A lens-less system for holographic imaging or a holographic imaging device is provided. The method/device includes a stationary image sensor to capture an image of a sample illuminated by light from a stationary illumination source. A reference lens-less holographic image may be captured and used as a base line to reduce image artifacts and/or remove noise from the lens-less holographic image. Since real wavefronts produced by a diverging point source are neither perfectly spherical nor planar but a combination of both qualities, theoretical estimates for wavefront reconstruction based on perfectly planar or spherical incident waves cannot be applied accurately. The method/device here provides a solution by performing a calibrated wavefront reconstruction based on equations governing coherent light propagation for both spherical waves and planar waves with a mathematical correlation between numerical magnification and propagation depth to produce accurate three-dimensional details of the object.

Disclosed are optical interrogation apparatus that can produce lens-free images using an optoelectronic sensor array to generate a holographic image of sample objects, such as microorganisms in a sample. Also disclosed are methods of detecting and/or identifying microorganisms in a biological sample, such as microorganisms present in low levels. Also disclosed are methods of using systems to detect microorganisms in a biological sample, such as microorganisms present in low levels. In addition or as an alternative, the methods of using systems may identify microorganisms present in a sample and/or determine antimicrobial susceptibility of such microorganisms.

There is provided an optical system having a viewing window. The optical system comprises a display device arranged to spatially modulated light in accordance with a hologram displayed thereon to form a holographic wavefront. The holographic wavefront forms a holographic reconstruction of an image downstream of the display device. The optical system further comprises a waveguide arranged to receive the holographic wavefront and waveguide the holographic wavefront between a pair of reflective surfaces thereof. One surface of the pair of reflective surfaces is partially transmissive such that a plurality of replicas of the holographic wavefront are emitted therefrom. The optical system further comprises an optical component between the holographic reconstruction and the waveguide, wherein the optical component is arranged to (a) form a virtual image of the holographic reconstruction upstream of the display device and (b) form an image of the displayed hologram at infinity or downstream of the waveguide.