Reptile Lamp Database

Colorimetry is the science to describe physically the human color perception. The wavelength range 380 nm - 780 nm is visible to humans and detected by three different photoreceptors. Many Reptiles see the range 350 nm - 800 nm and have an additional UV photoreceptor in their retina.

Whereas a spectrometer measures the intensity in every tiny wavelength interval resulting in thousands of individual intensities, the human eye only measures three intensities detected by the three cones. The same is true for the reptile eye with usually three or four photoreceptors. Effectively the detailled spectrum displayed above reduces to a much compacter bar graph displayed below. The photoreceptor sensitivites from these L-Cone, M-Cone, S-Cone, and U-Cone are used, they are chosen as an average of measured reptile photoreceptor sensitivity curves. The bar graph also shows as reference the intensity seen by the three or four photoreceptors for average sunlight (id 1).

From these three numbers the colour coordinate and the correlated colour temperature for humans are calculated using the CIE standard method. I adapted this concept to a "3 cone reptile (M,S,U)" and a "4 cone reptile (L,M,S,U)". I am sure, that this adaption to other colour spaces makes sense mathematically and this is also done in scientific research regarding colour vision of animals, however I have not seen calculation of colour temperatures for other animals in the scientific literature. Even if it is hypothetical, at least this shows, how arbitrary the colour temperature is, and that the colour temperature calculated for humans does not apply to reptiles. The colour spaces also show the colour coordinates of different phases of daylight ((ids 1, 338 – 451, 511 – 513 ), indicated by crosses, coloured in the appriximate colour perceived by a human.

	Human (CIE)	3 cone reptile	4 cone reptile
Cone Excitation
Colour Coordinate	( 0.3 ; 0.31 )	( 0.4 ; 0.44 )	( 0.25 ; 0.3 ; 0.33 )
CCT	7800 Kelvin	5100 Kelvin	5600 Kelvin
distance		0.1	0.084
colour space			3-D-graph not implemented yet

Vitamin D3 is produced by UVB radiation around 300 nm. 7DHC/ProD3 present in the skin is converted to PreD3 when absorbing an UV photon. PreD3 can be converted back to ProD3, to Lumisterol, or to Tachysterol when absorbing another UV photon or can be converted to Vitamin D3 in a warm environment.

This process prevents any overdose of vitamin D3 from UV radiation with a spectrum similar to sunlight. As a comparison the solar spectra at 20°(id:14) and at 85°(id:21) solar angle are shown.

The equilibrium of the photoproducts depends on the actual UV spectrum in the range 250 nm - 340 nm. With knowledge of the conversion probabilities and absorption spectra of 7DHC, PreD3, Tachysterol, and Lumisterol it is possible to calculate the ratio of photoproducts in equilibrium. This is based on scientific literature [1066], however the constants that are used for the calculation are not well calibrated with experiments. It is therefore not a solid method, but I consider it useful as a first guess how natural a UV spectrum is.

Caveat: This evaluation is extremely sensitive to the qualitiy of the spectral measurement in the range 220 nm - 340 nm. High quality spectrometers and good background calibration is needed to get the noise below 300 nm low enough for this evaluation. Please check at least the UV graph above for noise.

The ratio of the two solarmeters 6.2 (UVB) and 6.5 (UV index) readings has proven a useful and very simply number to acess the spectral shape in the vitamin-d3-active region.

Effective irradiances are calculated for all ranges, actionspectra and radiometers currently present in this database.

The calculation method is a numerical implementation (Simpson's rule) of the formula

To learn more about calculating effective irradiances and radiometers I recommend this excellent report on UVB meters: Characterizing the Performance of Integral Measuring UV-Meters (pdf).

