Wavelength stabilizer for narrow bandwidth laser
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorsHitoshi Wakata, Atsushi Sugitatsu, Hajime Nakatani, Yasushi Minamitani
Life of this patent
Estimating the term…
Abstract
A wavelength monitor/stabilizer for narrowly controlling the bandwidth of laser; the monitor/stabilizer uses parameters Q, F or G derived by measuring diameters of interference fringes given by the beam of the wavelength-controlled narrow bandwidth laser e.g. excimer laser and those given by the reference light e.g. of a mercury lamp. The controlling is made by controlling the parameter to be in a predetermined range. An image sensing unit for detecting the interference fringes are splitted into plural image sensors with adjustable distance for enabling more rapid measurement by skipping the in-between part.
Claims8
In a wavelength stabilizer for a narrow bandwidth laser, wherein an object oscillating wavelength of an object laser beam whose wavelength is to be stabilized is measured by utilizing interference fringes given by passing the beam through an etalon and said object oscillating wavelength of said narrow bandwidth laser is controlled based on the results of said wavelength measurement, including a calibration of said oscillating wavelength by utilizing a reference light source, measuring the reference diameters of the interference fringes given by the beam of said reference light source, and measuring the object diameters of said interference fringes given by said object laser beam,
- the improvement comprising:
- an arithmetic unit for processing measurement-based parameters derived from the measurements of said reference diameters and said object diameters and processing target-based parameters corresponding to the desired object oscillating wavelength of the object laser, and
- a control unit for controlling said object oscillating wavelength in a manner that said measurement-based parameters and said target-based parameters coincide each other.
In a wavelength monitor for a narrow bandwidth object laser, which detects a wavelength of the narrow bandwidth object laser by a spectroscopic device and an image sensing unit and outputs a signal for controlling the wavelength of said narrow bandwidth object laser based on the results of the detection, a wavelength monitor for narrow bandwidth object laser,
- the improvement that:
- said image sensing unit comprises plural image sensors and further comprising,
- a device for adjusting the distance between said plural image sensors.
In a wavelength monitor for a narrow bandwidth object laser, which detects a wavelength of the narrow bandwidth object laser by a spectroscopic element and an image sensing unit, and outputs a signal for controlling the wavelength of said narrow bandwidth object laser based on results of the detection, a wavelength monitor for narrow bandwidth object laser,
- the improvement comprising:
- a multiplexer comprising a switching means for selecting particular channels from an array of channels of optical detectors included in said image sensing unit and for reading detected light intensity signals carried on the selected channels.
In a wavelength monitor for a narrow bandwidth object pulse laser, which detects a wavelength of the narrow bandwidth object pulse laser by a spectroscopic element and an image sensing unit, and outputs a signal for controlling the wavelength of said narrow bandwidth object pulse laser based on results of the detection, a wavelength monitor for narrow bandwidth object pulse laser,
- the improvement that:
- an interval for reading the light intensity signal carried on the optical detectors included in said image sensing unit is selected to be integer times the repetitive interval of oscillation of said object pulse laser.
In a wavelength monitor for stabilizing a center wavelength of a narrow bandwidth object laser, a wavelength monitor for the narrow bandwidth object laser comprising means for observing the wavelength, the improvement that:
- said means for observing the wavelength is an etalon of a Fabry-Perot type, comprising spacers having a coefficient of linear expansion of 5.times.10.sup.-5 or smaller and comprising,
- a gas-tight container containing said Fabry-Perot type etalon therein.
Dependencies are inferred from the claim text.