Method for observing a sample comprising the steps of (a) illuminating the sample using a light source, the light source emitting an incident light wave that propagates toward the sample along a propagation axis (Z); (b) acquiring, using an image sensor, an image of the sample, which image is formed in a detection plane; (c) forming a stack of images, called reconstructed images, from the image acquired in step (b), each reconstructed image being obtained by applying, for one reconstruction distance, a numerical propagation operator; and (d) from each image of the stack of images, computing a clearness indicator for various radial positions, each clearness indicator being associated with one radial position and with one reconstruction distance.

The present disclosure provides a method and system for optimizing first-diffraction-order reconstruction of holograms, a device and a medium, and relates to the field of image processing. The method includes: acquiring a target image; determining a target image light field according to the target image; calculating a target diffraction field for the target image light field by performing backward propagation by a set distance; constructing a U-Net network model; and inputting the target diffraction field into a trained U-Net network model to acquire an optimized hologram. The trained U-Net network model is obtained by constructing a U-Net network model and training and optimizing the U-Net network model, thereby continuously improving the quality of the zero-diffraction-order reconstructed image of the initial hologram and finally achieving the effect of optimizing the first-diffraction-order reconstructed image of the hologram.

A plaque detection method and apparatus wherein at least one processor is programmed to receive above focus images to detect the presence of live cells without detecting the lysed cell materials, receive below focus images wherein virtual dark regions exist which are similar to cell shadows as seeds in a segmentation process and use contours around each resulting shape to obtain a subset that are more likely to be part of the cell population to define a cell map. A distance map is created in which each pixel value is the distance of that pixel from the nearest pixel of the cell map and the distance map is thresholded to create a first image of the places which are relatively far from the cells a second image with a smaller distance threshold to get an image that mimics the edges of the cells.

A device for detecting particles in air; said device comprising: a receiver for receiving a flow of air comprising particles; a particle capturing arrangement configured to transfer the particles from the flow of air to a liquid for collection of a set of particles in the liquid; a flow channel configured to pass a flow of the liquid comprising the set of particles through the flow channel; a light source configured to illuminate the set of particles in the flow channel, such that an interference pattern is formed by interference between light being scattered by the set of particles and non-scattered light from the light source; and an image sensor comprising a plurality of photo-sensitive elements configured to detect incident light, the image sensor being configured to detect the interference pattern.

An optical apparatus is comprising an optical imaging arrangement generating either an image of the original object field or the field of the original sample at the pupil plane which consist of both amplitude and phase information. The apparatus is further comprising a digital adaptive optics arrangement with a wave front sensor and a computing unit, which is adapted to generate at least one orthogonally translated digital copy of the original sample object field at the spatial Fourier or pupil plane and to analytically calculate a wave front error based on the phase difference between the original sample wave front and its digital copy or copies.

Provided is a determination method capable of non-destructively and simply determining a state of a sphere that is an aggregate of a plurality of cells. A phase difference image of a sphere that is an aggregate of a plurality of cells is generated from a hologram obtained by imaging the sphere, and a state of the sphere is determined on the basis of the phase difference image and a shape index value corresponding to a shape of the sphere.

A lensless holographic imaging system having a holographic optical element includes: a coherent light source for outputting a first light beam and a second light beam, wherein the first light beam irradiates a first inspection plane to form first object-diffracted light; a light modulator for modulating the second light beam into reading light having a specific wavefront; a multiplexed holographic optical element, wherein the first object-diffracted light passes through the multiplexed holographic optical element, and the reading light is input into the multiplexed holographic optical element to generate a diffracted light beam as system reference light; and an image capture device for reading at least one interference signal generated by interference between the first object-diffracted light and the system reference light. The lensless holographic imaging system has a relatively small volume and relatively high diffraction efficiency.

A system for analyzing a transparent particle including: an analysis pathway, including a first light source emitting an analysis light beam, and a first optical system focusing the analysis light beam in a focusing plane; and a position control pathway including a second light source, an image sensor, and a second optical system at least partially merged with the first optical system. The image sensor is offset relative to the image of the focusing plane by the second optical system. The system makes it possible to control correct positioning of the particle, even though it is transparent, and without disturbing the analysis pathway.

Disclosed is a method, implemented by a calculation unit, for estimating a depth map from a digital hologram representing a scene, the method including: reconstructing, using the digital hologram, of n images of the scene, each associated with a depth of the scene and including multiple pixels, each image being defined by a same window; for each image, forming thumbnails composed of contiguous pixels and associated with two-dimensional regions of the window; applying an operator to each thumbnail of each image associated with a depth to provide a metric per thumbnail and by depth; determining a depth associated with each region two-dimensional based at least on the metrics relating to the thumbnails associated with the two-dimensional region concerned; determining the depth of a pixel of the depth map by selecting the depth having a maximum repetition number in the two-dimensional regions including the pixel concerned.

The invention concerns a method for identifying biological particles from a stack of holographic images obtained by means of an optical system. A stack of image blocks centered on the biological particle to be analysed is extracted from the stack of images and a reference block corresponding to the focus plan is determined. A characteristic magnitude is calculated for each block of the stack and the profile of this characteristic magnitude along the optical axis of the system is compared with a plurality of standard profiles relative to known types of particle. Alternatively, blocks of the stack are extracted from the stack of blocks for predetermined defocusing deviations and the extracted blocks are compared with standard blocks relative to known types of particle.