Method for illuminating particles for the purpose of forming their images

• US 20040257450A1
• Filed: 06/16/2004
• Published: 12/23/2004
• Est. Priority Date: 06/20/2003
• Status: Active Grant

• Current Assignee: Airbus Operations SAS (Airbus SE)
• Original Assignee: Airbus France
• Inventors: Roques, Sandrine, Lopez, Christian
• Granted Patent: US 7,120,173 B2
• Time in Patent Office: Days
• US Class Current: 348/207.99
• CPC Class Codes: G01N 15/0227 using imaging; using holography

Abstract

According to the invention, the peak power of the coherent light beam generated by the laser (1) and injected into the optical fiber (2) is chosen so that the spectrum of the light beam (13) emanating from the latter, in order to illuminate the particles (8), includes Raman lines.

Claims

1. A method for illuminating particles (8) for the purpose of forming their images, in which method a coherent light beam (9) is injected into the core (10) of a monomode optical fiber (2), at one end (2a) of said fiber, and said particles (8) are illuminated by the light beam (13) emanating from said core (10) at the other end (2b) of said monomode optical fiber (2), wherein the peak power of said injected coherent light beam (9) is chosen so that the spectrum of said emanating light beam (13) has, alongside the wavelength of said injected coherent light beam (9), lines of shifted wavelengths generated by Raman conversion in the material of said core (10).

2. The method as claimed in claim 1,

wherein the Raman lines whose wavelength forms part of the infrared range and those whose wavelength is close to this range are removed from said spectrum.

3. The method as claimed in claim 2,

wherein said Raman lines corresponding to the infrared or close to the infrared are removed by adjusting the length of said monomode optical fiber (2).

4. The method as claimed in claim 1, in the implementation of which a monomode optical fiber having a specific wavelength is used, that is to say a monomode optical fiber in which the diameter of the core is matched to the wavelength of the beam to be transmitted by the optical fiber and is an increasing function of said wavelength,

wherein said coherent light beam (9), having a wavelength of λ

₁, is injected into the core (10) of a monomode optical fiber having a specific wavelength (2) matched to a wavelength λ

₂ of greater than λ

₁.

5. The method as claimed in claim 4,

wherein the λ

₂/λ

₁ ratio is at least approximately equal to 1.2.

6. The method as claimed in claim 4,

wherein λ

₁ is equal to 532 nm and λ

₂ is equal to 630 nm.