Laser scanning and multiple detection for video image processing

• US 4,286,293 A
• Filed: 05/30/1979
• Issued: 08/25/1981
• Est. Priority Date: 05/30/1979
• Status: Expired due to Term

• Current Assignee: AT&T Technologies Inc (Nokia Corporation)
• Original Assignee: Western Electric Co., Inc. (Nokia Corporation)
• Inventors: Jablonowski, Donald P.
• Primary Examiner(s): Martin, John C.
• Application Number:
  US06/043,953
• Time in Patent Office: 818 Days
• Field of Search: 358/101, 358/106, 358/107, 358/200, 358/208, 358/284, 358/285, 358/293, 358/209, 358/199, 358/282, 358/110, 358/206, 250/209, 250/224, 250/225, 250/562, 250/563, 250/572, 250/578, 250/571, 250/557, 250/560, 250/561, 356/222, 356/237, 356/364, 356/369, 356/430, 356/445, 356/448
• US Class Current: 348/126
• CPC Class Codes: H04N 3/02 by optical-mechanical means only H04N3/36 takes precedence

Abstract

An object (12) is raster scanned with a small, localized beam of laser light (22) and the backscattered radiation therefrom is monitored by a plurality of detectors (44). Each of the detectors (44) monitors a different characteristic of the backscattered radiation and an arithmetic operation is performed on the output of the detectors to provide a single composite video signal with enhanced contrast.

Claims

1. A method for obtaining an enhanced video signal, representing a ceramic substrate having a metallic pattern thereon, the method comprising the steps of:

raster scanning a narrow beam of illumination over the surface of the patterned substrate;

monitoring radiation scattered by the scattered substrate with a plurality of detectors wherein a first detector detects radiation scattered at low angles by the surface of the patterned substrate while a second detector detects the radiation scattered at high angles by said surface;

generating a video signal at the output of each detector, each video signal representing the scattered radiation impinging thereon; and

subtracting the video output of the second detector from the first detector to form a composite video signal having enhanced contrast.

2. A method for obtaining an enhanced video signal, representing a printed wiring board having a metallic pattern thereon, the method comprising the steps of:

raster scanning a narrow beam of illumination over the surface of the printed wiring board;

monitoring radiation scattered by the surface of the printed wiring board with a plurality of detectors wherein a first detector detects radiation scattered at low angles by the surface while a second detector detects the radiation scattered at high angles by said board surface;

generating a video signal at the output of each detector, each video signal representing the scattered radiation impinging thereon; and

subtracting the video output of the second detector from the first detector to form a composite video signal having enhanced contrast.

3. A method for obtaining an enhanced video signal representing a polished semiconductor wafer having diffusive portions on the surface thereof, the method comprising the steps of:

raster scanning a narrow beam of illumination over the surface of the wafer;

monitoring radiation scattered by the surface of the wafer with a plurality of detectors wherein a first detector detects radiation scattered at low angles by the surface of the wafer while a second detector detects the radiation scattered at high angles by said surface;

generating a video signal at the output of each detector, each video signal representing the scattered radiation impinging thereon; and

subtracting the video output of the second detector from the first detector to form a composite video signal having enhanced contrast.

4. A method for obtaining an enhanced video signal representing a ceramic substrate having a metallic pattern thereon, the method comprising the steps of:

raster scanning a narrow beam of polarized illumination over the surface of the patterned substrate;

monitoring the radiation scattered by the surface of the patterned substrate with a plurality of detectors wherein a first detector detects a parallel component of the radiation scattered at low angles by the surface while a second detector detects an orthogonal component of the radiation scattered at high angles by said surface;

generating a video signal at the output of each detector, each video signal representing the scattered radiation impinging thereon; and

substracting the video output of the second detector from the first detector to form a composite video signal having enhanced contrast.

5. A method for obtaining an enhanced video signal representing a printed wiring board having a metallic pattern thereon, the method comprising the steps of:

raster scanning a narrow beam of polarized illumination over the surface of the printed wiring board;

monitoring the radiation scattered by the surface of the board with a plurality of detectors wherein a first detector detects a parallel component of the radiation scattered at low angles by the surface while a second detector detects an orthogonal component of the radiation scattered at high angles by said surface;

generating a video signal at the output of each detector, each video signal representing the scattered radiation impinging thereon; and

subtracting the video output of the second detector from the first detector to form a composite video signal having enhanced contrast.

6. A method for obtaining an enhanced video signal representing a polished semiconductor wafer having diffusive portions on the surface thereof, the method comprising the steps of:

raster scanning a narrow beam of polarized illumination over the surface of the wafer;

monitoring the radiation scattered by the surface of the wafer with a plurality of detectors wherein a first detector detects a parallel component of the radiation scattered at low angles by the surface while a second detector detects an orthogonal component of the radiation scattered at high angles by said surface;

generating a video signal at the output of each detector, each video signal representing the scattered radiation impinging thereon; and

subtracting the video output of the second detector from the first detector to form a composite video signal having enhanced contrast.