CA1150049A - Electro-optical distance-measuring system - Google Patents
Electro-optical distance-measuring systemInfo
- Publication number
- CA1150049A CA1150049A CA000360955A CA360955A CA1150049A CA 1150049 A CA1150049 A CA 1150049A CA 000360955 A CA000360955 A CA 000360955A CA 360955 A CA360955 A CA 360955A CA 1150049 A CA1150049 A CA 1150049A
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- axis
- viewing
- radiation
- gathering
- along
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- Length Measuring Devices By Optical Means (AREA)
- Measurement Of Optical Distance (AREA)
Abstract
ELECTRO-OPTICAL DISTANCE-MEASURING SYSTEM
Abstract of the Disclosure Electro-optical apparatus for locating the surface of an object. A laser projects a beam along one axis. Light from the beam which is reflected by an impinged object is viewed along another axis, and is transmitted to a linear (straight-line) photodetector array. The array is specially oriented angularly relative to the viewing axis and to the laser beam axis, whereby, within the selected dynamic range of the apparatus, reflected light transmitted to the array is, under all circumstances, in sharp focus along the plane of the array.
Abstract of the Disclosure Electro-optical apparatus for locating the surface of an object. A laser projects a beam along one axis. Light from the beam which is reflected by an impinged object is viewed along another axis, and is transmitted to a linear (straight-line) photodetector array. The array is specially oriented angularly relative to the viewing axis and to the laser beam axis, whereby, within the selected dynamic range of the apparatus, reflected light transmitted to the array is, under all circumstances, in sharp focus along the plane of the array.
Description
j Background and Summa y_of the Invention ~` This inven~ion pertains to electro-optical distance~
measuring apparatus, and more particularly, to a unique positional and attitudinal arrangement of components in such apparatus which promotes a high degree of accurate performance over a relatively wide dynamic range of distances.
There are many ~nstances, such as for example in a plywood mill, where it is desired to make an accurate measurement of the distance between a known location and a particular object, so as to locate the object (or more particularly, the object's near surface) as precisely as possible in space. A
preferred embodiment of the present invention is described herein in conjunction with a block centering operation, wherein it is important to be able to position a log in a closely controlled position relative to a veneer peeler blade.
According to this preferred embodiment a small-diameter laser beam is projected along one axis toward what might be thought of as a viewing zone, in which logs are expected to appear prior to a block centering operation. "~ooking", so-to-speak, along another and intersecting axis is an optically sensitive viewer which looks for light from this beam which is reflected from a log's surface.
It is known, and expected, that logs appearing within this zone will have different diameters. For example, it miyht be typical to expect logs having diameters in the range of about 8-inches to about 48-inches. Obviously, the distance-measuring system of the invention must be capable of monitoring logs within such a diameter range. ~s will be more fully explained below, the angle between the beam-projection axis and the viewing axis is selected both to accommodate the "dynamic ranye" of expected log-diameter differences, and to maximize the resolution accuracy of viewed reflected light, so that such accuracy does not vary, 1.
s~
in any appreciable sense, over the entire selected dynamic range.
Employed in the "viewing" portion of the apparatus are a lens and a linear (straight-line) photodetector array. I~hen the laser beam strikes the surface of a log, the lens focuses onto the array an image of the reflected light. The position of such image J along the length of the array, is directly inter-pretable to indicate the distance to the impinged log surface~
Throughout the dynamic range of the apparatus, and as logs of different diameters are observed, imaged reflected light will strike the photodetector array at different specific points along its length.
A unique and important feature of the present invention is the discovery that the angular positioning of the photodetector array is critical to assuring that, throughout the dynamic range which is contemplated, a reflected image on the array will always be in sharp focus thereon. In other words, with proper attention to such angular positioning, the focus of the image is indepen-dent of log-surface distance. If attention is not paid to this important angular positioning of the array, the focus of a re-flected image thereon will change throughout the dynamic range, and will thus cause significant resolution accuracy differences.
