PlexBright Light Measurement Kit

Avoid inaccurate readings and wasted time with the PlexBright® Light Measurement Kit especially designed to accurately measure output from the exceptionally high performance, custom-drawn PlexBright optical fiber at various points throughout the light path.

For most researchers, understanding the true light exiting an optogenetics stimulation system and entering the tissue is important – if not critical. Knowing the stated light output from the source is valuable, but not as valuable as knowing the output level after a connection to an optical patch cable, or after another to an implanted fiber stub. Even if you had a specifications table of such values (and you do if using the PlexBright Optogenetic Stimulation System, found on the Technical Specs tab), it is important not to simply rely on its stated values for several reasons including:

  • 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.

The table below includes specifications and options for the components contained in the PlexBright Light Measurement Kit.

Feature Specifications and Options Remarks
Kit components
– THORLABS PM100D power meter,
– THORLABS S140C integrating sphere photodetector, and
– PlexBright Photodetector Adaptors.
It is possible to purchase the kit as a whole, or simply buy the PlexBright Photodetector Adaptors if your lab already has the appropriate THORLABS equipment.
PlexBright photodetector adaptors Three tip-specific adaptors for:
– FC Ferrule tip optical patch cables,
– Table-top LED Modules (FC connector), and
– LC Ferrule tip optical patch cables + Compact LED Modules (LC connector).
No adaptor is necessary for PlexBright Bare Fiber tip Optical Patch Cables.
Power meter display type 4″ Graphical LCD 320 x 240 pixels
Power meter viewing area 81.4 x 61.0mm
Power meter display update rate (max)
Power meter current input units
W, dBm, W/cm2, A
Power meter current input accuracy ±0.2% f.s. (5µA – 5mA)
±0.5% f.s. (50nA)
PlexBright photodetector adaptor attachment mechanism Two, M2.5 threaded screws
(2.5mm diameter x 5mm length)
Photodetector detector type Silicone photodiode
Photodetector wavelength range
350 – 1100nm
Photodetector optical power working range
1µW – 500mW
Photodetector resolution
1nW Measured with THORLABS PM100D console in bandwidth low setting.
Photodetector measurement uncertainty
±3% 350 – 450nm
±5% 451 – 1000nm
±5% 1001 – 1100nm
Beam diameter >1mm.
Photodetector response time
Photodetector active area
3.6mm x 3.6mm

Please reference the PlexBright Optogenetic Stimulation System Technial Specs tab for a comprehensive look at our PlexBright LED Power Output at Various Points Throughout the Light Path table.