NON-UNIFORM GRATING

• US 20130032734A1
• Filed: 04/26/2010
• Published: 02/07/2013
• Est. Priority Date: 04/26/2010
• Status: Active Grant

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Inventors: Santori, Charles M., Fattal, David A.
• Granted Patent: US 9,529,128 B2
• Time in Patent Office: Days
• US Class Current: 250/458.1
• CPC Class Codes: G01N 2021/646 Detecting fluorescent inhomogeneities at a position, e.g. for detecting defects
• CPC Class Codes: G01N 21/636 using an arrangement of pump beam and probe beam; using the measurement of optical non-linear properties; non-linear optics per se G02F1/35
• CPC Class Codes: G01N 21/6456 Spatial resolved fluorescence measurements; Imaging
• CPC Class Codes: G01N 21/87 Investigating jewels G01N21/88 takes precedence
• CPC Class Codes: G01N 2201/0635 Structured illumination, e.g. with grating
• CPC Class Codes: G02B 19/0009 having refractive surfaces only
• CPC Class Codes: G02B 19/0052 the light source comprising a laser diode coupling into light guides using intermediate optical elements G02B6/4204; semiconductor lasers having optical devices external to the laser cavity H01S5/005
• CPC Class Codes: G02B 27/0944 Diffractive optical elements, e.g. gratings, holograms gratings per se G02B5/18; holograms used as optical elements per se G02B5/32
• CPC Class Codes: G02B 5/18 Diffraction gratings holographic optical elements G02B5/32, G03H; integrally combined with optical fibres G02B6/02057; for coupling light guides G02B6/34; integrally combined with optical integrated light guides G02B6/12; grating systems G02B27/44
• CPC Class Codes: G02B 5/1838 for use with ultraviolet radiation or X-rays
• CPC Class Codes: G02B 5/1866 Transmission gratings characterised by their structure, e.g. step profile, contours of substrate or grooves, pitch variations, materials G02B5/1809, G02B5/1828, G02B5/1833, G02B5/1838 and G02B5/1847 take precedence

Abstract

A system includes a non-uniform grating having a first region with a first refractive index and second regions with a second refractive index. A pattern of the second regions varies with an angular coordinate such that phase shifts of an incident beam created by the grating cause destructive interference that creates an intensity minimum within an output beam from the grating.

Claims

1. A system comprising a non-uniform grating having:

a first region that has a first refractive index; and

second regions that have a second refractive index, wherein a pattern of the second regions varies with an angular coordinate such that phase shifts created by the grating in an incident beam cause destructive interference that creates an intensity minimum within an output beam from the grating.

2. The system of claim 1, wherein the output beam has a doughnut-shaped intensity profile.

3. The system of claim 1, wherein the first region comprises a substrate and the second regions comprise air gaps in the substrate.

4. The system of claim 1, wherein the second regions comprise rings or parallel lines having widths that vary with the angular coordinate.

5. The system of claim 1, wherein the second regions are arranged in a two-dimensional array and have sizes that vary with the angular coordinate.

6. The system of claim 1, wherein spacing of the second regions varies with the angular coordinate.

7. The system of claim 1, wherein the pattern of the second regions varies with a radial coordinate in a manner that focuses the output beam.

8. The system of claim 1, further comprising:

a first light source that produces an excitation beam having a first wavelength;

a second light source that produces a depletion beam that is incident on the grating, the depletion beam having a second wavelength; and

beam optics that combine the excitation beam and an output beam from the grating for projection onto an object being imaged.

9. The system of claim 1, further comprising:

a first light source that produces an excitation beam having a first wavelength;

a second light source that produces a depletion beam having a second wavelength; and

beam optics that combine the excitation beam and the depletion beam to produce a combined beam that is incident on the grating and then projected onto an object being imaged.

10. The system of claim 8, further comprising a sensor arranged to measure fluorescent light originating from the object.

11. A method comprising:

generating a first light beam having a first intensity profile; and

illuminating a grating with the first light beam so that the grating outputs a second light beam having a second intensity profile with an intensity minimum inside the second light beam for at least one spectral component of the second light beam, wherein the grating has a non-uniform pattern that varies with an angular coordinate such that phase shifts created by the grating in the first light beam cause destructive interference that gives the second light beam the second intensity profile.

12. The method of claim 11, wherein the first light beam is a monochromatic beam, and the second intensity profile is doughnut-shaped.

13. The method of claim 11, wherein the second light beam comprises a first spectral component having the intensity minimum, and a second spectral component that does not have an intensity minimum where the first spectral component has the intensity minimum.

14. The method of claim 11, further comprising using the second light beam in a stimulated emission depletion imaging process.