Experimental characterizations of the CaF2 substrates for applications of ArF excimer lasers are performed. The measured absorption for an excimer-grade CaF2 substrate with 5 mm thickness is equal to 922×10-6. The root-mean-square (RMS) surface ronghness measured by atomic force microscope (AFM) and white light interferometer (WLI) are 0.22 and 1.24 nm, respectively, and the corresponding calculated surface scattering losses are 0.005% and 0.25%, respectively. The emission of impurity of Ce3+ and Eu3+ ions in the ultraviolet (UV)-grade CaF2 substrates is detected and ascertained by fluorescence. No water molecular or other contamination on the surface of CaF2 is detected in Fourier transform infrared (FTIR) and Raman spectroscopy. The experimental results prove that laser calorimeters are suited to precisely measure the weak absorption of excimer-grade CaF2 substrates; the power spectral densities (PSDs) obtained by different measuring methods should be compared with each other and combined with the practical scattering losses to appropriately evaluate the surface roughness of CaF2 substrates; spectroscopy methods, such as fluorescence, FTIR and Raman spectroscopy, can effectively detect the trace impurities or defects in the CaF2 crystal and the contaminations on the surface of the polished CaF2 substrates.