Assertion: secondary reflector | /r/AtLocation | front of cassegrain focus
Facets:
value: more often
type: TEMPORAL
value: to focus the radiation
type: PURPOSE
Source sentences:
text: More often, a secondary reflector is placed in front of (Cassegrain focus) or behind (Gregorian focus) the focal point of the paraboloid to focus the radiation to a point near the vertex, or centre, of the main reflector.