A device of determination of the state of at least one particle by acquisition over time of a plurality of particles (11a-11f) present in a sample, said acquisition device comprising: - a spatially coherent or pseudo-coherent light source directed towards a first surface of said sample; - an optical system having an optical axis and achieving the conjugation between a plane of focus and a focal plane, directed towards a second surface of said sample opposite to said first surface, and placed relative to the sample so that the particles are not in the plane of focus; - an image sensor, placed in the focal plane of the optical system and configured to acquire an intensity image (Ih) formed by the interference between said light source and said sample; and - a computational processing unit comprising: o a unit of digital construction of a series of electromagnetic matrices (I 1 - IN) modeling, from the acquired image (Ih), the electromagnetic wave in planes parallel to the plane of focus and comprised in the sample for a plurality of offsets relative to said plane, o a unit for determining a first electromagnetic matrix (Ifmoy) at an average distance of focus on the particles (11a-11f) from the series of electromagnetic matrices ( I 1- IN); o a unit for identifying at least one of the particles (11a-11f) in the first electromagnetic matrix (Ifmoy) and for storing the coordinates of said particle; o a unit for determining a second electromagnetic matrix ( Ifp) at a distance of focus on a particle (11a-11f) identified from the components of the series of electromagnetic matrices ( I 1- IN) having the stored coordinates; and o a unit for determining a state of particle (11a-11f) as a function of the time variation of the stored coordinates. - a spatially coherent or pseudo-coherent light source directed towards a first surface of said sample; - an optical system having an optical axis and achieving the conjugation between a plane of focus and a focal plane, directed towards a second surface of said sample opposite to said first surface, and placed relative to the sample so that the particles are not in the plane of focus; - an image sensor, placed in the focal plane of the optical system and configured to acquire an intensity image (Ih) formed by the interference between said light source and said sample; and - a computational processing unit comprising: o a unit of digital construction of a series of electromagnetic matrices (I 1 - IN) modeling, from the acquired image (Ih), the electromagnetic wave in planes parallel to the plane of focus and comprised in the sample for a plurality of offsets relative to said plane, o a unit for determining a first electromagnetic matrix (Ifmoy) at an average distance of focus on the particles (11a-11f) from the series of electromagnetic matrices ( I 1- IN); o a unit for identifying at least one of the particles (11a-11f) in the first electromagnetic matrix (Ifmoy) and for storing the coordinates of said particle; o a unit for determining a second electromagnetic matrix ( Ifp) at a distance of focus on a particle (11a-11f) identified from the components of the series of electromagnetic matrices ( I 1- IN) having the stored coordinates; and o a unit for determining a state of particle (11a-11f) as a function of the time variation of the stored coordinates. o a unit of digital construction of a series of electromagnetic matrices (I 1 - IN) modeling, from the acquired image (Ih), the electromagnetic wave in planes parallel to the plane of focus and comprised in the sample for a plurality of offsets relative to said plane, o a unit for determining a first electromagnetic matrix (Ifmoy) at an average distance of focus on the particles (11a-11f) from the series of electromagnetic matrices ( I 1- IN); o a unit for identifying at least one of the particles (11a-11f) in the first electromagnetic matrix (Ifmoy) and for storing the coordinates of said particle; o a unit for determining a second electromagnetic matrix ( Ifp) at a distance of focus on a particle (11a-11f) identified from the components of the series of electromagnetic matrices ( I 1- IN) having the stored coordinates; and o a unit for determining a state of particle (11a-11f) as a function of the time variation of the stored coordinates.