Abstract
A self-recording spectroradiometer covering the wavelength range of 350mμ_??_2500mμ has been devised for the study of plant growth in artificially illuminated laboratory and in open air.
This spectroradiometer consists of a radiation receiving head which is made to move freely in all directions, an amplifier, a rectifier, a meter or recorder and a stabilized source of radiant energy which is a standard tungsten filament lamp. The radiation receiving head has a light scattering frosted quartz plate, neutral gray filters for incident light intensity attenuation, interference filters, an infrared filter, a chopper, a detector (photomultiplier for visible region and PbS photoconductive cell for near infrared region), and a chopper driving synchronous motor. Wavelength scanning is carried out by turning a disc on which the filters are mounted. The calibration of the meter is by measuring the energy of radiation in each of the filtered ranges impinging on the frosted quartz plate.
Spectral energy distributions obtained on various kinds of fluorescent lamps and mercury lamps agreed fairly well with Azuma's data.