These and various other objects and advantages which are attained by the invention ~ill become more fully apparent as the description which now follows is read in conjunctîon with the accompanying drawing.
Description of the Drawing The single drawing figure illustrates, in schematic form, a preferred embodiment of the distance-measuring apparatus of the invention. The drawing is not prepared to scale.
; Detailed Descript~`on of the Inventîon Turning now to the drawing, what is shown herein is a side schematic view illustrating the components o~ the distance-measuring apparatus contemplated herein, and of the special positional and attitudinal arrangement of such components. The parts are not drawn to scale. Included within the apparatus are a laser 10, aLso referred to as a beam-projecting means, a lens 12, also referred to as a gathering means) and a linear photo-de~ector array 14, which i5 also referred to as a radiation--~ sensing means. Each of these components is conventional in construction, and commercially available.
Indicated generally at 16 is what might be thought of as a viewing zone in which the apparatus is intended to monitor the positions of the near sides of logs. A log within this zone is shown at 18.
Laser 10 is positioned and oriented to project a small-diameter beam (typically about 1.5-millimeters in diameter) along a projection axis shown at 20. Axis 20 extends into zone 16, and occupies the plane of the drawing.
Lens 12 is positioned and oriented to view zone 16 generally along a central vie~ing a~is shown at 22. Axis 22 intersects axis 20 J and also lies in the plane Qf the drawing.
Lens 12 herein is a circular, double-convex lens which lies in a plane 24 that is normal both to ~he plane of the drawing, and to axis 22.
As was mentioned briefly earlier, the apparatus of the invention is designed to offer a pr~selected dynamic vie~Ing range suited to the particular setting in which it is employed.
In the 5pecific example now being described, the apparatus of the invention is used to locate t~e near surfaces of logs whose diameters lie within the range of about 8-inches to abbut 48-inches. Logs presented in viewing zone 16 will, through conven-tional log-handling apparatus which is in no way involved with the present invention, normally be placed in zone 16 with their approximate central axes always closely aligned with a predeter-mined axis that extends (~at a known location) through the viewing zone Csubstantially normal to the plane of the drawing~. Thus, with logs hàving such a range of expected diameters, the required dynamic range for the illustrated system is about 20-inches.
Referring to the left side of the drawing, circular line 26 represents one "end" of the selected dynamic range, and line 28 represents the other "end". More specifically, a log having a diameter o~ about 48-inches would, as viewed in the drawing, have its outside generally coincident with line 26. On the other hand, an 8-inch diameter log similarly viewed would have its outside generally coincident with line 28. Line 30 represents a log having a diameter o~ about 24-inches. Log 18 has a diameter of about 38-inches.
Still with reference to the left side of the drawing, it can be seen ~hat axis 20 intersects line 26 at a point 32, intersects the near surface of log 18 at a point 34, in~.ersects line 30 at a point 36, and intersects line 28 at a point 38.
These points are, of course, merely representative of the infinite number of points, between points 32, 38, where the beam from laser 10 could intersect, or impinge, the side of a log in zone 16.
With respect to the four particular points just men-tioned, and considering the operation of lens 12, t~e`lens, onits right side, images a beam-impingement occurring at poin~ 32 along a line~40, images an impingement at point 34 with log 18 ~ 9 along a line 42, images an impingement at point 36 along a line 44, and images an impingement at point 38 along a line 46. Lines 40, 42, 44, 46 all lie in the plane of the drawing.
The exact angle ~hich i5 used between axe~ 20, 22 is a matter of choice, and depends upon the specific application in which the apparatus is to be used. Generally speaking, and considering the use of a photodetector array having a particular length, the greater this angle, the smaller the dynamic range and the greater the optical resolution. Conversely, the smaller the angle, the greater the dynamic range and the poorer the optical resolution. In the particular application now being described, wherein the dynamic range is a~out 20-inches, the angle between these axes is about 14.5.
