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.
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.
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.
The Japanese Advanced Optical Satellite (called “ALOS-3”) is a successor of the optical mission of the Advanced Land
Observing Satellite (ALOS) “DAICHI” (2006-2011). The main objectives of the ALOS-3 project are to take images of
the global land area with high GSD (<1 m) and wide swath (>70 km), and build a large image database to prepare for
disasters, etc. By extracting the difference before and after the disaster, the situation of the damage would be grasped
quickly. ALOS-3 also contribute to maintenance and update of the geospatial information of all over the world. The
satellite has capabilities to take stereo images, thus the Digital Surface Model (DSM) of the interested area would also be
provided. The data which will be acquired by ALOS-3 is expected to be useful in various social needs. ALOS-3 is
scheduled to be launch in FY2020.
The "Advanced optical satellite" (tentative name) is a follow-on mission from ALOS. Mission objectives of the advanced optical satellite is to build upon the existing advanced techniques for global land observation using optical sensors, as well as to promote data utilization for social needs. Wide swath and high resolution optical imager onboard the advanced optical satellite will extend the capabilities of earlier ALOS missions. The optical imager will be able to collect high-resolution (< 1 m) and wide-swath (70 km) images with high geo-location accuracy. This paper introduces a conceptual design of the advanced optical satellite.
KEYWORDS: Calibration, Modulation transfer functions, Sensors, Infrared cameras, Satellites, Microbolometers, Temperature metrology, Data corrections, Contrast transfer function, Infrared detectors
Compact Infrared Camera (CIRC) is a technology demonstration instrument equipped with an uncooled infrared array detector (microbolometer) for space application. Microbolometers have an advantage of not requiring cooling system such as a mechanical cooler and are suitable for resource-limited sensor systems. Another characteristic of the CIRC is its use of an athermal optical system and a shutterless system. The CIRC is small in size (approximately 200 mm), is light weight (approximately 3 kg), and has low electrical power consumption (<20 W) owing to these characteristics. The main objective of CIRC is to detect wildfires, which are major and chronic disasters affecting various countries of Southeast Asia, particularly considering the effects of global warming and climate change. One of the CIRCs was launched in May 24, 2014 as a technology demonstration payload of the Advanced Land Observation Satellite-2 (ALOS- 2). Since the initial functional verification phase (July 4–14, 2014), the CIRC has demonstrated functions according to its intended design. We also confirmed that the noise equivalent differential temperature of the CIRC observation data is less than 0.2 K, the temperature accuracy is within ±4 K, and the spatial resolution is less than 210 m in the calibration validation phase after the initial functional verification phase. The CIRC also detects wildfires in various areas and observes volcano activities and urban heat islands in the operational phase. The other CIRC will be launched in 2015 onboard the CALorimetric Electron Telescope (CALET) of the Japanese Experiment Module (JEM) of the International Space Station. Installation of the CIRCs on the ALOS-2 and on the JEM/CALET is expected to increase the observation frequency. In this study, we present the on-orbit performance including observational results of the CIRC onboard the ALOS-2 and the current status of the CIRC onboard the JEM/CALET.
We have developed the Compact Infrared Camera (CIRC) with an uncooled infrared array detector (microbolometer) for space application. Microbolometers have an advantage of not requiring cooling system such as a mechanical cooler, and is suitable for resource-limited sensor system. Another characteristic of the CIRC is its use of athermal optics. The athermal optics system compensates for defocus owing to temperature changes. We also employ a shutter-less system which is a method to correct non-uniformity of the detector without a mechanical shutter.
The CIRC achieves a small size (approximately 200 mm), light mass (approximately 3 kg), and low electrical power consumption (<20 W) by employing athermal optics and a shutterless system.
The CIRC is launched in May 2014 as a technology-demonstration payload of Advanced Land Observation Satellite-2 (ALOS-2). Since the initial functional verification phase (July 4-14, 2014), the CIRC was demonstrated a function according to its intended design. We also confirmed the temperature accuracy of the CIRC observation data is within ±4K in the calibration validation phase after the initial functional verification phase. The CIRC also detected wildfires in various areas and observed the volcano activities in the operational phase.
In this paper, we present the on-orbit performance of the CIRC onboard ALOS-2.
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 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.
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