Method and System for Enhancing Resolution of Terahertz Imaging

Abstract

This disclosure presents a novel method and system for enhanced-resolution THz imaging whereby an enhanced-resolution THz image is developed by deconvolution of the original THz image that is developed using THz signals that are manipulated in time-domain and/or in frequency-domain and a point spread function (PSF) that is developed according to an equation wherein said THz signals in time-domain and/or frequency-domain are input parameters. By using this method and system, enhanced-resolution THz images with better quality and resolution than the quality and resolution of the conventional THz images are achieved. By implementing this method, finer features are observable in the resulted image and more accurate measurement is achieved.

1 . One or more non-transitory computer-readable media storing computer-executable instructions, for improving resolution of terahertz imaging of a sample, the instructions comprising:
 (a) instructions for receiving terahertz time-domain signals acquired by a terahertz time-domain spectroscopy system for acquiring a terahertz image,   (b) instructions for converting time-domain terahertz signals to frequency-domain signals,   (c) instructions for processing said frequency-domain signals by means of a frequency-domain filter or a plurality of frequency-domain filters to achieve processed frequency-domain signals,   (d) instructions for converting said processed frequency-domain signals back to time-domain signals,   (e) instructions for developing a terahertz image using said time-domain signals,   (f) instructions for developing an enhanced-resolution terahertz image by computing deconvolution of said terahertz image and a point spread function,   (g) instructions for displaying or storing, or displaying and storing, said enhanced-resolution terahertz image.   
     
     
         2 . The instructions recited in  claim 1 , wherein said frequency-domain filter is a low-pass filter, or a high-pass filter, or a band-pass filter encompassing a combination of a low-pass filter and a high-pass filter. 
     
     
         3 . The instructions recited in  claim 1 , further comprising using a time-domain filter for suppressing diffraction wherein for developing said terahertz image intensity of said processed time-domain signals at a time delay smaller than the time delay of the peak value of said terahertz time-domain signals is used. 
     
     
         4 . The instructions recited in  claim 1 , wherein said point spread function is modeled by means of a mathematical equation. 
     
     
         5 . The instructions recited in  claim 4 , wherein at least one optical parameter, or estimation of at least one optical parameter, of the imaging system of said terahertz time-domain spectroscopy system is used as an input for said mathematical equation for developing said point spread function. 
     
     
         6 . The instructions recited in  claim 5 , wherein at least one parameter, or estimation of at least one parameter, of said terahertz time-domain spectroscopy system, such as the spectrum of the terahertz pulse of said terahertz time-domain spectroscopy system, is used as an input for said mathematical equation for developing said point spread function. 
     
     
         7 . The instructions recited in  claim 6 , wherein at least one parameter, or estimation of at least one parameter, of said sample is used as an input parameter for said mathematical equation for developing said point spread function. 
     
     
         8 . The instructions recited in  claim 7 , wherein at least one parameter of the mathematical equation of said point spread function is tuned iteratively until said enhanced-resolution terahertz image is achieved. 
     
     
         9 . One or more non-transitory computer-readable media storing computer-executable instructions, for improving the resolution of terahertz imaging of a sample, the instructions comprising:
 (a) instructions for receiving terahertz data acquired by a continuous-wave terahertz imaging system for acquiring a terahertz image,   (b) instructions for developing a terahertz image using said terahertz data,   (c) instructions for developing an enhanced-resolution terahertz image by computing deconvolution of said terahertz image and a point spread function,   (d) instructions for displaying or storing, or displaying and storing, said enhanced-resolution terahertz image.   
     
     
         10 . The instructions recited in  claim 9 , wherein said point spread function is numerically estimated. 
     
     
         11 . The instructions recited in  claim 10 , wherein said estimated point spread function is tuned iteratively until said enhanced-resolution terahertz image is achieved. 
     
     
         12 . The instructions recited in  claim 9 , wherein said point spread function is modeled by means of a mathematical equation. 
     
     
         13 . The instructions recited in  claim 12 , wherein at least one optical parameter, or estimation of at least one optical parameter, of the imaging system of said continuous-wave terahertz imaging system is used as an input parameter for said mathematical equation for developing said point spread function. 
     
     
         14 . The instructions recited in  claim 13 , wherein at least one parameter, or estimation of at least one parameter, of said continuous-wave terahertz imaging system, such as the spectrum of the terahertz beam of said continuous-wave terahertz imaging system, is used as an input parameter for said mathematical equation for developing said point spread function. 
     
     
         15 . The instructions recited in  claim 14 , wherein at least one parameter, or estimation of at least one parameter, of said sample is used as an input parameter for said mathematical equation for developing said point spread function. 
     
     
         16 . The instructions recited in  claim 15 , wherein at least one parameter of the mathematical equation of said point spread function is tuned iteratively until said enhanced-resolution terahertz image is achieved. 
     
     
         17 . One or more non-transitory computer-readable media storing computer-executable instructions, for simulating a terahertz imaging system and developing a simulated terahertz image of a sample, the instructions comprising:
 (a) instructions for using a computer comprising a memory and a central processing unit for storing data and performing processes on said data,   (b) instructions for receiving, storing, and using an object function of said sample,   (c) instructions for generating an estimation or a model of the point spread function of imaging terahertz beam of said terahertz imaging system,   
       whereby said simulated terahertz image of said sample is developed by means of convolution of said point spread function and said object function wherein said convolution is computed by said computer. 
     
     
         18 . The instructions recited in  claim 17 , wherein said point spread function is modeled by means of a mathematical equation. 
     
     
         19 . The instructions recited in  claim 18 , wherein at least one optical parameter, or estimation of at least one optical parameter, of said terahertz imaging system is used as an input for said mathematical equation for developing said point spread function. 
     
     
         20 . The instructions recited in  claim 19 , wherein at least one parameter, or estimation of at least one parameter, of said terahertz imaging system, such as the spectrum of the terahertz beam of said terahertz imaging system, is used as an input for said mathematical equation for developing said point spread function. 
     
     
         21 . The instructions recited in  claim 20 , wherein at least one parameter, or estimation of at least one parameter, of said sample is used as an input parameter for said mathematical equation for developing said point spread function. 
     
     
         22 . The instructions recited in  claim 21 , wherein the model of said point spread function is tuned by adjusting at least one parameter of the mathematical equation of said point spread function iteratively until the least amount of deviation between said simulated terahertz image and a terahertz image of said sample measured by said terahertz imaging system is achieved.