Provided is a laser-based measurement device capable of forming a uniform light intensity distribution with a simple configuration and forming a parallel laser beam with no change in light amount, without changing the design or arrangement of the measurement device such as the aperture. The task is to do.

[0008]

In order to solve the above-mentioned problems, a laser utilizing measuring device according to the present invention converts a laser beam output from a laser oscillator into parallel laser beams having a constant width by a converting means, A laser in which the object to be measured is positioned within the width of the parallel laser beam, the light receiving element receives an amount of light other than that at which the object to be measured interrupts the parallel laser beam, and the size of the object to be measured is measured from the received data. The utilization measuring device is characterized in that an optical filter for a laser beam is provided on the optical path of the laser beam so that the light intensity distribution of the parallel laser beam becomes uniform while reaching the light receiving element. In particular, the laser utilizing measuring device outputs a laser beam, a laser oscillator, a first lens for converting the output laser beam into a parallel laser beam, and a laser beam for making the light intensity distribution of the parallel laser beam uniform. Optical filter, a second lens for expanding the parallel laser beam having a uniform light intensity, a third lens for converting the expanded laser beam into a wide parallel laser beam, and the wide parallel beam A light receiving lens for receiving a laser beam, and a controller for measuring and calculating the amount of received light. Further, the first lens is a collimator lens, and the second and third lenses are cylindrical lenses. It is characterized by consisting of.

[0009]

With the above construction, the laser beam emitted from the laser oscillator is converted into a parallel laser beam by means of a lens or the like. The converted parallel laser beam is converted into a parallel laser beam having a uniform light intensity distribution through the beam optical filter.
The non-measurement object is positioned in the area of the parallel laser beam, and the size of the non-measurement object is measured based on the signal of the light amount shielded by the measurement object.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a laser-based measuring device using a strip-shaped parallel laser beam according to the present invention. The laser-based measuring device 10 has a laser light source unit 14 including a laser diode 11 that emits a laser beam, a collimator lens 12, and an aperture 13. An optical filter 15 for a laser beam for uniformizing the light intensity distribution toward the emission direction of the laser beam from the laser light source unit 14, a cylindrical lens 16 for expanding the laser beam, and an aperture for cutting an extra laser beam. 17, a cylindrical lens 18 as a light projecting lens, a cylindrical lens 19 as a light receiving lens, a light receiving element unit 20 for sensing the total amount of light focused by the light receiving lens, and a controller 21. The controller 21 includes an internal oscillator that sends a signal to the laser light source unit 14, a signal processing unit that calculates a signal from the light receiving element unit 20, and a display unit that displays the measurement after the calculation to the user.

Next, the movement of the laser beam in the above-described laser utilizing measuring device 10 will be described. Upon receiving the output signal from the controller 21, a laser beam is emitted from the laser diode 11. The emitted laser beam is formed into a parallel laser beam by the collimator lens 12. In addition, the collimator lens 12
The laser beam which has received the aberration is blocked by the aperture 13 and only the laser beam necessary for measurement is emitted. This parallel laser beam becomes a parallel laser beam having a uniform light intensity by passing through the laser beam optical filter 15 that forms a uniform light intensity distribution. Next, the laser beam passes through the cylindrical lens 16 and is expanded into a laser beam having a width in the uniaxial direction. Further, a parallel laser beam having a uniform light intensity distribution having a width D is formed by a cylindrical lens 18 as a light projecting lens through an aperture 17 for limiting the measurement area. This parallel laser beam is condensed at a predetermined distance by a cylindrical lens 19 which is a light receiving lens, and a signal as light intensity is obtained by a light receiving element section 20.

As a method of measuring the object to be measured, the object to be measured 22 is positioned within the area of the width D of the parallel laser beam formed between the cylindrical lenses 18 and 19 described above. The amount of light corresponding to the shadow of the parallel laser beam blocked by the DUT 22 decreases. The light-receiving element section 20 receives a signal associated with the decrease in the amount of light, and the signal processing section of the controller 21 calculates the width of the measured object and displays it on the display section.

