Recently, the piezo‐optic constants of CaF2 single crystals have been measured in the infrared. These measurements indicate that the critical orientation in the sense of Joiner, Marburger, and Steier is within 1.9°±1.2° from the  direction. It follows that 〈111〉‐oriented CaF2 laser windows do not exhibit any detectable stress birefringence independently of the polarization of the incident beam. On using the best data currently available on relevant properties of single‐crystalline material at 3.39 μm, an evaluation of the optical distortion coefficient χ of 〈111〉‐oriented CaF2 yields an exceptionally small value: χ= (1.0±0.6) ×10−6 K−1. On this basis, it is shown that, in principle, a 1‐cm‐thick AR‐coated CaF2 window can handle average energy fluences of at least 300 kJ/cm2 without violating the Maréchal criterion.