The Compact Infrared Camera (CIRC) is an instrument equipped with an uncooled infrared array detector (microbolometer). We adopted the microbolometer, because it does not require a cooling system such as a mechanical cooler, and athermal optics, which does not require an active thermal control of optics. This can reduce the size, cost, and electrical power consumption of the sensor. <p> </p>The main mission of the CIRC is to demonstrate the technology for detecting wildfire, which are major and chronic disasters affecting many countries in the Asia-Pacific region. It is possible to increase observational frequency of wildfires, if CIRCs are carried on a various satellites by taking advantages of small size and light weight. <p> </p>We have developed two CIRCs. The first will be launched in JFY 2013 onboard Advanced Land Observing Satellite-2 (ALOS- 2), and the second will be launched in JFY 2014 onboard CALorimetric Electron Telescope (CALET) of the Japanese Experiment Module (JEM) at the International Space Station(ISS). We have finished the ground Calibration of the first CIRC onboard ALOS-2. In this paper, we provide an overview of the CIRC and its results of ground calibration.
Sumitomo Heavy Industries, ltd. (SHI) has been developing cooler and Dewar technology for space application with
Japan Aerospace Exploration Agency. SHI has four types of coolers to cover temperature range from 1.7K to 80K or
more. Those are Single stage Stirling coolers for 80K, two-stage Stirling coolers for 20K, 4K-class cooler and 1K-class
cooler. 4K and 1K class coolers consist of a Joule-Thomson cooler and a two-stage Stirling as a pre-cooler. SHI also
provided Dewars. In this paper, SHI’s cooler and Dewar technology are described.
Vegetation LIDAR, which measures an accurate canopy height, has been studied by JAXA. Canopy height is a very important parameter to estimate forest biomass, and global measurement of accurate canopy height leads to better understanding of the global carbon cycle. The vegetation LiDAR is designed based on the assumption that it is to be mounted on the Exposed Facility (EF) of the Japanese Experiment Module (JEM, also known as “Kibo”) on the International Space Station (ISS). The vegetation LIDAR uses an array detector (2x2) for dividing the ground footprint, making it possible to detect the slope of the ground for improving the accuracy of canopy height measurement. However, dividing the footprint may cause a reduction in reflected lights and signal-to-noise ratio (SNR); hence, the vegetation LiDAR system needs high sensitivity and low-noise array detector module. We made a prototype of the array detector module and it satisfied the tentative target SNR which we set. This presentation will introduce the mission objectives, the LiDAR system including experimental prototypes of array detector module, and some results of the study.
Fourier transform spectrometer (FTS) has many advantages, especially for greenhouse gases and air pollution
detection in the atmosphere, because a single instrument can provide wide spectral coverage and high spectral
resolution with highly stabilized instrumental line function for all wavenumbers. Several channels are usually
required to derive the column amount or vertical profile of a target species. Near infrared (NIR) and shortwave
infrared (SWIR) spectral regions are very attractive for remote sensing applications. The GHG and CO of
precursors of air pollution have absorption lines in the SWIR region, and the sensitivity against change in the
amounts in the boundary layer is high enough to measure mole fractions near the Earth surface. One disadvantage
of conventional space-based FTS is the spatial density of effective observation.
To improve the effective numbers of observations, an imaging FTS coupled with a two-dimensional (2D)-camera
was considered. At first, a mercury cadmium telluride (MCT)-based imaging FTS was considered. However, an
MCT-based system requires a calibration source (black body and deep-space view) and a highly accurate and
super-low temperature control system for the MCT detector. As a result, size, weight, and power consumption are
increased and the cost of the instrument becomes too high. To reduce the size, weight, power consumption, and
cost, a commercial 2D indium gallium arsenide (InGaAs) camera can be used to detect SWIR light. To
demonstrate a small imaging SWIR-FTS (IS-FTS), an imaging FTS coupled with a commercial 2D InGaAs camera
was developed. In the demonstration, the CH4 gas cell was equipped with an IS-FTS for the absorber to make the
spectra in the SWIR region. The spectra of CH4 of the IS-FTS demonstration model were then compared with
those of traditional FTS. The spectral agreement between the traditional and IS-FTS instruments was very good.
