Abstract:
Metrology measurement methods and tools are provided, which illuminate a stationary diffractive target by a stationary illumination source, measure a signal composed of a sum of a zeroth order diffraction signal and a first order diffraction signal, repeat the measuring for a plurality of relations between the zeroth and the first diffraction signals, while maintaining the diffractive target and the illumination source stationary, and derive the first order diffraction signal from the measured sums. Illumination may be coherent and measurements may be in the pupil plane, or illumination may be incoherent and measurements may be in the field plane, in either case, partial overlapping of the zeroth and the first diffraction orders are measured. Illumination may be annular and the diffractive target may be a one cell SCOL target with periodic structures having different pitches to separate the overlap regions.
Abstract:
Systems and methods are presented for modulating a beam of radiation, such that the modulated beam exhibits substantially null residual amplitude modulation (RAM). An electro-optical modulator (300) is presented that includes a waveguide (306), a first region associated with the waveguide and a second region associated with the waveguide. The waveguide is designed to guide a beam of radiation. A first electric potential applied (314a, 314b) to the first region causes a first modulation to the beam of radiation while a second electric potential applied (316a, 316b) to the second region causes a second modulation to the beam of radiation. The first modulation combined with the second modulation provides substantially null residual amplitude modulation of the beam of radiation.
Abstract:
Apparatus include a microscope including an objective and a stage for positioning a test object relative to the objective, the stage being moveable with respect to the objective, and a sensor system including a sensor light source, an interferometric sensor configured to receive light from the sensor light source, to introduce an optical path difference (OPD) between first and second portions of the light, the OPD being related to a distance between the objective lens and the stage, and to combine the light portions to provide output light, a detector for detecting the output light from the interferometric sensor, a fiber waveguide for directing light between the sensor light source, the interferometric sensor and the detector, a tunable optical cavity between the sensor light source and the interferometric sensor, and an electronic controller configured to determine information related to the OPD based on the detected output light.
Abstract:
Die Erfindung betrifft ein Interferometrie-Verfahren zur optischen Untersuchung von Schichten. Dieses kann beispielsweise als Weißlichtinterferometrie- oder als spektrales Dünnschichtinterferometrie-Verfahren ausgeführt sein. Hierbei wird ein Messfleck (18) mit einem Durchmesser (d) erzeugt, mit dem die Oberfläche (12) eines Messobjektes (11) optisch untersucht wird. Erfindungsgemäß ist vorgesehen, dass das Verfahren bei einem mit der Geschwindigkeit (v) bewegten Messobjekt (11) durchgeführt wird, wobei die Beleuchtung des Messobjektes mit Lichtpulsen einer Dauer (t) erfolgt. Dabei ist zu bercksichtigen, dass die Ausdehnung (a) des zu untersuchenden Schichtabschnittes größer sein muss als d + vt, damit eine Messung erfolgen kann. Erfindungsgemäß werden die Parameter (d, v und t) bei einer vorgegebenen Geschwindigkeit (v) des Messobjektes in geeigneter Weise gewählt. Vorteilhaft lässt sich das Messverfahren daher in der laufenden kontinuierlichen Produktion von Schichtbauteilen anwenden.
Abstract:
Polarization-sensitive optical coherence devices for obtaining birefringence information are presented. The polarization state of the optical radiation outgoing from the optical radiation source is controlled such that the polarization state of the optical radiation incident on a sample has a 45 degrees angle with respect to the anisotropy axis of the sample. A combination optical radiation is produced in a secondary interferometer by combining a sample portion with a reference portion of optical radiation reflected from a tip of an optical fiber of the optical fiber probe. Subject to a preset optical path length difference of the arms of the secondary interferometer, a cross-polarized, and/or a parallel-polarized component of the combined optical radiation, are selected. Time domain and frequency domain registration are provided. The performance of the device is substantially independent from the orientation of the optical fiber probe with respect to the sample.
Abstract:
Methods, fourier domain optical coherence tomography (FDOCT) interferometers and computer program products are provided for removing undesired artifacts in FDOCT systems using continuous phase modulation. A variable phase delay is introduced between a reference arm and a sample arm of an FDOCT interferometer using continuous phase modulation. Two or more spectral interferograms having different phase delay integration times are generated. The spectral interferograms are combined using signal processing to remove the undesired artifacts. Systems and methods for switching between stepped and continuous phase shifting Fourier domain optical coherence tomography (FDOCT) and polarization-sensitive optical coherence tomography (PSOCT) are also provided herein.
Abstract:
The present invention discloses simple and yet highly efficient configurations of optical coherence domain reflectometry systems. The combined use of a polarizing beam splitter with one or two polarization manipulator(s) that rotate the returned light wave polarization to an orthogonal direction, enables one to achieve high optical power delivery efficiency as well as fixed or predetermined output polarization state of the interfering light waves reaching a detector or detector array, which is especially beneficial for spectral domain optical coherence tomography. In addition, the system can be made insensitive to polarization fading resulting from the birefringence change in the sample and reference arms. Dispersion matching can also be easily achieved between the sample and the reference arm for high resolution longitudinal scanning.
Abstract:
An interferometery system (110) for making interferometric measurements of an object, the system including: a beam generation module (124) which during operation delivers an output beam that includes a first beam at a first frequency and a second beam at a second frequency that is different from the first frequency, the first and second beams within the output beam being coextensive, the beam generation module including a beam conditioner (122) which during operation introduces a sequence of different shifts in a selected parameter of each of the first and second beams, the selected parameter selected from a group consisting of phase and frequency; a detector assembly having a detector element (170); and an interferometer constructed to receive the output beam at least a part of which represents a first measurement beam at the first frequency and a second measurement beam at the second frequency, the interferometer further constructed to image both the first and second measurement beams onto a selected spot on the object (160) to produce therefrom corresponding first and second return measurement beams, and to then simultaneously image the first and second return measurement beams onto said detector element (170).
Abstract:
This application describes designs, implementations, and techniques for controlling propagation mode or modes of light in a common optical path, which may include one or more waveguides, to sense a sample.