An X-ray imaging apparatus which takes an image of an object to be detected, comprises: a first grating to form a periodic bright-dark pattern by a Talbot effect, based on an X-ray from an X-ray source; a second grating, disposed at a position where the bright-dark pattern is formed, to block a part
An X-ray imaging apparatus which takes an image of an object to be detected, comprises: a first grating to form a periodic bright-dark pattern by a Talbot effect, based on an X-ray from an X-ray source; a second grating, disposed at a position where the bright-dark pattern is formed, to block a part of the bright-dark pattern; a detector to detect an X-ray intensity distribution of the X-ray which passed through the second grating; and a calculator to calculate phase information of the X-ray based on the detected X-ray intensity distribution, wherein the second grating includes a first region having a first blocking pattern and a second region having a second blocking pattern, and a direction in which the first blocking pattern blocks a bright section of the bright-dark pattern is different from a direction in which the second blocking pattern blocks the bright section of the bright-dark pattern.
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1. An X-ray imaging apparatus which takes an image of an object to be detected, comprising: a first grating configured to form a periodic bright-dark pattern by a Talbot effect, on the basis of an X-ray from an X-ray source;a second grating, disposed at a position where the bright-dark pattern is fo
1. An X-ray imaging apparatus which takes an image of an object to be detected, comprising: a first grating configured to form a periodic bright-dark pattern by a Talbot effect, on the basis of an X-ray from an X-ray source;a second grating, disposed at a position where the bright-dark pattern is formed, configured to block a part of the bright-dark pattern;a detector configured to detect an X-ray intensity distribution of the X-ray which passed through the second grating; anda calculator configured to calculate phase information of the X-ray on the basis of the X-ray intensity distribution detected by the detector,wherein the second grating includes a first region in which a first blocking pattern has been formed and a second region in which a second blocking pattern has been formed,wherein a direction in which the first blocking pattern blocks a bright section of the bright-dark pattern and a direction in which the second blocking pattern blocks the bright section of the bright-dark pattern are different from each other,wherein the calculator calculates the phase information by obtaining a ratio of a sum of X-ray intensity information of the X-ray which passed through the first region and was detected in a pixel Pi of the detector and X-ray intensity information of the X-ray which passed through the second region and was detected in a pixel Pi+1 of the detector to a difference between the X-ray intensity information of the X-ray which passed through the first region and was detected in the pixel Pi of the detector and the X-ray intensity information of the X-ray which passed through the second region and was detected by the pixel Pi+1 of the detector, and then multiplying the obtained ratio by a proportionality constant, andwherein i is an integer equal to or greater than one. 2. The X-ray imaging apparatus according to claim 1, wherein the direction in which the first blocking pattern blocks the bright section of the bright-dark pattern and the direction in which the second blocking pattern blocks the bright section of the bright-dark pattern are opposite to each other. 3. The X-ray imaging apparatus according to claim 2, wherein the second grating includes a third region in which a third blocking pattern for blocking the bright section of the bright-dark pattern in a direction perpendicular to the direction in which the first blocking pattern blocks the bright section of the bright-dark pattern has been formed, and a fourth region in which a fourth blocking pattern for blocking the bright section of the bright-dark pattern in a direction opposite to the direction in which the third blocking pattern blocks the bright section of the bright-dark pattern has been formed, andthe first region, the second region, the third region and the fourth region are adjacent to others. 4. An X-ray imaging system comprising: the X-ray imaging apparatus described in claim 1; andan X-ray source configured to irradiate the first grating with the X-ray. 5. The X-ray imaging apparatus according to claim 1, wherein the proportionality constant is determined by a distance between the first and second gratings, and a period of the first grating. 6. The X-ray imaging apparatus according to claim 1, wherein the proportionality constant is D/4Z1, where D is a period of the bright-dark pattern, and Z1 is a distance between the first and second gratings. 7. The X-ray imaging apparatus according to claim 1, wherein the proportionality constant is λ/8d(n/4−⅛) when the first grating is a π phase grating, and λ/4d(n −½) when the first grating is a π/2 phase grating, where λis a wavelength of the X-ray, d is a grating period of the first grating, and n is a natural number. 8. The X-ray imaging apparatus according to claim 1, wherein the phase information is an average of the phase information in the pixel Pi and the phase information in the pixel Pi+1. 9. The X-ray imaging apparatus according to claim 1, wherein the calculator obtains the phase information by using following expressions: Ai=(−1)i×(Ii+1−Ii)/(Ii+1+Ii)=4ΔLi/D; andWxi=ΔLi/Z1, where Ii is an output of the pixel Pi, Ii+1 is an output of the pixel Pi+1, D is a period of the bright-dark pattern, Z1 is a distance between the first and second gratings, and Wxi is an inclination of a wavefront in the x direction at the position corresponding to the pixel Pi, Ai is a normalized intensity change obtained by dividing a difference between the outputs of the pixel Pi and the pixel Pi+1 by a sum of these outputs, and ΔLi is an average of the amount of the movements of the bright sections in the pixels Pand Pi+1.
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