Linearly variable long-pass and short-pass filters

Edmund Optics has introduced a new range of linearly variable filters, which are designed for both individual and combined use, and which available in both long-pass and short-pass options. Linearly variable filters are manufactured with an interference coating that is intentionally wedged in one direction, creating a linear shift of the centre wavelength across the length of the entire substrate. This linear shift allows the broad filtering capabilities that are demonstrated by the short-wave and long-wave variable filters. The two types of filters - short- and long-wave - work inversely to one another; the short-wave variable filter passes light throughout the filter's length until a blocking band is reached, while the long-wave variable filter blocks light until a transmission band is reached. These blocking and transmission bands may be adjusted by reorienting the filter to the light source. Using its broad blocking and transmission range, a single linear variable filter can replace an entire filter set.

The filters allow for blocking and passing of targeted wavelengths. When used independently, the linear variable short-wave pass filter has a wavelength range of 330-750nm with an average transmission of 97 per cent in the range 400-750nm. The linear variable long-wave pass filter has a wavelength range of 300-845nm and an average transmission of 97 per cent across its entire wavelength range. Both filters provide blocking of OD>4. When the short-pass and long-pass filters are combined, they can operate as a laser-line filter or as a variable bandpass filter with a tunable centre wavelength and bandwidth for a vast array of applications.