In normal critical discourse, "dramatic irony" occurs when the reader or viewer of a work knows something that is withheld from a character who appears in that work. In SF, there is a second use of the term, at least according to this reviewer, who has argued the case elsewhere: in SF, the sense of wonder is an affect of dramatic irony. It is what happens when the jaws of irony open. It is the feeling we have when the hero of a tale learns something we already know, especially something that reveals to him that universe is much larger than he could have guessed.
The sense of wonder, thus defined, may seem marginally less profound than what we feel when Oedipus discovers the truth about himself, but it is in terms of grammar the very same thing.
Dramatic irony is a verb-like device: it is a device which longs to open.
To allow us to share with the cast the wonder of the light.