(a) Conventional computerized tomography configuration. Parallel rays (electromagnetic or particle) from a source are used to obtain an image projection along an axis at a detector on the opposite side of the source. By obtaining multiple projections at different angles , image reconstruction is performed by the Fourier transform filtered back-projection algorithm. (b) Stripe sensor tomography where a sensor of width and thickness is mechanically scanned over a sample. Single line scan results in a one-dimensional projection of a two-dimensional sample. By scanning the sensor at different angles (or by rotating the sample by angle and scanning the sensor along the same line), multiple projections are obtained. The same Fourier transform filtered back-projection algorithm is used for image reconstruction.
(a) Experimental example for stripe sensor tomography. An elongated inductive coil loop detector is made from two parallel conductors inserted into capillary tubes for insulation and uniform separation. The loop is mounted on a linear mechanical translation stage with the axis of the linear motion indicated. The sample is a set of two circular coils, separated by a distance slightly larger than the thickness of the sensor but much smaller than the width of the sensor. The sample is mounted on the mechanical rotation stage visible in the figure. The magnified view of the two loop sources and the two conductors of the inductive stripelike coil detector are shown in (b).
Three example line scans (out of 18) representing three different 1D projections of a 2D sample at different angular orientations. (b) 2D image of the sample obtained through standard filtered back-projection image reconstruction.
Stripe sensor array tomographic imaging. By creating a meanderlike loop array and detecting voltages at sequential nodes in the array, signals are obtained without the requirement for linear translation of the sample or the array. Additionally, a single wire in the array is used in two detector loops, which minimizes the number of required wires, improves the imaging resolution, and simplifies the setup.
Stripe sensor array fabricated by conventional optical lithography. Wider wires connect to the array and fan out for contact access. The sample is a pair of two circular coils with 180° out of phase electric ac currents. The data are first collected sequentially from each loop of the array without any linear translation. The sample is then rotated by 10°, and procedure repeated. (b) The resulting 2D image, reconstructed using the standard filtered back-projection algorithm.
(a) Raster scanning point probe 2D imaging. The point probe measures and resolves, for a certain measurement time , each pixel of the image individually and only once during the course of the steps imaging sequence. (b) Sensor sensitivity functions for the case of an inductive point loop and an inductive stripe loop sensors. The circular loop is more sensitive for the sample region close to the sensor, while the stripe loop is more sensitive for the sample region further away from the sensor. (c) Nanofabricated version of the inductive loop sensor array.
Article metrics loading...
Full text loading...