We want to illuminate LensAlign with bright, uniform, and hi-quality light. The best way to provide this is with a large light source, as with portrait lighting, etc. But the word large is meant in comparison to the subject size which in the case of the MkIi is very small. So the easiest way to do this is to put the light source very close to the LensALign. An LED panel works well, but so will a floodlight with reflector in a setup that looks like the drawing below. The ruler is uniformly and evenly lit, and while the focus target will have slightly less light than the ruler, that is not important as long as it is uniform to the target itself. This lighting also eliminates any shadows or glare.
Portable Lighting Setup Example
Here is my own setup with LED panel light, Heavy Duty Light Stand, and Paul C Buff Offset Arm, at Artie Morris' house recently: