Reducing symmetric polarization aberrations in a lens by annealing

Radially symmetric retardance was found in antireflection coated, molded aspheric glass lenses by measurement with a Mueller matrix imaging polarimeter. The source of the unexpected polarization aberration is traced to a remarkably symmetric radial stress birefringence in the glass believed to arise during fire-polishing of the surfaces. While annealing the lenses relieves much of the stress birefringence, reducing the retardance of the lenses by a factor of five, the lenses remained unusable.