Microbolometer characterization with the electronics prototype of the IRCAM for the JEM-EUSO mission

Abstract

JEM-EUSO is a space observatory that will be attached to the Japanese module of the International Space Station (ISS) to observe the UV photon tracks produced by Ultra High Energy Cosmic Rays (UHECR) interacting with atmospheric nuclei. The observatory comprises an Atmospheric Monitoring System (AMS) to gather data about the status of the atmosphere, including an infrared camera (IRCAM) for cloud coverage and cloud top height detection. This paper describes the design and characterization tests of IRCAM, which is the responsibility of the Spanish JEM-EUSO Consortium. The core of IRCAM is a 640x480 microbolometer array, the ULIS 04171, sensitive to radiation in the range 7 to 14 microns.The microbolometer array has been tested using the Front End Electronics Prototype (FEEP). This custom designed electronics corresponds to the Breadboard Model, a design built to verify the camera requirements in the laboratory. The FEEP controls the configuration of the microbolometer, digitizes the detector output, sends data to the Instrument Control Unit (ICU), and controls the microbolometer temperature to a 10 mK stability. Furthermore, the FEEP allows IRCAM to preprocess images by the addition of a powerful FPGA. This prototype has been characterized in the laboratories of Instituto de Astrofisica de Canarias (IAC). Main results, including detector response as a function of the scene temperature, NETD and Non-Uniformity Correction (NUC) are shown. Results about thermal resolution meet the system requirements with a NETD lower than 1K including the narrow band filters which allow us to retrieve the clouds temperature using stereovision algorithms.

Performance Assessment of Low-Cost Thermal Cameras for Medical Applications

“…This camera has been previously used for prototyping and testing purposes in astrophysics instrumentation [31]. However, it has to be mentioned that new microbolometers with 1024 × 960 pixels already exist in the market.…”

“…The NETD is a figure of merit for infrared sensors which represents the temperature change that produces an output signal equivalent to the rms noise [31,[38][39][40][41]. Thus, this value defines the thermal resolution, that is, the minimum resolvable temperature increment, which can be expressed as follows [34]:…”

“…Therefore, the same setup and methodology were used in all performed tests to ensure comparable results. In order to compute the spatial noise without including unwanted non-uniformity effects, an accurate procedure previously used at our laboratory for scientific tests was employed [31]. This procedure consisted of acquiring a series of one hundred consecutive images and, subsequently, subtracting consecutive images pairwise, thereby offering ninety-nine differential images and ensuring the removal of the constant non-uniformity.…”

“…In this work, NUC was performed in a controlled environment, that is, the climatic chamber's temperature was set at 25 • C. An LSE with nine blackbody (T obj ) temperature points was employed, ranging from 10 • C to 50 • C in 5 • C steps. A set of sixteen images for each temperature point were acquired following the previously described procedure [31,47]. Once G i,j and B i,j are computed, the corrected image, X i,j , and its mean value are defined as follows:…”

“…Furthermore, the quality of the correction provided by the same NUC algorithm can vary according to the respective camera characteristics, such as the noise, the stability of the measurements and other features included in the cameras as internal shutters (ST and INO IRXCAM-640) or TECs to stabilize the FPA temperature (INO IRXCAM-640). In order to validate the quality of the performed NUCs, the residual non-uniformity (RNU) was estimated as described in [31,48]:…”