This EXCEL spreadsheet is an example of one method of extracting optical thin film constants from measured spectral data. The example uses data from an article titled “Characterizing Optical Thin Films (II)”. The reader is authorized to download the spreadsheet and to use it as they see fit. The author of the spreadsheet and Denton Vacuum, LLC take no responsibility for the materials in the spreadsheet and the results obtained in using the spreadsheet as it is and/or any future modifications by the user.