Plots below were acquired with a Verity EP200MSd scanning monochromator with 2x 100 micron slits (0.4 nm bandpass) except as noted, and 2.5M Polymicro FVP600660710UVM cable (unterminated). Focal length (the distance from the focusing mirror to the exit slit) is 0.2 meters.

Notes:

• The selected overlay in each plot is the approximate action spectrum for zooxanthellae isolated from the stony coral Favia, extrapolated from the 400-700 nm plot referenced in http://www.advancedaquarist.com/2007/10/review. Portions of the overlay outside this range are not meaningful

• Plots are corrected for photomultiplier tube response (Hamamatsu R928) but not fiber or grating loss. Absolute amplitude is uncalibrated; relative amplitude comparisons are meaningful only between plots with matching PMT voltages

• Wavelength scale accuracy is approximately +/- 1 nm in the 400-700 nm range

• Power/control interface schematic

• Dana Riddle, Aquarium Equipment: PAR Meters and LEDs - How Accurate are the Measurements? (2013) (.pdf) Great article that also includes some info on constructing an integrating sphere, which my measurements didn't use. It's not clear whether/why an integrating sphere is better than simply aiming an unterminated fiber at the source under test. There is definitely some dependence on light entry angle at the EP200's input aperture -- is this still an issue at the end of a fiber? More info is needed.

• Teardown, Upgrade, and Experiments with a Verity Visible Wavelength Monochromator Extensive, informative video presentation on the EP200's inner workings from Shahriar Shahramian's blog The Signal Path.

• Yet Another Scanning Monochromator Build Kerry Wong drives his EP200 manually with a position sensor, rather than by adding a stepper motor and controller as Shahriar did. Includes Arduino and MATLAB code

• Some EEVBlog posts on wavelength calibration