Please log error messages and problems in this log.

11/2025 service updates

Serial for unit: GDP.1180646.10060

Serial for “head” GDP.1001H.1311

Service contract renewals at coherent are all handled by annette.davis@coherent.com

10/21/2022 service note

We identified the issue of causing the error. It is due to motor homing problem every time when we turn the laser from active to standby. The motor sometimes doesn’t home correctly so the output wavelength can be off from the required wavelength quite a bit (usually more than +/- 5nm is problematic).

The current solution which is quite simple is that: from the chameleon GUI if you see that the wavelength reading is more than +/- 5nm from what you required, go to the prompt tab and simple type in command ‘hm=1’ to home the motor. Wait 2 mins until the homing is done and proceed. This should correct the wavelength problem.

The chameleon software is currently not correctly connected to the laser because of a non-functional usb to serial cable. I already purchased a new one and will set it up next week.

Vision-S is a femtosecond Ti:Sapphire laser that we use for two-photon imaging in Berg-1 and Berg-2.

Manual#

📎 Coherent_Vision-S_manual.pdf

Specs#

(+) narrow pulse width (75 fs, repetition rate: 80 MHz)

(+) widely tunable wavelength (690-1050 nm)

(+) built-in pre-compensation

(-) hard to get a replacement

We typically use the laser at 940 nm, and at this wavelength, the average power is ~1200 mW.

We typically use GDD ~9000 fs^2 for dispersion pre-compensation, but this needs to be tweaked empirically by looking at the actual fly sample.

Connecting the laser to the computer#

You can monitor and control the laser though this software (scroll down to download the .zip file).

Two connections are required to use this software.

• laser controller unit via serial & USB
  • Make sure to install the driver for the serial to USB conversion board, e.g. ATEN UC232A).
  • Make sure to specify the correct COM port in the software (left most tab).
• spectrometer (Ocean Optics, USB4000) via USB

What’s inside the laser head#

MRU (miniature recirculating unit)#

A black box that sits on top of the controller that dehumidifies and cleans the air. Desiccant needs to be replaced if it’s starting to turn pink. Molecular sieve needs to be replaced if the blue band is starting to fade and the color is becoming similar to the surrounding, but that is rare, and this is designed to last the lifetime of the laser.