Owing to its high specific stiffness and high thermal stability, silicon carbide is one of the materials most suitable for large space-borne optics. Technologies for accurate optical measurements of large optics in the vacuum or cryogenic conditions are also indispensable. Within the framework of the large SiC mirror study program led by JAXA, we manufactured an 800-mm-diameter lightweight telescope, all of which is made of HB-Cesic, a new type of carbon-fiber-reinforced silicon carbide (C/SiC) material developed jointly by ECM, Germany and MELCO, Japan. We first fabricated an 800-mm HB-Cesic primary mirror, and measured the cryogenic deformation of the mirror mounted on an HB-Cesic optical bench in a liquid-helium chamber. We observed the cryo-deformation of 110 nm RMS at 18 K with neither appreciable distortion associated with the mirror support nor significant residual deformation after cooling. We then integrated the primary mirror and a high-order aspheric secondary mirror into a telescope. To evaluate its optical performance, we established a measurement system, which consists of an interferometer in a pressure vessel mounted on a 5-axis adjustable stage, a 900-mm auto-collimating flat mirror, and a flat mirror stand with mechanisms of 2-axis tilt adjustment and rotation with respect to the telescope optical axis. We installed the telescope with the measurement system into the JAXA 6-m chamber and tested them at a vacuum pressure to verify that the system has a sufficiently high tolerance against vibrations in the chamber environment. Finally we conducted a preliminary study of sub-aperture stitching interferometry, which is needed for telescopes of our target missions in this study, by replacing the 900-mm flat mirror with a rotating 300-mm flat mirror.
We have developed the compact infrared camera (CIRC) with an uncooled infrared array detector (microbolometer) for
space application. The main mission of the CIRC is the technology demonstration of the wildfire detection using a large
format (640×480) microbolometer. Wildfires are major and chronic disasters affecting numerous countries, especially in
the Asia-Pacific region, and may get worse with global warming and climate change.
Microbolometers have an advantage of not requiring cooling systems such an a mechanical cooler, and is suitable for
resource-limited sensor systems or small satellites. Main characteristic of the CIRC is also an athermal optics. The
thermal optics compensates the defocus due to the temperature change by using Germanium and Chalcogenide glass
which have different coefficient of thermal expansion and temperature dependence of refractive index. The CIRC
achieves a small size, light weight, and low electrical power by employing the athermal optics and a shutter-less system.
Two CIRCs will be carried as a technology demonstration payload of ALOS-2 and JEM-CALET, which will be
launched in JFY 2013 and 2014, respectively. We have finished the ground calibration test of the CIRC Proto Flight
Model (PFM). Athermal optical performance of the CIRC have been confirmed by measuring modulation transfer
function (MTF) in a vacuum environment and at environmental temperature from -15 to 50 °C. As a result, MTF was
found to be effective at capturing clear images across the entire range of operating temperatures. We also provide an
overview of the CIRC and radiometric test results in this presentation.
We present the development status of Type II superlattice (T2SL) infrared detector in JAXA. Since 2009, we have
started a basic research on InAs/GaSb T2SL infrared detectors. Our final goal is to realize the T2SL array detector
having a cutoff wave length of λc=15 μm.
In order to confirm a technical feasibility of 15 μm cutoff T2SL detector, we fabricated T2SL samples having a different
thickness of InAs/ 7 monolayers (ML) GaSb. These crystals are designed for the cutoff wavelength from 6 μm to 15
μm. The X-ray Diffraction measurement shows a mismatch between the substrate and superlattice layers is below
0.006%. The surface morphology of the samples with an atomic force microscope is 1.5-3.3 Å RMS for 5×5 μm square
regions. We also fabricated single pixel detectors with these crystals. We show the results of the spectral response
measurement using a FTIR system. We also show the development status of an array detector. The array detector having
the cutoff wavelength of 6 μm is successfully demonstrated. However, further improvements are required for a future 15
μm cutoff array detector.
It is very important to watch the spatial distribution of vegetation biomass and changes in biomass over time,
representing invaluable information to improve present assessments and future projections of the terrestrial carbon cycle.
A space lidar is well known as a powerful remote sensing technology for measuring the canopy height accurately. This
paper describes the ISS(International Space Station)-JEM(Japanese Experimental Module)-EF(Exposed Facility) borne
vegetation lidar using a two dimensional array detector in order to reduce the root mean square error (RMSE) of tree
height due to sloped surface.
