Sodium-vapor lamp

A high-pressure sodium street light in Toronto
A high-pressure sodium-vapor lamp
An HPS lamp that isn't entirely off

A sodium-vapor lamp is a gas-discharge lamp that uses sodium in an excited state to produce light at a characteristic wavelength near 589 nm.

Two varieties of such lamps exist: low pressure and high pressure. Low-pressure sodium lamps are highly efficient electrical light sources, but their yellow light restricts applications to outdoor lighting, such as street lamps, where they are widely used.[1] High-pressure sodium lamps emit a broader spectrum of light than the low-pressure lamps, but they still have poorer color rendering than other types of lamps.[2] Low-pressure sodium lamps only give monochromatic yellow light and so inhibit color vision at night.

Single ended self-starting lamps are insulated with a mica disc and contained in a borosilicate glass gas discharge tube (arc tube) and a metal cap.[3][4] They include the sodium-vapor lamp that is the gas-discharge lamp in street lighting.[5][6][3][4]

  1. ^ Department of Public Works (1980). San Jose: Study and report on low-pressure sodium lighting. San Jose: City of San Jose. p. 8. Archived from the original on 2016-03-04. Retrieved 2013-12-06.
  2. ^ Luginbuhl, Christian B. "Low-Pressure Sodium Issues and FAQ". Flagstaff, Arizona: U.S. Naval Observatory. Archived from the original on 2015-09-10. Retrieved 2013-12-05.
  3. ^ a b "The Low Pressure Sodium Lamp".
  4. ^ a b "The Low Pressure Sodium Lamp".
  5. ^ "Lighting Comparison: LED vs High Pressure Sodium/Low Pressure Sodium". StouchLighting.com.
  6. ^ "The Sodium Lamp - How It Works and History". EdisonTechCenter.org.