Survival-Training

Quality control procedures used in LASER COMPONENTS´ lead salt laser production.

Our IR diode lasers, available from 3 - 25 µm, are designed to fulfill the following criteria: at least 0.1 mW single-mode power, at a precisely specified frequency, for one year. Guaranteed.

To ensure that these stringent specifications are fulfilled and exceeded, we have developed a series of demanding tests which all lasers must undergo prior to delivery. The most significant of these are described below.

1.) Ageing

Long-term laser storage at ambient temperature can lead to changes in the laser´s characteristics due to various thermally activated processes.
Such effects can be largely pre-empted by an artificial ageing process whereby the lasers are stored at elevated temperatures for several hours. This procedure has the additional benefit of improving the thermal contact between laser chip and heat sink, which in turn leads to more efficient laser cooling and, ultimately, better output power and lifetime characteristics.

2.) Thermal cycling

Lead salt lasers generally require liquid nitrogen cooling for operation, but are frequently stored at ambient temperature when not in use. Such temperature changes can lead to a shifting of the laser´s emission wavelength, usually during the first few temperature cycles. In order to prevent such unpleasant surprises we have introduced a pre-emptive temperature cycling process, in which all our lasers are cycled 20 times between 77 K and room temperature, before their wavelength characteristics are measured. This procedure has yielded extraordinarily good results and enables us to guarantee our lasers against wavelength drift.

3.) Burn-in

The most strenuous test our lasers have to endure is a room temperature burn-in, in which substantial currents are passed through the lasers for several hours. This process simulates long-term laser operation, and has a stabilising effect on laser output power, which can otherwise vary somewhat for some diodes in the early stages of their operating lifetimes.

The results of this procedure are that, following a total energy input of 20 kJ, no significant subsequent power fluctuations are observed.

Those lasers which survive the torture described above can then be fully characterised and shipped. Our lasers have become known for their ability to reliably demonstrate their design specifications over the guarantee period and long thereafter. The extraordinarily low customer complaint level speaks for itself.

Further information:

Chris Varney: 01245 491 499

Products: Laser diodes