METHOD AND APPARATUS FOR OPTICALLY DETECTING THE PRESENCE OF AN ELEMENT IN A SUBSTANCE

• US 3,740,144 A
• Filed: 11/22/1971
• Issued: 06/19/1973
• Est. Priority Date: 11/22/1971
• Status: Expired due to Term

• Current Assignee: Winston G. Walker
• Original Assignee: Winston G. Walker
• Inventors: Walker, Winston G.
• Primary Examiner(s): Wibert, Ronald L.
• Assistant Examiner(s): Godwin, Paul K.
• Application Number:
  US05/200,775
• Time in Patent Office: 575 Days
• Field of Search: 356/53,83,93,97,95,100,204,205,229 350/163,164,285,311
• US Class Current: 356/53
• CPC Class Codes: A01K 43/00 Testing, sorting or cleaning eggs investigating or analysing eggs, e.g. by candling G01N33/08; Conveying devices for batteries A01K31/165; Pick-up devices
• CPC Class Codes: G01J 3/433 Modulation spectrometry; Derivative spectrometry

Abstract

A system for detecting blood in eggs in which a beam of substantially monochromatic light or at least light within a very narrow wavelength band in the region of 578 nanometers (nm) is passed through an egg to be tested. The band is continually shifted in wavelength a number of times per second between substantially the shortest and the mid-length wavelengths of the broader blood absorption band, i.e. 578 to 573 nm. In a preferred embodiment, this is effected by a Fabry-Perot type interference filter placed in a light beam and oscillated about an axis by an electromagnetic device. A photoelectric device senses the light transmitted by the egg and the output signal derived therefrom is compared with an oscillating signal transmitted in time with the oscillation of the filter. If one phase relation exists between such signals, the egg is rejected as having blood present therein and if an opposite phase relation exists, the egg is retained as clear.

Claims

1. The method of detecting the presence of an element in a substance wherein said element is effective to absorb radiant energy within a particular band of wave lengths, comprising the steps of passing a radiant energy beam of a narrow band of wave lengths within said particular band through said substance, oscillating the wave lengths of said narrow band between predetermined limiting wave lengths within said particular band, converting that portion if said beam which passes through said substance into a first signal which varies in accordance with the intensity of said portion of said beam, creating a second signal which varies in accordance with the wave lengths of said narrow band, and creating a third signal indicative of the presence of said element in said substance when a predetermined phase relationship occurs between said first signal and said second signal.

2. The method according to claim 1 wherein said limiting wave lengths comprise substantially a mid-length wave length and a wave length within and adjacent one end of said particular band.

3. The method of detecting eggs having blood therein comprising the steps of passing a light beam of a narrow band of wave lengths through an egg being tested, oscillating the lengths of said wave lengths in said narrow band at least substantially between 578nm and 573nm, converting that portion of said beam which passes through said egg into a first signal which varies in accordance with the density of said portion of said beam, creating a second signal which varies in accordance with the wave lengths of said narrow band, and creating a third signal only when said second signal varies substantially in phase with said first signal to indicate the presence of blood in said egg.

4. The method according to claim 3 which comprises conveying said eggs past said beam, and oscillating said wave lengths of said narrow band a plurality of times while each of said eggs is in said beam.

5. Apparatus for detecting the presence of an element in a substance wherein said element is effective to absorb radiant energy within a particular band of wave lengths, comprising means for directing a beam of radiant energy of a narrow band of wave lengths within said particular band through said substance and for oscillating the wave lengths of said narrow band substantially between a mid-length wave length and a wave length within and adjacent one end of said particular band, photosensitive means for receiving that portion of said beam passing through said substance and for creating a first signal which varies with the intensity of the radiant energy contained in said portion of said beam, means controlled by said first mentioned means for creating a second signal which varies with the wave lengths of said narrow band, a signal device for indicating the presence of said element in the said substance, and means for comparing the phase relationship between said first and said second signals and for actuating said signal device when a predetermined phase relationship exists between said first and second signals.

6. Apparatus according to claim 5 wherein said limiting wavelengths comprise substantially the shortest and the mid-length wavelengths in said particular band.

7. Apparatus for detecting eggs having blood therein comprising means for pasSing a light beam of a narrow band of wave lengths within a particular band of wave lengths absorbed by blood through an egg being tested and for oscillating the wave lengths of said narrow beam between substantially the shortest and the midlength wave length within said particular band, photosensitive means for receiving that portion of said beam passing through said egg and for creating a first signal which varies with the intensity of the light contained in said portion of said beam, means controlled by said first mentioned means for creating a second signal which varies with the wave lengths of said narrow beam, an egg ejecting device, and means for comparing the phase relationship between said first and second signals and for causing operation of said ejecting device when said first and second signals are substantially in phase.

8. Apparatus according to claim 7 wherein said first mentioned means comprises means including a light source, a dielectric band pass filter in said beam, and means for oscillating said filter about an axis extending parallel to the plane of said filter whereby to oscillate the wave lengths of said narrow band.

9. Apparatus according to claim 8 comprising means supporting said filter for adjustment about a second axis normal to said first axis whereby to change the wave lengths passed by said filter at one end of the oscillation thereof.

10. Apparatus according to claim 8 wherein said oscillating means oscillates said filter equal amounts on opposite sides of a plane normal to the length of said beam, and said means for creating said second signal comprises means controlled by said oscillating means for oscillating said second signal at twice the frequency of oscillation of said filter.

11. Apparatus according to claim 7 wherein said first mentioned means comprises means including a light source;

and a rotatable dielectric band pass filter in said beam, said filter oscillating said wave lengths of said narrow band during rotation of said filter.

12. Apparatus according to claim 7 wherein said first mentioned means comprises a tunable laser, oscillating means, and means controlled by said oscillating means for tuning said laser to change the wavelength of light emitted by said laser between substantially said shortest and said mid-length wavelength.

13. Apparatus according to claim 7 comprising means for conveying said eggs past said beam and wherein said first mentioned means oscillates the lengths of said narrow band a plurality of times while each of said eggs is in said beam.