A flow cytometer imaging system for off-axis holography, the system comprising: an illumination source configured to emit light that is divided into a sample beam path and a reference beam path; said sample beam path including: sample illumination optics (CL, L) configured to focus the light along the sample beam path to illuminate a sample with a line-focused beam, and collection optics (TL, CL1, CL2, CL3, M1) configured to collect, along the sample beam path, light scattered from the sample; and a detector system (44, 45, 47, 49) configured to detect both the collected scattered light along the sample beam path and reference light along the reference beam path such that, at detection, the detected reference light is angularly offset in relation to the detected scattered light, wherein the detector system (44, 45, 47, 49) is being connected to a data processor wherein the system includes a flow channel defined in a substrate that is configured to flow a sample suspended in a suspension medium continuously across the line-focused beam during translation of the sample at a flow rate within the flow channel, characterized in that the detected reference light and the detected scattered light are used to detect interferogram images including angular spectra for varying locations, η, of the sample, wherein the detector system (44, 45, 47, 49) is configured to map phase data and amplitude data of the angular spectra to a three-dimensional representation, to form a two-dimensional Fourier transform of the mapped angular spectra and to map the Fourier transformed angular spectrum to a scattering potential of the sample in a spatial frequency space. an illumination source configured to emit light that is divided into a sample beam path and a reference beam path; said sample beam path including: sample illumination optics (CL, L) configured to focus the light along the sample beam path to illuminate a sample with a line-focused beam, and collection optics (TL, CL1, CL2, CL3, M1) configured to collect, along the sample beam path, light scattered from the sample; and sample illumination optics (CL, L) configured to focus the light along the sample beam path to illuminate a sample with a line-focused beam, and collection optics (TL, CL1, CL2, CL3, M1) configured to collect, along the sample beam path, light scattered from the sample; and a detector system (44, 45, 47, 49) configured to detect both the collected scattered light along the sample beam path and reference light along the reference beam path such that, at detection, the detected reference light is angularly offset in relation to the detected scattered light, wherein the detector system (44, 45, 47, 49) is being connected to a data processor wherein the system includes a flow channel defined in a substrate that is configured to flow a sample suspended in a suspension medium continuously across the line-focused beam during translation of the sample at a flow rate within the flow channel, characterized in that the detected reference light and the detected scattered light are used to detect interferogram images including angular spectra for varying locations, η, of the sample, wherein the detector system (44, 45, 47, 49) is configured to map phase data and amplitude data of the angular spectra to a three-dimensional representation, to form a two-dimensional Fourier transform of the mapped angular spectra and to map the Fourier transformed angular spectrum to a scattering potential of the sample in a spatial frequency space.