Troland

The Troland ( unit symbol t d ) is a unit of retinal illuminance ( also called pupil - light intensity ). The adjustment of the pupil is taken into account based on ambient light. The Troland is not a legal entity in Germany. It is named after the American researcher Leonard Thompson Troland ( April 26, 1889 - MAY 1932), who proposed to provide a measure of the brightness stimulus is the product of luminance and effective pupil area.

Definition

Retinal illuminance is obtained from the product of the luminance of a visual stimulus, and the pupil surface of the observing eye.

Are you doing the luminance in candelas per square meter ( cd / m² ) and the pupil area in mm ² to one, the retinal illuminance in Troland. When a pupil surface of the retinal illuminance is equal to the luminance

Application

The retinal illuminance is used to specify visual stimulus parameters in physiological studies. As the unit, it is especially suitable for artificial pupil, since their surface area is exactly known. They continue to play in the study of visual thresholds is relevant, as can be described by their visual stimuli depending on the adaptation state of the eye.

Since the luminance of the area photopia (tags marriages) is defined, the pupillary light intensity can also become valid only for the calculation of the peg- oriented brightness impression.

Sources

• Photometric unit
• Eye