Comparison type colorimeter

• US 4,123,172 A
• Filed: 09/07/1976
• Issued: 10/31/1978
• Est. Priority Date: 09/07/1976
• Status: Expired due to Term

• Current Assignee: Sterndent Corp.
• Original Assignee: Sterndent Corp.
• Inventors: French, Park
• Primary Examiner(s): Evans, F. L.
• Application Number:
  US05/721,107
• Time in Patent Office: 784 Days
• Field of Search: 350/96 R, 350/96 B, 350/293, 356/39-41, 356/88, 356/89, 356/93-97, 356/104, 356/204, 356/205, 356/211, 356/212, 356/179, 356/180, 356/184, 356/186, 356/188, 356/189, 240/1 LP, 362/32
• US Class Current: 356/418
• CPC Class Codes: G01N 21/255 Details, e.g. use of specially adapted sources, lighting or optical systems

Abstract

A comparison type colorimeter concentrates unknown and reference light beams onto the same surface area portion of a single photosensor and additionally filters the unknown and reference light beams by the same color filters and, preferably, portions thereof. Moreover, an enclosed light source produces light for the colorimeter to eliminate shift in illumination due to dust accumulation on the lamp and/or reflector of the light source.

Claims

1. A system for directing two different light beams onto substantially the same portion of the surface area of a photosensor, comprising:

focusing means for focusing light onto a portion of the surface area of the photosensor, said focusing means comprising a lens positioned about one focal length from said photosensor,

first collimating means for substantially collimating a first beam of light and directing the same to said focusing means,

second means positioned in the path of at least part of said first beam for directing generally coaxially with said first beam, a second beam of light along a path in common with the path of said first beam of light to said focusing means, and

chopper means for cyclically alternately passing light to said respective first and second means for directing,

whereby said focusing means sequentially focuses each of said first and second beams of light onto substantially the same portion of the surface area of the photosensor,

said first means for directing including means for supplying said first beam of light to said focusing means in a path having a relatively large cross-sectional area, and said second means for directing including means for directing said second beam of light to said focusing means as substantially collimated light having a relatively small cross-sectional area.

2. A system as set forth in claim 1, wherein said collimating means comprises a collimating lens and said second means is positioned between said lens and said collimating lens.

3. A system as set forth in claim 1, further comprising an infrared filter positioned between said focusing means and both of said first and second means to filter both of said light beams prior to impingement on the photosensor.

4. An illuminating apparatus for an optical measuring system, comprising means for generating light, housing means for substantially completely enclosing said means for generating light to shield the same from dust and the like, and light pipe means exposed to light in said housing means for directing such light exteriorly of said housing means to illuminate an external object, said housing means including reflector means for concentrating light from said means for generating light onto said light pipe means, said reflector means being generally of partial ellipsoidal shape, said means for generating light being positioned at least proximate the internal focus of such ellipsoid, and said light pipe means having a light input end positioned beyond the external focus of such ellipsoid relative to said means for generating light to receive generally diverging light.

5. An illuminating apparatus as set forth in claim 4, wherein said housing means includes end plate means for mounting said input end of said light pipe means to said housing means in alignment with said diverging light to be fully illuminated thereby.

6. An illuminating apparatus as set forth in claim 5, wherein the optical measuring system includes photosensitive measuring means for measuring light directed thereto from such external object, and the illuminating apparatus further comprises further light pipe means secured to said end plate means and exposed to light in said housing for directing a reference beam of light to said photosensitive measuring means.

7. An illuminating apparatus as set forth in claim 5, further comprising a second light pipe means, said second light pipe means having an input end also mounted by said end plate means in alignment beyond said external focus to be fully illuminated by said diverging light.

8. A system for directing two different light beams onto substantially the same portion of the surface area of a photosensor, comprising:

focusing means for focusing light onto a portion of the surface area of the photosensor,

first means for directing a first beam of light to said focusing means, and

second means for directing a second beam of light to said focusing means,

whereby said focusing means focuses both said first and second beams of light onto substantially the same portion of the surface area of the photosensor,

said focusing means comprising a lens positioned approximately one focal length away from the photosensor,

said first means comprising collimating means for substantially collimating said first beam of light, whereby said first beam of light directed to said lens is substantially collimated light,

said second means having at least a portion positioned in the path of at least part of said first beam of light for directing said second beam of light along a path in common with the path of said first beam of light, said second means comprising further collimating means for substantially collimating said second beam of light, whereby said second beam of light directed to said lens is substantially collimated light, said further collimating means including aperture means for blocking a portion of said second beam of light with opening means for passing a portion of said second beam of light substantially as collimated light and elongate prism reflector means aligned with said opening means and said lens for directing said collimated light portion of said second beam of light to said lens, and

wherein said collimating means comprises a collimating lens and at least a portion of said prism reflector means is positioned between said lens and said collimating lens.