Another factor which is a matter of choice, and which depends upon the particular application for the apparatus, is the distance of the apparatus from the viewing zone. In the parti-cular apparatus illustrated herein, :Lens 12 is located about 60-inches from previously mentioned point 38.
Turning attention now to a key aspect of the invention, in order to maximize the resolution accuracy of the apparatus, it ; is important th~t, throughout the selected dynamic range, reflec-tion images produced by len~ 12 on array 14 all be in sharp focus where they impinge the array. For example, an image reflection from point 32 which strikes the surface of the array where the same is intersected by a line 4Q should be as sharply in focus as an imaged reflection derived from any other point of intersection between the beam of the`laser and the surface of a log in zone 16. ~ith specific reference to the several illustrated points, the imaged reflection from impingement point 34 ~ith log 18 strikes the photodetector ~here the same is intersected b~ line 42; one derived from point 36 strikes the`photodetector where it is intersected by line`44; and one`derived from point 38 strikes the photodetector where it is intersected by line 46.
To achieve the kind of consistant, dynamic-range, sharp focusing now being discussed, it is critical that the surface of array 14 which faces lens 12 lie along a line which intersects axis 20 at the same point where axis 20 is intersected by the plane containing lens 12. Such a line for the array is repre-sented by line 48, and can be seen to intersect axis 20 and plane 24 at a point 50. Tl~e photodetector array may occupy different angular orientations which may be a matter of choice, but will only perform with the accuracy praposed by the present invention if the "point 50" intersection geometry just descrîbed is observed.
Further, while line 48 may be disposed at a slight angle extending either toward or away from the plane of the dra~ing, according to a preferred embodiment of the apparatus, line 48 also lies in the plane of the drawing.
So long as the above geometrical arrangement is observed, for any selected dynamic range for the apparatus, all reflected images directed onto the photodetector array throughout the range will be in sharp conslstant focus thereon. Thus, information derived from the apparatus will exhibit uniform and consistant accuracy.
Completing a description of what is shown in the drawing, indicated ~enerally iTl block form at 52 is a convention-al scan control and signal processing unit. This unit repetîtive-ly scans the light-receiving condition of array 14, and produces, on an output conductor 54, a signal directly reflective of the position along the array at ~hich an image appears. The present invention is not concerned ~ith the details of unit 52. ~ommer-cially available units, like unit 52, are readily available to perform the functions just des;cribed.
It is thus now beIieved to be obvious ho~ appa~atus in accordance with the`present invention ma~ be constructed, arranged ~ 9 and used to produce extremely accurate dîstance measurements.
Obviously, îf it îs desirable`to look, for example, at multiple different points along the length of a long obj.ect such as a log, a plurality pf apparatus units., such as t~e one shown in the drawing, may be used which are distributed in such a fashion to take views at predetermined interYals along the object~ Further, it will be`obvious that the inventîon is useable in an extremely ; wide variety of applications involving industries other than the wood products industry~
10While a preferred embodiment of the invention has been described herein, it is appreciated that variations and modifica-tions, some of which have been suggested above, may be made without departing from the spirit of the invention~
measuring apparatus, and more particularly, to a unique positional and attitudinal arrangement of components in such apparatus which promotes a high degree of accurate performance over a relatively wide dynamic range of distances.
There are many ~nstances, such as for example in a plywood mill, where it is desired to make an accurate measurement of the distance between a known location and a particular object, so as to locate the object (or more particularly, the object's near surface) as precisely as possible in space. A
preferred embodiment of the present invention is described herein in conjunction with a block centering operation, wherein it is important to be able to position a log in a closely controlled position relative to a veneer peeler blade.
According to this preferred embodiment a small-diameter laser beam is projected along one axis toward what might be thought of as a viewing zone, in which logs are expected to appear prior to a block centering operation. "~ooking", so-to-speak, along another and intersecting axis is an optically sensitive viewer which looks for light from this beam which is reflected from a log's surface.
