Koji Nakau

Ground calibration of compact infrared camera (CIRC) for earth observation

The compact infrared camera (CIRC) is an uncooled infrared array detector (microbolometer) with the primary goal of detecting wildfires, which are major and chronic disasters affecting numerous countries in the Asia-Pacific region. Eliminating the cooling system reduces the size, cost, and electrical power of the sensor. Two CIRCs have been developed, which will be launched in JFY 2013 and 2014 onboard the Advanced Land Observing Satellite-2 (ALOS-2) and CALorimetric Electron Telescope (CALET). We have finished the ground calibration test of the CIRC Proto Flight Model (PFM) onboard ALOS-2 and CALET. The imaging quality and radiometric quality have been confirmed. We obtained the data needed for image correction and constructed a data correction algorithm. An airborne experiment with a ground test model was also carried out to verify the data correction algorithm. In this paper, we provide an overview of the CIRC and the ground calibration results.

Development of the compact infrared camera (CIRC) for Earth observation

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.

On-orbit performance of the Compact Infrared Camera (CIRC) with uncooled infrared detector

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.

Compact infrared camera (CIRC) for earth observation adapting athermal optics

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.

Comparison of the effects of prior information on the time of liner leak for selecting groundwater remediation design in a heterogeneous aquifer

It is often necessary to use subjective information such that all effective information is used in decision making problems. The methods and key issues for the technical use of subjective information are analyzed. We present a technique for using subjective information about the time of liner leak for the planning of optimal groundwater remediation in an uncertain transmissivity field. The technique uses Monte Carlo simulation and Bayesian estimation theory. We also present applications of the technique to a fictitious problem. The results show that the prior distribution significantly affected optimal design planning. Therefore, the complete exclusion of subjective information may result in an unrealistic overestimate of uncertainty and hinder optimal planning.