DEVELOPMENT OF AN ARRAY CALORIMETER DETECTOR AND MEASUREMENT OF KRF LASER INTENSITY

A new array calorimeter detector has been developed and was used to me asure the spatial profile of a KrF laser with 300 J energy and a 267 m m diameter in near field. The detector contains 441 (21x 21) calorimet ers. A tantalum foil is used as the absorber. The boiling of liquid ni trogen is used as the reference temperature of the thermocouples, as i t is both insulating and stable. Thus, it is the basis of the physical measurement in the sub-mu V-mV level with a multithermocouple detecto r. The response of the tantalum foil is linear in the range of fluence from 30 mJ/cm(2) to 1.1 J/cm(2). The experimental results show that t he spatial profile of the KrF laser pumped by two side electron beams is saddle shaped with a valley at the center and one peak at each side of the center on the coaxial Line of electron beams in the near field . With a decrease of the laser's gas pressure, the distribution become more even rather than Aat. (C) 1998 American Institute of Physics.