Optical Property of Bio-material: Illumination

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Optical Property of Bio-materialIllumination

• Physical Properties of Bio-Materials (VI-C)

Poching Wu, Ph.D. Department of Bio-Mechatronic
Engineering National Ilan University
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Standard IlluminantsCIE (The Commission
Internationale de lEclairage)

• Illuminant A is provided by a gas-filled tungsten
  lamp operating at a color temperature of 2856?K.
• Illuminant C, designed to present daylight from
  an overcast sky, is tungsten light filtered to
  give a color temperature of 6774?K.
• Illuminant D65 is based on measurements of total
  daylight of sun plus sky, and has a correlated
  color temperature of 6500?K.

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Photometric Units

• The international candle was a standard of
  luminous intensity corresponding roughly to that
  of a standard candle but was maintained by carbon
  filament lamps of special construction.

Candela
The luminous intensity per square cm of a black
body at the temperature of solidification of
platinum was defined as 60 candelas.
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The construction of a suitable black-body
radiator (01/01/1948)
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Luminance
Luminous Flux

• The unit of luminous flux is the lumen and is
  defined as the flux emitted into unit solid angle
  by a uniform point source whose luminous
  intensity in all direction is one candela.
• It will be seen that the total flux emitted by
  such a uniform point source is 4? lumens.

• Luminance is luminous intensity per unit
  projected area and is expressed in candelas per
  square cm (known as stilbs) or candelas per
  square meter (known as nits).

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Lux

• The usual metric unit of illumination is the lux.
• The illumination is 1 lux when the surface
  receives 1 lumen per square meter.
• The lux has been called a meter-candle and
  defined as the illumination on the surface of a
  sphere of radius 1 meter due to a uniform point
  source of 1 candle placed at its center.
• On the British system the illumination is
  expressed in lumens per square foot or
  foot-candles.
• A alternative metric unit is the phot or lumen
  per square cm.

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The Physical and Psychophysical Attributes of the
Color
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Tungsten Light
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Fluorescent Lamp
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Energy Efficiency of Various Light Sources