ELOG MINICAV installation

Manar Amer, Fixed, report, mechanics | lasers and optics | detectors and electronics | cabling, Optical room, Minicav Updated SetUp

Mon, 27 Sep 2021 10:08:01 +0200

Enclosed is the current setup of the minicavity

** made by Fred

Manar Amer, Fixed, report, mechanics, Other, Mirrors Mounts

Mon, 05 Jul 2021 10:04:21 +0200

Update, they are received and the order is logged in MINICAV orders

Mounts placed in SAS cupboard

Manar Amer wrote:

The minicavity mirror mounts are located in the preparation room before the clean room in the cupboard.

There are three mounts and two primary mounts for the mounts to be placed on.

Need another one to have a set of four --→ They are made specifically by the lab, order extra one

Ronic Chiche, Fixed, info, lasers and optics | vacuum, Optical room, Vacuum and locking tests

Fri, 07 May 2021 16:18:07 +0200

Today, the vacuum pressure inside the Minicav was good : 7.8e-6 mbar
the Gauge model is a Leybold PTR 90N => see picture for details
surprisingly, the same gauge connected to the TurboVac SL 80 was not read with the same value (see pictures)
the Pfeiffer pumping system has its own gauge which gives an expected lower pressure value : 8.94e-7 mbar.

we made a leakage test with the cavity valve closed:
we lost 0.2e-6 mbar in 15s which is roughly equivalent to 1e-3mbar in 20h !!!

we made also a test of locking with the pumping system ON:
the silent block works pretty well and the locking doesn't seem perturbated.
(air flow OFF and no talking during the lock)
we clearly saw a sensitivity of the lock to the laser power => we can think to a feedback loop on the laser power with and AOM for example.

Manar Amer, Fixed, report, mechanics | lasers and optics, Other, Optical Windows installed

Thu, 06 May 2021 17:40:49 +0200

A new optical window was installed in place of the old broken one (it was broken from the sides, a sign there might have been a leakage before !!! )

The old broken window is placed in a container in SAS room in the gray cupboard titled "old window broken on the side"

The one changed is the output window behind M2 and M4

Properties of the new window attached

Manar Amer, Fixed, report, mechanics | vacuum, Other, vacuum Joint installed

Thu, 06 May 2021 17:36:20 +0200

The placement of the new ordered optical joint for the minicav

Manar Amer, Fixed, report, lasers and optics, Other, Telescope to match Koheras with minicav

Thu, 22 Apr 2021 16:59:12 +0200

The telescope to adjust the beam size was made only using one lens with very long focal length (1 meter)

it is placed a distance of 40 cm from the collimeter and 1 meter from the center of the beam waist between the planar mirrors.

This way the two beam (of laser and cavity) have the shape when they propagate

( ) /-----------()------- 40 cm ----------(collimater)_______[Koheras]

\ w|--------------/-------100 cm -------------/

Manar Amer wrote:

The beam waist of the Koheras CW laser after the collimater is bigger than the Waist required for injection inside the cavity at M1.

A Telescope is to be made to match the two beams.

Details will be added ......

Manar Amer, Fixed, report, lasers and optics, Other, Telescope to match Koheras with minicav

Tue, 20 Apr 2021 15:57:49 +0200

The beam waist of the Koheras CW laser after the collimater is bigger than the Waist required for injection inside the cavity at M1.

A Telescope is to be made to match the two beams.

Details will be added ......

Ronic Chiche, Under Process, report, lasers and optics, Other, First alignement of the Koheras with the FP cavity

Tue, 20 Apr 2021 15:56:05 +0200

We changed the mirrors position back to the original reference (0, 0, 0, 0) for all mirrors, but the alignment could not be found.
The course of action will be :

- abandon the alignment done previously with Helium Neon Laser

- Set and distance between the spherical M3-M4 to a value that stabilizes the cavity, and keep the distance between the planar at zero reference.

