"Classical" Lifetime Test

Lifetime test explained:

Use this test for:

• Prediction of optics lifetime in fs and ps regime at kHz repetition rate

Test description

A classical lifetime testing approach is based on S-on-1 testing, were S represents maximum irradiation dose in pulses or time. To estimate lifetime multiple S-on-1 tests are needed with different irradiation dose S. But let’s discus how a single S-on-1 test is conducted first.

Sample’s surface is divided into a virtual matrix of sites. Each test site is visually inspected under microscope prior laser exposure. An inspected site is then exposed to a burst of maximum S laser pulses with fixed laser peak fluence.  Distinct fluences levels are applied for individual test sites. After exposure, the status of irradiated site is inspected with offline microscopy and interpreted as either “survived”, “non-catastrophic” or “catastrophic” damage. Collected statuses and damage statistics are then used to calculate damage threshold of every  failure mode for the applied laser pulses (exposure dose S).

Next maximum, different amount of applied laser pulses S is set and S-on-1 procedure is repeated again. By continuing in this type of testing multiple times, the LIDT dependence versus the number of applied laser pulses (exposure dose) is obtained for each failure mode.

Finally, by having LIDT data trend versus time it is possible to use an extrapolation to make a prediction of the future. By applying advanced statistical methods, a prognosis of long-term behavior is made for each failure mode. Now, by having prognosis of LIDT, a useful lifetime can be estimated at the selected fluence level of interest.

Currently we offer “Classical lifetime” testing
at these (fs, ps) conditions:

⁽¹⁾ effective pulse duration measured at Full Width Half Maximum