This Yellow Barrier Filter from Ikelite is designed to fit over a diving, scuba, or snorkeling mask. It can then enable the viewing of fluorescence being emitted by fish or coral that are exposed to a blue or UV excitation light.

Fluorescence is a process that begins with chemical compounds called fluorophores as they absorb light energy from an outside source. Atoms and molecules within the fluorophores then emit their own light at lower energies and wavelengths that correspond to the original light source, making the fluorophores appear to glow. The proteins in many fish, coral, or other underwater life contain fluorophores, which create unusual or unique viewing opportunities. Since blue or UV wavelengths with their relatively high energy levels can yield the most intense fluorophore reactions, blue or UV light sources are considered ideal for producing the most colorful fluorophore effects.

However, because the light from a blue or UV lamp used to excite the atoms and molecules within the fluorophores is more intense than the lower-energy fluorophore glow, such lamps can end up obscuring that glow from fish or corals. The Ikelite Yellow Barrier Filter for Dive Mask makes it possible to perceive fluorescence from underwater life by blocking the light from a blue or UV excitation light; allowing the resulting glow to be seen through the filter and the diving, scuba, or snorkeling mask it is placed over.

This Ikelite Yellow Barrier Filter is constructed from rigid acrylic that is 6" high, up to 2.25" wide, and is shaped to accommodate the nose pocket on a diving, scuba, or snorkeling mask. It also features an adjustable, nylon woven-elastic head strap with two tri-glide buckles that allows this wearable filter to fit a circumference range of 19" to 36".