Contact Rainbow Research Optics for Optical Filters. They specialize in custom optics and more! Some of the optical filters that Rainbow Research Optics offers are: Interference Bandpass Filters, Reflective Neutral Density Filters, Absorptive Neutral Density Filters, Long Wave Pass Filters and Short Wave Pass Filters. Online you will find informational graphs for their optical filters and more information about Rainbow Research Optics. Visit today to see what Rainbow Research Optics can do for your company or group!