Active Light Sensor

• US 20080291455A1
• Filed: 04/23/2008
• Published: 11/27/2008
• Est. Priority Date: 11/07/2003
• Status: Abandoned Application

• Current Assignee: Kyle H. Holland Trustee Of The Maranatha Trust
• Original Assignee: Kyle H. Holland Trustee Of The Maranatha Trust
• Inventors: Holland, Kyle Harold
• Application Number:
  US12/108,371
• Publication Number:
  US 20080291455A1
• Time in Patent Office: Days
• US Class Current: 356/445
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01J 3/36 Investigating two or more bands of a spectrum by separate detectors
• CPC Class Codes: G01N 2021/3155 Measuring in two spectral ranges, e.g. UV and visible
• CPC Class Codes: G01N 2021/635 Photosynthetic material analysis, e.g. chrorophyll
• CPC Class Codes: G01N 2021/8466 Investigation of vegetal material, e.g. leaves, plants, fruits
• CPC Class Codes: G01N 21/31 Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry G01N21/72 takes precedence
• CPC Class Codes: G01N 21/3563 for analysing solids; Preparation of samples therefor
• CPC Class Codes: G01N 2201/1244 Ambient light detector, e.g. for invalidating

Abstract

An apparatus is described for assessing plant status remotely sensed by the invention thereby allowing selective monitoring or treatment of individual plants. Additionally, the apparatus may be utilized for measuring the reflectance characteristics of soil or of objects in general. The apparatus utilizes a solid state light source to illuminate a plant canopy or object under investigation. An array of spectrally sensitive photosensors are incorporated into the apparatus to detect light reflected from a plant or object resulting from the integral light source. The instrument may be mounted to a vehicle, mounted to a tripod or held in the hand of an operator for use. A controller can be used in conjunction with the invention to analyze measured reflectance signals and can respond by activating a device to take some action with respect to the plant and/or object or store the analyzed signals with corresponding DGPS position in the controller'"'"'s memory for later analysis.

Claims

1. A method for measuring the reflectance of a plant, comprising the steps of:

(a) simultaneously projecting light of a first, visible wavelength from a solid-state polychromatic light source and light of a second, infrared wavelength from the light source, modulating the first and second light sources, and setting and monitoring optical power of the first and second light sources;

(b) receiving reflected visible light originating from the light source in a reflected light receiver comprising a first photodetector sensitive to visible light, and reducing the effects of ambient light on the first photodetector in an ambient light compensation means; and

a first output;

(c) configuring the photodetectors for a chosen optical band by applying at least one spectral selectivity means to at least one of the photodetectors, wherein the spectral selectivity means is fitted to removably attach to the photodetector;

(c) positioning a second photodetector sensitive to infrared light to receive reflected infrared light originating from the light source, and reducing the effects of ambient light on said second photodetector in an ambient light compensation means; and

a second output;

(c) distinguishing the light originating from said light source and reflected by the object from ambient light; and

(d) calculating in a computational device a vegetative index based on reading said first output and said second output and light source power.

2. The method of claim 1, further comprising the step of configuring the photodetectors by applying the spectral selectivity means in the field.