• If each exposed end of optical fiber (such as both ends of an optical patch cable, the output of an LED module, etc.) throughout the complete system is not properly cleaned prior to each use, the smallest contaminants may degrade the light transmission.
• It is possible that when assembling the equipment, a connection might not be as tight or secure as necessary, and/or
• The reality that each piece of equipment varies ever so slightly – regardless of how tight the tolerances might be.

Thus, properly measured output is likely to be more accurate than manufacturer reported average values.

Accordingly, Plexon encourages the validation of optogenetic stimulation as it exits the system prior to entering the tissue. In most cases the conversation might end here; however, the PlexBright Optogenetic Stimulation System is an exceptionally high power, high performance LED system that requires special consideration when measuring output.

One way in which Plexon achieves the transmission of such high intensities throughout the light path relates to the custom-drawn, exceptionally high numerical aperture (NA) optical fiber. The higher the NA, the wider the cone of light that is exiting the fiber. In accordance with standard light properties, it is necessary to capture the entire cone of light on the photodetection sensor to register an accurate reading. With most optogenetic research equipment, this is not an issue and standard sensors are adequate. With Plexon’s high NA fiber generating such a wide cone, it is very easy to clip some of the light resulting in a low, inaccurate reading. This is where the PlexBright Light Measurement Kit becomes relevant.

Plexon teamed up with THORLABS to generate the PlexBright Light Measurement Kit with custom adapters yielding an accurate reading every time. The kit includes a power meter, an integrating sphere photodetector and – most importantly – several tip-specific PlexBright Photodetector Adaptors. The PlexBright Adaptors enable the appropriate positioning of PlexBright equipment over the photodetector, eliminating light cone clipping and ensuring an accurate reading. Plexon highly recommends one PlexBright Light Measurement Kit for each lab utilizing PlexBright equipment for output validation and for dependable troubleshooting.

For more information, read the PlexBright Light Measurement Kit Guide found on the Resources tab.