dioptric

Later a dioptric apparatus was installed in the tower and came into operation on 29 September 1864.

The original apparatus was a fourth order dioptric with a totally reflecting glass mirror.

The development kit also includes interchangeable lenses that will allow for simple dioptric correction.

In 1910 the fixed light was changed to a fifth order dioptric lens, flashing with a character of one flash every three seconds.

Convex lenses have a positive dioptric value, which causes the light to focus closer than its normal range.

Concave lenses have negative dioptric value and generally correct myopia (nearsightedness).

Another built-in feature that's neat, but not unique, is a dioptric correction adjustment in the viewfinder eyepiece.

In 1922 a 3rd order Fresnel double bullseye dioptric lens, group flashing white (5 sec.)

A 1909 listing describes the tower as a wooden tower, carrying a fixed fourth order dioptric apparatus.

A vertometer is an ophthalmic bench instrument used to measure dioptric power of a lens.

Its optics were either catadioptric or dioptric.

The model has a very changing nature, its shown that a model of the blur perception is in dioptric space while in near viewing.

Dioptric correction is the expression for the adjustment of the optical instrument to the varying visual acuity of a person's eyes.

The intensity of the light was increased by a combination of a dioptric fixed lens and catoptric mirrors.

This was later replaced by a dioptric lens system; the light was first lit by oil, then acetylene and finally electricity in 1930.

In March 1881 a new first order dioptric lamp was fitted and in 1887 a locally made revolving apparatus was installed.

The beacon was altered in 1812 and then replaced in 1864 with a dioptric lens housed in a new lantern, which is that used today.

Originally, the light comprised reflectors but changed to a dioptric (refracting) mechanism in 1838; the appearance of the original lantern is not known.

Incandescent oil dioptric light with 'Hood' burner was used in 1931 with a 3rd Order 500 mm optic.

Established in 1857, it incorporated a new 'condensing' apparatus developed by Thomas Stevenson as an improvement to the dioptric system.

Bell and Rhodan took aim, adjusted the primitive-looking dioptric screws for the distance and pulled the trigger.

This lantern holds the original housing of the Chance Bros. 1st order bivalve dioptric Fresnel lens.

Galileo Ferraris researched the fundamental properties of dioptric instruments and made elementary representation of the theory and its applications.

In 1860, the oil powered light was upgraded to a dioptric light and the fort that surrounds the tower was built by the War Department.

The original lens was a fourth order Chance Brothers dioptric apparatus, and the original light source was a fixed kerosene lamp.