JPS61196104A - Position detecting method and its photo-receiving device by means of laser beam - Google Patents

Abstract

PURPOSE:To enable to obtain a highly accurate detective value irrespective of a spot diameter by scattering a laser beam with a photo-scattering filter and taking it out as a photo-intensity signal with a photo-sensor or located on a photo-receiving surface. CONSTITUTION:A photo-filter 1, a photo-scattering filter 2 and a photo-sensor 4, etc. are installed. A laser beam 9 is introduced to the filter 2 via the filter 1, scattered as an arrow 9a and irradiated on a photo-receiving surface 3 while eliminating the high frequency range of the spatial frequency of a laser beam. Thus, removing an influence of the folded frequency enables to obtain the meaningful data when the recording is regenerated. I.E., by irradiating a scattered laser beam on the sensor 4 located on the photo-receiving surface 3, a photo- intensity signal of an irradiated beam is taken out by the sensor 4 and the signal is calculated with a Gaussian distribution characteristic by a computer 5. Thus, a center position of a laser beam irradiation spot can be obtained accurately.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention provides a method for propelling a shield excavator along a predetermined planned line in shield tunnel construction, etc.
The present invention relates to a position detection method using a laser beam, such as when a laser beam is applied to a light receiving plate provided on a shield excavator to detect a position, and a position detection light receiving device used therein.

(Prior art) A conventional position detection method using a laser beam, for example,
As shown in the figure, a laser oscillator is installed at point A, a condensing lens is installed at point B to condense the light, and a dedicated light receiving element is placed at the focused position to transmit the light through the dedicated circuit of the light receiving element. A signal was extracted to detect the center position of the laser beam.

(Problems to be Solved by the Invention) However, according to the above-described conventional method, the detection accuracy changes depending on the size of the spot diameter of the laser beam.

That is, the smaller the diameter of the spot projected onto the light-receiving element surface, the higher the accuracy of detecting its center. Therefore, when the spot diameter of the light irradiated by the laser oscillator is large,
In order to obtain detection accuracy comparable to that obtained when the spot diameter is small, the focal length of the condensing lens must be changed to reduce the spot diameter condensed on the light receiving element surface.

In other words, in FIG. 6, if a small-diameter projection light indicated by arrow a at position A is condensed as a spot with a diameter indicated by arrow a2 at position C via a condensing lens at position B, then a large diameter spot indicated by arrow b1 In order to condense the projected light having the same diameter as the arrow a2 into a spot (arrow b2) with the same diameter, the focal length of the condenser lens must be changed.

Another problem is that the dedicated light-receiving element and its dedicated circuit in the conventional device described above are very expensive.

The present invention was made to solve the above-mentioned problems, and it enables high-precision detection regardless of the size of the spot diameter of the laser beam, and can be done at low cost by using a photosensor on the light receiving surface. The purpose is to do so.

(Means for Solving the Problems) In order to solve the above-mentioned problems, in the present invention, a laser beam is guided through a light scattering filter to a light receiving surface on which photosensors are distributed, and each XY A photo sensor with coordinate values extracts a light intensity signal, and a computer applies this signal to Gaussian distribution characteristics and calculates the center position of the spot in XY.
Obtain it as a coordinate value.

It also includes a light scattering filter, a light-receiving surface on which photosensors are distributed, and a computer that calculates by applying the intensity signal of light extracted by the photosensor having each XY coordinate value of this light-receiving surface to Gaussian distribution characteristics. A light-receiving device for position detection using a laser beam is configured.

(Function) As described above, in the present invention, a laser beam is scattered by a light scattering filter, and is extracted as a light intensity signal by a photosensor on a light receiving surface, and
Since the center position of the spot is detected by calculating by applying Gaussian distribution characteristics using a computer, highly accurate detection values can always be obtained regardless of the size of the spot diameter.

In addition, since an inexpensive photosensor is used on the light receiving surface instead of the expensive dedicated light receiving element and dedicated circuit used in the conventional device, the device of the present invention is significantly cheaper than the conventional device. Become.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram explaining the principle of the present invention. In the figure, 1 is an optical filter, and 2 is a ground glass-like light scattering filter with one side smooth and the other side roughened with minute irregularities.This filter can also be made from acrylic resin. .

