Photonics Dictionary

A piece of glass, quartz or other transparent material formed roughly by molding or cutting into the approximate shape and size of the finished part.

A piece of glass with a high refractive index that is fused to the major blank.

A threadlike inclusion within a blank of optical glass. Rarely found in quality optical materials.

The concave portion of a surface, formed on a blank, on which the disk of higher refractive glass will be fused to form a multifocal spectacle lens.

A piece of glass that eventually becomes the bifocal segment as it appears prior to being fused to the blank.

A piece of glass having a crude plano surface on each side.

A noncrystalline, inorganic mixture of various metallic oxides fused by heating with glassifiers such as silica, or boric or phosphoric oxides. Common window or bottle glass is a mixture of soda,...

A condition in which the solid inclusions within a glass blank are very numerous, such as 25 or more to the square inch.

A lens blank is a piece of optical material in a raw, unfinished state, typically in the form of a disk or block, from which lenses are eventually fabricated. Lens blanks are made from various...

The production of rough glass lens blanks that are pressed while red-hot to the approximate size and shape of the finished lens, ready for fine grinding and polishing. Large companies often do their...

A blank to which a piece of glass of a different refractive index will be fused to form a multifocal lens.

A mirror blank refers to the initial piece of material from which a mirror is made. It is typically a flat or slightly curved piece of glass or other substrate that serves as the starting point for...

A blank whose basic surface curves are attained by heating and forming a given weight of raw glass; a rough glass blank resembling the finished lens in size and shape. After molding, a precision lens...

Optical glass refers to a type of glass specifically engineered and manufactured for use in optical components and systems, such as lenses, prisms, mirrors, and filters. Optical glass is...

A blank having basic surface curves attained by forming heat-softened glass that is pressed in a mold.

Trade name for a type of borosilicate glass manufactured by Corning Glass Works, noted for its low coefficient of thermal expansion. Used most often for mirror blanks; not suitable for light...

A term used to denote the condition of a few easily visible coarse inclusions within a blank of glass.

In multifocal spectacles, a term used to denote glass with a high refractive index that has been fused to the blank and ground to a curvature, resulting in added power.

A formed piece of glass, one surface of which has been ground and polished to the required curvatures.