Method and system of swept coded aperture real-time femtophotography

Patent metadata

Field	Value
Publication number	US-2023283917-A1
Application number	US-202318170887-A
Country	US
Kind code	A1
Filing date	Feb 17, 2023
Priority date	Mar 7, 2022
Publication date	Sep 7, 2023
Grant date	—

Abstract

A method and a system for imaging a dynamic scene, by time-spectrum mapping when a single chirped pulse probes the dynamic scene, storing temporal information at different wavelengths, spectral shearing, spatial encoding and reverse spectral shearing; spatiotemporal integration; and image reconstruction from a resulting captured snapshot, using a laser source configured to emit a linearly chirped laser probe pulse; an imaging unit; a shearing and reversing shearing unit; an encoder; a detector; and a computer; wherein the imaging unit is configured to record the linearly chirped laser probe pulse transmitted by the dynamic scene in a snapshot; the shearing and reversing shearing unit is configured to spectrally shears the linearly chirped laser pulses received from the imaging unit to the encoder, the detector records a compressed snapshot of a temporal information of the dynamic scene read out by the probe pulse; and the computer processes the snapshot and yields a(x,y,t) datacube of the dynamic scene.

First claim

1 . A method for imaging of a dynamic scene, comprising data acquisition and image reconstruction from acquired data,
said data acquisition comprising imaging the scene using a single chirped pulse; time-spectrum mapping when the single chirped pulse probes the dynamic scene and storing temporal information at different wavelengths, spectral shearing, spatial encoder and reverse spectral shearing; and spatiotemporal integration; and said image reconstruction comprising processing a resulting captured snapshot by a computer; yielding an image of the dynamic scene.

2 . The method of claim 1 , comprising illuminating the scene with a single ultrafast probe pulse from a laser; a first spectral shearing (S) of the dynamics scene; spatial encoder (C), a second spectral shearing in a reverse direction (S′); and spatiotemporal integration of a resulting spatially encoded dynamic scene, yielding a captured snapshot E[m,n] linked with transmittance modulated by the dynamic scene a(x,y,t) as follows: E[m,n]=Oa(x,y,t), (x,y,t) being a datacube of the dynamic scene, T being an exposure time, m and n being pixel indices of a detector, and O an operator O=TS′CSM.

3 . The method of claim 1 , comprising processing the resulting captured snapshot by the computer by building a sparse matrix of operations of said data acquisition; creating an initialization based on a forward model; and solving an optimization problem to recover the image of the dynamic scene.

4 . The method of claim 1 , comprising illuminating the scene with a single ultrafast probe pulse from a laser; a first spectral shearing (S) of the dynamics scene; spatial encoder (C), a second spectral shearing in a reverse direction (S′); spatiotemporal integration of a resulting spatially encoded dynamic scene, yielding a captured snapshot E[m,n] linked with transmittance modulated by the dynamic scene a(x,y,t) as follows: E[m,n]=Oa(x,y,t), (x,y,t) being a datacube of the dynamic scene T being an exposure time, m and n being pixel indices of a detector, and O an operator O=TS′CSM; processing the resulting captured snapshot by the computer by building a sparse matrix of operations of said data acquisition; creating an initialization based on a forward model; and solving an optimization problem to recover the datacube (x,y,t) of the dynamic scene.

5 . The method of claim 1 , comprising illuminating the scene with a single ultrafast probe pulse from a laser; a first spectral shearing (S) of the dynamics scene; spatial encoder (C), a second spectral shearing in a reverse direction (S′); spatiotemporal integration of a resulting spatially encoded dynamic scene, yielding a captured snapshot E[m,n] linked with transmittance modulated by the dynamic scene a(x,y,t) as follows: E[m,n]=Oa(x,y,t), (x,y,t) being a datacube of the dynamic scene T being an exposure time, m and n being pixel indices of a detector, and O an operator O=TS′CSM; processing the resulting captured snapshot by the computer by building a sparse matrix of operations of said data acquisition; creating an initialization based on a forward model; and solving an optimization problem to recover the datacube (x,y,t) of the dynamic scene as follows:

a
^

=

arg
⁢
min

a
∈
A

⁢

{

1
2

⁢



Oa
-
E



2
2

+

R
⁡
(
a
)

+

I
+

(
a
)

}

where ∥⋅∥ 2 represents the l 2 norm;

1
2

⁢



Oa
-
E



2
2

is a fidelity term representing the similarity between measurement and estimated result; R(⋅) is an implicit regularizer that promotes sparsity in the dynamic scene; I + (⋅) represents a non-negative intensity constraint.

6 . The method of claim 1 , comprising directing the probe pulse transmitted by the scene to a first 4f imaging system and an encoder, a first spectral dispersion shearing temporal information that is contained in wavelengths to different positions for spatial encoder by the encoder; relaying the probe pulse to a detector using a second 4f imaging system, the second 4f imaging system providing a second spectral shearing in a reverse direction relative to the first 4f imaging system; and recording a compressed snapshot of the temporal information of the scene by the detector.

7 . The method of claim 1 , comprising directing the probe pulse transmitted by the scene to a first 4f imaging system and second 4f imaging system, the probe pulse being first imaged by the first dispersive 4f imaging system, yielding a first spectral dispersion shearing temporal information that is contained in wavelengths to different positions for spatial encoder by an encoder; and the second dispersive 4f imaging system achieving a second spectral shearing in a reverse direction relative to the first dispersive 4f imaging system, in a symmetrical configuration of the first and the second dispersive 4f imaging, yielding first and second spectral dispersion shearing temporal information that is contained in wavelengths, respectively, to different positions for spatial encoder.

8 . The method of claim 1 , comprising:
time-spectrum mapping (M) when the single chirped pulse probes the dynamic scene; storing temporal information at different wavelengths; a first spectral shearing (S) of the dynamics scene; spatial encoder (C); a second spectral shearing in a reverse direction (S′); spatiotemporal integration of a resulting spatially encoded dynamic scene on a camera, by spatially integrating over each pixel and temporally integrating over exposure time (T); linking the captured snapshot E[m,n] with transmittance modulated by the dynamic scene a(x,y,t) as follows: E[m,n]=Oa(x,y,t), where m and n are pixel indices of the camera and operator O=TS′CSM; and reconstruction of the image from the captured snapshot E[m,n].

9 . A system for imaging of a dynamic scene, comprising:
a laser source configured to emit a linearly chirped laser probe pulse; an imaging unit;

Assignees

• Inst Nat Rech Scient

Inventors

• Liang Jinyang
• Légaré François
• Liu Jingdan
• Ibrahim Heide
• Liu Xianglei
• Lai Yingming

Classifications

• H04N23/12 Primary

  with one sensor only · CPC title

• H04N23/56

  provided with illuminating means · CPC title

• H04N23/95 Primary

  Computational photography systems, e.g. light-field imaging systems · CPC title