DELTA Light & Optics Launches Linear Variable UV Band Pass Filter

By Dr.-Ing. Oliver Pust, Business Development Manager, Optical Thin Film Filters

DELTA has lifted the application range of variable filters to new levels by introducing a new powerful type of linear variable filter (LVF). One LVF offers the performance of several standard filters within one single filter.

Since DELTA Light & Optics offered the first linear variable filters in 2010, development never stopped, and after offering linear variable short and long pass filters the next step was a linear variable dichroic.

The brand new and unique linear variable UV band pass filter (LVUVBP) will extend the application range largely. The LVUVBP will be presented to the public during the BIOS 2012 and the SPIE Photonics West 2012.

An LVF is a wedged filter, whose spectral properties vary linearly along the long side of the filter. It is possible to adjust the position of the edge by sliding the filter with respect to the incident light.

A single LVF can replace a number of dedicated filters in an instrument and thereby decrease complexity and cost. This opens up for new design possibilities of analytical and diagnostic instruments such as spectrometers.

By combining linear variable short and long pass filters, band-pass filters can be constructed that can be tuned continuously with center wavelengths from 320 nm to 850 nm, with the added benefit of tunable bandwidth.

Besides setting new standards in transmission level and edge steepness, the filters offer blocking levels better than OD 3 over the complete reflection range or even OD 5 by placing to filters in series.

The filters are coated on single quartz substrates for minimal auto-fluorescence and high laser damage threshold. All of DELTA's LVF are coated with ultra-hard surface coatings (UHC) that offers much higher packing density than traditional hard coatings.

The benefits of UHC are best spectral stability (no spectral drift), increased lifetime, optimal mechanical stability and minimal water uptake. This brings use of advanced filter technology out of the laboratory and into the field.