Measurements of detector nonlinearity at 193 nm.

We have developed a measurement system based on a correlation method to characterize the nonlinearity of a detector's response over a large range of laser pulse energy. The system consists of an excimer-laser source, beam-shaping optics, a beam splitter, a monitor detector, a set of optical filters, and the detector under test. Detector nonlinearities as large as 10% or greater over an entire measurement range at an excimer-laser wavelength of 193 nm are observed. The measurement range of the current system is approximately 300 nJ to 50 mJ of laser pulse energy at the detector under test. The typical expanded measurement uncertainty of nonlinearity is 0.6% (k = 2).