Increase your projector power output by 13% with this one weird trick!
Formlabs hates him! Clickbait title aside...
So.. I like to tinker. I also have a G&R Labs Model 221 light meter (http://www.grlabs.com/uv-light-meters/meters/model-221/). I calibrate my printer every few months by dividing my build area into 15 test points. I was watching Garage Science's mirror replacement video re: UV pass filter (will discuss later) and it got me thinking: Is there ANYTHING I can do to bump this performance up without modding my machine further? For the record, my projector is a Viewsonic PJD7822HDL and I love it.
Turns out... yes there is! After an hour or two of tinkering with settings, I have found that adjusting the color temperature of my projector yields an average of 13% light intensity increase (as measured in mW/cm^2 @ 405nm) across my 15 test points.
To lay some numbers down, with a build area of 170mm x 94mm (roughly), I was averaging 8.81mW/cm^2 4 months ago, 8.54mW/cm^2 before fiddling, and 9.63mW/cm^2 after, at an 'equivalent lamp hours' of 690.
To note: my projector varies a TON across the build area. I tend to print in a 75mm x 100mm portion of my full build area that sits around 11mW/cm^2 @ 405nm. Also, I have no idea what an "equivalent lamp hour" means. It's a Viewsonic thing.
So, what did I actually do? Well, after tinkering with every setting I could find, I noticed that setting a "custom" profile to the "PC" settings and adjusting color temperature from "T2" (default) to "T1" is all it took. I suspect the temperature nomenclature will vary from projector to projector, but the important bit is this: Your projector, due to stock settings, is likely intentionally kicking out a notable amount less of relevant curing light than it could be. The color of your input light doesn't matter here - white is best for this... the projector takes the input, adjusts it, and throws it.
TL;DR: I increased my projector output at relevant curing wavelengths by roughly 13% by changing color temperature from T2 to T1, with "PC" display settings. While I did not technically increase the amount of blue-ish light the projector COULD output, I found that by default it was setup to not actually kick out all that it was able to do in the first place.
Oh, and because I said I'd discuss it... The Garage Science video I was talking about relates to installing a UV-pass filter ( check him out if you don't know him already, he is on the forums too I believe). The mirror he recommends is a UV-pass filter (https://www.pnta.com/lighting/dichroics/rosco-permacolor-dichroic-filter-3660-double-coated-uv-pass/), but I'm considering going for their slightly-greater-allowance "deep purple" version (https://www.pnta.com/lighting/dichroics/rosco-permacolor-dichroic-filter-4200-deep-purple/). I presume he picked the UV-pass due to its sharper cutoff on the lower (and more damaging to DLP chips) wavelengths... but if he/you read this, I'd love to hear more info on your decision.
Anyway, that's that. All the best!