Optical measuring apparatus

• US 3,885,162 A
• Filed: 07/01/1974
• Issued: 05/20/1975
• Est. Priority Date: 10/31/1973
• Status: Expired due to Term

• Current Assignee: Lloyd M. Geertz
• Original Assignee: Lloyd M. Geertz
• Inventors: Geertz, Lloyd M.
• Primary Examiner(s): Stolwein, Walter
• Application Number:
  US05/484,798
• Time in Patent Office: 323 Days
• Field of Search: 250/573,574,216,233,572,56Y,565,578 340/237S 356/201,205,207,208
• US Class Current: 250/573
• CPC Class Codes: G01N 21/534 by measuring transmission alone, i.e. determining opacity

Abstract

A measuring apparatus for measuring the density of smoke and the like comprising a light source for emitting a beam of radiant energy which is directed through the smoke which is to be measured, and a first reflector positioned in the path of said beam for redirecting said beam. Chopping means are movable periodically into the path of the beam for interrupting the passage of the beam to the first reflector means. A second reflector means on the chopping means is movable in the path of the beam when the beam is interrupted by said chopping means. Means are provided for directing the light reflected by the first reflector means and the reflector means to a light sensitive means. This invention relates to optical measuring apparatus and particularly to measuring apparatus for measuring the optical transmittance of smoke and the like.

Claims

1. In a measuring apparatus for measuring smoke density and the like, the combination comprising a stack or duct;

a light source for emitting a beam of radiant energy through a portion of the sTack;

first retro-reflector means in the path of said beam for redirecting said beam after it passes through the stack;

chopping means in the stack movable periodically into the path of the beam for interrupting the passage of the beam to the first reflector means;

second retro-reflector means on the chopping means movable in the path of the beam when the beam is interrupted by said chopping means;

light sensitive means externally of the stack; and

means for directing the light reflected by said first reflector means and said second reflector means to said light sensitive means.

2. The combination set forth in claim 1 wherein said chopping means comprises a rotating disc having an aperture therein;

said second retro-reflector means being mounted on said disc.

3. The combination set forth in claim 1 wherein said means for directing said light from said first reflector means and said second reflector means comprises beamsplitter means externally of the stack between the light source and said first reflector means;

said beamsplitter means redirecting the light from said first reflector means and said second reflector means to said light sensitive means.

4. The combination set forth in claim 1 including second aperture means in the stack between said light source and said first aperture means.

5. The combination set forth in claim 1 including a lens between said light source and said first reflector means.

6. The combination set forth in claim 1 including filter means in the path of light directed to said light sensitive means.

7. In an optical measuring apparatus, the combination comprising a light source for emitting a beam of radiant energy;

a first reflector in the path of said beam for redirecting said beam;

chopping means movable periodically into the path of the beam for interrupting the passage of the beam to the first reflector means;

second retro-reflector means on the chopping means movable in the path of the beam when the beam is interrupted by said chopping means;

light sensitive means; and

means for directing the light reflected by said first reflector means and said second reflector means to said light sensitive means.

8. The combination set forth in claim 7 wherein said chopping means comprises a rotating disc having an aperture therein, said second retro-reflector means being mounted on said disc.

9. The combination set forth in claim 7 wherein said means for directing said light from said first reflector means and said second reflector means comprises beamsplitter means between the light source and said first reflector means;

said beamsplitter means redirecting the light from said first reflector means and said second reflector means to said light sensitive means.

10. The combination set forth in claim 7 including second chopping means between said light source and said first chopping means.

11. The combination set forth in claim 7 including a lens between said light source and said first reflector means.

12. The combination set forth in claim 7 including filter means in the path of light directed to said light sensitive means.