Wavefront

About: Wavefront is a research topic. Over the lifetime, 22678 publications have been published within this topic receiving 326734 citations. The topic is also known as: wave surface.

Optical scanning with aberration correction

Abstract: An optical head scans the information layer (3) of an optical record carrier (1) by means of a radiation beam (13). Optical aberrations in the beam such as coma and spherical aberration, caused by tilt and thickness variations in the optical disc respectively, are compensated by an aberration compensator (27) arranged in the radiation beam. The tilt or thickness variation is measured by a detector (30) and used to control the aberration compensator. The radiation beam is focused onto the information layer by an objective system (11). A displacement of the objective system in the transverse direction (26) as used for radial tracking of the optical beam, causes a mismatch between the wavefront to be compensated and the wavefront introduced by the aberration compensator (27). The detrimental effects of the mismatch are reduced by compensating only part of the aberration. The degree of compensation depends on the maximum displacement of the objective system and the tolerable wavefront error.

Scanning image-formation optical system, optical scanner and image forming device

Abstract: PROBLEM TO BE SOLVED: To realize a new scanning image-formation optical system capable of effectively correcting the curve of a scanning line and the deterioration of wave front aberration in an obliquely incident type optical scanner. SOLUTION: The scanning image-formation optical systems L1 and L2 are used in the optical scanner where one or more coupled beams from a light source side are deflected toward the deflecting and reflecting surface 4A of the light deflector 4 of a system where the surface 4A is rotated around a rotary shaft Ax parallel with the surface 4A by being obliquely made incident on a surface orthogonal to the rotary shaft Ax, and the deflected beams are condensed toward a surface to be scanned 5 by the scanning image-formation optical system so as to form a light spot on the surface 5, whereby the scanning of one or more scanning lines of the surface 5 is performed. The optical system includes two or more special tilt surfaces where the tilt amount of cross-sectional shape in a subscanning direction is changed in a main scanning direction.

Laser beam and resonator calculations on desktop computers

Abstract: There is a continuing interest in the design and calculation of laser resonators and optical beam propagation. In particular, recently, interest has increased in developing concepts such as one-sided unstable resonators, supergaussian reflectivity profiles, diode laser modes, beam quality concepts, mode competition, excess noise factors, and nonlinear Kerr lenses. To meet these calculation needs, I developed a general-purpose software package named PARAXIA$\sp{\rm TM}$, aimed at providing optical scientists and engineers with a set of powerful design and analysis tools that provide rapid and accurate results and are extremely easy to use. PARAXIA can handle separable paraxial optical systems in cartesian or cylindrical coordinates, including complex-valued and misaligned ray matrices, with full diffraction effects between apertures. It includes the following programs: ABCD provides complex-valued ray-matrix and gaussian-mode analyses for arbitrary paraxial resonators and optical systems, including astigmatism and misalignment in each element. This program required that I generalize the theory of gaussian beam propagation to the case of an off-axis gaussian beam propagating through a misaligned, complex-valued ray matrix. FRESNEL uses FFT and FHT methods to propagate an arbitrary wavefront through an arbitrary paraxial optical system using Huygens' integral in rectangular or radial coordinates. The wavefront can be multiplied by an arbitrary mirror profile and/or saturable gain sheet on each successive propagation through the system. I used FRESNEL to design a one-sided negative-branch unstable resonator for a free-electron laser, and to show how a variable internal aperture influences the mode competition and beam quality in a stable cavity. VSOURCE implements the virtual source analysis to calculate eigenvalues and eigenmodes for unstable resonators with both circular and rectangular hard-edged mirrors (including misaligned rectangular systems). I used VSOURCE to show the validity of the virtual source approach (by comparing its results to those of FRESNEL), to study the properties of hard-edged unstable resonators, and to obtain numerical values of the excess noise factors in such resonators. VRM carries out mode calculations for gaussian variable-reflectivity-mirror lasers. It implements complicated analytical results that I derived to point out the large numerical value of the excess noise factor in geometrically unstable resonators.

Computer-controlled high-accuracy optical measurement

Abstract: In measurements which are influenced by external parameters, computer control and automation can help to improve the accuracy. This is also true of basically optical measurement set-ups such as certain interferometers for measuring flatness or wavefront aberrations, or set-ups for measuring the optical transfer function of lenses, for example. For the latter, a critical external parameter is the temperature variation resulting in expansion and therefore defocusing effects. New developments and measurement principles leading to improved accuracy are discussed.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Methods and systems for measuring an aberated wave front

Abstract: Methods and systems are described for a system for measuring aberrations in a wave front. In the improved system multiple closely-spaced, small-aperture laser beams traverse an aberrating flow that introduces deflections of small-aperture laser beams from which aberrated wavefronts can be constructed. These beams may then be focused on position sensing devices using focusing lenses. The position sensing devices may then detect the positions of these beams and a difference between the detected position and the unaberrated position of the beams detected. This information may then be used to determine information regarding the optical aberrations introduced by the flow that may be used, for example, in improving communications systems and/or laser weapon systems.