All Semrock filters are hard coated with sophisticated Ion Beam Sputtering (IBS) technology, resulting in patented state-of-the-art filters with extremely durable hard glass coatings on a single hard glass substrate. No absorbing glass and no lamination is necessary. The result is exceptionally durable “no burn out” fluorescence filters of the highest performance.

Even with the advances in IBS technology, the vast majority of optical filters in the field today are soft coated.  Semrock’s hard-coated filters have been tested to demonstrate their resistance to optical damage as compared to those of leading competitors’ soft-coated and absorbing glass filters. The photographs below demonstrate how a conventional soft coated DAPI excitation filter burns out, while the hard coated BrightLine® DAPI filter is not affected by intense light sources, such as the mercury, xenon, and metal-halide lamps used in modern fluorescence imaging systems.

Both filters below were subjected to a Xe arc lamp at 8 W/cm2 for 1 day and then 1 W/cm2 continuously.  The soft coated DAPI filter degraded rapidly and even cracked after less than 2 weeks of exposure, while the hard coated DAPI filter from Semrock continued to be unaffected after more than 1000 hours of continuous exposure.

 

Soft Coated DAPI Exciter Filter

 

Semrock Hard-coated DAPI Exciter Filter

< 300 Hours Exposure

 

> 1000 Hours Exposure

 Soft coated filter burn out

 

 hard coated filter doesn't burn out
 

 

The graphs below show how the exposure affected the spectral properties of each filter. After the first day, the soft coated DAPI filter’s transmission dropped by 42%.  We similarly tested other common exciter filters and found that  each soft coated filter experienced loss of transmission and passband shift, while the hard coated Semrock filters remain unaffected. 

 

 graph showing soft coated filter burn out

                                                      

 graph showing soft coated filter burn out

Transmission spectra of DAPI exciters before (blue) and after (red) exposure to 8 W/cm2 (over 15 mm diameter) for 1 day.

 

Transmission spectra of soft-coated exciters (for GFP and Texas Red) compared to a Semrock hard-coated exciter (for FITC) before (blue) and after (red) exposure to 1 W/cm2 (over 25 mm diameter) for 5 days.