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What is a troland?
Summary
Trolands, a measure of retinal illuminance, are redefined as angular flux density. This clarifies their interpretation as the intensity of an equivalent point source, independent of eye size.
Area of Science:
- Vision Science
- Visual Optics
- Photometry
Background:
- Trolands are a standard unit for retinal illuminance.
- Existing definitions and interpretations of trolands lack consensus.
Purpose of the Study:
- To establish a clear conceptual framework for interpreting trolands.
- To resolve ambiguities surrounding the troland unit in vision science.
Main Methods:
- Simplified optical analysis of retinal illuminance.
- Conceptual redefinition of trolands based on angular flux density.
Main Results:
- Trolands represent the intensity of an equivalent point source at the posterior nodal point.
- This interpretation holds for extended light sources.
- Total retinal light flux is the product of troland value and subtended solid angle, irrespective of eye size.
Conclusions:
- Trolands provide a consistent measure of angular flux density.
- The redefined interpretation clarifies troland usage in visual optics.
- This framework simplifies calculations of retinal illuminance for extended sources.
