A brief update on the ALS laser issue

This is a good news.

In this morning, we confirmed that the Prometheus (2143A, the one had the issue of suddenly shutting itself down when the current is high) stayed on overnight.

To clarify the situation, here is a list of things that happened or we did in the chronological order.

• Aug.8th: We brought 2143A from the POP table to the PSL table.
• Aug.9th, afternoon: The issue was discovered.
• Aug.9th, late evening: The temperature guard indicators were found to be on for both the A and B diodes.
• Aug.9th, late evening: Following the instruction written in the manual, we cranked up the temperature set point of diode A from the nominal of 24.05 deg to 25.00 deg. After this, we were able to raise the current as high 2.0 A and left the laser on.
• Aug.10th (today): 2143A was found to have stayed on overnight without shutting itself down.
• Aug.10th (today): The temperature setpoint of diode B was also cranked up from the nominal of 26.01 deg to 26.5 deg. So far so good.

The latest settings:

• The temperature setpoint for diode A = 25.0 deg (c.f., nominal is 24.05 deg)
• The temperature setpoint for diode B = 26.5 deg (c.f., nominal is 26.01 deg)
• The diode injection current = 2.2 A, the nominal value.
• Any other parameters were set exactly to the values listed in the data-sheet/test-report.