OPTICAL DEVICE WITH A PAIR OF DIFFRACTIVE OPTICAL ELEMENTS

• US 20100134869A1
• Filed: 07/20/2007
• Published: 06/03/2010
• Est. Priority Date: 07/20/2007
• Status: Active Grant

• Current Assignee: Medizinische Universitã¤T Innsbruck
• Original Assignee: Medizinische Universitã¤T Innsbruck
• Inventors: Bernet, Stefan, Ritsch-Marte, Monika
• Granted Patent: US 8,335,034 B2
• Time in Patent Office: Days
• US Class Current: 359/290
• CPC Class Codes: G02B 15/00 Optical objectives with means for varying the magnification anamorphotic objectives G02B13/08
• CPC Class Codes: G02B 26/06 for controlling the phase of light G02B26/08 takes precedence , measuring optical phase difference G01J9/00
• CPC Class Codes: G02B 27/4277 being separated by an air space
• CPC Class Codes: G02B 5/001 Axicons, waxicons, reflaxicons
• CPC Class Codes: G02B 5/1828 having means for producing variable diffraction controlling the direction of light by means of one or more diffracting elements G02B26/0808; acousto-optical elements G02F1/11, G02F1/33; electro- or magneto-optical diffraction G02F1/292, G02F1/2955

Abstract

The present invention provides an optical device comprising a pair of specifically designed plate-like diffractive optical elements successively arranged in parallel to each other.,. Placing the two diffractive optical elements in succession and in parallel to each other in a certain distance, the combination optically corresponds to a single diffractive optical element, and it can perform similar tasks, acting as a lens, an axicon, a phase shifter, or a spiral phase plate. If one of the diffractive optical elements is rotated with respect to the other around a common central axis, the property of the optical device, like the focal length, the refractive power, helical index, or phase shift changes continuously.

Claims

1. Optical device comprising a pair of plate-like diffractive optical elements successively arranged in parallel to each other each, the diffractive optical elements having a phase profile imprinted thereon so that the pair of diffractive optical elements in combination acts as a lens, an axicon, a phase shifter, or a spiral phase plate, wherein one (or both) of the diffractive optical elements is adapted to be rotated relative to the other around an axis perpendicular to its surface, the rotation resulting in a continuous change of an optical property of the optical device.

2. Optical device according to claim 1, wherein when the pair of diffractive optical elements in combination acts as a lens, the continuously changing optical property is the focal length.

3. Optical device according to claim 1, wherein when the pair of diffractive optical elements in combination acts as an axicon, the continuously changing optical property is the refractive power.

4. Optical device according to claim 1, wherein when the pair of diffractive optical elements in combination acts as a spiral phase plate, the continuously changing optical property is the helical index.

5. Optical device according to claim 1, wherein when the pair of diffractive optical elements in combination acts as a phase shifter, the continuously changing optical property is the phase shift.

6. Optical device according to claim 3, wherein the diffractive optical elements are circular plates having a diameter of 50 mm or less.

7. Optical device according to claim 1, wherein the diffractive optical elements are arranged in a distance of 10 μ

m or less.

8. Optical device according to claim 1, wherein the phase profile imprinted on the diffractive optical elements has pixels with a size of 10 μ

m or less.

9. Optical device according to claim 1, wherein the phase profile of one of the diffractive optical elements is a mirror image of the phase profile of the other diffractive optical element.

10. Optical device according to claim 1, wherein the phase profiles of the diffractive optical elements are described by a complex transmission function.

11. Optical device according to claim 10, wherein a discontinuity in the phase profiles of the diffractive optical elements along a line extending from a center to an edge of the diffractive optical elements is avoided by rounding the argument of the transmission function.

12. Optical device according to claim 1, further comprising a sector-shaped absorber covering a sector of the pair of diffractive optical elements.

13. Optical device according to claim 12, wherein the sector covered by the sector-shaped absorber has an angle corresponding to the angle of rotation of the one diffractive optical element with respect to the other.

14. Optical device according to claim 1, wherein the one of the diffractive optical elements is adapted to be rotated relative to the other by an angle between 90°

and −

90°

.

15. Optical device according to claim 1, wherein one of the diffractive optical elements is adapted to continuously rotate for continuously changing the optical property of the optical device.

16. Optical device according to claim 1, wherein the pair of diffractive optical elements together acts as a combination of at least two of a lens, an axicon, a spiral phase plate, and a phase shifter.

17. Optical device according to claim 6 wherein the phase profile of one of the diffractive optical elements is superposed by a phase profile corresponding to a strongly diverging lens, and the phase profile of the other one of the diffractive optical elements is superposed by the phase profile of a strongly converging lens that compensates for the effect of the strongly diverging lens.