Since we have often encountered problems with lasers after the first wave of Covid-19 due to improper shutdown of cooling units and circuits during prolonged closure of laboratories and workplaces, we have decided to prepare a general guide to help you avoid more serious damage to your equipment or the need for major service intervention, mainly for more complex lasers.
In general, the longer the fluid sits in the system, the greater the risk of deposits or algae and subsequent complications.
We therefore recommend:
- Allow the water to circulate all day during the working week without turning off the chiller.
- The chiller can be switched off at the weekend
- If a shutdown of more than 5-6 days is necessary, we recommend to drain the water from the chiller and flush the cooling circuit with nitrogen or other high purity gas. A pump with a conical connector is a good tool for pumping out the water.
In general, the more complex the system, the more susceptible it is to water quality issues. For example, a flash lamp-pumped pulsed laser from Quantel can tolerate poorer water quality than an ultrafast amplifier from Coherent, in which every deposit on the cooling block means degradation of operation, degradation of parameters and shortening of crystal life .
We recommend using distilled water produced by reverse osmosis as the main cooling medium. Deionized water is not suitable.
Many systems (mainly those pumped by flash lamps) have a DI filter on the cooling circuit which needs to be changed periodically along with the water. The DI filter detects the low conductivity of the water because the flash lamp and electrical connectors are immersed in water.
Diode-pumped lasers do not have DI filters, but use distilled water with the addition of a Hydratech CoolFLow-type anticorrosive. If you don't have the option of getting the recommended inhibitor, it is better to add 10% methanol to the water than to use nothing.
Follow the instructions described in your equipment manual for the exact recommended coolant change time. However, we generally do not recommend using the same batch of fluid for more than 3-6 months.
If you have any questions or problems, please contact us at servis@optixs.cz.