Aspherical lens with grating

• US 7,082,000 B2
• Filed: 06/07/2004
• Issued: 07/25/2006
• Est. Priority Date: 06/06/2003
• Status: Active Grant

• Current Assignee: Hon Hai Precision Industry Co., Ltd.
• Original Assignee: Hon Hai Precision Industry Co., Ltd.
• Inventors: Chen, Ga-Lane
• Primary Examiner(s): THOMPSON, TIMOTHY J
• Application Number:
  US10/862,949
• Publication Number:
  US 20040246594A1
• Time in Patent Office: 778 Days
• Field of Search: 359/719, 359/721, 359/722, 359/724, 359/708, 369/112.26, 369/112.13, 369/112.08, 369/44.14
• US Class Current: 359/708
• CPC Class Codes: G02B 27/4211 correcting chromatic aberrations G02B27/0056, G02B27/4222, G02B27/4227 take precedence
• CPC Class Codes: G02B 3/04 with continuous faces that are rotationally symmetrical but deviate from a true sphere , e.g. so called "aspheric" lenses
• CPC Class Codes: G02B 5/1814 structurally combined with one or more further optical elements, e.g. lenses, mirrors, prisms or other diffraction gratings G02B5/189 takes precedence

Abstract

An aspherical lens (10, 10′) has an aspherical surface (101, 101′) and an opposite flat surface (102, 102′). A multiple-step grating is defined in the flat surface by a photolithographic method. The aspherical lens has a reduced chromatic aberration effect, and can thus provide a clear image. Furthermore, an effect of the aspherical lens having the grating is equivalent to that of a conventional aspherical lens unit. Thus, when the aspherical lens is used in an optical system, it can reduce a bulk and a weight of the optical system.

Claims

1. An aspherical lens comprising a first aspherical surface, an opposite second substantially flat surface, and a grating defined in the second surface;

wherein the grating has “

n”

sections of uniform length, and a stepped structure comprising a plurality of steps is defined along each section.

2. The aspherical lens as claimed in claim 1, wherein the grating is formed by means of photolithography.

3. The aspherical lens as claimed in claim 1, wherein the steps defined along each section are symmetrical.

4. The aspherical lens as claimed in claim 1, wherein the steps have a same width.

5. The aspherical lens as claimed in claim 1, wherein the steps have a same height.

6. The aspherical lens as claimed in claim 1, wherein a height of each step is less than 100 nanometers.

7. The aspherical lens as claimed in claim 1, wherein a number of the steps defined along each section is more than two.

8. A lens comprising a first curved surface and an opposite second surface, wherein a step structure comprising a plurality of steps is repeated on the second surface, and a height of each step is less than 100 nanometers.

9. The lens as claimed in claim 8, wherein the steps are symmetrically formed with regard to a vertical center line of the step structure.

10. The lens as claimed in claim 8, wherein a number of steps between two consecutive uppermost steps is an odd number.

11. An aspherical lens comprising a first aspherical surface and an opposite second surface, wherein a grating comprising a plurality of steps is defined in the second surface, and a height of each step is less than 100 nanometers.

12. The aspherical lens as claimed in claim 11, wherein the second surface is substantially flat.

13. The aspherical lens as claimed in claim 11, wherein the grating is formed by means of photolithography.

14. The aspherical lens as claimed in claim 11, wherein the grating has “

n”

sections of uniform length, and a plurality of the steps is defined along each section.

15. The aspherical lens as claimed in claim 14, wherein the steps defined along each section are symmetrical.

16. The aspherical lens as claimed in claim 11, wherein the steps have a same width.

17. The aspherical lens as claimed in claim 11, wherein the steps have a same height.

18. The aspherical lens as claimed in claim 14, wherein a number of the steps defined along each section is more than two.