Contact Rainbow Optics for all your Optical Filter needs. They offer Multiple-Order Quartz Waveplates, Zero-Order Quartz Waveplates and Optical Beam Isolators to name a few. For more information, Rainbow Optics provides a graph and specifications online for more precise ordering. Rainbow Research Optics offers many more optic services as well! To view the optical filter graphs or for more information visit www.rainbowoptics.com today!