Abstract:
In general, in one aspect, the invention features methods that include interferometrically monitoring a distance between an interferometry assembly and a measurement object along each of three different measurement axes while moving the measurement object relative to the interferometry assembly, determining values of a first parameter and a second parameter for different positions of the measurement object from the monitored distances, wherein for a given position the first parameter is based on the monitored distances of the measurement object along each of the three different measurement axes at the given position, and for a given position the second parameter is based on the monitored distance of the measurement object along each of two of the measurement axes at the given position, and deriving information about a surface figure profile of the measurement object from the first and second parameter values.
Abstract:
PROBLEM TO BE SOLVED: To provide a desired beam pattern by a simple interferometer system. SOLUTION: The interferometer system 100 contains first and second optical element stacks. In a first optical element stack, the inclined surface of a first prism 102 is mounted on the inclined surface of a second prism 104, and the interface between the inclined surfaces contains a first PBS 106. In a second optical element stack, the inclined surface of a third prism 112 is mounted on the inclined surface of a fourth prism 114, and the interface between the inclined surfaces contains a second PBS 116. The inclined surfaces of the first and the second prisms are aligned with the inclined surface of the fourth prism. First to fourth length board elements 122 to 128 are arranged in a beam path between a rhombus assembly and at least one of a measurement optical element and a reference optical element, and a redirect optical element 132 is arranged adjacent to the vertical plane of at least the first and the first prisms. COPYRIGHT: (C)2006,JPO&NCIPI
Abstract:
A polarising double-passed interferometer comprises a polarising beamsplitter (16), a reference mirror (20) in the path of a reference beam (14) and a movable measurement mirror (26) in the path of a measurement beam (12). The reference and measurement beams have different polarisations. An angular beam deflection device such a glass wedge or prism (32) acts to remove or separate out an error beam (30) caused by leakage of light of one polarisation into the path of light of the other polarisation.
Abstract:
The device comprises : a laser device (10, 20) for the frequency n1 (11) and the frequency n2 (21), each provided with a polarizing beam splitter (12, 22) for producing crossed polarized partial beams of frequency n1 (13, 14) and n2 (23, 24), respectively, with a modulator (18, 28) for shifting the frequency of each of the partial beams to the frequency f1 or f2, respectively, with a pair of deflecting mirrors (15, 17, 25, 27) and with a polarizing beam splitter (16, 26) for uniting (19, 29) the partial beams n1, n1+f1, n2, n2+f2; two photodetectors (35, 45) before each of which a polarizer (34, 44) is arranged; a Michelson interferometer; a non-polarizing beam splitter (30) for distributing each of the partial beams (19, 29) into a measurement light beam (32) or a reference light beam (33). The reference light beam is transmitted to the corresponding photodetector (35). The measurement light beam (32) is transmitted to the Michelson interferometer and then to the corresponding photodetector (45).The photodetector signals are modulated in function of the amplitude, and the phase difference between the two modulated signals is determined. This phase difference depends only on the position of the test object and the equivalent wavelenght of the difference, n1-n2. For stabilization or correction, the device can be executed in duplicate and one of the executions used as a reference. The corresponding process can be applied to determine positions or distances as the interval between two positions. Uncertainties can be eliminated by shifting the distance or changing the frequency with simultaneous integration of the phase difference over time.
Abstract:
In general, in one aspect, the invention features methods that include interferometrically monitoring a distance between an interferometry assembly (100) and a measurement object (120) along each of three different measurement axes while moving the measurement object relative to the interferometry assembly, determining values of a first parameter and a second parameter for different positions of the measurement object from the monitored distances, wherein for a given position the first parameter is based on the monitored distances of the measurement object along each of the three different measurement axes at the given position, and for a given position the second parameter is based on the monitored distance of the measurement object along each of two of the measurement axes at the given position, and deriving information about a surface figure profile of the measurement object from the first and second parameter values.
Abstract:
The present invention relates to an apparatus and to a method of monitoring an interferometer (2), comprising the steps of: coupling a first optical signal (62) into the interferometer (2) and into a wavelength reference element (18), detecting a first resulting interference signal (68) being a result of interference of parts of the first optical signal (62) in the interferometer (2), detecting a resulting reference signal (70) of the wavelength reference element (18), the resulting reference signal (70) being a result of interaction of the first optical signal (62) with the wavelength reference element (18), and comparing the first resulting interference signal (68) with the resulting reference signal (70) to detect a drift of the interferometer (2), if any.
Abstract:
A polarization interferometer comprises a light source (1), a collimator (2), a first polarization element (3), a system of double-refracting elements (4, 5, 6) and a second polarizing element (7) which polarizes the light emerging from the double-refracting element (4, 5, 6) and directs it to a photon detector (8). The double-refractive element (4, 5, 6) consists of two optical wedges (5, 6) which together constitute a right parallepiped and which are arranged so as to slide relative to each other along opposed side surfaces, and a double-refracting plate (4) with parallel faces which acts as a compensator. The optical axis of the compensator (4) makes a finite angle with those of the two wedges (5, 6) in the plane perpendicular to the light beam, the optical axes of both wedges (5, 6) being coincident. The optical axes of the two polarizers (3, 7) are mutually perpendicular or parallel and are not aligned parallel to the axes of the two wedges (5, 6) of the double-refractive element (4, 5, 6).
Abstract:
La présente invention concerne un système interférométrique comprenant des moyens de séparation de polarisation (10), des premiers moyens de conversion de polarisation (1 1 ), un interféromètre (2) de type Mach-Zehnder comprenant un premier (4) et un second (5) bras reliés entre eux par une première (6) et une seconde (7) extrémités de manière à ce qu'un premier et un second faisceaux (20, 21 ) de même polarisation parcourent l'interféromètre de manière réciproque suivant des directions de propagation respectivement opposées pour former un premier et un second faisceaux interférométriques (22, 23), des seconds moyens de conversion de polarisation (1 1 ) pour obtenir un faisceau interférométrique converti en polarisation (24), des moyens de combinaison de polarisation (10) et des moyens de détection (8) aptes à détecter un faisceau de sortie (25).
Abstract:
A polarising double-passed interferometer comprises a polarising beamsplitter (16), a reference mirror (20) in the path of a reference beam (14) and a movable measurement mirror (26) in the path of a measurement beam (12). The reference and measurement beams have different polarisations. An angular beam deflection device such a glass wedge or prism (32) acts to remove or separate out an error beam (30) caused by leakage of light of one polarisation into the path of light of the other polarisation.