What is scotopic and photopic ratio?
The scotopic/photopic ratio, or S/P ratio, is a multiplier that measures how much emitted light is useful to the human eye. These useful lumens are known as visually effective lumens (VELs).
What is photopic scotopic and Mesopic vision?
Scotopic and Photopic Vision Scotopic vision uses only rods to see, meaning that objects are visible, but appear in black and white, whereas photopic vision uses cones and provides color. Mesopic vision is the combination of the two and is used for most scenarios.
What is photopic lumens?
Photopic lumen output is the amount of light registered by cones in the human eye and is measured by standard lumen and footcandle meters. The second type is called scotopic lumens, which represent the sensitivity of the eye under typical lighting conditions and cannot be measured directly with a standard light meter.
How is SP ratio calculated?
Lamps / light sources are assigned an SP ratio – this ratio is a calculation of the Scotopic lumens the lamp produces divided by the Photopic lumens.
What is meant by photopic?
Definition of photopic : relating to or being vision in bright light with light-adapted eyes that is mediated by the cones of the retina.
Are rods used in photopic vision?
Rods, usually associated with highly sensitive dim-light vision, contribute to vision even in bright photopic intensities.
What is mesopic pupil size?
Mesopic pupil size was 5.96 ± 0.8 mm in hyperopic astigmatism, 6.36 ± 0.83 mm in high astigmatism, and 6.51 ± 0.8 mm in myopic astigmatism. The difference in mesopic pupil size between all refractive subgroups was statistically significant (p < 0.001).
What is mesopic illumination?
Mesopic vision is a combination of photopic vision and scotopic vision in low but not quite dark lighting situations. Mesopic light levels range from luminances of approximately 0.01 cd/m2 to 3 cd/m2. Most nighttime outdoor and street lighting scenarios are in the mesopic range.
Which cells in the eye are responsible for scotopic vision?
The retina is comprised of two types of photoreceptor cells: rods and cones. Rods are the cells primarily responsible for scotopic vision, or low-light vision.
What is the unit of illumination?
lux
lux, unit of illumination (see luminous intensity) in the International System of Units (SI). One lux (Latin for “light”) is the amount of illumination provided when one lumen is evenly distributed over an area of one square metre.
What is SP on a bulb?
The word “SP” means single pole. The neutral is permanently connected after it switches one wire. “Double Pole” is what DP means. Both the P and the neutral are switched.