# US 2018/0027201 A1 · Lensless imaging system using an image sensor with one or more attenuating layers

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- Number: US 2018/0027201 A1
- Document ID: US20180027201A1
- Status: Published application
- Kind: A1
- Application number: 15/547,235
- Filed: 2016-01-29
- Published: 2018-01-25
- Earliest claimed: 2015-01-29
- Assignees: William Marsh Rice University
- Applicants: William Marsh Rice University
- Inventors: Aswin Sankaranarayanan; Ashok Veeraraghavan; Lisa A. Hendricks; Richard Baraniuk; Ali Ayremlou; M. Salman Asif
- Web page: https://patentgrep.com/patent/US20180027201A1

## CPC

- G01T 1/295: {using coded aperture devices, e.g. Fresnel zone plates (handling of radiation of particles, e.g. using diaphragms, collimators, diffraction G21K1/00)}
- G02B 27/42: Diffraction optics {, i.e. systems including a diffractive element being designed for providing a diffractive effect}(G02B27/60 takes precedence)
- H04N 23/955: for lensless imaging
- G02B 2207/129: Coded aperture imaging
- G01T: MEASUREMENT OF NUCLEAR OR X-RADIATION (radiation analysis of materials, mass spectrometry G01N23/00; tubes for determining the presence, intensity, density or energy of radiation or particles H01J47/00)
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

A lens-free imaging system for generating an image of a scene includes an electromagnetic (EM) radiation sensor; a mask disposed between the EM radiation sensor and the scene; an image processor that obtains signals from the EM radiation sensor while the EM radiation sensor is exposed to the scene; and estimates the image of the scene based on, at least in part, the signals and a transfer function between the scene and the EM radiation sensor.

## Claims

### Claim 1

A lens-free imaging system for generating an image of a scene, comprising:
an electromagnetic (EM) radiation sensor;
a mask disposed between the EM radiation sensor and the scene; and
an image processor configured to:
obtain signals from the EM radiation sensor while the EM radiation sensor is exposed to the scene, and
estimate the image of the scene based on, at least in part, the signals and a transfer function between the scene and the EM radiation sensor.

### Claim 2 (depends on 1)

The system of claim 1, wherein the mask is disposed at a distance less than 0.5 times a width of the EM radiation sensor from the EM radiation sensor.

### Claim 3 (depends on 1)

The system of claim 1, wherein the mask comprises:
a first plurality of regions that are opaque to EM radiation; and
a second plurality of regions that are transparent to EM radiation.

### Claim 4 (depends on 1)

The system of claim 1, wherein the mask comprises:
a first plurality of regions comprising a material having a first refractive index; and
a second plurality of regions comprising a second material having a second refractive index,
wherein the first refractive index is different than the second refractive index.

### Claim 5 (depends on 3)

The system of claim 3, wherein the first plurality of regions and second plurality of regions are disposed on a two dimensional surface.

### Claim 6 (depends on 5)

The system of claim 5 wherein the two dimensional surface is curved, wherein the EM radiation sensor is curved

### Claim 7 (depends on 3)

The system of claim 3, wherein there are a first number of regions of the first plurality of regions and a second number of regions of the second plurality of regions.

### Claim 8 (depends on 7)

The system of claim 7, wherein the first number and second number are the same.

### Claim 9 (depends on 2)

The system of claim 2, where in the regions of the first plurality of regions and the regions of the second plurality of regions are distributed randomly across the mask.

### Claim 10 (depends on 7)

The system of claim 7, wherein the distribution of the first plurality of regions and the second plurality of regions is based on a convolution of a first one dimensional sequence and a second one dimensional sequence.

### Claim 11 (depends on 10)

The system of claim 10, wherein the two one-dimensional sequences are random sequences.

### Claim 12 (depends on 10)

The system of claim 10, wherein the first one dimensional sequence is a maximum length sequence and the second one dimensional pattern is a second maximum length sequence.

### Claim 13 (depends on 12)

The system of claim 12, wherein the maximum length sequence and the second maximum length sequence are the same.

### Claim 14 (depends on 1)

The system of claim 1, wherein the transfer function comprises a first binary sequence and a second binary sequence.

### Claim 15 (depends on 13)

The system of claim 13, wherein the first binary sequence has a number of entries equal to the number of regions across a width of the mask.

### Claim 16

A method of generating an image using a lens-free imaging system, the method comprising:
obtaining, by the lens-free imaging system, a transfer matrix that relates electrical signals generated by an image sensor when exposed to electromagnetic (EM) radiation from a scene to an image of a scene; and
generating, by the lens-free imaging system, an image of a scene based on the transfer matrix and the electrical signals generated by the image sensor when exposed to the scene.

### Claim 17 (depends on 16)

The method of claim 16, wherein obtaining the transfer matrix comprises:
obtaining, by the lens-free imaging system, a first plurality of electrical signals generated by a electromagnetic (EM) radiation sensor, wherein each electrical signal of the first plurality of electrical signals is generated by the EM radiation sensor while exposed to one of a plurality of patterns;
obtaining, by the lens-free imaging system, a second plurality of electrical signals generated by a electromagnetic (EM) radiation sensor, wherein each electrical signal of the second plurality of electrical signals is generated by the EM radiation sensor while exposed to one of a second plurality of patterns;
determining, by the lens-free imaging system, a first one dimensional convolution sequence based on the first plurality of electrical signals;
determining, by the lens-free imaging system, a second one dimensional convolution sequence based on the second plurality of electrical signals; and
generating, by the lens-free imaging system, the transfer matrix based on the first one dimensional convolution sequence and a second one dimensional convolution sequence.

### Claim 18 (depends on 16)

The method of claim 16, wherein obtaining the transfer matrix comprises:
simulating an electromagnetic characteristic of a mask of the lens-free imaging system; and
generating, by the lens-free imaging system, the transfer matrix based on the electromagnetic characteristic of the mask.

### Claim 19 (depends on 16)

The method of claim 16, wherein the image of the scene is based on, at least in part, solving a least-squares problem that relates the electrical signal and the transfer matrix.

### Claim 20 (depends on 16)

The method of claim 16, wherein the image of the scene is based on, at least in part, solving a regularized least-squares problem that relates the electrical signal and the transfer matrix,

### Claim 21 (depends on 20)

The method of claim 20, where the regularization is one selected from the group consisting of Total variation, Tikhonov, and Wavelet sparsity.

### Claim 22 (depends on 16)

The method of claim 16, wherein each pattern of the plurality of patterns is a one-dimensional pattern.

### Claim 23 (depends on 16)

The method of claim 16, wherein each pattern of the plurality of patterns is a unique Hadamard pattern.