9. A system for directing two different light beams onto substantially the same portion of the surface area of a photosensor, comprising:

focusing means for focusing light onto a portion of the surface area of the photosensor,

first means for directing a first beam of light to said focusing means, and

second means for directing a second beam of light to said focusing means,

whereby said focusing means focuses both said first and second beams of light onto substantially the same portion of the surface area of the photosensor,

said focusing means being positioned relative to the photosensor a distance such that said focusing means is operable to concentrate substantially collimated light supplied thereto onto the surface area portion of the photosensor, said first means for directing including means for supplying said first beam of light to said focusing means as substantially collimated light in a path having a relatively large cross-sectional area, and said second means for directing including means at least partly interposed in part of such path for directing said second beam of light to said focusing means as substantially collimated light having a relatively small cross-sectional area, and

further comprising chopper means for cyclically and sequentially passing light to said first and second means for directing, said chopper means including color filter means for passing a predetermined color light and movable support means for moving said color filter means into position to pass such color light to only one of said first and second means for directing and subsequently into position to pass such color light to only the other of said first and second means for directing.

10. A system as set forth in claim 9, wherein said chopper means includes a plurality of color filter means for respectively passing different color light, and said movable support means includes means for cyclically and sequentially moving each of said color filter means to pass respective color light sequentially to said one and said other of said first and second means for directing.

11. A system as set forth in claim 10, further comprising an illuminating apparatus including means for generating light, housing means for substantially completely enclosing said means for generating light to shield the same from dust and the like, first light pipe means exposed to light in said housing means for directing such light exteriorly of said housing means to illuminate an external object thereby to produce said first beam of light and second light pipe means exposed to light in said housing means for directing such light exteriorly of said housing means to produce said second beam of light.

12. A system for directing two different light beams onto substantially the same portion of the surface area of a photosensor, comprising:

focusing means for focusing light onto a portion of the surface area of the photosensor,

first means for directing a first beam of light to said focusing means,

second means for directing a second beam of light to said focusing means,

whereby said focusing means focuses both said first and second beams of light onto substantially the same portion of the surface area of the photosensor, and

an illuminating apparatus including means for generating light, housing means for substantially completely enclosing said means for generating light to shield the same from dust and the like, first light pipe means exposed to light in said housing means for directing such light exteriorly of said housing means to illuminate an external object thereby to produce said first beam of light and second light pipe means exposed to light in said housing means for directing such light exteriorly of said housing means to produce said second beam of light.

13. A system as set forth in claim 12, wherein said housing means includes reflector means for concentrating light from said means for generating light onto said light pipe means, said reflector means being generally of partial ellipsoidal shape, said means for generating light being positioned at least proximate the internal focus of such ellipsoid, said housing means further including end plate means for mounting respective input ends of said first and second light pipe means to said housing means such that said input ends are positioned beyond the external focus of such ellipsoid relative to said means for generating light, and said housing means further including intermediate means between said reflector means and said end plate means for securing the same together, thereby to enclose said means for generating light.

14. A system as set forth in claim 13, further comprising means relatively remotely positioned with respect to said illuminating apparatus for filtering infrared light from both of said light beams prior to impingement of said light beams on the photosensor.

15. A system for directing two different light beams onto substantially the same portion of the surface area of a photosensor, comprising:

focusing means for focusing light onto a portion of the surface area of the photosensor,

first means for directing a first beam of light to said focusing means,

second means for directing generally coaxially with said first beam, a second beam of light to said focusing means, and

chopper means for cyclically alternately passing light to said respective first and second means for directing,

whereby said focusing means sequentially focuses each of said first and second beams of light onto substantially the same portion of the surface area of the photosensor, and

said second means comprising aperture means for blocking a portion of said second beam and opening means for passing a portion of said second beam substantially as collimated light, and reflector means aligned with said opening means and said focusing means and including a portion generally in said first beam for directing said collimated light portion of said second beam, generally coaxially to said first beam, to said focusing means.

16. A system as set forth in claim 15, wherein said reflector means comprises an elongate prism having one surface for receiving at least part of said collimated light portion of said second beam, and another surface comprising said reflector means portion positioned generally in said first beam.

17. A system for directing two different light beams onto substantially the same portion of the surface area of a photosensor, comprising:

focusing means for focusing light onto a portion of the surface area of the photosensor,

first means for directing a first beam of light to said focusing means,

second means for directing a second beam of light to said focusing means,

chopper means for cyclically alternately and sequentially passing light to said respective first and second means for directing, said chopper means including color filter means for passing a predetermined color light and movable support means for alternately moving said color filter means into positions to pass light, third means aligned with said chopper means for directing one beam of light to and through only one portion of said color filter means when the latter is transmissively aligned therewith for delivery of such color light to only one of said first and second means for directing and fourth means aligned with said chopper means for directing another beam of light to and through the same portion of said color filter means as the latter is subsequently moved into transmissive alignment therewith for delivery of such color light to only the other of said first and second means for directing.

18. A system as set forth in claim 17, wherein said chopper means includes a plurality of color filter means for respectively passing different color light, and said movable support means includes means for cyclically and sequentially moving each of said color filter means to pass respective color light sequentially to said one and said other of said first and second means for directing.