Linear spectrometer

• US 20020054289A1
• Filed: 09/12/2001
• Published: 05/09/2002
• Est. Priority Date: 08/19/1999
• Status: Active Grant

• Current Assignee: Institut national d'optique
• Original Assignee: Institut national d'optique
• Inventors: Thibault, Simon, Paquet, Carl
• Granted Patent: US 6,650,413 B2
• Time in Patent Office: Days
• US Class Current: 356/328
• CPC Class Codes: G01J 2003/2866 Markers; Calibrating of scan
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0208 using focussing or collimating elements, e.g. lenses or mirrors; performing aberration correction
• CPC Class Codes: G01J 3/28 Investigating the spectrum using colour filters G01J3/51
• CPC Class Codes: G02B 13/0005 having F-Theta characteristic scanning systems employing movable or deformable optical elements G02B26/10

Abstract

A linear spectrometer for spectrally measuring an optical signal. The spectrometer has an input receiving the signal which is then diffracted onto a diffraction grating. The signal is therefore divided into its spectral components, each component being diffracted at an angle θ. A correcting element, such as a lens, a group of lenses, a mirror, etc. is provided for focusing the spectral components on an image plane where they are detected. The correcting element is designed so that the resulting distribution of the spectral components on the image plane is linear with respect to the component'"'"'s wavelength.

Claims

1. A linear spectrometer for spectrally measuring an optical signal, comprising:

an input for receiving said optical signal along an optical axis;

a diffraction grating for separating the optical signal received at the input into spectral components thereof, each spectral component being diffracted at a diffraction angle θ

from said optical axis;

an optical correcting element having an effective focal length f, said optical correcting element focusing said spectral components on an image plane in accordance with an f sin(θ

) distribution; and

detecting means for detecting said spectral components in the image plane.

2. A linear spectrometer according to claim 1, wherein said optical correcting element comprises a lens.

3. A linear spectrometer according to claim 1, wherein said optical correcting element comprises a group of lenses.

4. A linear spectrometer according to claim 1, wherein said optical correcting element comprises a mirror.

5. A linear spectrometer according to claim 4, wherein said mirror is concave.

6. A linear spectrometer according to claim 1, wherein said input is a slit.

7. A linear spectrometer according to claim 1, wherein said input is an end of an optical fiber.

8. A linear spectrometer according to claim 1, further comprising a collimator for collimating the optical signal received at the input.

9. A linear spectrometer according to claim 8, wherein said collimator comprises a concave reflector.

10. A linear spectrometer according to claim 1, wherein said diffraction grating is a plane grating.

11. A linear spectrometer according to claim 1, wherein said detecting means comprise a linear photodetector.