It is known, and expected, that logs appearing within this zone will have different diameters. For example, it miyht be typical to expect logs having diameters in the range of about 8-inches to about 48-inches. Obviously, the distance-measuring system of the invention must be capable of monitoring logs within such a diameter range. ~s will be more fully explained below, the angle between the beam-projection axis and the viewing axis is selected both to accommodate the "dynamic ranye" of expected log-diameter differences, and to maximize the resolution accuracy of viewed reflected light, so that such accuracy does not vary, 1.
s~
in any appreciable sense, over the entire selected dynamic range.
Employed in the "viewing" portion of the apparatus are a lens and a linear (straight-line) photodetector array. I~hen the laser beam strikes the surface of a log, the lens focuses onto the array an image of the reflected light. The position of such image J along the length of the array, is directly inter-pretable to indicate the distance to the impinged log surface~
Throughout the dynamic range of the apparatus, and as logs of different diameters are observed, imaged reflected light will strike the photodetector array at different specific points along its length.
A unique and important feature of the present invention is the discovery that the angular positioning of the photodetector array is critical to assuring that, throughout the dynamic range which is contemplated, a reflected image on the array will always be in sharp focus thereon. In other words, with proper attention to such angular positioning, the focus of the image is indepen-dent of log-surface distance. If attention is not paid to this important angular positioning of the array, the focus of a re-flected image thereon will change throughout the dynamic range, and will thus cause significant resolution accuracy differences.
These and various other objects and advantages which are attained by the invention ~ill become more fully apparent as the description which now follows is read in conjunctîon with the accompanying drawing.
Description of the Drawing The single drawing figure illustrates, in schematic form, a preferred embodiment of the distance-measuring apparatus of the invention. The drawing is not prepared to scale.
; Detailed Descript~`on of the Inventîon Turning now to the drawing, what is shown herein is a side schematic view illustrating the components o~ the distance-measuring apparatus contemplated herein, and of the special positional and attitudinal arrangement of such components. The parts are not drawn to scale. Included within the apparatus are a laser 10, aLso referred to as a beam-projecting means, a lens 12, also referred to as a gathering means) and a linear photo-de~ector array 14, which i5 also referred to as a radiation--~ sensing means. Each of these components is conventional in construction, and commercially available.
Indicated generally at 16 is what might be thought of as a viewing zone in which the apparatus is intended to monitor the positions of the near sides of logs. A log within this zone is shown at 18.
Laser 10 is positioned and oriented to project a small-diameter beam (typically about 1.5-millimeters in diameter) along a projection axis shown at 20. Axis 20 extends into zone 16, and occupies the plane of the drawing.
Lens 12 is positioned and oriented to view zone 16 generally along a central vie~ing a~is shown at 22. Axis 22 intersects axis 20 J and also lies in the plane Qf the drawing.
Lens 12 herein is a circular, double-convex lens which lies in a plane 24 that is normal both to ~he plane of the drawing, and to axis 22.
As was mentioned briefly earlier, the apparatus of the invention is designed to offer a pr~selected dynamic vie~Ing range suited to the particular setting in which it is employed.
In the 5pecific example now being described, the apparatus of the invention is used to locate t~e near surfaces of logs whose diameters lie within the range of about 8-inches to abbut 48-inches. Logs presented in viewing zone 16 will, through conven-tional log-handling apparatus which is in no way involved with the present invention, normally be placed in zone 16 with their approximate central axes always closely aligned with a predeter-mined axis that extends (~at a known location) through the viewing zone Csubstantially normal to the plane of the drawing~. Thus, with logs hàving such a range of expected diameters, the required dynamic range for the illustrated system is about 20-inches.
Referring to the left side of the drawing, circular line 26 represents one "end" of the selected dynamic range, and line 28 represents the other "end". More specifically, a log having a diameter o~ about 48-inches would, as viewed in the drawing, have its outside generally coincident with line 26. On the other hand, an 8-inch diameter log similarly viewed would have its outside generally coincident with line 28. Line 30 represents a log having a diameter o~ about 24-inches. Log 18 has a diameter of about 38-inches.
