Adaptive optical methods and devices for enhancing image contrast in the presence of bright background

• US 10,264,190 B2
• Filed: 04/16/2016
• Issued: 04/16/2019
• Est. Priority Date: 04/24/2015
• Status: Active Grant

• Current Assignee: Omnitek Partners LLC
• Original Assignee: Omnitek Partners LLC
• Inventors: Rastegar, Jahangir S, Dhadwal, Harbans, Feng, Dake
• Primary Examiner(s): Hernandez Hernandez, Nelson D.
• Application Number:
  US15/130,945
• Publication Number:
  US 20160316127A1
• Time in Patent Office: 1,095 Days
• CPC Class Codes: A61B 1/00006 of control signals
• CPC Class Codes: A61B 1/00096 Optical elements
• CPC Class Codes: G02B 21/0028 specially adapted for specific applications, e.g. for endoscopes, ophthalmoscopes, attachments to conventional microscopes
• CPC Class Codes: G02B 21/0032 Optical details of illumination, e.g. light-sources, pinholes, beam splitters, slits, fibers G02B21/0036 - G02B21/008; means for illumination of specimens in general G02B21/06
• CPC Class Codes: G02B 21/0048 scanning mirrors, e.g. rotating or galvanomirrors, MEMS mirrors
• CPC Class Codes: G02B 21/008 Details of detection or image processing, including general computer control
• CPC Class Codes: G02B 23/243 Objectives for endoscopes
• CPC Class Codes: G02B 23/2484 Arrangements in relation to a camera or imaging device processing or control of video signals generated by an endoscope H04N23/60, H04N23/70
• CPC Class Codes: G02B 26/0816 by means of one or more reflecting elements
• CPC Class Codes: G02B 27/46 Systems using spatial filters
• CPC Class Codes: H04N 23/45 for generating image signals from two or more image sensors being of different type or operating in different modes, e.g. with a CMOS sensor for moving images in combination with a charge-coupled device [CCD] for still images
• CPC Class Codes: H04N 23/555 for picking-up images in sites, inaccessible due to their dimensions or hazardous conditions, e.g. endoscopes or borescopes
• CPC Class Codes: H04N 23/56 provided with illuminating means
• CPC Class Codes: H04N 23/60 Control of cameras or camera modules
• CPC Class Codes: H04N 23/741 by increasing the dynamic range of the image compared to the dynamic range of the electronic image sensors
• CPC Class Codes: H04N 23/75 by influencing optical camera components

Abstract

A device including: an image sensor for imaging an object field reflected from an object to be imaged; a first objective lens for focusing a background field from the object into a concentrated energy field on a spatial frequency plane of the first objective lens; and a programmable spatial light modulator positioned in an optical path at the spatial frequency plane, the programmable spatial light modulator being programmed to display an opaque region and a substantially transparent region outside of the opaque region, the opaque region corresponding to a position of the concentrated energy field.

Claims

1. A device comprising:

an image sensor for imaging an object field reflected from an object to be imaged;

a first objective lens for focusing a background field from the object into a concentrated light spot on a spatial frequency plane of the first objective lens;

a programmable spatial light modulator positioned in an optical path at the spatial frequency plane, the programmable spatial light modulator being programmed to display an opaque region and a substantially transparent region outside of the opaque region, the opaque region corresponding to a position of the concentrated light spot; and

a controller operatively connected to the programmable spatial light modulator, the controller;

determining the position on the programmable spatial light modulator to display the opaque region such that the concentrated light spot is at least partially blocked from being incident on the image sensor; and

controlling the programmable spatial light modulator to display the opaque region at the position.

2. The device of claim 1, further comprising a light source for outputting illumination light to the object to be imaged, the object reflecting both the object field and the background field.

3. The device of claim 1, further comprising a second objective lens for focusing the object field on a surface of the image sensor.

