One of the stringent requirements of the FTIRm system includes the use of a matching 36\(\times\) Schwarzschild IR reflecting objective and condenser (NA = 0.5). During our first attempt to apply the non-scanning CAI method, the above 36\(\times\) Schwarzschild objective lens (SOL) was replaced by a 15\(\times\) Cassegrain objective lens (COL) to increase the beam diameter in the sample plane, and the single pixel MCT detector was replaced by a focal point array (FPA) detector. However, due to the peculiar beam profile, the experiment could not be extended beyond a pinhole. Therefore, in that case, a semi-synthetic analysis was only carried out using synthetic objects and recorded and averaged using point spread functions (PSFs) [12]. The outcome of the experiment revealed the possibility of achieving 3D imaging based on the following facts and observations. To achieve 3D imaging using CAI, a sharp autocorrelation and a low cross-correlation along depth (SALCAD) are needed. This SALCAD property is easily achieved using a scattering mask, which is one of the reasons why it has been widely used for 3D imaging [13]. Based on the observations made in [12], even deterministic intensity distributions may exhibit SALCAD properties. Thereafter, the CAI method was repeated in the replica off-line FTIRm system of the Australian Synchrotron, which is not connected to the synchrotron beam but uses a Globar source [14]. The light from a Globar source is uniform and so it supported the application of the CAI method significantly better than the synchrotron beam. The FPA detector was used for recording the intensity distribution and the COL was used as the coded aperture. A new computational reconstruction algorithm called the Lucy-Richardson-Rosen algorithm (LRRA), integrating the Lucy-Richardson algorithm (LRA) [15; 16] with non-linear reconstruction (NLR) [17], was developed for reconstructing three-dimensional (3D) information from the recorded intensity distributions of objects and the PSF library. The preliminary results were promising. However, the recorded intensity distributions were low resolution due to the limited number of pixels of the FPA. Moreover, the intensity is not as high as the beam from the synchrotron. Since most of the measurements at the Australian Synchrotron involve the use of the synchrotron beam, it is crucial to extend this idea to the online FTIRm system. In a recent study with the LRRA, it was found that it is possible to use a wide range of optical beams with peculiar intensity and phase distributions [18]. In another recent study, the high resilience of the LRRA to detector noises was verified [19]. In this manuscript, we report for the first time computational imaging using the IR synchrotron beam at the Australian Synchrotron using the LRRA. The method is unique because coded aperture holography has been implemented by a scanning approach for the first time. We call this technique coded aperture scanning holography (CASH). CASH can be implemented for deblurring, removing aberrations and 3D imaging  
Figure 1: Schematic of the FTIRm system in transmission mode. BS—beam splitter, M—mirror, L—lens, MSP—Motorized sliding plate, A—aperture, MIR—mid-infrared. The synchrotron beam is extracted using the gold coated mirror with a central slit and enters the FTIR spectrometer and then the IR/VISIBLE transmission microscope. The image of the beam entering the FTIRm is shown with a dotted blue line. The normalised intensity distribution for different wavelengths is shown. The scanning mode is shown for a pinhole. and is suitable for extreme imaging scenarios such as low-resolution detectors and imaging through highly scattering media, and can improve almost all facets of imaging except time resolution. This manuscript consists of five sections. The methodology is described in the next section, experimental results are presented in the third section and the final two sections present the discussion and conclusions from the study.