UVA (EU) ( 315 nm - 400 nm)	175 µW/cm² = 1.75 W/m²
UVA (US) ( 320 nm - 400 nm)	159 µW/cm² = 1.59 W/m²
UVB (EU) ( 280 nm - 315 nm)	19.1 µW/cm² = 0.191 W/m²
UVB (US) ( 280 nm - 320 nm)	35.2 µW/cm² = 0.352 W/m²
UVC ( 0 nm - 280 nm)	0.845 µW/cm² = 0.00845 W/m²
vis. UVA ( 350 nm - 380 nm)	35.3 µW/cm² = 0.353 W/m²
purple ( 380 nm - 420 nm)	32.7 µW/cm² = 0.327 W/m²
blue ( 420 nm - 490 nm)	158 µW/cm² = 1.58 W/m²
green ( 490 nm - 575 nm)	158 µW/cm² = 1.58 W/m²
yellow ( 575 nm - 585 nm)	19.3 µW/cm² = 0.193 W/m²
orange ( 585 nm - 650 nm)	94.3 µW/cm² = 0.943 W/m²
red ( 650 nm - 780 nm)	86.4 µW/cm² = 0.864 W/m²
VIS ( 380 nm - 780 nm)	549 µW/cm² = 5.49 W/m²
PAR ( 400 nm - 700 nm)	514 µW/cm² = 5.14 W/m²
total ( 0 nm - 0 nm)	746 µW/cm² = 7.46 W/m²
UVA1 ( 315 nm - 350 nm)	133 µW/cm² = 1.33 W/m²
VIS Rep3 ( 350 nm - 600 nm)	424 µW/cm² = 4.24 W/m²
VIS Rep4 ( 350 nm - 700 nm)	556 µW/cm² = 5.56 W/m²
IRA ( 700 nm - 1400 nm)	37 µW/cm² = 0.37 W/m²
IRB ( 1400 nm - 3000 nm)	0 µW/cm² = 0 W/m²

Erythema	1.42 UV-Index
Pyrimidine dimerization of DNA	12.2 µW/cm²
Photoceratitis	2 µW/cm²
Photoconjunctivitis	0.766 µW/cm²
DNA Damage	0.955
Vitamin D3	4.59 µW/cm²
Photosynthesis	366 µW/cm²
Luminosity	1360 lx
Human L-Cone	200 µW/cm²
Human M-Cone	174 µW/cm²
Human S-Cone	129 µW/cm²
CIE X	181 µW/cm²
CIE Y	188 µW/cm²
CIE Z	241 µW/cm²
PAR	2430000 mol photons
Extinction preD3	0.0434 m²/mol
Extinction Tachysterol	0.146 m²/mol
Extinction Lumisterol	0.011 m²/mol
Extinction 7DHC	0.0118 m²/mol
L-Cone	166 µW/cm²
M-Cone	196 µW/cm²
S-Cone	217 µW/cm²
U-Cone	77.8 µW/cm²
UVR - ICNIRP 2004	1.55 Rel Biol Eff
Melatonin Supression	181 µW/cm²
Blue Light Hazard	144 µW/cm² (106 µW/cm² per 1000 lx)
CIE 174:2006 PreVit D3	4.96 µW/cm²
Lumen Reptil	1500 "pseudo-lx"
Vitamin D3 Degradation	7.07 µW/cm²

Solarmeter 6.2 (UVB, pre 2010)	44.8 µW/cm²
Solarmeter 6.5 (UV-Index, pre 2010)	1.44
Leybold UVB	30.3 µW/cm²
Leybold UVA	110 µW/cm²
Leybold UVC	0.585 µW/cm²
DeltaOhm UVB	87 µW/cm²
DeltaOhm UVC	10.4 µW/cm²
Vernier UVB	8.6 µW/cm²
Vernier UVA	124 µW/cm²
Gröbel UVA	141 µW/cm²
Gröbel UVB	14.4 µW/cm²
Gröbel UVC	0.641 µW/cm²
Solarmeter 6.4 (D3)	4.48 IU/min
UVX-31	94.4 µW/cm²
IL UVB	0.0193 µW/cm²
IL UVA	120 µW/cm²
Solarmeter 6.5 (UVI, post 2010)	1.21 UV-Index
Solarmeter 6.2 (UVB, post 2010)	31.2 µW/cm² (Solarmeter Ratio = 25.9)
Solarmeter AlGaN 6.5 UVI sensor	16.9 UV Index
GenUV 7.1 UV-Index	1.02 UV-Index
Solarmeter 10.0 (Global Power)	6.6 W/m²
Solarmeter 4.0 (UVA)	1.54 mW/cm²