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Havis-Shields Equipment Corp. All About Lighting I
Overview • About Light • Eye perception • Lighting Technologies • Sources • Measures • Properties • Applications • How to use the right source • Optics
About Light – Eye Perception • All that matters is what the eye perceives • Color vs. contrast • High light levels, we see color • Low light levels, we see contrast (B&W) Color spectrum - www.photo.net
About Light – Eye Perception • Cones – See color, bright light (Photopic) • Rods – See B&W, low light (Scotopic) Eye diagram - www.photo.net
About Light – Eye Perception • Rods and cones do not see the same! • Cones see yellow-green best • Rods see blue-green best www.yorku.ca www.venturelighting.com
About Light – Eye Perception • Scotopic (low light) vision sees very little red! Scotopic/photopic vision - www.4colorvision.com
About Light – Eye Perception • We are concerned with outdoor lighting • Photopic vision in bright areas • Scotopic vision in dim areas • Mesoptic (transitional) vision in most areas • In short, we need lots of full-spectrum green, with some red and some blue for the best visibility
Lighting Technologies • Artificial light sources (except halogen/ incandescent) are NOT full-spectrum! Cool-white fluorescent spectrum - www.photo.net
Lighting Technologies • Halogen & Incandescent • High yellow, some green, some blue • Incandescent is slightly more red than halogen • Very low efficiency • Good for Photopic, bad for Scotopic vision http://www.users.mis.net/~pthrush/lighting/glow.html
Lighting Technologies • Metal Halide and Xenon HID • High green, moderate blue, some red • Xenon HID is slightly more blue than std. MH • High efficiency • Excellent for both Photopic and Scotopic vision Standard MH Enhanced MH Daylight
Lighting Technologies • Fluorescent • Moderate red, green, and blue • Can vary colors by changing phosphors • High efficiency • OK for both Photopic and Scotopic vision • Cool white is best for all-purpose viewing www.squ1.com
Lighting Technologies • High Pressure Sodium • High red, moderate green, very little blue • Very high efficiency • Good for Photopic, terrible for Scotopic vision • All objects have strong orange cast www.salsburg.com
Measures • Lumen – Quantity of light (standardized) • Effective Lumen – Quantity of light (usable) • Color Temperature – Color of light • Color Rendering Index – Quality of light
Measures - Lumen • What is a lumen? • Quantity of light • Defined at a specific wavelength (color) of light – yellow • A lumen is NOT a lumen! • Need to compare “effective” lumens • Studies based upon street lighting and reaction time
Measures - Effective Lumen • From IESNA: • An example – Best Case: • 150W HPS = 16,000 lm => 4,100 lm effective • 150W MH = 13,000 lm => 13,000 lm effective • 150W Hal = 2,400 lm => 1,600 lm effective
Measures - Color Temperature • All light sources we are concerned with are termed “White” light • The color can be represented on a red-blue scale derived from optical pyrometry – Kelvin scale • Note—does not account for green! Daylight Artificial Light en.wikipedia.org
Measures - Color Temperature • Color Temperature Table Daylight: Blue to Very Blue! Optimal is right here! Most Artificial Light Red to Blue
Measures - Color Temperature • Summary: • Optimal color temperature is about 4,000-5,000K for both light and dark lighting conditions • Higher color temperature is better for dim lighting • Lower color temperature is better for bright light • Good guideline, but does not account for green • Light source must have lots of green to work well in all lighting conditions
Measures - Color Rendering • CCRI = Correlated Color Rendering Index • Percent of colors that can be seen at a specified color temperature • Most overall colors can be seen at 3,500K • A CCRI of 90 at 4,500K means that 90% of all the colors that can be perceived at 4,500K will be perceived with this light source. • A CCRI of 90 at 4,500K is NOT comparable to a CCRI of 90 at any other color temperature!
Measures - Color Rendering • Good indication of the fullness of the spectrum • Higher CCRI is better • CCRI > 65 is suitable for general lighting • CCRI > 80 is suitable for office lighting • CCRI > 90 is suitable for retail lighting
Measures • Summary: • For outdoor lighting, Metal Halide (and Xenon HID) are far and away the best • Fluorescent can also be good, if the phosphors are correct • Halogen is fair for bright lighting, but is very inefficient, and not good for low lighting • High Pressure Sodium is good for bright lighting, but very poor for low lighting
Properties of Lighting Sources • Operational properties: Note: All lighting sources except for Halogen require a ballast to regulate light output. Ballast and lamp design will determine On time and Restrike time. HPS ballasts and lamps are generally not designed for rapid on or restrike.