We have developed Compact Infrared Camera (CIRC) with an uncooled infrared array detector (microbolometer) for
space applications. The main mission of the CIRC is to demonstrate technology for wildfire detection. Wildfires are a
major and chronic disaster that affects many countries, especially those in the Asia-Pacific region, and the situation may
get worse with global warming and climate change. The CIRC detector has the largest format (640 × 480 pixels) ever
used for observations of Earth from space. Microbolometers have the advantage of not requiring cooling systems such as
a mechanical cooler and are suitable for resource-limited sensor systems or small satellites. In addition, the CIRC
employs athermal optics and a shutter-less system, and hence, it is of a small size, is lightweight, and consumes low
electrical power. The CIRC design was based on a commercial infrared camera and employs commercial-off-the-shelf
(COTS) parts to reduce the cost and time for development. The CIRC will be carried as a technology demonstration
payload of ALOS-2 and ISS/JEM, which will be launched in 2013 and 2014. We have developed the CIRC Proto Flight
Model (PFM) and performed experiments for calibration in January 2012. In this paper, we present the verification
results of the athermal characteristics and the calibration of the shutter-less system.
The performance of space-borne infrared detectors is required higher sensitivity, higher resolution, or larger format in
comparison with that of ground-based infrared detectors. In order to realize higher mission requirements, JAXA decided
to position the infrared detector technology as one of the strategic technologies of JAXA and to promote the
development of the infrared detectors.
InAs/GaSb Type II superlattice (T2SL) is the only known infrared material that has a theoretically predicted higher
performance than HgCdTe. If the T2SL detector is realized, it can be applied for high sensitivity infrared sensors, which
are required for many advanced instruments such as an imaging Fourier Transform Spectrometer. The final goal of the
T2SL detector development is to realize an array detector having a cutoff wavelength of λc=15μm.
We have started a basic research on the T2SL detector. In this paper, we report on the first results of the development of
T2SL detectors of mid-wave infrared regime. The detector structure is a pin photodiode with SL of 9 InAs monolayers
(MLs) and 7 GaSb MLs. We present results of optical evaluation of the detector. The cutoff wavelength is 5.5μm at 30K.
The responsivity is 0.33±0.05A/W at 4.5 μm.
We report the development of a 2-million-pixel, that is, a 2000 x 1000 array format, SOI diode uncooled IRFPA with 15
μm pixel pitch. The combination of the shrinkable 2-in-1 SOI diode pixel technology, which we proposed last year ,
and the uncooled IRFPA stitching technology has successfully achieved a 2-million-pixel array format. The chip size is
40.30 mm x 24.75 mm. Ten-series diodes are arranged in a 15 μm pixel. In spite of the increase to 2-million-pixels, a
frame rate of 30 Hz, which is the same frame rate as our former generation (25 μm pixel pitch) VGA IRFPA, can be
supported by the adoption of readout circuits with four outputs. NETDs are designed to be 60 mK (f/1.0, 15 Hz) and 84
mK (f/1.0, 30 Hz), respectively and a τ<sub>th</sub> is designed to be 12 msec. We performed the fabrication of the 2-million-pixel
SOI diode uncooled IRFPAs with 15 μm pixel pitch, and confirmed favorable diode pixel characteristics and IRFPA
operation where the evaluated NETD and τ<sub>th</sub> were 65 mK (f/1.0, 15 Hz) and 12 msec, respectively.
This paper reports on a space-qualified cooling system for submillimeter SIS mixer receiver (SIS: superconductor- insulator-superconductor). Designed cooling capacity of the system is 20 mW at 4.5 K, 200 mW at 20 K, and 1000 mW at 100 K. The combination of two-stage Stirling cooler and Joule- Thomson one has demonstrated the capacity with a power consumption of less than 300 W, including losses of drive electronics. The cryostat has a thermal insulation structure of S2-GFRP straps to fasten its 100 K stage. 20 K stage of the cryostat is held with GFRP pipes on the 100 K stage, while 4 K stage is supported with CFRP pipes on the 20 K stage. The cooling system accommodates two SIS mixers at 4.5 K, two IF amplifiers at 20 K, and two more IF amplifiers at 100 K. The mass of the cooling system is 40 kg for the mechanical cooler itself, 26 kg for the cryostat, and 24 kg for the driver electronics. The system has been developed for a 640 GHz receiver for an atmospheric limb-emission sounder SMILES, which is to be aboard the International Space Station in 2005. The engineering model of the system has been built and tested successfully.
