Co-planar electromagnetic profile scanner

• US 5,986,745 A
• Filed: 03/24/1997
• Issued: 11/16/1999
• Est. Priority Date: 11/29/1994
• Status: Expired due to Term

• Current Assignee: Alexander Thomas Hermary, Terrance John Hermary
• Original Assignee: Alexander Thomas Hermary, Terrance John Hermary
• Inventors: Hermary, Alexander Thomas, Hermary, Terrance John
• Primary Examiner(s): Laufer, Pinchus M.
• Application Number:
  US08/823,532
• Time in Patent Office: 967 Days
• Field of Search: 356/376, 356/3.03, 356/3.06, 356/3.07, 250/559.22, 250/559.23, 382/106, 382/199
• US Class Current: 356/3.03
• CPC Class Codes: G01B 11/245 using a plurality of fixed, simultaneously operating transducers G01B11/2408 - G01B11/2425, G01B11/255 take precedence
• CPC Class Codes: G01B 11/25 by projecting a pattern, e.g. one or more lines, moiré fringes on the object G01B11/255 takes precedence ; image analysis for depth or shape recovery G06T7/50

Abstract

A co-planar system for determining the shape and dimensions of a surface of an object includes a projector for projecting in a selected plane onto the object a spatially coded pattern of radiation, e.g., light. The system also includes a receiving device capable of imaging the reflected pattern in the selected plane, and a discriminator for determining which portion of the reflected pattern corresponds to which portion of the projected pattern. By this means, a received signal representing less than the complete reflection from the projected pattern can be correlated with a discrete portion of the scanned object. The object is moved relative to the selected plane and the procedure repeated to obtain enough reliable data to generate a reasonably reliable surface profile. The resulting set of received signals and correlations are used to calculate the shape and dimensions of the object.

Claims

1. A co-planar profile scanner, comprising:

(a) an illuminator for illuminating a portion of the surface of an object along the line of intersection of a plane with the object by projecting in the plane onto the surface of the object a spatially varied pattern of electromagnetic radiation selected so that any portion of the pattern of at least some preselected minimum size is distinguishable from any other portion of the pattern, said pattern comprised of an array of spatially arranged pattern elements of at least two mutually distinguishable types, where each pattern element comprises at least a first and a second discrete physical characteristic, each discrete physical characteristic being associated with a discrete type of information;

(b) a detector for receiving electromagnetic radiation reflected in the plane from the illuminated portion of the object;

(c) a converter for converting the received electromagnetic radiation into reflection data;

(d) a discriminator for processing said reflection data for correlating each distinguishable portion of the projected pattern with its reflection by comparing transmission data representing the pattern of the illuminating beam with the reflection data, so as to establish a match of an identifiable portion of the reflected radiation and a corresponding portion of the illuminating beam, whereby the portion of the surface of the object from which the reflected radiation has been reflected is ascertained; and

(e) a coordinate calculator for computing the spatial coordinates of the portion of that surface of the object on which each distinguishable portion of the pattern falls.

2. The co-planar profile scanner as defined in claim 1, wherein the converter converts the received electromagnetic radiation into computer-readable digital reflection data.

3. The co-planar profile scanner as defined in claim 1, wherein the pattern is comprised of a plurality of parallel bands alternating between high and low intensity, the bands each having a selected one of at least two mutually distinguishable widths.

4. The co-planar profile scanner as defined in claim 3, wherein the pattern elements are arranged in a sequence that can be represented by a binary number comprising 1'"'"'s and 0'"'"'s, where each 0 represents a narrow high-intensity band followed by a wide low-intensity band, and each 1 represents a wide high-intensity band followed by a narrow low-intensity band, and where any sequence of 1'"'"'s and 0'"'"'s greater in length than a predetermined sequence is unique.

