le 
dth 
ave 
‘ier 
ring 
(-Y 
tral 
.nm ) 
served 
= 545 -— 
2-2. BATTERY OPERATED HAND SPECTRORADIOMETER 
This radiometer is light weight ( 1.8 kg ) and small sized and 
can be easilly used in the field, where an electric source is not 
available. 
Photo l is a photography of this instrument and the schematic 
diagram is shown inFig.2-2, The incident radiation is divided into 
the photometric component and the view finder component by the beam 
splitter. 
The. photometric component consists of the objective lens ( f-28mm, 
F- 1: 2.8 ) and the aperture which defines the effective field of 
the view. 
The radiation, passed throuth the aperture and the interference 
filter, are again divided into the visual radiation and the new IR 
radiation by the cold mirror, and detected separately by the visual 
light senser( G As P cell ) and the IR( Si cell ). Interference 
filters are installed into the filter turlet, which is rotated by 
the hand. 
The output of each senser are amplified by the individual 
logarithmic circuits. The output signal of each sensor, are 
separately amplified by the individual logarithmic circuits and 
fed to the electric indicator of which the scale plate becomes a 
part of the view finder component. 
So the observer can read the output voltage while he is sighting 
the target. The logarithmic amplifier circuits for each sensors 
are automatically changed ober by the rotation of the filter turlet 
and connected to the recorder via the external output terminals., 
if desired. The main properties of this instrument are listed as 
shown in Table 1. 
The output of the battery operated hand spectroradiometer is 
defined as: 
LOg-LeE( A) =) HC) (4... ee eere esennoneeve( Q ) 
‚where c (M is a constant. With this relation the spectral radiance 
factor of the object /obj(X) is expressed with the indicated value 
for the object 77 obj (A) and for the white board Mstd (x) as: 
Log Öobj (A) = Log. Le:0bj(^) / Le-std(\) + Log ß std (X) 
=nobj (X) = fnstd(N + Log8 BEAD) sevens iD) 
‚where (à std Y is the spectral radiance factor of the white standard 
board, and the measurement was done on cloudy day when the illumination 
was a distributed light source.