3 is a large number of photosensors 4 as shown in FIG.
5 is a light-receiving surface having XY coordinate values of the light-receiving surface 3. The center position of the spot is calculated by applying the intensity signal of the light taken out by the retosensor 4 to Gaussian distribution characteristics. In the computer which can obtain XY coordinate values, 5a is its arithmetic circuit, 5b is a microcomputer, 5C is a display, 5d is a printer, and 5e is an XY plotter.

FIG. 3 shows an example of a light-receiving device for position detection using a laser beam according to the present invention. In the figure, the same reference numerals as those mentioned above refer to the same elements, so a description thereof will be omitted. 6 is a case of the light receiving device, 7 is a cord for connecting an external power supply, and 8 is an opening/closing switch thereof.

As mentioned above, the frequency of the laser beam is reflected by the photosensors 4 distributed on the light receiving surface 3.
According to Shannon's sampling theorem, the maximum spatial frequency that can be recorded and reproduced without being affected by quenc y aliasi ng is at most 1/2d, where d is the arrangement interval of the photosensors 4.

Generally, a laser beam is spatially close to a delta function as shown in FIG. 4, and its spatial frequency far exceeds 1/2d. Therefore, it is difficult to accurately detect the center position of the laser beam projected by the photosensor 4 as it is, but in the present invention, as shown in FIG. The laser beam 9 is introduced into the light scattering filter 2 through the optical filter 1, and is scattered as shown by the arrow 9a and irradiated onto the light receiving surface 3. As shown in FIG. 5, the spatial frequency of the laser beam is high. area is cut. By reducing the spatial frequency of the laser beam to 1/2d or less in this manner, the influence of frequency aliasing can be removed and meaningful data can be obtained for recording and reproduction.

That is, by irradiating the photosensor 4 placed on the light receiving surface 3 with the scattered laser beam,
A light intensity signal based on the Gaussian distribution characteristic of the light irradiated by the photosensor 4 having coordinate values is extracted, and this signal is applied to the Gaussian distribution characteristic by the computer 5 for calculation, thereby determining the center position of the irradiation spot of the laser beam. can be obtained with high precision as XY coordinate values.

(Effects of the Invention) As described above, in the present invention, a laser beam is scattered by a light scattering filter, and it is extracted as a light intensity signal by a photosensor on a light receiving surface, and at the same time,
Since the center position of the spot is detected by calculation by applying Gaussian distribution characteristics using a computer, the excellent effect is that highly accurate detection values can always be obtained regardless of the size of the spot diameter. It will be done.

Furthermore, in place of the expensive dedicated light-receiving element and its dedicated circuit used in the conventional device, the present invention uses an inexpensive photosensor on the light-receiving surface. It also has the effect of being significantly cheaper.

Brief explanation of the previous aspects Figure 1 is a diagram explaining the principle of the present invention, Figure 2 is a front view of the photosensor, Figure 3 is a sectional view of the light receiving device of the present invention, Figures 4 and 5 are illustrations of the laser A Gaussian distribution characteristic diagram of light rays, FIG. 6 is an explanatory diagram of a conventional device.

1... Optical filter 2...Light scattering filter 3... Light receiving surface 4...Photo sensor 5... Computer

Claims (1)

[Claims] 1. A laser beam is guided through a light scattering filter to a light-receiving surface on which photosensors are distributed, and a light intensity signal is extracted by the photosensor having each XY coordinate value of the light-receiving surface. A position detection method using a laser beam, characterized in that the center position of a spot is obtained as an XY coordinate value by applying a signal to a Gaussian distribution characteristic using a computer and performing calculations. 2. A light scattering filter, a light-receiving surface on which photosensors are distributed, and a computer that calculates by applying the intensity signal of light extracted by the photosensor having each XY coordinate value of this light-receiving surface to Gaussian distribution characteristics. A light receiving device for position detection using a laser beam, comprising: