Cut off wavelength formula
Sputtered or ion-assisted PVD oxide-based designs can transmit over 80% down to about 250 nm and fluoride-based designs can transmit even lower. The disadvantages include low transmission (often under 20%) and spectral edges that are not very steep. These filters are very inexpensive to produce, comprising only a handful of layers and providing high blocking over the entire visible wavelength range. The traditional design of bandpass filters in the UV involves induced transparency in a metal (usually Al or Ag). These can be designed to work at angle (below is an example designed to work at 45 deg) for combined steering and wavelength management or at normal incidence. Notch filters are designed to reject specific wavelengths so the absorption properties of the materials are less important for these designs and can be useful in some respects. UV Filter Subtypes UV Rejection Band (RB) or Notch Filters Common materials used for ultraviolet dielectric thin-film coatings Common Name Simple filter designs only have blocking up to ~20% of the center wavelength - more extensive blocking can be accomplished by adding a metal layer which significantly reduces the %T in the transmitting region, adding a colored glass absorbing filter, or by adding dielectric layers (for instance, adding a short-pass filter design to the other side of the substrate). Another challenge for the short pass and bandpass filters is wide-wavelength blocking. Most interference filters are designed with the assumption that light is only transmitted or reflected and not absorbed. Working in the UV (less than about 400 nm) is a challenge for filter manufacturers, because many of the commonly used materials begin to absorb light at these wavelengths.
#Cut off wavelength formula skin#
UVA and UVB can cause sunburns and skin cancer, while the shorter wavelength UVC light can cause corneal damage in the eye. It can be used to measure DNA and to sterilize our water and the air we breathe. While useful for many things, it can also be harmful. UV light can be used in photolithography or dentistry to photoset polymers, and in biomedical applications to excite molecules during surgery.
UV light (in the 200 nm - 400 nm range) has many commercial and consumer-level applications. Omega has been manufacturing UV filters for over 50 years. Design, Engineering and Manufacturing Capabilities.Longpass (LP) and Shortpass (SP) filters.