Website Search Engine for PDFs

Hi, I need a search engine that I can implement into a website that is capable of indexing and searching PDF files. This will be it’s sole use.

There will be about 20 large PDF files (100 pages+), ideally i need a search engine that can return results from within these files and then link the user straight to the page where the result is located.

Does anybody know of any search engine software that can do this? It needs to be PHP.

I came accross this on Google, but I’m not sure it can do what I need it to. (Specifically, linking to pages within the PDF files.) Has anyone here ever used it, and how did you find it?