Abstract: A method of determining at least one optical property of a projection exposure system is described, wherein the exposure system includes a beam delivery system having a light source for generating an exposure optical beam having light of a first wavelength (?1) and a second wavelength (?2), wherein a first ratio is defined as an intensity of light ?2 to an intensity of light ?1 in the exposure optical beam. The method includes supplying at least one measuring optical beam including light of at least ?1 to the projection optical system, detecting wavefronts having traversed the projection optical system, and determining an optical property in dependence of the detected wavefronts, wherein a second ratio of an intensity of light of ?2 to an intensity of light of ?1 in the measuring optical beam being incident on the detector of the wavefront detection system is less than the first ratio.

Abstract: A method of determining at least one optical property of a projection exposure system is described, wherein the exposure system includes a beam delivery system having a light source for generating an exposure optical beam having light of a first wavelength (?1) and a second wavelength (?2), wherein a first ratio is defined as an intensity of light ?2 to an intensity of light ?1 in the exposure optical beam. The method includes supplying at least one measuring optical beam including light of at least ?1 to the projection optical system, detecting wavefronts having traversed the projection optical system, and determining an optical property in dependence of the detected wavefronts, wherein a second ratio of an intensity of light of ?2 to an intensity of light of ?1 in the measuring optical beam being incident on the detector of the wavefront detection system is less than the first ratio.

Abstract: The invention is directed to a frequency-doubling solid state laser having pump light sources at opposite ends thereof. A folding and out-coupling mirror is antireflection coated on both sides with respect to the wavelength of the light generated by the pump light sources. The pump light sources include a total of four laser diodes with each laser diode generating 3 Watts of light power. An output power at 532 nm is obtained using a Nd:YAG laser rod and a frequency-doubling crystal made of potassium titanyl phosphate. The folding angle defined by the folding and out-coupling mirror is in the range of 10.degree. to 60.degree. and is typically 50.degree..

Abstract: The invention is directed to a cooling arrangement for a semiconductor pump source which develops heat during operation. The cooling arrrangement includes a heat sink defining a seat for accommodating the pump source thereon and a cooling channel is formed in the heat sink for conducting a coolant therethrough to remove a major portion of the heat. A Peltier device is connected to the heat sink for finely controlling the temperature of the heat sink so as to permit the semiconductor pump source to emit radiation having a predetermined optional wavelength.