Abstract: A method of rapidly determining surface relief of an object or a structure without making contact therewith based on quantifying the degree to which the image of an illuminated point or small spot on the surface is defocussed. Said point or spot is illuminated by a source of electromagnetic radiation such as a laser, and the relief is determined in the form of a profile where the height of any point on the profile is represented by the ratio of the energy values of two beams derived by splitting a single beam reflected from the surface under investigation: one of the beams acting as a reference and the other of the beams being limited by the action of a diaphragm and constituting a measurement beam.

Abstract: Particle analyzer apparatus using the silhouette projecting method, comprising a fixed laser, a reflecting fixed cylinder of axis orthogonal to the direction of the incident laser beam, and adapted to send back the light towards and through a sheet of particled material, a light receiving device generating signals representative of the light received, means for processing the said signals and display means.The receiving device may be constituted by a linear array of photodiodes, associated to a system for digitizing the projected silhouettes of the grit particles and for displaying same in the form of a television type image.Said receiving device may also be constituted by a battery of lenses in the focal point of which are placed analog photoelectrical cells in order to generate signals representative of the covering power of the particles.