Light Sources

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Wikipedia: Ultraviolet

UV 400-10nm UV-A 400-315nm UV-B 315-280nm UV-C 280-100nm

The UV absorption crosssection of O₃ (in a spreadsheet)

Mercury Vapor Lamp[edit]

Wikipedia: Mercury Vapor Lamp

The strongest peaks of the emission line spectrum are:

Wavelength (nm) Color
184.45 ultraviolet (UVC)
253.7 ultraviolet (UVC)
365.4 ultraviolet (UVA)
404.7 violet
435.8 blue
546.1 green
578.2 yellow-orange

In low-pressure mercury-vapor lamps only the lines at 184 nm and 253 nm are present. Only the light at 253 nm is usable. Synthetic quartz can be used in the manufacturing to keep the 184 nm light from being absorbed. In medium-pressure mercury-vapor lamps, the lines from 200–600 nm are present. The lamps can be constructed to emit primarily in the UV-A (around 400 nm) or UV-C (around 250 nm). High-pressure mercury-vapor lamps are those lamp commonly used for general lighting purposes. They emit primarily in the blue and green.

GravesLab has a UVP Pen-Ray light source—this is a low-pressure mercury discharge lamp in a quartz envelope:

UV LEDs[edit]

Wikipedia: Ultraviolet LEDs

LED efficiency at 365 nm is about 5–8%, whereas efficiency at 395 nm is closer to 20%, and power outputs at these longer UV wavelengths are also better.

UV-A,B,C LEDs from International Light Technologies

Wavelength Range Output Price
265nm UV-C 0.5-1.0 mW $456.20
280nm UV-B 1.0-1.5 mW $390.36
310nm UV-B 1.0-1.5 mW $392.18
365nm UV-A 3.0 mW $15.75
395nm UV-A 3.0 mW $3.45

GravesLab has a stock of Nichia NC4U133APE high-power UV-LED arrays:

ID    1244926
Type    NC4U133APE
Date    2012.03.02
Rank    UaP9d32b
This rank corresponds to: P9d32b 1660mW min; 1820mW max

Qty    3 pcs
engineering samples
runs at ~15.8V volts with a 1Ω series resistor

Visible Light[edit]


The hot filament of an incandescent bulb emits blackbody radiation according to Planck's Law:

[math] B_{\lambda}(T) = \frac{2h c^{2}}{\lambda^5}\frac{1}{e^{\frac{h*c}{\lambda*k_{B}*T}}-1} [/math]

This can be plotted in Sage Math.


High-Intensity Discharge (HID)[edit]



ASTM G173 Insolation Reference Spectra

Solar Irradiance data:

Calculations on insolation, with/without atmospheric protection

ETR = Extraterrestrial Radiation (solar spectrum at top of atmosphere) at mean Earth-Sun distance. Direct = Direct Normal Irradiance Nearly parallel (0.5 deg divergent cone) radiation on surface with surface normal tracking (pointing to) the sun, excluding scattered sky and reflected ground radiation

Circumsolar = Spectral irradiance within +/- 2.5 degree (5 degree diameter) field of view centered on the 0.5 deg diameter solar disk, but excluding the radiation from the disk

"Global Tilt" = spectral radiation from solar disk plus sky diffuse and diffuse reflected from ground on south facing surface tilted 37 deg from horizontal

Biological Action Spectra[edit]