How Dark Reader Technology Works

Many Fluorophors Absorb Visible Light
Excitation spectra of SYBR Green and EGFP The excitation maxima for many popular dyes, including SYBR Green and red-shifted GFPs, are between 400 and 500 nm - not in the UV (see Fig.1). These wavelengths correspond to blue-green light which is well within the visible light spectrum.
Excitation spectra of SYBR Green and EGFP
The Dark Reader uses Visible Light
Light output from a Dark Reader and a UV transilluminator The light sources in Dark Reader devices generate maximum light output between 400 and 500 nm - close to where dyes such as SYBR Green, SYPRO Orange, eosin, fluorescein and ethidium bromide are excited. UV transilluminators, on the other hand, typically output light around 300 nm - well removed from the absorption maxima of most common dyes.
A comparison of the output of the Dark Reader and a 312 nm UV transilluminator.
The Dark Reader uses 2 Filters to reveal Fluorescence
If visible light is used for excitation of a fluorophor, any fluorescence from the sample is not directly detectable by the naked eye due to the large amount of incident light from the light source itself that reaches the observer.

The Dark Reader achieves the removal of incident light in 2 steps. The first filter is between the light source and the DNA. This removes any green and red components from the lamp and allows through to the DNA only blue excitation light.

A second filter is placed between the DNA and observer that removes the blue incident light but allows passage of the red and green fluorescent components.
optical principles behind the Dark Reader
Click on the image above to view an animation that attempts to simulate how the Dark Reader filter system is used to view a DNA gel
Dark Reader® devices including transilluminators, hand lamps and electrophoresis units as well as associated accessories such as viewing glasses, screens and camera filters are for use under one or more of US patents 6198107, 6512236, 6914250 and international patent pending.
Clare Chemical Research

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