With TimeMachine there isn't a way to verify what and if it's backing anything up you just have to trust it is and hope it restores when you need it.
If your photos are more precious, then consider other backup options like external storage drives, bootable clones and even burned DVD's.
FYI, iPhoto keeps your photo's in a iPhoto Library located in your Pictures folder, if you right or control key click on the iPhoto Library you can "open package contents" and it's really a folder and inside is a Originals or Masters folder with your original files so you can Finder > Duplicate that folder and move it out.
Don't mess around in that iPhoto Library or store things in there, it's only for emergency access.
Most commonly used backup methods