Properties of Lighting Sources • Performance: Note: More stars indicates better performance.
Properties of Lighting Sources • Cost breakout: Note: More dollar signs indicates higher cost.
Properties of Lighting Sources • Summary • Metal Halide and Xenon HID are the highest performance and lowest cost over the lifetime of the fixture • Fluorescent can be a good choice, if suitable optical control can be achieved • Halogen/Incandescent is the highest cost and lowest performance over the lifetime of the fixture
Applications • Clearly, Metal Halide and Xenon HID should be used whenever possible • Some fluorescents could be suitable for some applications • Fixture must be designed to use any light source effectively • Bad fixture design can reduce the benefits of using a good light source
Applications - Metal Halide • Common wattages: 50-2000 • Requires electronic ballast for instant-on and instant-restrike • Only practical up to about 150W today • Future could include 250W or possibly 400W • Moderate color shift and lumen depreciation • Lamps vary widely in quality and spec's from manufacturer to manufacturer • Many color temperatures available • Higher than about 5,000K is inefficient • Some lamps are position-sensitive
Applications - Xenon HID • Common wattages: 10-50 • Small color shift and lumen depreciation • Lamps vary widely in quality and spec's from manufacturer to manufacturer • Havis-Shields lamps are proprietary and made specific for our applications • Our lamps are 4,200-5,000K for optimal performance • Higher than about 5,000K is inefficient
Applications - Fluorescent • Common wattages: 2-40 • No color shift, small lumen depreciation • Havis-Shields lamps are proprietary and made specific for our applications • Our lamps are 4,500K for optimal performance • Higher than about 5,000K is OK • Lamps are temperature-sensitive, and may need extra technologies to use outdoors • Lamps are long and slender, not suitable for good light control
Applications - HPS • Common wattages: 35-1000 • Small color shift and lumen depreciation • Light quality is very bad for low-lighting applications, so not recommended • No commonly-available lamps or ballasts are available for instant-on or instant-restrike
Applications - Halogen • Common wattages: 5-2000 • No ballast required • Small color shift and lumen depreciation • Lamps vary widely in quality and spec's from manufacturer to manufacturer • Lamps are typically 2,700-3,000K • Higher than 3,000K is not common • Lamps have short life • Lamps are good for optical control
Applications - Optics • Common lamp designs: Double-ended Good for wide flood lighting Single-ended Good for spot lighting
Applications - Optics • Reflectors • Reflect light into a specific pattern • Reflectivity of suface correlates with efficiency • 78%, 85%, 90%, 94% Reflectivities • Potential for hot-spots • Specially textured surfaces can improve uniformity • Common materials • Hydroform • Spun • Sheet metal • Plastic • Glass • White paint
Applications - Optics • Controlling reflectivity • Polished & Anodized • Moderate cost, 78-85% reflective • Sensitivity to dirt & fingerprints: Moderate • Polished & Metalized • High cost, 90%+ reflective • Sensitivity to dirt & fingerprints: High • Sheet Metal (Pre-Processed) • Low cost, 85-94% reflective • Sensitivity to dirt & fingerprints: Low • Glass (Molded) • Moderate cost, 78%+ reflective • Sensitivity to dirt & fingerprints: Low
Applications - Optics • Refractors & Lenses • Bend light into a specific pattern • Transmissivity correlates with efficiency • 85%, 90%, 92% Transmissivities • Refractors direct light over an area • Good to bend light up to about 30o • Lenses good to focus light – or diffuse it • Good to collimate light or spread it uniformly • Common materials • Glass (molded) • Plastic • Can be expensive • Must be used with a reflector
Applications - Optics • Flood lighting: Spot Beam angle (Spread) Flood
Applications - Optics • Flood lighting:
Applications - Optics • Single-ended lamp reflectors • Spot is typically 8 degrees max • NEMA types only apply to floods • Double-ended lamp reflectors • NEMA type always apply • H x V format (Horizontal by Vertical) • More sophisticated designs • Downward • Multiple-beam • Area
Applications - Optics • Design methods • Computer design increases design quality • Ray trace over 1,000,000 rays per simulation
Summary • Definition of light & spectrum • Lighting technologies • Green is good • How to select the right source • When in doubt, use Metal Halide/Xenon HID • Applications • Direct light with reflectors, refractors • Describe reflectors with angles, NEMA types • Questions?