I made some KAIZENs (what does kaizen mean ? ) for the PSL green setup.
I replaced the lenses for the modematching of the two green lights at the PSL table, and the beams now look pretty identical.
Also I tuned the temperature setpoint of the doubling crystal and eventually the green light increased to 14 uW at the PSL table.
Once I finish the modification of the RFPD tomorrow, I am going to search for the beat note signal.
( details )
- In-vac green mirrors
I found one of the green steering mirror, which stands at the corner of the MC table, was clipping the green light.
So I steered another mirror, which sends the beam to the clipping mirror after the downward periscope.
I touched also the last steering mirror in the OMC chamber to correct the alignment.
- temperature of the doubling crystal
I took a quick temperature scan in order to find an optimum point for the crystal temperature.
The scan was performed by just turning the heater off after I heated up the crystal up to 40 deg.
Using the NewPort power meter I found the optimum point around 37.3 deg. So I set the temperature to that point.
- mode matching lenses
As written in this entry , Kevin and I had put some lenses to make the two green beam almost the same size at the RFPD.
But today while I was checking these mode-profiles by using a sensor card, I found they were not so matched.
Therefore I replaced these lenses to match them more.
The idea of this replacement is t to let them have a long Rayleigh range, such that they can efficiently and easily interfere because of the flatness of their wave fronts along a distant.
For the green light from the chamber, I put one more lens to form a Keplerian beam shrinker (see here about the Keplerian lens configuration).
They look pretty identical now.