Method and apparatus for stabilizing the frequency of a laser beam
AssigneeLambda Physik Forschungs-Und Entwicklungs-GmbH
InventorsPeter Lokai, Heribert Rosenkranz
Life of this patent
Estimating the term…
Abstract
For stabilizing the frequency of a narrow-band Excimer laser beam the interference rings of a Fabry-Perot interferometer 16 are projected onto a solid-state image sensor 18 and by means of the solid-state image sensor an electrical signal is generated which is dependent on the frequency of the laser beam. The electrical signal is compared with a stored reference signal to derive an adjusting signal 32 for an optical reflection grating 38 with which the frequency of the laser beam 12 is regulated to a desired value. The absolute value of the frequency of the laser beam 12 is determined by means of the optogalvanic effect.
Claims11
A method of stabilizing the wavelength of a laser beam (12) emitted by an Excimer laser which includes a wavelength-selective means (38) for adjusting said wavelength, and a spectral apparatus (16) into which a part (12') of the laser beam is introduced to derive an adjusting signal for adjustment of the wavelength-selective means, including the steps of:
- projecting an image (B) onto a solid-state image sensor, by means of the spectral apparatus (16), said image being dependent on the wavelength of the laser beam (12);
- generating, by means of the solid-state image sensor (18), an electrical signal (20) dependent on the wavelength of the laser beam (12);
- comparing the electrical signal (20) with a predetermined reference signal;
- and
- deriving from the comparing step an adjusting signal (32) for the wavelength-selective means (38).
An apparatus for stabilizing the wavelength of a laser beam (12) emitted by an Excimer laser which includes wavelength-selective means (38) for adjusting the wavelength, comprising:
- a spectral apparatus (16) into which a part (12') of the laser beam is introduced to derive an adjusting signal for adjustment of the wavelength-selective means for generating an image (B) dependent on the wavelength of the laser beam (12);
- a solid-state image sensor on which the image (B) generated by the spectral apparatus (16) is imaged for generating an electrical signal (20) corresponding to said image;
- and
- a comparison circuit (66) coupled to said image sensor for comparing said electrical signal corresponding to said image (B) with a reference signal for generating an adjusting signal (32) for the wavelength-selective means (38).
A method of stabilizing the wavelength of a laser beam (12) emitted by a laser which includes a wavelength-selective means (38) for adjusting said wavelength, and a spectral apparatus (16) such as a Fabry-Perot interferometer into which a part (12') of the laser beam is introduced to derive an adjusting signal for adjustment of the wavelength-selective means, including the steps of:
- projecting an image (B) onto a solid-state image sensor, by means of the spectral apparatus (16), said image being dependent on the wavelength of the laser beam (12);
- generating, by means of the solid-state image sensor (18), an electrical signal (20) dependent on the wavelength of the laser beam (12);
- comparing the electrical signal (20) with a predetermined reference signal;
- and
- deriving from the comparing step an adjusting signal (32) for the wavelength-selective means (38).
An apparatus for stabilizing the wavelength of a laser beam (12) emitted by a laser which includes wavelength-selective means (38) for adjusting the wavelength, comprising:
- a spectral apparatus (16), such as a Fabry-Perot interferometer, into which a part (12') of the laser beam is introduced to derive an adjusting signal for adjustment of the wavelength-selective means for generating an image (B) dependent on the wavelength of the laser beam (12);
- a solid-state image sensor on which the image (B) generated by the spectral apparatus (16) is imaged for generating an electrical signal (20) corresponding to said image;
- and
- a comparison circuit (66) coupled to said image sensor for comparing said electrical signal corresponding to said image (B) with a reference signal for generating an adjusting signal (32) for the wavelength-selective means (38).
Dependencies are inferred from the claim text.