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Precision Extended-Area Low Temperature Blackbody BB100-V1
for IR Calibrations in Medium Background Environment
S. Ogarev, M. Samoylov, V. Sapritsky, A. Panfilov
All Russian Research Institute for Optical and Physical Measurements (VNIIOFI), Moscow, Russia.
Suzuki Koichi, Takahiro Kawashima
NEC Toshiba Space Systems, Ltd., Tokyo, Japan
Abstract. Paper reviews a new large-area
high-precision blackbody BB100-V1, designed at
the All-Russian Research Institute for
Opto-Physical Measurements (VNIIOFI, Russia) as
a source within 240 to 350 K temperature range for
preflight calibration of space-borne radiometric
instruments at such research organizations as
NEC TOSHIBA Space Systems and JAXA (Japan),
Keldysh Space Center (Russia). The temperature
non-uniformity and long-term stability account for
less than 0.1K and 0.1% for 1.5 μm to 15 μm
wavelength region under cryo-vacuum conditions
of medium background environment.
Introduction
The 10-year implementation plan for the GEOSS (The
Global Earth Observation System of Systems) program
by representatives of more than 50 countries and more than
30 international organizations, besides the other tasks,
assumes development of optical instruments that can
measure radiance, reflective properties, and radiant
temperature of objects of observation [1]. Calibration of
IR sensors, thermal imagers, instrumentation for remote
earth sensing, signature recognition, and low background
spaceborne radiometers requires development of low- and
near-ambient-temperature reference standard sources
capable of operating in vacuum at low or medium
background conditions. The required accuracy and
long-term stability of measurement account
correspondingly for 0.1% and 0.02% per decade within the
0.2 to 3 μm spectral region; and 0.1K and 0.01K per
decade for 3 to 15 μm region. The most stringent
requirements for radiometric measurements come from
climatology, which requires decades-long high-quality
time series. The uniformity of those measurements should
be based upon uniform scales for the radiometric quantities
to be measured – spectral radiance and spectral irradiance.
The requirements can only be met if the ground calibration
is executed at a very high level of accuracy. As an
additional requirement, many applications require a
compact standard planckian source – blackbody (BB) for
near ambient temperatures operating both in vacuum and
in air with optional window and having high accuracy in
temperature setting.
In order to provide complete metrological support and
such precise pre-flight calibration of spaceborne
instruments, the development of precision BB sources of
radiation operating within VIS-IR wavelength ranges, like
BB100-V1, is of a great importance.
Blackbody BB100-V1 specifications
The blackbody BB100-V1 under consideration is
basically an extended area blackbody for low temperatures
(250 K up to 350 K), which operates under cryo-vacuum
conditions. The BB100-V1 was designed and
manufactured designed at the All-Russian Research
Institute for Opto-Physical Measurements (VNIIOFI,
Russia) for calibration of space-borne radiometric
instruments at NEC TOSHIBA Space Systems; JAXA
(Japan), and Keldysh Space Center (Russia). BB100-V1
specifications (obtained in tests) are presented in Table 1.
Table 1. BB100-V1 specifications
Parameter
Value
Operating temperature range
240 K - 350 K
Spectral range
1.5 μm – 15 μm
Cavity effective emissivity 0.997 ± 0.001
Opening (non-precision aperture)
Ø100 mm
System Field-of-View (FOV) 12 mrad (0.688º)
Environment operation
conditions
Temperature non-uniformity
across opening
Temperature set point resolution
Maximum temperature instability
under thermostabilization
Limitation on the blackbody
warning-up time (approx.)
Total Wattage (approx.)
Input Voltage
Blackbody temperature set up
and control
Temperature sensors for control
system
Calibration traceability of Pt
RTD to NIST
Operating Environment Pressure
Orientation of the blackbody
Cable (tubing) length
BB100-V1 prototypes and realization
Vacuum chamber
(10 -6 Torr, below 100 K)
Air environment
(clean room at 23 ± 3ºC)
0.1 K
0.01 K
0.05 K
2 hrs.
3500 W
(with usage of thermostat
LAUDA Proline PR1845)
100 V AC or 200 V AC
External controller with
RS-232 interface to
(optional) PC computer
Pt RTD, 5 pieces
(by MINCO Products, Inc.)
Yes, assumed for one
Pt RTD only
10 -6 Torr
Facing down (±30º leaned)
5 m inside and outside
vacuum chamber
In order to meet the requirements to accuracy and
long-term stability of measurements, the design of
BB100-V1 was based on the prototypes of high-precision
unique BBs developed within the last decade at VNIIOFI
[2,3]. Among them there are variable-temperature and
fixed-point models BB100, BB300, BB900, BB1000,
Proceedings NEWRAD, 17-19 October 2005, Davos, Switzerland 269