Distortion can be corrected in an image by placing a fourth-order aspheric optical element near the image plane. Moving the aspheric surface longitudinally changes the amount of distortion that is added by theaspheric surface without changing the paraxial image. Third-order astigmatism limits the performance ofdistortion correctors and may be eliminated by adding another fourth-order aspheric surface. Exampleelements were fabricated by diamond turning and were shown to introduce distortion withoutsignificantly degrading image quality. Three arrangements of distortion correctors are discussed: asingle-element planoaspheric arrangement, an antisymmetric two-element arrangement, and a biaspheric arrangement in which distortion is not adjustable.
- Aspheric optics
- Diamond turning
- Wave-front correction
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics