## How is Trolands calculated?

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However Troland is linked to retinal illuminance in lux=lm/m2 as follows. Assuming the corneal luminance L from an extended source, the pupil diameter p and the focal length of the eye F, the retinal luminance is: Lr [lm / m^2] = pi * L / 4 / (f/#)^2 ~ pi * L * p^2 / 4 / F^2.

**What is one Troland?**

Definition of troland : a unit of intensity of light at the retina equal to the illumination received per square millimeter of a pupillary area from a surface having a brightness of one candle per square meter.

### What is retinal luminance?

[′ret·ən·əl i′lü·mə·nəns] (optics) A psychophysiological quantity which is a measure of the brightness of a visual sensation; it is measured in trolands.

**What does Troland mean in science?**

The troland (symbol Td ), named after Leonard T. Troland, is a unit of conventional retinal illuminance. It is meant as a method for correcting photometric measurements of luminance values impinging on the human eye by scaling them by the effective pupil size.

#### What is the troland unit of retinal light?

It is equal to retinal illuminance produced by a surface whose luminance is one nit when the apparent area of the entrance pupil of the eye is 1 square millimeter. The troland unit was proposed in 1916 by Leonard T. Troland, who called it a photon.

**What is the difference between Troland and ordinary Troland?**

The troland typically refers to the ordinary or photopic troland, which is defined in terms of the photopic luminance: where L is the photopic luminance in cd m−2 and p is pupil area in mm2. A scotopic troland is also sometimes defined: where L′ is the scotopic luminance in cd m−2 and p is pupil area in mm2.

## What is the optical interpretation of Trolands?

This optical interpretation of trolands reveals that total light flux in the image of an extended object is the product of the troland value of the source and the solid angle subtended by the source at the first nodal point, independent of eye size. Humans Ocular Physiological Phenomena*