Lighting High pressure sodium

The lamp above is more properly called a low-pressure sodium lamp. Such lamps are ideal for street and road illumination, but the monochromatic nature of the emission makes seeing in colour impossible. An adaptation which emits a range of colours is the high-pressure sodium-vapour lamp, which is similar to that described above but contains a mixture of mercury and sodium. Such lamps emit a whiter light and are useful for extra-bright lighting in places such as road intersections, car parks and sports stadia. 

Technical limits of exitance also impose minima for the dimensions of medium-pressure light sources (length of arc, length and diameter of bulb), for example, medium-pressure (doped) mercury arcs, high-pressure sodium vapor lamps, and incandescent lamps. 

High Pressure Sodium light fixture 400 watt to 1000 watt with light moving rail... 

High-pressure sodium-vapor lamps, IR windows, lighting tubes and lamps, laser materials, light memory, video display and storage, light modulation and shutters. 

High-pressure sodium vapor lamp Lighting tube, special-purpose lamp, infrared transmission window materials Laser materials... 

Plant growth conditions All A. thaliana plants were grown in controlled growth chambers, under continuous fluorescent illumination (150-200 pE m sec" ) at 22°C. All B. napus plants were grown under natural light supplemented with high pressure sodium lamps with a 16 hour photoperiod (16 h light/8 h dark), at 22°C, and a relative humidity of 25-30%. 

How effectively shonld yonr light source render colors The higher the color rendering index (CRI) of a lamp, the better individual colors will be rendered. The CRI compares how closely a light sonrce will render colors to a standard.The standard is usually an incandescent lamp, which is, by definition, a black body and has a CRI of 100, the highest rating (Table 5.40). Metal halide lamps nsnally have a CRI between 65 and 85. By comparison, high-pressure sodium lamps have a CRI of 22. 

Fig. 99.4 High-pressure sodium lamps that light Wallens Ridge are visible for miles...

The light output of a high-pressure sodium lamp is a ... 

The intermediate color-rendering properties of most fluorescent light sources are closer to the best than to the worst. Mercury vapor and high-pressure sodium sources, widely used for street lighting, have poor color-rendering properties that fall between those of fluorescent and low-pressure sodium illumination. 

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