110930 color rendering

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Transcript of 110930 color rendering

  • 1. AN INTRODUCTION TO TES November 7, 2008 Color Rendering Presented By: Sarah Douglass September 30, 2011
  • 2. Color Rendering Color rendering is the effect of a light source on the color appearance of objects by comparison with their appearance under a reference light source Reference sources have a Color Rendering Index of 100 CRI ranges from 0 (worst) to 100 (best) Low CRI sources are cheap to operate but give off low quality light High CRI sources cost more to operate but have higher quality light
  • 3. Color Rendering of Daylight
  • 4. Types of Light Sources 1. Incandescent 2. Halogen 3. Fluorescent 4. Mercury 5. Metal Halide 6. High Pressure Sodium 7. Low Pressure Sodium
  • 5. Incandescent Tungsten filament heated to a high temperature, causing it to glow Bulb protects the filament from air to reduce the rate of tungsten evaporation CRI = 100
  • 6. Halogen Incandescent lamp filled with halogen gas Higher operating temperature Dimmable CRI = 100
  • 7. Fluorescent Cathode creates current Mercury droplets radiate UV radiation Phosphor coating produces light due to the UV radiation Different phosphors affect the output spectrum CRI = 50-85
  • 8. Mercury Lamp has UV radiation emissions At high pressure, mercury gas re-emits radiation as light Emission is concentrated in 5 narrow bands CRI = 17-49
  • 9. Metal Halide Metal halides are added to mercury lamps (thallium, indium, sodium iodide) Improves color quality CRI = 85
  • 10. Low Pressure Sodium When turned on, small current passes through the sodium in the bulb, giving off a faint red discharge When the sodium evaporates, the resulting vapor produces a yellow emission Used almost solely for street lighting CRI = 5
  • 11. High Pressure Sodium Not as efficient as low pressure sodium lamps Radiate energy across the visible spectrum CRI = 24
  • 12. ` Common Light Source Indexes Type of Light Source CRI Low Pressure Sodium 5 Clear Mercury 17 High Pressure Sodium 24 Coated Mercury 49 Standard Fluorescent 50-70 Metal Halide 85 Triphospher Fluorescent 85 Incandescent/Halogen 100
  • 13. Interactive Color Booth