Looking for Angelic symbols?

I am looking for a guide to angelic symbols/language; specifically I am looking for the symbol for the Archangel Raphael. Any help, be it a web link, a book suggestion, or a description would be appreciated. I have looked at many pages online and have yet to run into that specific symbol. I want to get this symbol as a tattoo as an homage to my dearest, best of friends and soulmate, whose name is Rafael.