Institute National Doptique | Date: 2015-09-22
An optical assembly has an optical element mounted in the cavity of a barrel. A flexible ring is in contact with one of the surfaces of the optical element. The flexible ring has ring threads engaging barrel threads within the cavity. The flexible ring has a biased state in which the ring threads press against the barrel threads, and is resiliently deformable to a compressed state allowing screwing of the flexible ring within the cavity. In one variant, multiple subassemblies each having an optical element and a flexible ring are provided in the cavity of a barrel. The optical elements of subassemblies subsequent to the first one are supported by the flexible ring of the previous subassembly. The pressing of the ring threads against the barrel threads prevents a lateral shift of the flexible ring within the cavity, eliminating the decentering observed with conventional retaining rings.
Institute National Doptique | Date: 2014-09-19
A method for phase error correction in a synthetic aperture (SA) imaging system is configured to image a target region of a scene from a platform in relative movement with respect to the scene. The method includes acquiring target SA data from the target region and reference SA data from a reference region of the scene, using a SA acquisition unit. One or more phase correction factors are determined from the reference SA data based on an assumption that the reference region has a known topography. The phase correction factors are representative of uncompensated optical-path-length fluctuations along the optical path between the reference region and the SA acquisition unit mounted on the platform. A phase correction is applied to the target SA data based on the phase correction factors so as to obtain phase-corrected target SA data. A SA imaging system implementing the method is also disclosed.
Institute National Doptique | Date: 2014-02-03
Method and system for emitting optical pulses in view of a desired output energy of the optical pulses and a variable external trigger signal, using a laser system having a seed laser oscillator optically coupled to one or more cascaded optical amplification stages. For each amplification stage, a plurality of sets of pump pulse parameters are provided, each associated with specific values of the output energy and the trigger period. Proper pumping parameters associated with the received desired value of the output energy and the trigger period of the received trigger signal are selected for each amplification stage, which is pumped accordingly before a seed optical pulse is launched through the system.
Institute National Doptique | Date: 2015-07-20
Optical assemblies have one or more optical elements mounted in the cavity of a barrel. The optical element has a curved abutment surface engaging a seat provided in the cavity. The barrel has an inner wall provided with a set of internal threads. External threads are provided on a peripheral wall of the optical element or on a perimeter wall of a retaining ring securing the optical element within the cavity. The internal and external threads have a thread profile including a load-bearing thread face perpendicular to the center axis of the cavity. The thread profile may define a Buttress thread profile or a square thread profile.
Institute National Doptique | Date: 2015-05-28
Methods and systems for the controlled generation of microcavitation bubbles in a medium having a liquid phase are generally provided. Laser pulses having a time-dependent pulse parameter controllable over their duration are generated. The medium is irradiated with the laser pulses with a radiant exposure sufficient to initiate microcavitation within the medium during each laser pulse. The time-dependent pulse parameter of each laser pulse is controlled according to a generally positive variation over the pulse duration such that the medium absorbs a greater quantity of energy from the laser pulse at an end of the pulse duration than at a beginning thereof. Such methods and systems may be used for various applications such as biology, medicine or material processing.