| CANDELA-7308 Flicker Measurement Device |
Definition
- Flicker
Perception of visual unsteadiness induced by a light stimulus whose luminance or spectral distribution fluctuates with time, for a static observer in a static environment. ~0-80Hz
- Phantom Array
Perception of a spatially extended series of light spots when making a saccade (image transition across the retina) across a light source that fluctuates with time. ~50Hz-2kHz
- Stroboscopic Effects
Change in motion perception induced by a light stimulus whose luminance or spectral distribution fluctuates with time, for a static observer in a non-static environment. ~50Hz-2kHz
- Temporal Light Artifact
An undesired change in visual perception, induced by a light stimulus whose luminance or spectral distribution fluctuates with time, for an observer in a certain environment.
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Sources of TLA
1. Source voltage changes (noise)
2. Externally coupled noise sources
3. Dimmer phase angle instabilities (when dimming)
4. Driver instabilities
5. Driver (intended) operation
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Current flicker metrics
• Simple
– Percent Flicker
– Flicker Index
• Complex
– RPI LRC ASSIST
– IEC PST
– SVM
– IEEE
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Uses of Flicker Index and Percent Flicker
• Poor indicator of perceivable flicker
– But, could be used to compare lamps with similar characteristics (operating frequency)
• Energy Star Lamps specification
– Values are to be reported only; no limit
• California Title 24 Joint Appendix (JA) 8
– Percent Flicker must be <30% at <200Hz
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