- Align the cavity from the start with the koheras

- after finishing the alignment, change the distance between the planar mirrors M1-M2 mirrors to match the rep. frequency 876.3636 MHz

While maintaining the alignment.

Ronic Chiche wrote:

today with Manar, we brought the Koheras to the Minicav optical room and aligned it with the Iris used for the cavity.

but if I properly understood what Manar said to me, the cavity mirrors have been moved by roughly 1cm after Daniele and Manar finished the alignment.
with what we saw today, it seems the cavity is not aligned anymore.... we will check that tomorrow with Daniele.
we have a beam at the output window but

Ronic Chiche, Under Process, report, lasers and optics, Other, First alignement of the Koheras with the FP cavity

Mon, 19 Apr 2021 18:21:51 +0200

today with Manar, we brought the Koheras to the Minicav optical room and aligned it with the Iris used for the cavity.

the other important point for us is the room temperature.
it seems to be set at 25.5°C or something like that.
it's much too high.
Aurélien, who is the person to contact to change this temperature?
a setting around 21°C would be much more convenient...

Manar Amer, Fixed, report, mechanics, Other, Mirrors closely backed when Fixed

Tue, 23 Mar 2021 14:36:01 +0100

Throughout all the range of motion for the motors

-→ no problem with the mirrors close together (M1-M3 and M2-M4) hitting each other.

-⇾ the problem with the pinholes hitting each other was fixed by trimming their edges a little, no issue for M1-M3 and M2-M4 now.

Manar Amer wrote:

The mirrors were placed in the wrong orientation, it was adjusted correctly

but the issue of having the mirrors/irises hitting each other was still there.

The motors need to be moved in the longitudinal position to avoid this issue.

Manar Amer wrote:

As shown in the image attached when placing the mirror mounts (or irises) of the very close mirrors on the mounts they hit each other.

The motor's location needs to be changed for them not to hit each other (pushed a little to the back or the front)

This restricts the motion of the motors later on.

Not sure if this was the case before changing the plate or only after

Manar Amer, Fixed, issue, mechanics, Other, Mirrors closely backed when Fixed

Thu, 11 Mar 2021 11:04:55 +0100

The mirrors were placed in the wrong orientation, it was adjusted correctly

but the issue of having the mirrors/irises hitting each other was still there.

The motors need to be moved in the longitudinal position to avoid this issue.

Manar Amer wrote:

As shown in the image attached when placing the mirror mounts (or irises) of the very close mirrors on the mounts they hit each other.

The motor's location needs to be changed for them not to hit each other (pushed a little to the back or the front)

This restricts the motion of the motors later on.

Not sure if this was the case before changing the plate or only after

Manar Amer, Fixed, issue, mechanics, Other, Mirrors closely backed when Fixed

Mon, 08 Mar 2021 18:47:39 +0100

As shown in the image attached when placing the mirror mounts (or irises) of the very close mirrors on the mounts they hit each other.

The motor's location needs to be changed for them not to hit each other (pushed a little to the back or the front)

This restricts the motion of the motors later on.

Not sure if this was the case before changing the plate or only after

Manar Amer, Not Fixed, report, mechanics, Other, Screws Length

Mon, 08 Mar 2021 18:35:06 +0100

Specific length (5 mm) for the screws used to fix the mirrors and the irises in the cavity box

need to search for extra, don't have enough

the amount needed (3 x 4 = 12) at least, each mirror is fixed with three screws

Manar Amer, Not Fixed, report, lasers and optics, Other, Spare Mirrors

Mon, 08 Mar 2021 18:33:41 +0100

There are spare mirrors placed in the preparation room of the minicavity

the exact number to be investigated

approx ~ 12 -→ 9 of them are injection

Manar Amer, Not Fixed, issue, lasers and optics, Other, Mirrors Damage

Mon, 08 Mar 2021 18:33:24 +0100

The mirrors have what seems to be damage spots on them

To be investigated after finishing the alignment

attached a picture of the mirror (To show the mirror size scale)