IMAGE NOISE REDUCTION USING MODULATION AND DEMODULATION – MODULATION TECHNIQUES

1 . A method for filtering noise from image data, comprising:

obtaining an input optical signal input to an optical system;

modulating the input optical signal to obtain a modulated image signal, wherein the input optical signal is modulated based at least in part on manipulating a point spread function (PSF) of the optical system;

providing the modulated image signal to a read-out integrated circuit (ROIC); and

obtaining a filtered image signal from the ROIC, wherein the ROIC filters the modulated image signal to remove at least part of excess noise in image signal data.

2 . The method of claim 1 , wherein the input optical signal is an infrared signal.

3 . The method of claim 1 , wherein the excess noise is removed from the image signal data in real time.

4 . The method of claim 1 , wherein a predefined frequency of the modulated image signal is higher than an excess noise knee frequency.

5 . The method of claim 1 , wherein modulating the input optical signal includes up-converting an image signal to a modulated frequency to obtain the modulated image signal.

6 . The method of claim 1 , wherein manipulating the PSF of the optical system comprises:

causing an optical lens that directs the input optical signal to a focal plane to move between in focus and out of focus at a predefined frequency.

7 . The method of claim 6 , wherein the optical lens is mounted to a bezel by a set of flexures, and wherein causing the optical lens to move between in focus and out of focus comprises causing the optical lens to move axially according to the predefined frequency by actuating a plurality of voice coils.

8 . The method of claim 1 , wherein manipulating the PSF of the optical system comprises:

controlling at least one motor to drive one or more cam shafts,

wherein:

a first cam shaft in the set of cam shafts has a variable radii; and

rotation of the cam shaft causes an optical lens to move between in focus and out of focus at the predefined frequency.

9 . The method of claim 8 , wherein an axial position of the optical lens follows a cam radii for the set of cam shafts as the set of cam shafts are rotated.

10 . The method of claim 8 , wherein the optical lens is mounted to a bezel by a set of flexures, and the bezel is preloaded with a spring to keep the optical lens motion in contact with a cam radii of the set of cam shafts as the optical lens is moved between an in focus axial position and an out of focus position.

11 . The method of claim 1 , wherein manipulating the PSF of the optical system comprises:

controlling a set of non-spherical lenses to move between an aligned position and a non-aligned position at the predefined frequency.

12 . The method of claim 11 , wherein the controlling a set of non-spherical lenses to move between the aligned position and the non-aligned position comprises:

causing a first lens and a second lens to relatively rotate with respect to each other at a predefined frequency.

13 . The method of claim 1 , wherein manipulating the PSF of the optical system comprises:

driving an electro-optical modulator to modify an index of refraction of a medium through which the input optical signal propagates, wherein the index of refraction is modified a predefined frequency.

14 . The method of claim 1 , wherein manipulating the PSF of the optical system comprises:

modifying an index of refraction of an input optical signal path,

the index of refraction of the input optical signal path is modified based on rotating a phase delay wheel configured in the input optical signal path to permit the input optical signal to pass therethrough,

wherein:

the phase delay wheel being rotated at a predefined frequency; and

the phase delay wheel has a plurality of different portions comprising one or more of (i) different indices of refraction and (ii) different physical thicknesses.

15 . The method of claim 1 , wherein the modulated image signal is demodulated to obtain the filtered image signal.

16 . An optical system, comprising:

an optical component configured to obtain an input optical signal;

a component configured to cause the input optical signal to be modulated to obtain a modulated image signal, wherein the input optical signal is modulated based at least in part on manipulating a point spread function (PSF) of the optical system;

a read-out integrated circuit (ROIC) configured to process a modulated input optical signal;

a processor configured to obtain a filtered image signal from the ROIC, wherein the ROIC filters the modulated image signal to remove at least part of excess noise in the image signal data; and

a memory coupled to the processor and configured to provide the processor with instructions.