Dear abhijeet, before proceed further, i just want to ask one thing that, the above sentence "15.12.2013 343 S030.tif" is this was written in any cell in the excel worksheet or this was a file name which was saved in your system.
Dear Abhijeet,
If the format is not fix, you should explain, how you want the formula to get your desired result. In the above "15.12.2013 343 S030.tif" we are thinking that first 10 digits (15.12.2013) then your required 3 digits (343), so should adjust/know the position of your required data and some text formulas you can apply.
Otherwise please provide sample data, so that we can know the how many formats you are having