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