Prototype PZT assembly
Before we glue the PZT assembly, we need to build a prototype. This is to confirm the heat cure process
does not cause any cracking of the PZT or glass components. The CTE of the PZT is 2~3ppm
(depends on the direction) while the one for Fused Silica is 0.55ppm.
- A fused silica substrate, 1/2" in dia. Supplied from Garilynn. I defined the chamfered side as the front side.
- PZT: Noliac NAC2124, serial #24, this is a spare PZT as this has the worst length to angle coupling.
- Mounting Prism: D1102069 SN22. This has the worst perpendicularity among the prisms.
D1300185 aLIGO OMC CURVED MIRROR BONDING FIXTURE ASSY
D1300186 aLIGO OMC CURVED MIRROR BONDING FIXTURE FRONT
D1300187 aLIGO OMC CURVED MIRROR BONDING FIXTURE BACK
D1300188 aLIGO OMC CURVED MIRROR BONDING FIXTURE RING
- Wipe all of the components with the isopropanol.
- Attach the back piece of the fixture on the Al wrapped bracket.
(The current 4-40 screws for the middle piece are too long and stick out from the back side of the back piece.
Therefore a 1/16" shim for a 1/2" rod is inserted between the bracket and the back piece)
- Brought a glue package to the lab (10:40PM)
- Loosely attach the middle piece to the back piece with four 4-40 screws.
- Insert the mounting prism in the fixture. Insert the PZT in the fixture too.
- Insert a dummy substrate in the fixture.
- Attach the front piece with spring loaded screws.
- Align the PZT and the optic in the fixture. (Basically apply downward force to them)
- Test the rigidity of the assembly (11:30PM)
- Remove the PZT and the mirror. Apply UV epoxy.
(A single dub was applied for each PZT surface of the PZT but this was too much.)
- Make sure the PZT and the optic are aligned by applying the downward force.
- Illuminate UV light from the front.
- Illuminate UV light from the back. (11:50PM)
- Long 4-40 screws (described above)
- As the PZT is not constrained with the middle piece, it tends to move vertically and rotationally
because of the wire tension. (This is not a mistake but the design so that the PZT is constrained by the optic.)
Therefore after applying glue on the PZT, the motion of the PZT spreads the glue on the back surface of
the curved mirror.
(Solution to be tried) Our solution is to glue the PZT and the mounting prism first with a dummy optics (made of SF2).
The wires should be tacked somewhere on the mount
- The amount of glue on the PZT was too much. I gave one dub of glue for each side.
As a result, excess glue leaks out along the ring.
- The front plate has a chamfered hole but this tends to slip and move the mirror vertically.
Later I used the flat side of the plate to hole the mirror.
(Circumvented) It seems that this hold the mirror in a better way as the plate can't rock
- Spring load for the front plate was too strong. This was because the natural length of the spring was too long.
(Circumvented) The spring was cut at the length of the 4-40 screw. Then attaching the screws became completely fine.