© PSI (Photon Systems Instruments), spol. s r. o.
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PolyPen RP400 & RP410 (in further text - PolyPen) is a portable, handheld spectro-radiometer. The PolyPen
features a complete system primarily designed for a measurement of spectral reflectance of leaves or other
planar samples. However, the device can be easily implemented also for simple measurement of spectra of any
external light sources e.g. sun, lamps in growth chambers, etc. The system is convenient for both, indoor as well
as field applications owing to an inbuilt GPS module.
The PolyPen is a self-contained instrument powered by a Lithium-ion battery which is rechargeable via a PC and
a USB cable. However, it does not require a PC for operation. Reflectance spectra and calculated reflectance
indices are instantly displayed on the PolyPen touch screen and all stored in the device internal memory.
Integrated USB communication allows data transfer to a PC at a later time. Measured spectra and calculated
indices are stored as full spectrum and individual values (respectively).
The PolyPen device integrates an internal light source (Xenon incandescent lamp) with radiation range 380 –
1050 nm. Two versions of detectors are available for UV/VIS and NIR spectral regions.
VERSIONS
POLYPEN RP 400 UVIS
Spectral response range: 380 to 780 nm.
POLYPEN RP 400 NIR
Spectral response range: 640 to 1050 nm.
The PolyPen device incorporates formulas of commonly used reflectance indices (e.g. NDVI, NDGI, PRI etc.)
directly in its software and displays values of the selected indices instantly. The PolyPen allow calculation of the
following pre-defined parameters:
Transmittance –
calculated using the following formula
T
=
I
/
I
0
Where:
I
0
is reference light intensity
I
is measured light intensity
Absorbance –
calculated data using the following formula
A
= log(
I
0
/
I
)
Where:
I
0
is reference light intensity
I
is measured light intensity
List of vegetation indices are automatically calculated for the measured sample based on the reflectance
spectra.
LIST OF CALCULATED VEGETATION INDEXES:
Normalized Difference Vegetation Index (
NDVI
)
Reference: Rouse et al. (1974)
Equation:
NDVI
= (
R
NIR
-
R
RED
) / (
R
NIR
+
R
RED
)
Simple Ratio Index (
SR
)
Reference: Jordan (1969); Rouse et al. (1974)
Equation:
SR
=
R
NIR
/
R
RED
Modified Chlorophyll Absorption in Reflectance Index (
MCARI1
)
Reference: Haboudane et al. (2004)
Equation:
MCARI1
= 1.2 * [2.5 * (
R
790
- R
670
) - 1.3 * (
R
790
- R
550
)]
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GENERAL INFORMATION
