Optical differentiation between plants and background utilizing a single CCD camera

• US 5,621,460 A
• Filed: 06/29/1995
• Issued: 04/15/1997
• Est. Priority Date: 10/11/1994
• Status: Expired due to Fees

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Hatlestad, John D., Sauter, Gerald F.
• Primary Examiner(s): GARBER, WENDY RAE
• Application Number:
  US08/496,615
• Time in Patent Office: 656 Days
• Field of Search: 348/262, 348/265, 348/336, 348/337, 348/338
• US Class Current: 348/265
• CPC Class Codes: A01M 7/0089 Regulating or controlling systems the delivery being related to the movement of a vehicle B05B9/06
• CPC Class Codes: H04N 23/11 for generating image signals from visible and infrared light wavelengths
• CPC Class Codes: H04N 23/16 Optical arrangements associated therewith, e.g. for beam-splitting or for colour correction
• CPC Class Codes: H04N 5/33 Transforming infrared radiation cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20

Abstract

An optical system for detecting vegetation with the use of a single image sensor, such as a charge coupled device (CCD) camera is provided by optical elements which project separate red and near infrared (NIR) images onto the CCD camera. The camera then can supply output signals representative of the two images to a signal processing device that determines the nature of the vegetation that provided the original image. Embodiments are described where the imaging sensor utilizes unitary optical splitters to provide wide-angle separate images. In another version a single lens and a group of mirrors provide a narrow-angle telescope device. Another version includes two separate lens, red and NIR filters, each adjacent to one of the lenses so as to project an image on separate areas of the CCD camera.

Claims

1. An optical image sensor means for receiving a sensed light image comprising:

a plurality of planar sensing means located in a first plane, each of said sensing means being capable of providing an output signal that is representative of an optical frequency passband beam that impinges thereon,

a plurality of optical filter means located in a second plane adjacent said first plane, and each of said optical filter means is located to receive one of a plurality of split optical image beams and to provide an optical frequency passband beam to only one of said sensing means,

an optical beam-splitting means positioned to receive an optical image beam and to split said optical image beam into said plurality of split optical image beams that are each substantially identical in frequency composition and are each directed along independent paths such that each of said plurality of split optical image beams impinges upon a respective one of said optical filter means,

wherein all of said optical filter means are positioned adjacent said optical beam-splitting means without any intervening air space between said filter means, and said optical beam-splitting means, and said optical beam-splitting means comprises a block of optically transparent material and a plurality of non-dichroic mirrors that are attached to said block without any intervening air space so that said split optical image beams are received and passed through said block to their respective optical filter means without any intervening air space.

2. An optical image sensor means as claimed in claim 1 wherein said optical image sensor means further comprises lens means positioned to receive said optical image beam and to direct said optical image beam into said block.

3. An optical image sensor as claimed in claim 2 wherein said lens means is attached to said block without any intervening air space.

4. An optical image sensor as claimed in claim 3 wherein said lens is divided by said plurality of mirrors so as to form said plurality of split optical image beams such that each of said plurality of split optical image beams is confined into its own independent channel in said block so as to be directed to a respective one of said filter means and each of said filter means supplies an optical frequency passband that corresponds to the split optical image beam that is received by said respective filter means.

5. An optical image sensor as claimed in claim 4 wherein each of said sensing means of said plurality of sensing means comprises an independent sensing area of a single planar charge-coupled sensing device for receiving one of said optical frequency passband image beams.

6. An optical image sensor means as claimed in claim 5 wherein a first one of said optical filter means provides a red optical frequency passband image beam to a first sensing area of said charge-coupled sensing device, and a second one of said optical filter means provides a near-infrared optical frequency passband image beam to a second sensing area of said charge-coupled sensing device.

7. An optical image sensor means as claimed in claim 1 wherein a first one of said optical filter means provides a red optical frequency passband image beam to a first sensing means, and a second one of said optical filter means provides a near-infrared optical frequency passband image beam to a second sensing means.

8. An optical image sensor as claimed in claim 1 wherein each of said sensing means of said plurality of sensing means comprises an independent area of a single sensing device.

9. An optical image sensor means as claimed in claim 8 wherein a first one of said optical filter means provides a red optical frequency passband image beam to a first sensing means, and a second one of said optical filter means provides a near-infrared optical frequency passband image beam to a second sensing means.