This is a conceptual drawing of how the optical components for the PRM-OpLev on the receiver-side are to be aligned.
The drawing is in scale with the real components on the breadboard. The breadboard itself is represented as the underlying white surface with a mesh-grid on it. The places of the M6 screw-holes are the intersections of the mesh-lines.
The optical components' representations are simplified to their basic forms.
Addendum: for PRM there is an update including an additional QPD stage and a BS. Those are indicated in light gray.