Definition

Noun: - A lens designed to correct astigmatism: An anastigmatic lens is an optical lens, often used in eyeglasses, cameras, or other instruments, that is specifically constructed to eliminate or significantly reduce the visual defect known as astigmatism. Astigmatism causes blurred vision due to an irregular curvature of the eye's cornea or lens, and this lens corrects it by having different optical powers in different meridians.

Usage Examples

• Noun:
  • The optometrist prescribed an anastigmatic lens to correct her astigmatism.
  • High-quality cameras often use anastigmatic lenses to produce sharp, distortion-free images.

Advanced Usage

• Technical Context: In advanced optics, an "anastigmat" refers to a compound lens system that is corrected for astigmatism, spherical aberration, and coma, allowing for sharp focus across the entire image field.
  • The photographer invested in an anastigmatic lens for his architectural work to ensure straight lines remained straight.

Variants and Related Words

• Anastigmat (n): Another term for an anastigmatic lens or a lens system free from astigmatism.
  • This vintage camera is prized for its high-quality anastigmat.
• Astigmatism (n): The visual defect that an anastigmatic lens is designed to correct.
  • Astigmatism can cause headaches and eye strain.

Synonyms

• Corrective lens (for astigmatism): A general term for a lens that corrects refractive errors, including those for astigmatism.
• Toroidal lens: A lens with a toric surface, which is a common design for correcting astigmatism.

Related Terms (Not Phrasal Verbs)

• Lens correction: The process or result of designing a lens to counteract optical aberrations.
• Optical aberration: An imperfection in image formation by an optical system, such as astigmatism.

Noun

1. a lens designed to correct astigmatism