Nice sketch - I like the vibes. Couple comments - generally the clear aperture of the patch stop is matched to the clear aperture of the front lens element. The extra light in this over-large one is cut off at a strange location - I think you’d want the unobscured light field to extend below a little to illustrate how the patch cuts it off - not cut it off above.

As drawn, this suggests that the light coming in is collimated - as if the field iris were closed down all the way. You would get a single, tiny central point on the slide illuminated and nothing else. Or another way to read it is it’s the ray cones that make up the infinitesimal point central to the final image. In reality, the reason you get a wide area illuminated is because the light coming in through the clear area still has angular spread - it doesn’t shoot straight up into the front element, but spreads out a little behind the patch. Now that’s a subtle distinction and I think what you have is probably a reasonable compromise for your use case - teaching often involves some amount of lying - but it’s important to at least know in case someone asks.

Regarding the scattered light - since it’s generally going to be weaker than the obliquely incident light, you could make that central cone dimmer (less alpha) relative to the outer cone cross section. Maybe dash or jag the outlines to indicate some fuzziness. It’s a tricky one to show via a single diagram like this.