5. A co-planar profile scanner, comprising:

(a) an illuminator for illuminating a portion of the surface of an object along the line of intersection of a plane with the object by projecting in the plane onto the surface of the object a spatially varied pattern of electromagnetic radiation selected so that any portion of the pattern of at least some preselected minimum size is distinguishable from any other portion of the pattern, said pattern comprised of an array of spatially arranged pattern elements of at least two mutually distinguishable types, where each pattern element comprises at least a first and a second discrete physical characteristic, each discrete physical characteristic being associated with a discrete type of information;

(b) means for forming an image of the illuminated portion of the object from the electromagnetic radiation reflected in the plane from the object;

(c) means for correlating the projected pattern with the image, so as to establish a match of each identifiable portion of the reflected radiation with a corresponding portion of the projected pattern, whereby the portion of the surface of the object from which the reflected radiation from the corresponding portion of the projected pattern has been reflected is ascertained; and

(d) a coordinate calculator for computing the spatial coordinates of the portion of that surface of the object on which each distinguishable portion of the projected pattern falls.

6. The co-planar profile scanner as defined in claim 5, wherein the pattern is comprised of a plurality of parallel bands alternating between high and low intensity, the bands each having a selected one of at least two mutually distinguishable widths.

7. The co-planar profile scanner as defined in claim 6, wherein the pattern elements are arranged in a sequence that can be represented by a binary number comprising 1'"'"'s and 0'"'"'s, where each 0 represents a narrow high-intensity band followed by a wide low-intensity band, and each 1 represents a wide high-intensity band followed by a narrow low-intensity band, and where any sequence of 1'"'"'s and 0'"'"'s greater in length than a predetermined sequence is unique.

8. A co-planar profile scanner, comprising:

a frame surrounding a planar scan zone through which an object whose profile is to be measured may pass; and

at least three scanning heads mounted to the frame and approximately uniformly angularly spaced about the center of the scan zone,

each discrete scanning head having

an illuminator for illuminating a portion of the surface of the object along the line of intersection of the plane which includes the scan zone with the object by projecting in the plane toward the scan zone and onto the surface of the object a spatially varied pattern of electromagnetic radiation selected so that any portion of the pattern of at least some preselected minimum size is distinguishable from any other portion of the pattern, said pattern comprised of an array of spatially arranged pattern elements of at least two mutually distinguishable types, where each pattern element comprises at least a first and a second discrete physical characteristic, each discrete physical characteristic being associated with a discrete type of information, and

a detector for receiving electromagnetic radiation reflected in the plane which includes the scan zone from the illuminated portion of the object, and

each discrete scanning head further being associated with and connected to

a converter for converting the received electromagnetic radiation into reflection data,

a discriminator for processing said reflection data for correlating each distinguishable portion of the projected pattern with the image of its reflection by comparing transmission data representing the pattern of the illuminating beam with the reflection data, so as to establish a match of an identifiable portion of the reflected radiation and a corresponding portion of the illuminating beam, whereby the portion of the surface of the object from which the reflected radiation has been reflected is ascertained, and

a coordinate calculator for computing the spatial coordinates of the portion of that surface of the object on which each distinguishable portion of the pattern falls.

9. The co-planar profile scanner as defined in claim 8, comprising at least four scanning heads.

10. The co-planar profile scanner as defined in claim 8, wherein the converter converts the received electromagnetic radiation into computer-readable digital reflection data for processing in the discriminator.

11. The co-planar profile scanner as defined in claim 8, wherein the pattern is comprised of a plurality of parallel bands alternating between high and low intensity, the bands each having a selected one of at least two mutually distinguishable widths.

12. The co-planar profile scanner as defined in claim 11, wherein the pattern elements are arranged in a sequence that can be represented by a binary number comprising 1'"'"'s and 0'"'"'s, where each 0 represents a narrow high-intensity band followed by a wide low-intensity band, and each 1 represents a wide high-intensity band followed by a narrow low-intensity band, and where any sequence of 1'"'"'s and 0'"'"'s greater in length than a predetermined sequence is unique.

13. The co-planar profile scanner as defined in claim 12, wherein each discrete scanning head has a discrete converter, a discrete discriminator, and a discrete coordinate calculator.

