Multi-spectral imaging method for ultraweak photon emission and system thereof

A two-dimensional imaging method for high-resolution optical modulation by compressive sensing and digital light processing and using a linear array single-photon detector as a detection element, said method comprising:

• 1) compressive sampling by a digital micro-mirror device (DMD) control system, a first lens and a second lens, to convert two-dimensional image data into a one-dimensional data sequence to complete compressive sampling of signals to be measured, wherein the compressive sampling includes
• filtering stray light by a light filter, imaging the light at the DMD control system through the first lens, controlling reflecting photons to the second lens by the DMD control system controlling focusing of the photons by the second lens;
• and imaging the light with different wavelengths by the linear array single-photon detector;
• and
• 2) completing a sparse reconstruction by a combination of a central processing unit and the linear array single-photon detector to reconstruct the two-dimensional image data and obtain a two-dimensional photon density image, wherein
• i) the compressive sampling further includes mapping the signals to be measured from high-dimensional signals to low-dimensional signals where,
• where xεRn is data to be measured, yεRk is observation data, ΦεRk×n is a measurement matrix (k<<n) and e εRk is measurement noise, the compressive sample precess is
• y=Φx+e (1)
• ii) where a value of measurement times is k, a number of pixels in the two-dimensional image is n, a measurement matrix in formula (1) is Φ={Φ1, . . . , Φi, . . . , Φk wherein Φ1 is an ith row of Φ wherein columns of the two-dimensional images of size √{square root over (n)}×√{square root over (n)} are connected end to end to form an nx1 one-dimensional column vector, and corresponding to x in formula (1), each element of the nx1 one-dimensional column vector represents a photon density at a corresponding position;
• in the DMD control system, each micro-mirror has a same resolution and columns of the micro-mirrors of the DMD control system are connected end to end to form a 1xn one-dimensional row vector, which corresponds to a row in the measurement matrix Φ, wherein each element indicates whether the photon at a corresponding position is transmitted to the second lens;
• iii) where a measurement period is T and during this period the DMD control system is kept unchanged, light with certain wavelength directly projected onto the linear array single-photon detector with a corresponding wavelength;
• where a number of the photons detected by the linear array single-photon detector corresponding to a certain wavelength in the linear array single photon detector is N, then N/T is equivalent to an inner product value of the photon density image and measurement number array Φ on the DMD control system, corresponding to an element
• y
• i
• =
• ∑
• j
• =
• 1
• n
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• Φ
• i
• ,
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• x
• j
• of an observation vector y in formula (1), wherein Φi,j and xj are jth elements of Φi and x respectively;
• according to the measurement matrix Φ, the DMD control system is modified each time, repeat k times of the measurement procedure, and the whole observation data y;
• and
• iv) the sparse reconstruction solves x in formula (1) using the observation data y and measurement matrix Φ determined in steps ii) and iii) above, and x is equal to:
• min
• ⁡
• (
• 1
• 2
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• 
• y
• -
• ΦΨ
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• ϑ
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• +
• τ
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• Ψ
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• where, Ψ is a wavelet transform matrix, θ is a Gaussian random matrix, and τ is a weight.