Still with reference to the left side of the drawing, it can be seen ~hat axis 20 intersects line 26 at a point 32, intersects the near surface of log 18 at a point 34, in~.ersects line 30 at a point 36, and intersects line 28 at a point 38.
These points are, of course, merely representative of the infinite number of points, between points 32, 38, where the beam from laser 10 could intersect, or impinge, the side of a log in zone 16.
With respect to the four particular points just men-tioned, and considering the operation of lens 12, t~e`lens, onits right side, images a beam-impingement occurring at poin~ 32 along a line~40, images an impingement at point 34 with log 18 ~ 9 along a line 42, images an impingement at point 36 along a line 44, and images an impingement at point 38 along a line 46. Lines 40, 42, 44, 46 all lie in the plane of the drawing.
The exact angle ~hich i5 used between axe~ 20, 22 is a matter of choice, and depends upon the specific application in which the apparatus is to be used. Generally speaking, and considering the use of a photodetector array having a particular length, the greater this angle, the smaller the dynamic range and the greater the optical resolution. Conversely, the smaller the angle, the greater the dynamic range and the poorer the optical resolution. In the particular application now being described, wherein the dynamic range is a~out 20-inches, the angle between these axes is about 14.5.
Another factor which is a matter of choice, and which depends upon the particular application for the apparatus, is the distance of the apparatus from the viewing zone. In the parti-cular apparatus illustrated herein, :Lens 12 is located about 60-inches from previously mentioned point 38.
Turning attention now to a key aspect of the invention, in order to maximize the resolution accuracy of the apparatus, it ; is important th~t, throughout the selected dynamic range, reflec-tion images produced by len~ 12 on array 14 all be in sharp focus where they impinge the array. For example, an image reflection from point 32 which strikes the surface of the array where the same is intersected by a line 4Q should be as sharply in focus as an imaged reflection derived from any other point of intersection between the beam of the`laser and the surface of a log in zone 16. ~ith specific reference to the several illustrated points, the imaged reflection from impingement point 34 ~ith log 18 strikes the photodetector ~here the same is intersected b~ line 42; one derived from point 36 strikes the`photodetector where it is intersected by line`44; and one`derived from point 38 strikes the photodetector where it is intersected by line 46.
To achieve the kind of consistant, dynamic-range, sharp focusing now being discussed, it is critical that the surface of array 14 which faces lens 12 lie along a line which intersects axis 20 at the same point where axis 20 is intersected by the plane containing lens 12. Such a line for the array is repre-sented by line 48, and can be seen to intersect axis 20 and plane 24 at a point 50. Tl~e photodetector array may occupy different angular orientations which may be a matter of choice, but will only perform with the accuracy praposed by the present invention if the "point 50" intersection geometry just descrîbed is observed.
Further, while line 48 may be disposed at a slight angle extending either toward or away from the plane of the dra~ing, according to a preferred embodiment of the apparatus, line 48 also lies in the plane of the drawing.
So long as the above geometrical arrangement is observed, for any selected dynamic range for the apparatus, all reflected images directed onto the photodetector array throughout the range will be in sharp conslstant focus thereon. Thus, information derived from the apparatus will exhibit uniform and consistant accuracy.
Completing a description of what is shown in the drawing, indicated ~enerally iTl block form at 52 is a convention-al scan control and signal processing unit. This unit repetîtive-ly scans the light-receiving condition of array 14, and produces, on an output conductor 54, a signal directly reflective of the position along the array at ~hich an image appears. The present invention is not concerned ~ith the details of unit 52. ~ommer-cially available units, like unit 52, are readily available to perform the functions just des;cribed.
It is thus now beIieved to be obvious ho~ appa~atus in accordance with the`present invention ma~ be constructed, arranged ~ 9 and used to produce extremely accurate dîstance measurements.
