23
it. The LI-191SA is sealed against normal weather conditions, but may leak
if submerged.
The LI-191SA may be cleaned with a mild detergent and water, but care
should be observed to avoid disturbing the silicone rubber seal which is
adjacent to the diffuser. Do not attempt to disassemble the sensor, as the
weatherproof seal will be broken and the calibration and spatial response
will be affected.
An anodized aluminum "nose cone" is provided which can be screwed into
the 1/4-20 threaded hole on the end of the sensor. This will allow easier
insertion of the sensor into dense foliage.
WARNING:
Do not drop the
sensor since the point of the nose cone could cause injury!
Cosine Correction Properties
Due to the large non-symmetrical sensing area of 1 meter by 12.7 mm, the
LI-191SA cannot be compensated completely for true cosine response.
Figure 7 shows the approximate cosine error for collimated light at angles
of incidence from 0
°
(normal) to 90
°
. Under conditions of partial or full
diffuse radiation the errors will generally be negligible.
Since the sensing area is a flat acrylic diffuser, the response at a given angle
of incidence is fairly constant as the azimuth angle around the sensor is
varied. It is specified at less than
±
2% at a 45
°
angle of elevation for 360
°
of sensor rotation.
Surface Variation Errors
The response uniformity along the 1 meter sensing length is specified to
vary less than
±
7% when tested with a beam of light that is one inch in
width. It is determined by the diffuser and internal optical design.
Spectral Response
The spectral response of the LI-191SA is comparable to that of the
LI-190SA Quantum Sensor. All LI-COR quantum sensors use computer
tailored filter glasses to achieve a response that closely approximates the
desired ideal quantum response. See Figure 4.
Содержание LI-190SA
Страница 17: ...16 Figure 5 LI 200SA Spectral Response Curve ...
