With the Quantitative Light Standard, scientists can for the first time test the light source and collection systems of microscopes and microplate readers – and generate the consistent, quantitative reports they need to make their research results comparable and reproducible across labs and across time. The QLS product line consists of four parts: a base module and three light chambers – the Benchmark™, RatioLite™, and Illume™.

Benchmark is a light source. It uses LEDs to project any of three colors – red, green, or blue – at a defined, consistent wavelength. It produces flat-field illumination at any of 100 user-controlled, repeatable intensities. This makes it possible to test, quantify, and correct for variations in the light collection system in a microscope or microplate reader.

To use Benchmark, scientists slide it onto the stage of a microscope or microplate reader, turn off the illuminator, and turn on the Benchmark. Benchmark shines through the light collection system in a flat field, at a known wavelength and intensity. To the extent that a camera or recorder does not receive light at those specifications throughout the viewing field – to the extent that it shades off toward the edges, for example – scientists learn where they have issues with their light collection system. In fact, Benchmark yields a precise, quantitative map of any such variations, making it possible to correct for them mathematically in experimental results. This enables scientists to generate data that are independent of the conditions of any particular system.

RatioLite is also a light source, but with a difference. While Benchmark generates narrowband light, one wavelength at a time, RatioLite projects two wavelengths simultaneously – in ratios defined and controlled by the user. It does this with two independently controllable white LEDs, plus filters inside the light chamber. This makes it possible to model – and test for a system’s detection of – the specific wavelengths emitted by experimental dyes.

Illume is a light detector. It monitors and records the intensity level of the illuminator or dye exciter in a microscope or microplate reader. It uses a photodiode to collect and read light intensity, either from trans-illuminators or epi-illuminators. Just as Benchmark and RatioLite offer maps of a light collection system, Illume yields a quantitative map of the illumination generated by a system’s light source. This makes it possible to correct for any variations mathematically, and to generate experimental data that are independent of the condition of that light source. With that, scientists can compare the data from two different systems in two different labs on a consistent basis. Alternatively, they can compare the data generated on a single system, but at two different times, abstracting out the effects of aging of its illuminator.

All of these light chambers – the Benchmark, RatioLite, and Illume – are the same size, and all plug easily into the fourth component of the QLS system, the base module or controller. A controller with one light chamber, together, fits precisely into the stage of an industry-standard microtiter plate. In that position, the aperture of the light chamber sits at the center point of the objective.

An integral part of the QLS system is the software that researchers can use to control it, set its parameters, organize tests, and record the results. With this software, researchers can easily run any QLS module from a graphical user interface on a personal computer.

In processing the results of these tests, the QLS software also helps normalize assay data. The software uses light intensity at the center of the field as a reference. It then calculates intensity at every other point in the field as a percentage of that central figure. This generates a mathematical map of any shading or irregularity. To normalize assay results, the software then multiplies assay data by the inverse of the figures in that map. In this way, while scientists gather and analyze experimental data, the QLS system corrects for variations in their optics. This helps scientists share data with colleagues, abstract from their optics, and make their results more comparable and reproducible across labs and across time.

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