Obviously, îf it îs desirable`to look, for example, at multiple different points along the length of a long obj.ect such as a log, a plurality pf apparatus units., such as t~e one shown in the drawing, may be used which are distributed in such a fashion to take views at predetermined interYals along the object~ Further, it will be`obvious that the inventîon is useable in an extremely ; wide variety of applications involving industries other than the wood products industry~
10While a preferred embodiment of the invention has been described herein, it is appreciated that variations and modifica-tions, some of which have been suggested above, may be made without departing from the spirit of the invention~
Claims (4)
1. Electro-optical distance-measuring apparatus having a defined dynamic viewing range comprising means for projecting a beam of optical radiation along a defined projection axis, means aimed along a defined viewing axis for gathering and transmitting radiation from said beam reflected by an object impinged thereby, said gathering means generally occupying a plane which is normal to said viewing axis and which intersects said projection axis at a known point, and elongated, linearly distributed optical-radiation sensing means having a length relating to said viewing range, positioned to be impinged by reflected radiation transmitted by said gathering means, said sensing means including plural side-by-side adjacent sensors arranged along a substantially straight line which passes through said known point.
2. Electro-optical distance-measuring apparatus having a defined dynamic viewing range comprising means for projecting a beam of optical radiation along a defined projection axis, means aimed along a defined viewing axis for gathering and transmitting radiation from said beam reflected by an object impinged thereby, said gathering means generally occupying a plane which is normal to said viewing axis and which intersects said projection axis at a known point, and elongated, linearly distributed optical-radiation sensing means having a length relating to said viewing range, positioned to be impinged by reflected radiation transmitted by said gathering means, said sensing means including plural side-by-side adjacent sensors arranged along a substantially straight line which both intersects said viewing axis and passes through said known point.
3. Electro-optical distance-measuring apparatus having a defined dynamic viewing range comprising means for projecting a beam of optical radiation along a defined projection axis, means aimed along a defined viewing axis for gathering and transmitting radiation from said beam reflected by an object impinged thereby, said gathering means generally occupying a first plane which is normal to said viewing axis, which plane intersects said projection axis at a known point, said projection and viewing axes occupying a second plane and being disposed at an oblique angle relative to one another, and elongated, linearly distributed optical-radiation sensing means having a length relating to said viewing range, positioned to be impinged by reflected radiation transmitted by said gathering means, said sensing means including plural side-by-side adjacent sensors arranged along a substantially straight line which both intersects said viewing axis and passes through said known point.
4. Electro-optical distance-measuring apparatus having a defined dynamic viewing range comprising means for projecting a beam of optical radiation along a defined projection axis, means aimed along a defined viewing axis for gathering and transmitting radiation from said beam reflected by an object impinged thereby, said gathering means generally occupying a first plane which is normal to said viewing axis and which inter-sects said projection axis at a known point, said projection and viewing axes occupying a second plane which is normal to said first plane, with said axes disposed at an oblique angle relative to one another, and elongated, linearly distributed optical-radiation sensing means having a length relating to said viewing range, positioned to be impinged by reflected radiation trans-mitted by said gathering means, said sensing means including plural side-by-side adjacent sensors arranged along a substan-tially straight line which both intersects said viewing axis and passes through said known point.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000360955A CA1150049A (en) | 1980-09-24 | 1980-09-24 | Electro-optical distance-measuring system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000360955A CA1150049A (en) | 1980-09-24 | 1980-09-24 | Electro-optical distance-measuring system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1150049A true CA1150049A (en) | 1983-07-19 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000360955A Expired CA1150049A (en) | 1980-09-24 | 1980-09-24 | Electro-optical distance-measuring system |
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| CA (1) | CA1150049A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5262838A (en) * | 1990-02-09 | 1993-11-16 | Vx Optronics Corp. | Apparatus and means for binocular, switchable to binocular rangefinder without light loss |
-
1980
- 1980-09-24 CA CA000360955A patent/CA1150049A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5262838A (en) * | 1990-02-09 | 1993-11-16 | Vx Optronics Corp. | Apparatus and means for binocular, switchable to binocular rangefinder without light loss |
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