4. The device of claim 1, further comprising:

a display screen;

first and second objective lens;

first and second mirrors;

a first beam splitter positioned between the first objective lens and the programmable spatial light modulator to project the concentrated light spot onto the display screen;

the first objective lens projecting the concentrated light spot on the display screen onto the first mirror;

the second mirror reflecting the concentrated light spot from the first mirror towards the second objective lens;

the second objective lens projecting the concentrated light spot towards a second beam splitter;

the second beam splitter positioned to project the concentrated light spot on the image sensor when the programmable spatial light modulator is not displaying the opaque region;

wherein the controller determines the location of the concentrated light spot on the image sensor; and

the controller determines the position on the programmable spatial light modulator to display the opaque region based on the location of the concentrated light spot on the image sensor.

5. The device of claim 1, wherein:

the image sensor captures a low contrast image of the object when the programmable spatial light modulator is not displaying the opaque region; and

the controller extracts a spatial Fourier transform of the low contrast image corresponding to a spatial distribution in the spatial frequency plane and controls the programmable spatial light modulator to display the opaque region based on the spatial Fourier transform.

6. A device of claim 4, further comprising:

an image sensor for imaging an object field reflected from an object to be imaged;

a first objective lens for focusing a background field from the object into a concentrated energy field on a spatial frequency plane of the first objective lens; and

a programmable spatial light modulator positioned in an optical path at the spatial frequency plane, the programmable spatial light modulator being programmed to display an opaque region and a substantially transparent region outside of the opaque region, the opaque region corresponding to a position of the concentrated energy field;

a controller operatively connected to the programmable spatial light modulator, the controller;

determining the position on the programmable spatial light modulator to display the opaque region such that the concentrated energy field is at least partially blocked from being incident on the image sensor; and

controlling the programmable spatial light modulator to display the opaque region at the position;

a display screen;

an other image sensor;

a beam splitter positioned between the first objective lens and the programmable spatial light modulator to project the concentrated energy field on the display screen; and

one or more additional objective lens for projecting the concentrated energy field on the screen onto the other image sensor;

wherein the other image sensor is operatively connected to the controller for inputting the location of the concentrated energy field on the other image sensor; and

the controller determines the position on the programmable spatial light modulator to display the opaque region based on the location of the concentrated energy field on the other image sensor.

7. A method comprising:

imaging an object field reflected from an object to be imaged;

focusing a background field from the object into a concentrated light spot on a spatial frequency plane;

displaying an opaque region at the spatial frequency plane on a programmable spatial light modulator, the opaque region corresponding to a position of the concentrated light spot;

determining the position on the programmable spatial light modulator to display the opaque region such that the concentrated light spot is blocked from being incident on the image sensor; and

controlling the programmable spatial light modulator to display the opaque region at the position.

8. The method of claim 7, further comprising outputting illumination light to the object to be imaged, the object reflecting both the object field and the background field.

9. The method of claim 7, further comprising focusing the object field on a surface of an image sensor.

10. The method of claim 7, further comprising:

projecting the concentrated light spot on the image sensor when the programmable spatial light modulator is not displaying the opaque region;

determining a location of the concentrated light spot on the image sensor; and

determining the position on the programmable spatial light modulator to display the opaque region based on the location of the concentrated light spot on the image sensor.

11. The method of claim 7, further comprising:

capturing a low contrast image of the object on the image sensor when the programmable spatial light modulator is not displaying the opaque region;

extracting a spatial Fourier transform of the low contrast image corresponding to a spatial distribution in the spatial frequency plane; and

controlling the programmable spatial light modulator to display the opaque region based on the spatial Fourier transform.

12. A method comprising:

imaging an object field reflected from an object to be imaged;

focusing a background field from the object into a concentrated energy field on a spatial frequency plane; and

displaying an opaque region at the spatial frequency plane on a programmable spatial light modulator, the opaque region corresponding to a position of the concentrated energy field;

determining the position on the programmable spatial light modulator to display the opaque region such that the concentrated energy field is blocked from being incident on the image sensor;

controlling the programmable spatial light modulator to display the opaque region at the position;

projecting the concentrated energy field onto an other image sensor; and

determining the position on the programmable spatial light modulator to display the opaque region based on the location of the concentrated energy field on the other image sensor.