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US 7,253,905 B2Granted
Determination and correction for laser induced CCD camera degradation
OwnerDirk L. Basting, Kai Schmidt +2inventors
InventorsDirk L. Basting, Kai Schmidt, Holger Bald, Christian Schramm
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Abstract
A process for the determination and correction of laser induced damages of the optical and electronic components within the beam path of a monitor module of a 193 nm excimer lasers is provided herein. Especially state of the art detectors like CCD cameras degrade under UV radiation. With a special correction of the sensitivity of each camera pixel this problem can be solved.
Claims6
A method for determination and correction of laser induced CCD lines degradation, comprising the steps of:
- employing a laser to emit radiation having a finely adjustable wavelength;
- employing a spectrometer to determine the wavelength of the emitted laser radiation;
- projecting interference fringes produced by said spectrometer onto a CCD line formed by a plurality of camera pixels:
- correcting a sensitivity of each camera pixel to compensate for damage to each camera pixel caused by said radiation by shifting the wavelength of said radiation by small, incremental steps;
- employing a CCD camera to record each interference pattern after each wavelength shift;
- summing all recorded interference patterns;
- calculating an average interference pattern R(i);
- evaluating the sensitivity of each individual pixel i of the CCD camera and;
- increasing the sensitivity of said CCD camera by an amount that compensates for the loss of sensitivity determined by said evaluation.
6 more elements
Dependencies are inferred from the claim text.