Some details on the CW diode laser (fibre coupled) that we plan to use for the interferometer.
This laser could also be used as an IR alignment laser for FACET S20 in general.
Model: I0785SL0050PA-USB
Central wavelength 785nm +- 0.5nm.
Class 3B
The laser has a closed loop interlock (RJ-11 port).
Implementation at S20
Laser enclosure with shutter enclosing the full laser (see in comparison enclosure for B40 where only fibre as enclosed).
Using a fibre-coupled collimator F280APC-780 (https://www.thorlabs.com/thorproduct.cfm?partnumber=F280APC-780) to expand to a few mm's (~4mm).
The fibre is either P3-780PMY-2 (https://www.thorlabs.com/thorproduct.cfm?partnumber=P3-780PMY-2) or P3-780PM-FC-2 (https://www.thorlabs.com/thorproduct.cfm?partnumber=P3-780PM-FC-2
Then used a X3 beam expander GBE03-B (https://www.thorlabs.com/thorproduct.cfm?partnumber=GBE03-B) to > 1cm.
Co-injected with the main laser through a polariser.
The beam was spatially overlapped on DMNear/Far or the focal spot camera and DMFar.
The divergence was adjusted using the beam expander such that the beam was brought to focus on DMFar and the focal spot camera.
- Collimation matched with main beam (Jan 2022): http://physics-elog.slac.stanford.edu/facetelog/show.jsp?dir=/2022/05/31.01&pos=2022-01-31T16:29:11
- Spatial overlap with main beam (Jan 2022): http://physics-elog.slac.stanford.edu/facetelog/show.jsp?dir=/2022/01/03.01&pos=2022-01-03T17:25:01
- Update on implementation (Dec 2021/Jan 2022): http://physics-elog.slac.stanford.edu/facetelog/show.jsp?dir=/2022/01/03.01&pos=2022-01-03T10:21:04
Finding a spot for the laser: here a photo before closing up the enclosure (Dec 2021):
Implementation at B40
Laser enclosure as at B40, with a 2" Macor shutter.
To activate the laser one has to push a button on the front panel.
This means one cannot enclose the full laser, but only shutter with the fiber termination.
Some lens tube is used to restrict access to the fiber connectors and to protect the fiber from mechanical damage.
In S20, we enclosed the full laser with the reasoning that we will keep the laser on for extended periods of time, so we will not have to access the button.