14. A co-planar profile scanner for measuring an object by measuring the spatial coordinates of the line of intersection of a plane with the surface of the object, comprising

(a) an illuminator for illuminating a portion of the surface of the object along the line of intersection of the plane with the object by projecting in the plane onto the surface of the object a coded spatially varied pattern of electromagnetic radiation selected so that any portion of the pattern of at least some preselected minimum size is distinguishable from any other portion of the pattern, said pattern comprised of an array of spatially arranged pattern elements of at least two mutually distinguishable types, where each pattern element comprises at least a first and a second discrete physical characteristic, each discrete physical characteristic being associated with a discrete type of information;

(b) a detector for receiving electromagnetic radiation reflected in the plane from the illuminated portion of the object;

(c) a converter for converting the received electromagnetic radiation into computer-readable digital reflection data;

(d) a discriminator for processing said data for correlating each distinguishable portion of the projected pattern with its reflection by comparing transmission data representing the pattern of the illuminating beam with the reflection data, so as to establish a match of an identifiable portion of the reflected radiation and a corresponding portion of the illuminating beam, whereby the portion of the surface of the object from which the reflected radiation has been reflected is ascertained; and

(e) a coordinate calculator for computing the spatial coordinates of the portion of that surface of the object on which each distinguishable portion of the pattern falls.

15. The co-planar profile scanner as defined in claim 14, additionally comprising means for coordinating the illuminator, the detector, the converter, the discriminator, and the coordinate calculator to perform a series of scans of the surface of the object by measuring the spatial coordinates of lines of intersection of a series of discrete planes with the surface of the object, thereby to measure the coordinates of the surface of the object.

16. The co-planar profile scanner as defined in claim 15, wherein the illuminating means comprises a laser light source, a cylindrical lens receiving light from the laser light source and generating therefrom a fan-shaped beam of light, and a mask having said pattern created therein by means of alternating transparent and opaque regions, said mask receiving the fan-shaped beam of light from the cylindrical lens and superimposing the pattern on the beam as the beam passes through the mask.

17. The co-planar profile scanner as defined in claim 14, wherein the pattern is comprised of a plurality of parallel bands each band having a selected one of at least two mutually distinguishable intensities.

18. The co-planar profile scanner as defined in claim 14, wherein the pattern is comprised of a plurality of parallel bands alternating between high and low intensity, the bands each having a selected one of at least two mutually distinguishable widths.

19. The co-planar profile scanner as defined in claim 18, wherein the pattern elements are arranged in a sequence that can be represented by a binary number comprising 1'"'"'s and 0'"'"'s, where each 0 represents a narrow high-intensity band followed by a wide low-intensity band, and each 1 represents a wide high-intensity band followed by a narrow low-intensity band, and where any sequence of 1'"'"'s and 0'"'"'s greater in length than a predetermined sequence is unique.

20. The co-planar profile scanner as defined in claim 14, wherein the pattern is comprised of a plurality of parallel bands of alternating high and low intensity and a selected one of at least two mutually distinguishable widths, so arranged that when read from one end of the pattern, the pattern comprises elements each comprising a high intensity band and a following low intensity band.

21. A method for measuring an object by measuring the spatial coordinates of the line of intersection of a plane with the surface of the object, comprising the steps of:

(a) illuminating the surface of the object along the line of intersection of the plane with the object by projecting in the plane onto the surface a spatially varied pattern of electromagnetic radiation selected so that any portion of the pattern of at least some preselected minimum size is distinguishable from any other portion of the pattern, said pattern comprised of an array of spatially arranged pattern elements of at least two mutually distinguishable types, where each pattern element comprises at least a first and a second discrete physical characteristic, each discrete physical characteristic being associated with a discrete type of information;

(b) detecting electromagnetic radiation reflected in the plane from the illuminated portion of the object;

(c) converting the received electromagnetic radiation into computer-readable digital reflection data;

(d) correlating each distinguishable portion of the projected pattern with the image of its reflection by comparing transmission data representing the pattern of the illuminating beam with the reflection data, so as to establish a match of an identifiable portion of the reflected radiation and a corresponding portion of the illuminating beam, whereby the portion of the surface of the object from which the reflected radiation has been reflected is ascertained; and

(e) computing the spatial coordinates of the portion of that surface of the object on which each distinguishable portion of the pattern falls.

22. The method defined in claim 21, wherein the surface of the object is measured by moving the object relative to the plane and repeating steps (a) through (e).