DropLit Assembly Guide
Next, attach the two Mirror Base Side Plates to the bottom base plate.
The mirror that comes with your DropLit is a first
surface mirror. This means that the silvering on the
mirror isn't covered and is directly exposed, thus “first”
surface. A normal mirror has this silvering protected with
a coat of paint – this makes a standard mirror a “second”
surface mirror. The reason the DropLit uses this special
mirror is that the light will have to pass through the glass
twice before it reaches the bottom of the resin vat. The
first pass is when the light from the projector goes
through the glass on its way to the silver layer and then
when it passed back out through the glass after being
reflected. This will cause an image “ghost” that would ruin your print. If you're curious, here's a nice
description of the effect:
http://en.wikipedia.org/wiki/First_surface_mirror
The mirror that SeeMeCNC ships has had protective film applied to the primary surface,
making it easy to identify how to orient the mirror. Using your Super Glue, attach the mirror to the
mirror frame – please make sure that the side plates are as square as possible to the base plate before
gluing the mirror in. The reason for this is that the tabs on the side plates fit into slots on the DropLit,
under the Dish Base.
You'll want to clean the back of the mirror with
isopropyl alcohol in order to remove any finger oils from
it. This will help the Super Glue get a better grip on the
glass.
65
Fig. 7-2: Ready for the mirror!
Fig. 7-3: Mirror glued into place.