Delta Electronics SS1-UM-1.05 user manual PAR Performance, Spectral response

PAR Performance

The graphs below show the actual spectral and cosine response curves for the SunScan system.

Spectral response

The spectral response curve shows that the SunScan response is almost entirely within the PAR wavelength band of 400 nm - 700 nm. The GaAsP sensors used have an increased sensitivity towards the red end of the spectrum, but this is compensated for by the sharp cut-off at 670 nm. In practice, we have found that these sensors read to within a few percent of an accurate PAR sensor in natural daylight conditions above or within the canopy. However, if you are working under artificial or strongly coloured light you should check the SunScan readings against an accurate PAR sensor if you need to know absolute PAR levels.

Spectral response

SunScan

Ideal

	160
	140
%	120
response	100
	80
relative	60
	40
	20
	0
	350	400	450	500	550	600	650	700	750

wavelength nm

72 • Technical Reference section Document code: SS1-UM-1.05