A submillimeter wave limb emission sounder, that is to be aboard the Japanese Experiment Module (JEM, dubbed as 'KIBO') at the International Space Station, has been designed. This payload, Superconducting Submillimeter-wave Limb Emission Sounder (SMILES), is aimed at global mappings of stratospheric trace gasses by means of the most sensitive submillimeter receiver ever operated in space. Such sensitivity is ascribed to a Superconductor-Insulator- Superconductor (SIS) mixer, which is operated at 4.5 K in a dedicated cryostat combined with a mechanical cooler. SMILES will observe ozone-depletion-related molecules such as ClO, HCl, HO<SUB>2</SUB>, HNO<SUB>3</SUB>, BrO and O<SUB>3</SUB> in the frequency bands at 624.32 - 626.32 GHz, and 649.12 - 650.32 GHz. A scanning antenna will cover tangent altitudes from 10 to 60 km in every 53 seconds, while tracing latitudes from 38S to 65N along its orbit. This global coverage makes SMILES a useful tool of observing the low- and mid-latitudinal areas as well as the Arctic peripheral region. The molecular emissions will be detected by two units of acousto-optic spectrometers (AOS), each of which has coverage of 1.2 GHz with a resolution of 1.8 MHz. This high-resolution spectroscopy will allow us to detect weal emission lines attributing to less-abundant species.
A submillimeter limb-emission sounder, that is to be aboard the Japanese Experiment Module (JEM, dubbed as KIBO) at the International Space Station, has been designed. This payload, Superconducting Submillimeter-wave Limb-emission Sounder (SMILES), is aimed at global mappings of stratospheric trace gases by means of the most sensitive submillimeter receiver ever operated in space. Such sensitivity is ascribed to a Superconductor-Insulator- Superconductor (SIS) mixer, which is operated at 4.5 K in a dedicated cryostat combined with a mechanical cooler. SMILES will observe ozone-depletion-related molecules such as ClO, Hcl, HO<SUB>2</SUB>, HNO<SUB>3</SUB>, BrO and O<SUB>3</SUB> in the frequency bands at 624.32-626.32 GHz and 649.12-650.32 GHz. A scanning antenna will cover tangent altitudes from 10 to 60 km in every 53 seconds, while tracing the latitudes form 38 S to 65 N along its orbit. This global coverage makes SMILES a useful tool of observing the low- and mid- latitudinal areas as well as the Arctic peripheral region. The molecular emissions will be detected by two units of acousto-optic spectrometers (AOS), each of which has coverage of 1.2 GHz with a resolution of 1.8 MHz. This high-resolution spectroscopy will allow us to detect weak emission lines attributing to less-abundant species.
Design of the OCTS, a high-precision remote-sensing instrument for NASDA's Advanced Earth Observing Satellite (ADEOS) for simultaneous measurements of the ocean color and sea-surface temperatures, is presented. The OCTS uses a rotating mirror to scan a swath of the earth 1400 km wide from sun-synchronous orbit at 800 km altitude. It is planned to be placed into orbit in 1995 to provide 3 Mbps image data for visible to thermal infrared spectral range, in 12 bands.
The Advanced Earth Observing Satellite (ADEOS) installs eight sensors for earth observation, including two core sensors developed by the National Space Development Agency of Japan (NASDA). ADEOS is planned to develop Japanese earth observation technology and to contribute to international monitoring of global environmental change of the Earth. The ADEOS program is now in phase C (basic design phase). Preliminary design review was held in summer 1991.
The Ocean Color and Temperature Scanner (OCTS) is a piece of observation equipment that measures ocean color and temperature from a scientific satellite. The OCTS is equipped with two focal plane assemblies: one observes ocean color in the range of visible to near infrared, and the other measures ocean temperature in the infrared region. We report here results of the so-called break boad model of the latter focal plane assembly. This focal plane assembly contains four infrared detectors that are cooled to 100 K by radiational cooling. We have evaluated this cooled focal plane assembly, and have confirmed that it has satisfied such NEP (noise equivalent power) values, registration accuracy and power consumption as are required in view of the OCTS performance characteristics.