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the calibration light source based on a mercury-argon lamp with a line
spectrum; as well as a registration system sensitivity calibration in the
range of 250 to 750 nm according to the standard procedure using the
calibration light source DH2000-CAL. The detector background noise was
also registered based on the brightness intensifier. The obtained background
noise distribution was recorded in a file and was subsequently subtracted
from the measured spectra. It allowed reducing their influence partially,
thereby increasing the signal-to-noise ratio.
The polychromator slit width of 200 mkm was chosen in order to
measure the fluorescence spectra. It provides spectral resolution of 5 nm.
At the same time, for registering the reflected laser beam intensity the
entrance slit width was set to be equal to 4 mm, which allowed both
reducing the luminous flux entering the polychromator input and receiving
signals without saturation.
Experimental studies were carried out using fast-growing and unpreten-
tious species of plant, i.e. different types of lettuce, cucumbers (as an
example of cultivated plants), grass.
Discussion of the results.
Fig. 2 shows some typical examples of
plants’ measured fluorescence spectra in good conditions. There are
Fig. 2. Fluorescence spectra of plants in good condition
74 ISSN 0236-3933. HERALD of the BMSTU. Series “Instrument Engineering”. 2015. No. 2