Better optical filters can increase the signal, or brightness, attained by a microscope or other instrument. Better optical filters can reduce the background that comes from sample and instrument autofluorescence outside the emission band. And better optical filters can reduce excitation light noise, or stray and scattered light from the excitation source. In summary, by choosing the right filters one can achieve the best possible signal and signal-to-noise ratio. For more details on how filters impact signal and signal-to-noise ratio, see Optical Filters Impact Fluorescence Fidelity .
In an ideal set of filters the spectra of the exciter and emitter filters would exhibit perfectly rectangular passband profiles with 100% transmission in each passband and complete blocking outside the passbands (including within the passband of the companion filter).
The spectrum of the dichroic beamsplitter would have 100% reflection in the exciter passband, 100% transmission in the emitter passband, and a perfectly vertical transition between the two bands. To prevent excitation light noise between the passbands, the exciter and emitter filters must not overlap.
Although real filters do not possess these ideal properties, manufacturers must try to come as close as possible. Key specifications that distinguish filters are the average passband transmission, bandwidth, edge steepness, and edge wavelength accuracy. The last of these is not apparent from looking at a single plot of the filter spectra, but rather is based on a statistical sample of a large number of filters.
It is crucial for guaranteeing consistency in high-volume instrumentation applications as well as in end-user systems such as microscopes. Another critical feature of fluorescence filters is blocking - the filters must provide sufficient blocking over the most critical wavelength ranges. In some cases, the blocking must be much higher than is possible to measure directly with standard test and measurement instrumentation, making it difficult for one to determine how well the filters will function without trying them in the actual instrument.
Why are BrightLine® filters better than other fluorescence filters?
The patented* BrightLine filter technology has set a new standard for fluorescence filters. Semrock's superior coating technology - combined with its expertise in designing optical filters specifically for fluorescence systems - has resulted in the simplest, most durable, and highest-performance fluorescence filters available anywhere. With BrightLine filters, you'll find:
- Highest peak transmission for maximum brightness;
- Exclusively hard coatings and no adhesive in the optical path for unrivaled filter life;
- Certified zero-pixel-shift imaging performance available for the most demanding multi-exposure applications.
Maximum Brightness
BrightLine filters offer the highest throughput for blazing measurement speed!
Just one look at the transmission spectra of BrightLine filters and you'll see the difference. The spectra demonstrate the high average passband transmission, precise bandwidths, steep spectral features and exceptional wavelength accuracy that is characteristic of all Semrock filters. But if filter spectra alone aren't convincing, then take a look at some fluorescence images to see what you've been missing:
up to four times brighter ... and twice the contrast
Comparisons done under identical imaging conditions using an Olympus BX61WI microscope outfitted with DSU spinning-disk confocal unit and Hamamatsu ORCA-ER monochrome CCD camera. Sample of Rat Kidney Mesangial Cells courtesy of Mike Davidson, Molecular Expressionsª, using: Hoechst 33258, Alexa Fluor 488 Ð Phalloidin, MitoTracker Red CMXRos, and Vimentin (Ms) - Cy5.
