Apparatus for collecting light and its method of manufacture

• US 5,615,294 A
• Filed: 06/07/1995
• Issued: 03/25/1997
• Est. Priority Date: 11/30/1992
• Status: Expired due to Fees

• Current Assignee: Breault Research Organization Inc.
• Original Assignee: Breault Research Organization Inc.
• Inventors: Castonguay, Raymond J.
• Primary Examiner(s): Lee, John D.
• Application Number:
  US08/479,663
• Time in Patent Office: 657 Days
• Field of Search: 385/115, 385/116, 385/120, 385/121
• US Class Current: 385/115
• CPC Class Codes: G01N 2021/4719 using a optical fibre array
• CPC Class Codes: G01N 2021/4742 comprising optical fibres
• CPC Class Codes: G01N 21/00 Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light G01N3/00 - G01N19/00 take precedence
• CPC Class Codes: G01N 21/474 Details of optical heads therefor, e.g. using optical fibres
• CPC Class Codes: G01N 21/55 Specular reflectivity
• CPC Class Codes: G02B 6/02 Optical fibres with cladding with or without a coating
• CPC Class Codes: G02B 6/04 formed by bundles of fibres G02B6/24 takes precedence

Abstract

A portable scatterometer and/or an angular radiated light measurement instrument that uses a measurement head which includes a double tapered fiber optic bundle with a concave front face to simultaneously collect partial or full hemispherically scattered light reflected from a point on a surface illuminated by a depolarized, telescopically focused, laser diode source, the light rays being received by each fiber normal to its face. The image of the collected light beams is minifled and coupled by the fiber optic bundle into an anti-blooming CID camera with an x-y scanning area array which converts the light beams to electrical signals. In a unique real time, 486-computer-controlled, data acquisition and reconstruction process, a frame grabber and a unique algorithm are used to collect over 200,000 points of light, reconstruct the data into a 2D or 3D scatter profile, and display the results, all within one second. Multiple embodiments of the tapered fiber optic bundle collector include a full hemispherical version with the laser source directed through the boule, a unitary boule fused from two tapered halves, a linear in-plane tapered bundle and a partial taper with imaging lens mode. Alignment mechanisms provide z-translation, azimuth, and focus adjustments. The measurement unit is in a compact, rugged aluminum housing which is adapted to be secured to a production line machine for a variety of services, such as, a quality control inspection device.

Claims

1. An apparatus for collecting light from a common light source which comprises:

a plurality of individual fiber optic elements one end of each of which is fixed in spaced relation to each other and an other end of each of which is arranged in an indexed array,

the plurality of fiber optic elements have a common field of view and a face at the one end of each of which is fixed in a curved surface having a radius of curvature such that the longitudinal axis of each fiber optic element at the one end substantially converges at the common light source which, with respect to each fiber optic element, radiates light normal to a plane which is both tangent to the face of the fiber optic element at the normal axis and perpendicular to the longitudinal axis of the fiber optic element,

whereby the light radiating angularly from the light source is received simultaneously at the one end by each fiber optic element and is transmitted to the other end.

2. The apparatus as recited in claim 1, wherein the curved surface is a full hemisphere.

3. The apparatus, as recited in claim 2, further comprising:

a rigid hemi-dome which has a plurality of openings in each one of which is secured one end of one of the fiber optic elements.

4. The apparatus, as recited in claim 2, wherein the plurality of fiber optic elements form a tapered bundle.

5. The apparatus, as recited in claim 4, wherein the tapered bundle is fused.

6. The apparatus, as recited in claim 1, wherein the curved surface is a spherical segment.

7. The apparatus, as recited in claim 6, wherein

the plurality of fiber optic elements is a tapered fiber optic bundle, and

the spherical surface is in the tapered portion of the bundle.

8. The apparatus, as recited in claim 7, wherein the curved surface is in the one end which is a wide end of the bundle and the other end is a narrow end of the bundle.

9. The apparatus, as recited in claim 7, wherein the tapered fiber optic bundle is a unitary bundle which has a wide central portion, a first tapered portion in which the spherical surface is located at the one end and a second tapered portion which terminates at the other end, the first and second tapered portions being tapered in opposite directions.

10. The apparatus, as recited in claim 9, wherein the bundle is fused.

11. The apparatus, as recited in claim 9, wherein the first and second tapered portions each terminate at wide ends which are bonded together to form the wide central portion.

12. The apparatus, as recited in claim 11, wherein the first and second tapered portions are rotated 45°

relative to each other prior to being bonded.

13. The apparatus, as recited in claim 9, wherein the unitary bundle is a double tapered fused fiber optic bundle.

14. The apparatus, as recited in claim 13, wherein the light source is a point on a surface to be tested and further comprising:

a path cut through the bundle for transmitting therethrough light from a remote light source to illuminate the point.

15. The apparatus, as recited in claim 14, further comprising:

means to suppress a specular beam reflected from the point.

16. The apparatus as recited in claim 7, further comprising:

the bundle having an upper portion,

a longitudinal slot in the upper portion of the bundle for input of a source beam of various angles of incidence.

17. The apparatus, as recited in claim 1, wherein the curved surface is a segment fixing the one ends of all the fiber optic elements in a common plane containing their longitudinal axis.

18. The apparatus, as recited in claim 17, further comprising:

an aperture block which has a plurality of radial spaced passages in each one of which is secured one fiber optic element.

19. The apparatus, as recited in claim 1, further comprising:

the fiber optic elements are a bundle and a narrow band coating is on the outside of the fiber bundle.

20. The apparatus of claim 1 wherein the other end is flat.

21. A method of manufacturing a fiber optic bundle comprising the steps of:

a) forming a tapered fiber optic bundle, and

b) cutting a concave face in the tapered portion of the bundle such that for each fiber in the bundle a plane tangent to the face at the normal axis to the fiber is also perpendicular to the longitudinal axis of the fiber.