Flat-field illumination: The
QLS Benchmark™ and RatioLite™ modules generate
homogeneous illumination – a flat field of light,
with less than 0.5% variance across the 2 mm aperture
of their light chambers – with no dependence on
user preparation or any component of the system being
tested. They do this by reflecting LED output multiple
times within their chambers. Ultimately, that light
reaches a final reflecting surface from all directions
with equal intensity, and then shines directly through
the aperture.
Monochromatic output: Benchmark generates light
in three colors – red, green, and blue –
as selected by the user. Within each color, the output
is monochromatic, making it useful for wavelength-sensitive
tests, such as camera gain or quantum efficiency versus
wavelength.
Fine granularity: With QLS, researchers can select
any of 100 different, equally spaced intensity levels
for each LED. That offers an unprecedented fineness
of control. Additionally, by automating a scan through
all output levels, from 0 to 100 percent, QLS enables
researchers to test the linearity of light detection
in their systems.
High-speed operation: Benchmark and RatioLite
bring their LEDs from zero to any output level in less
than 50 microseconds. This is important, as it enables
researchers to use the QLS in transient and frequency-response
tests of the light detectors that they’ll then
use in dye recordings. With Benchmark and RatioLite,
researchers can measure the time between emission of
a light pulse and the recording of that pulse by detection
equipment, enabling them to determine how quickly their
systems respond to intensity. The QLS is able to work
at speeds facilitating such tests because it stores
LED output characteristics – drive current vs.
light intensity – in on-board static memory.
Simulation of dye experiments: With RatioLite,
researchers can ramp up or down between initial and
final intensities of two different wavelengths over
a pre-determined span of time. This enables them to
simulate experiments in which dyes fade from one wavelength
to another as an indicator of the course of biochemical
processes.
NIST-traceable calibration in absolute radiometric
units: With the functionality outlined here, the
QLS provides output of fixed optical power, consistent
between instruments, in absolute radiometric units traceable
to National Institute of Standards and Technology calibration.
That is, with the Quantitative Light Standard, researchers
world-wide will be able to compare data and reproduce
experiments, starting from known, consistent optical
conditions.
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