Computational imaging system

• US 8,212,914 B2
• Filed: 04/21/2010
• Issued: 07/03/2012
• Est. Priority Date: 07/24/2009
• Status: Expired due to Fees

• Current Assignee: Gold Charm Limited (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Hon Hai Precision Industry Co., Ltd.
• Inventors: Chiu, Chi-Wei
• Primary Examiner(s): Villecco, John
• Application Number:
  US12/764,102
• Publication Number:
  US 20110019068A1
• Time in Patent Office: 804 Days
• Field of Search: 348/218.1, 348/335, 348/340, 348/345, 348/360, 348/362, 348/363, 348/367, 250/363.06, 378/2, 396/435
• US Class Current: 348/345
• CPC Class Codes: G02B 5/3016 involving passive liquid crystal elements optical properties of liquid crystals G02F1/0063; polarising elements associated with active liquid crystal devices G02F1/133528

Abstract

An imaging sub-system, a liquid crystal (LC) element, and a digital focus processor are provided. The LC element is placed in the light path of the imaging sub-system, functioning as the aperture of the imaging sub-system, and includes a periodically patterned electrode which is patterned according to a periodical modulation function and configured to blur an intermediate image captured by the imaging sub-system by applying a controllable voltage thereto. The digital focus processor is configured to deconvolute the periodical modulation function to remove the blur away from the intermediate image and determine an all-in-focus real image.

Claims

1. A computational imaging system comprising;

an imaging sub-system;

a transmissive liquid crystal (LC) element placed in the light path of the imaging sub-system and functioning as the aperture of the imaging sub-system;

the LC element comprising a periodically patterned electrode which is patterned according to a periodical modulation function and configured to deliberately blur an intermediate image captured by the imaging sub-system by applying a controllable voltage thereto; and

a digital focus processor configured to deconvolute the periodical modulation function to remove the blur away from the intermediate image and determine an all-in-focus real image.

2. The computational imaging system of claim 1, wherein the periodical modulation function is:

H(x,y)=cos 2π

(s_xx+s_yy)

where the origin of the oxy coordinate system is the center of the LC element, the x axis extends along the widthwise direction of the LC element, the y axis extends along the lengthwise direction of the LC element, s_x is a spatial frequency of the electrode along the x axis, and s_y is a spatial frequency of the electrode along the y axis.

3. The computational imaging system of claim 2, wherein the electrode is selected from the group consisting of:

a set of concentric annuluses, a rectangular spiral line, a circular dot array, and a rectangular dot array.

4. The computational imaging system of claim 1, wherein a transmittance of the electrode is controlled above 50% by the controllable voltage.

5. The computational imaging system of claim 1, wherein the digital focus processor comprising:

a Fourier transforming device being configured for transforming a spatial amplitude function of the intermediate image and the periodical modulation function into a frequency intermediate image function and a frequency modulation function;

a deconvolution device being configured to deconvolute the periodical modulation function using the frequency intermediate image function and the frequency modulation function to produce a frequency real image function;

an inverse Fourier transforming device being configured for transforming the frequency real image function into a spatial real image amplitude function; and

a refocusing device being configured for determining a focal length of each point of the all-in-focus real image according to the spatial real image amplitude function.