Optimal design of step stress accelerated degradation test plan for solid-state lasers

In this paper, we apply SSADT to assess solid-state lasers’ reliability. Different from previous study on SSADT, as for solid-state lasers, we need to consider the fact that the failure criteria in this test is not degradation variables but the joint effect of both degradation variables and accelerate stress levels. On the basis of this characteristic, we establish a performance model of solid-state lasers which is determined by two factors: photoelectric change efficiency and input electrical power. We assume that the degradation of photoelectric change efficiency follows Wiener process, and the degradation rates under each stress level tend to consist with inverse power law model. With the restriction of the overall expenses of experiment not exceeding the predetermined budget, we aim to minimalize the asymptotic variance of the pth percentile of lifetime. An algorithm is presented to solve the optimization problem afterwards. The optimum test design contains the optimum sample size and optimum testing time corresponding to each stress level. In the end, an example of solid-state lasers is presented to exemplify and illustrate the method.