Definition

1. Noun:
   • The primary lens or mirror in an optical instrument: "object-glass" refers to the main lens (or mirror) in a telescope, microscope, or other optical device that collects light from the object being observed and forms an initial image. It is the lens closest to the object.

Usage Examples

• Noun:
  • The telescope's object-glass was carefully polished to reduce distortion. (The main lens that gathers light from distant stars.)
  • In a microscope, the object-glass is the lens situated near the specimen. (The lens that first receives light from the sample.)

Advanced Usage

• "to adjust the object-glass": to focus or calibrate the primary lens for clearer viewing.
  • The astronomer adjusted the object-glass to sharpen the image of Saturn's rings. (He fine-tuned the main lens for better clarity.)
• "objective" as a synonym: In modern optics, "objective" is often used interchangeably with "object-glass" for the same component.
  • The microscope's objective lens has a magnification of 40x. (The primary lens that magnifies the specimen.)

Variants and Related Words

• Object-lens (n): an alternative term for "object-glass," meaning the same component.
  • The object-lens of the refracting telescope must be free of bubbles. (The primary lens must be flawless.)
• Objective (n): a shortened, modern term for the object-glass in optical instruments.
  • The objective of this camera is a high-quality glass element. (The primary lens.)

Synonyms

• Primary lens: the first lens in an optical system that collects light.
• Objective lens: the lens that forms the initial image in a microscope or telescope.

Related Idioms

• "Object-glass" is primarily a technical term and does not have common idiomatic uses. It appears almost exclusively in scientific or historical contexts describing optical instruments.