After passing through the vertical illuminator, the light is then reflected by a beam splitter (a half mirror or elliptically shaped first-surface mirror) through the objective to illuminate the specimen.
(the light; is reflected; by a beam splitter (a half mirror or elliptically shaped first-surface mirror; T:After passing through the vertical illuminator; T:then)
the light
is reflected
by a beam splitter (a half mirror or elliptically shaped first-surface mirror T:After passing through the vertical illuminator T:then