Patent Number: 
Section: claims

1. A laser protection arrangement with a safety cutoff, comprising:a passive laser protection wall which stores the radiation energy of impinging radiation of a laser of a laser material processing installation;a laser protection foil which comprises an expandable plastic and is fixed in an expanded state and undergoes a detectable change when struck by laser radiation being arranged in front of the passive laser protection wall in the direction of the laser radiation; andat least one sensor being connected to the laser by a threshold switch in order to switch off the laser when a detector signal received by the at least one sensor exceeds or falls below a predetermined threshold value. 2. The laser protection arrangement according to claim 1;wherein the sensor is an expansion sensor. 3. The laser protection arrangement according to claim 2;wherein the laser protection foil is expanded in only one direction and the expansion sensor is an expansion measurement strip which is glued on in the expansion direction so that when struck by laser radiation the laser protection foil is destroyed at the point of incidence and a tear extends perpendicular to the expansion direction and leads to a drop in the tensile strain which is determined as a threshold value. 4. The laser protection arrangement according to claim 1;wherein the sensor is an acoustic sensor. 5. A laser protection arrangement with a safety cutoff, comprising:a passive laser protection wall which stores the radiation energy of impinging radiation of a laser of a laser material processing installation;a laser protection foil with integrated optically conducting fibers comprising a fiber core and a fiber cladding, the laser protection foil undergoing a detectable change when struck by laser radiation being arranged in front of the passive laser protection wall in the direction of the laser radiation; andat least one sensor being connected to the laser by a threshold switch in order to switch off the laser when a detector signal received by the at least one sensor exceeds or falls below a predetermined threshold value. 6. A laser protection arrangement with a safety cutoff, comprising:a passive laser protection wall which stores the radiation energy of impinging radiation of a laser of a laser material processing installation;a laser protection foil which is a double foil that is formed by at least one gas-filled hollow chamber, the laser protection foil undergoing a detectable change when struck by laser radiation being arranged in front of the passive laser protection wall in the direction of the laser radiation, the laser protection foil being configured to be exchangeable with another laser protection foil without having to exchange the passive laser protection wall with another passive laser protection wall; andat least one sensor being connected to the laser by a threshold switch in order to switch off the laser when a detector signal received by the at least one sensor exceeds or falls below a predetermined threshold value. 7. The laser protection arrangement according to claim 6;wherein the at least one hollow chamber is filled with a gas which can be detected, and the sensor is a gas sensor. 8. The laser protection arrangement according to claim 7;wherein an overpressure exists in the at least one hollow chamber and the sensor is a pressure sensor. 9. The laser protection arrangement according to claim 7;wherein the double foil forming the at least one hollow chamber is connected by a plurality of webs so that the expansion of the chamber is limited by the height of the webs. 10. A laser protection arrangement with a safety cutoff, comprising:a passive laser protection wall which stores the radiation energy of impinging radiation of a laser of a laser material processing installation;a laser protection foil which is a bubble foil, the laser protection foil undergoing a detectable change when struck by laser radiation being arranged in front of the passive laser protection wall in the direction of the laser radiation; andat least one sensor being connected to the laser by a threshold switch in order to switch off the laser when a detector signal received by the at least one sensor exceeds or falls below a predetermined threshold value.