The present study is aimed at investigating the effect of acid etching durations on the surface roughness and birefringence of lightweight mirrors made of ZERODUR® glass ceramic. Four acid etching durations (15, 20, 25 and 30 min) have been chosen at a fixed concentration. By using the photoelasticity, surface profiler and laser microscope, the results before and after acid etching have been obtained. It is found the maximum value of the retardation for the polished lightweight ZERODUR® mirror is up to 30 nm. In addition, residual stresses induced by the grinding process with an average grain size of 149 μm are relived after removing ZERODUR® material of a thickness of 60 μm.