| 摘要 |
PROBLEM TO BE SOLVED: To enable light absorptance to be calculated by employing the same measuring sample holder and directly comparing an echo signal intensity generated when light with their different wavelength is applied. SOLUTION: Wavelengths of an excimer laser 13 are approx. 193nm and approx. 248nm respectively when gas introduction of ArF and KrF, and a pulse width is approx. 20 seconds. Emission light is focused and applied to a sample 17 in a sample holder 20 via a slit 14, a relay lens 15, and an objective lens 16 (a lens system with its different ArF and KrF is used). Irradiation light quantity is monitored by a light quantity sensor 19 on a known divergence light path due to surface reflection of a crystal glass 18. Measurement light is applied on the sample 17, and output of a piezoelectric echo detection element 23 is measured. The absorptance of the sample 17 is optically measured in advance at a wavelength of the KrF laser of approx. 248nm by a spectrophotometer, and a proportional coefficient of the absorption quantity relevant to the echo signal intensity is obtained. The absorption quantity during ArF laser light irradiation can be obtained multiplying this proportional coefficient for the echo signal intensity. |
