The next major step will be to test M5. James finished designing the fixturing last week & the bits were subsequently manufactured in Cape Town.
With M4 safely in its box, the pinhole mount & its associated XY stages could be assembled & integrated. The stages are supported by a ring & vanes that attach to the M4 mounting points.
The X stage went on next, then the Y one.
The M5 test's pinhole assembly is similar to the M4 spider & will attach to brackets on the Y stage.
Z adjustment of the pinhole is achieved with a pair of 200 micron thick laser-cut carbon fibre flexures.
The LED light source & ground glass diffuser slot in through the side of the tube that holds the pinhole.
Here's the whole lot screwed together...
While we were in Cape Town, Francois set up a microscope to explore the CGH, in search of the elusive reference marks reputed to exist on the surface.
Instead of the tiny marks at intervals across the CGH, he found a "bull's eye" at the centre that will be invaluable later on for aligning the CGH for the system test! The image below shows a minute portion of the centre of the CGH - keep in mind that there are ~24 thousand rings on the surface, not many of which are shown here. The origin of the offset ring remains a mystery...