The laser beam optical filter 15 may be arranged between the light receiving element section 20 and
There is no limitation in the place of arrangement. Further, the optical filter 15 for laser beam is formed by forming a thin film layer of a metal such as iron or aluminum or several special metal alloys, or a synthetic resin on a transparent or translucent glass substrate by vapor deposition or sputtering. I will do it. As the substrate material, transparent or translucent plastic or the like can be used. In addition to the above, a film for recording light intensity distribution on a photographic film or a substrate coated with an organic dye can be used.

Further, in the present embodiment, as the laser-using measuring device, the beam expanding type measuring device has been described, but it can be suitably used also in the scanning type measuring device.

[0015]

INDUSTRIAL APPLICABILITY The present invention is a laser-based measuring device using a light source such as a parallel laser beam having a non-uniform light intensity distribution, and the non-uniformity of the parallel laser beam can be obtained without changing the design or arrangement of the device. By recording the light transmission distribution, which is the reciprocal of the distribution data of the various light intensity distributions, on the filter substrate and correcting it as an optical filter for the laser beam, it is possible to form a parallel laser beam with uniform light intensity with high precision and high accuracy. A measuring device having a resolution can be provided.

In the embodiment, the distribution change rate of the output parallel laser beam can be made smaller than the conventional one in the effective measurement area. For this reason, in the past, the use was limited to the limit setting (GO, LOW, HI) at the same measurement position, but the present invention enables detection or measurement of the object to be measured at any measurement position of the effective measurement width. became.

Further, in the prior art, in order to obtain a uniform light intensity distribution, a laser utilizing measuring device is designed by using a portion near the central portion of the laser beam where the distribution change is small, so that the laser output can be made higher. It was necessary to increase the light receiving sensitivity. However, according to the present invention, since the utilization rate of the output laser beam is almost 100%, a high output laser beam is not required, that is, even if the output of the laser beam is small, the light intensity equivalent to that of the conventional one is obtained. I was able to get

[0018]

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an embodiment according to the present invention.

FIG. 2 is a diagram showing a light intensity distribution of a laser beam shape.

FIG. 3 is a diagram showing a conventional laser-based measuring device.

FIG. 4 is a diagram showing a light intensity distribution of a conventional laser-based measuring device.

FIG. 5 is a diagram showing a light intensity distribution of a conventional laser-based measuring device.

FIG. 6 is a diagram showing a light intensity distribution of a conventional laser-based measuring device.

[Explanation of symbols]

 10 Laser-based measuring device 11 Laser diode 12 Collimator lens 13 Aperture 14 Laser light source section 15 Laser beam optical filter 16 Cylindrical lens 17 Aperture 18 Cylindrical lens 19 Cylindrical lens 20 Light receiving element section 21 Controller

Claims (3)

[Claims] 1. A laser beam output from a laser oscillator is converted into parallel laser beams having a constant width by a conversion means, an object to be measured is positioned within the width of the parallel laser beam, and the object to be measured is parallel. In a laser-based measuring device in which a light receiving element receives an amount of light other than that for blocking the laser beam and measures the size of the object to be measured from the received data, the laser beam is parallel to the optical path of the laser beam while it reaches the light receiving element. A laser-use measuring device characterized in that an optical filter for a laser beam is provided so that the light intensity distribution of the laser beam becomes uniform. 2. The laser utilizing measuring device outputs a laser beam, a laser oscillator, a first lens for converting the output laser beam into a parallel laser beam, and a uniform light intensity distribution of the parallel laser beam. An optical filter for laser beam, a second lens for expanding the parallel laser beam with uniform light intensity, a third lens for converting the expanded laser beam into a wide parallel laser beam, and the wide width 2. The laser utilizing measuring device according to claim 1, further comprising a light receiving lens for receiving the parallel laser beam of 1. and a controller for measuring and calculating the received light amount. 3. The laser measuring apparatus according to claim 1, wherein the first lens is a collimator lens, and the second and third lenses are cylindrical lenses.