You can add specify which file types to search in the File Types view.
Figure 15.6 Setting File Types Preferences
Check Use exclude list if you want to exclude certain file types even though they match the pattern in the Search Specifications boxes. Enter the patterns to exclude in the Exclude box, with multiple patterns separated by whitespace.
Check Use include list if you want to only include certain file types, even if the pattern in the Search Specifications should allow other types. Enter the patterns to include in the Include box, with multiple patterns separated by whitespace.
You cannot choose both of these options simultaneously.