Started using optics WB recently. I get following message when "(Re)start simulation" is clicked after making some changes to the beam or lense:

name 'isOpticalObject' is not defined.

Then the beam in tree shows error icon.

Please advise.

Little experiment with Optics WorkBench, in FREECAD!

Might be a PERFECT BLACK BODY, using a tubular object as lens.

Not a single ray escaping the outer periphery of the tube!!

Shall we name it as BLACK-LENS?

(NEED TO VERIFY WITH REAL EXPERIMENT).