AR COATING/INTERFERENCE Flashcards
Interference
The interaction of 2 or more waves
Constructive interference
2 crests meet then the reinforcement occurs and a larger wave in created (in phase)
Destructive interference
When a trough meets a crest, cancelling eachother out causing neutralisation and no wave is produced (out of phase)
Requirements for destructive interference
Path condition and amplitude condition
Path condition
Waves must travel the same distance at the same time (in phase)
Amplitude condition
Relates to the strength of the waves, must be high
Costing requirements
- adhere well to pens
- deposit evenly in vacuum
- strong
- affordable
Commonly used material for single layer AR coating
Magnesium fluoride
N = 1.38
Refractive index formula
nf = (square root) of ng
Define luminance
Power of a light source in a given direction per unit area
Define illuminance
The light falling on a surface area in a given direction
Define glare
Unwanted light in the visual field. Generally caused by a bright object being surrounded by an area of lower illumination
Define discomfort glare
Caused by excess or unwanted light in the visual field.
Effects visual comfort but doesn’t reduce resolution acuity
Define disability glare
Caused by internal light scatter. Reduces resolution acuity
Dispensing solution for disability glare
Selection of tints/ filters considering the required spectral and luminous transmissions
