Rainbow is the name of at least four bands:
These are photos from concerts where Rainbow played, so they may be of other bands that played the concert as well.
Rainbow Nov 25, 1975 Santa Monica, California, United States Uploaded by Zimtrim
Rainbow / UFO Nov 17, 1975 Pittsburgh, Pennsylvania, United States Uploaded by Zimtrim
Rainbow / Argent Nov 10, 1975 Montréal, Québec, Canada Uploaded by Zimtrim