Definition

1. Noun:
   • Optical glass of low dispersion and low refractive index: A type of glass specifically formulated for lenses and optical elements, characterized by its ability to bend light less and separate colors (dispersion) less than other types of optical glass like flint glass.
   • A glass blown into a globe which is later flattened and spun to form a disk: A historical method of producing window glass, resulting in a characteristic bullseye pattern at the center of the pane.

Usage Examples

• Noun:
  • The microscope's objective lens was made from high-quality crown glass to minimize chromatic aberration.
  • The old cottage windows, made of crown glass, had a distinctive wavy texture and a central bullseye.

Advanced Usage

• Technical Context: In optics, "crown glass" is often paired with "flint glass" in achromatic doublet lenses to correct for color distortion.
  • An achromatic lens corrects chromatic aberration by combining a convex lens of crown glass with a concave lens of flint glass.

Variants and Related Words

• Flint glass (n): A contrasting type of optical glass with high dispersion and high refractive index.
• Optical glass (n): The general category of glass manufactured for use in optical devices.
• Bullseye pane (n): A pane of glass, typically from the historical crown glass process, featuring a thickened, rounded center.

Synonyms

• Optical crown (n): A synonym used specifically in optical engineering and lens design.
• Broad glass (n): A historical term sometimes used interchangeably for window glass made by similar spinning methods.

Notes on Different Meanings

The two primary meanings of "crown glass" belong to distinct fields: 1. Materials Science/Optics: Refers to a specific composition of glass with defined optical properties. 2. Historical Glassmaking: Refers to an antique manufacturing process and the resulting product, valued for its aesthetic character in restoration projects.

Noun

1. optical glass of low dispersion and low refractive index
2. a glass blown into a globe which is later flattened and spun to form a disk