This is really interesting stuff. I just wanted to add some context to the discussion, here, regardless of what has been heard.
No laser spot is a perfect circle. Creating a laser module with a spot that captures most of the energy within a specified diameter with tolerances both reliably and repeatedly is a classic engineering and product development challenge. Some amount of light outside of that diameter (whether in the form of a “tail” or a uniform gaussian spread “galaxy”) is inherent in the process. This is something that we’ve been aware of for some time, and we’ve run tests not so different from your own. In our QA, we actively attempt to minimize it to within our specification.
If we find a laser module that doesn’t meet our specification, it doesn’t ship with a Form 1+. In our tests, the power in our “tails” is a small fraction of the overall energy deposited. For most prints, that’s not a problem. For taller pieces, where the layer profile is the same over and over, you may start to see an effect from this “tail”. Cured bits can accumulate on the part or in the tank. Most of the time, they’re undercured, so you can just wipe them away, and your part looks fine. What I’m seeing here, though, indicates that this is still a critical question, and we’re going to continue to take a hard look at it.
Things like running the laser spot test twice and then showing the cured bit, while a good way to get an profile of the entire laser spot, isn’t how our resin curing process works in vivo. Our raster cures only a circle (where the vast majority of the power is), because it moves so fast, and it takes more energy than is available in the tail to cure at those speeds. That doesn’t mean there isn’t some residual curing, but we work hard to keep it negligible.
With our current laser specification, we think we’ve hit a sweet spot between quality and manufacturability. We’re always looking to see if we can make it better, and welcome suggestions, but lasers are a tricky beast.
As always, if you’re seeing persistent part failures, you should get in touch with our support team.