Several thousands of 1st Gen IR Systems operated by Integral Stirling Cooler HD1033 are still in service worldwide. Replacing the HD 1033 Stirling by a Linear Drive Cooler will result in a significant reliability enhancement of these IR system of about a factor of three. These attempts had been unsuccessful in the past due to excessive EMI noise induced by the linear cooler compressor. So a main goal for such a development is the elimination of various EMI distortions in the IR system by EMI filtering and shielding. Additionally, the synchronization of the cooler power to the predominant scanning frequency of the IR system significantly improves the image quality. Technical details of the solution, MTTF data and performance data are described in detail.
Advanced Split Linear and Integral Stirling cryocoolers for IR applications are controlled by external or integrated control electronics to provide a stable preset temperature at the focal plane. AIM produces a family of Split Linear Stirling coolers with integrated control electronics inside the compressor housing. The new AM 7 electronic is standardized to one configuration which meets the different input power requirements and temperature settings of all AIM coolers ranging between 10W to 105W input power. AIM has completed the development of the AM 7 electronics to improve temperature stability over the entire range of operating conditions and to optimize ramp up of input power for different cool down conditions. Thus, reduced cooldown time at high ambients and softer startup at low temperatures are achieved. Optionally, the electronics can be supplemented with an external add-on microprocessor unit for advanced system requirements. The 3rd generation electronics will be implemented into rate production 4Q2002.
Performance and reliability parameters of the AIM Stirling coolers have been presented in several previous publications. This paper focuses on recent developments at AIM for the COP improvement of cryocoolers in IR-detectors and systems applications. Improved COP of cryocoolers is a key for optimized form factors, weight and reliability. In addition, some systems are critical for minimum input power and consequently minimum electromagnetic interference or magnetic stray fields, heat sinking or minimum stress under high g-level, etc. Although performance parameters and loss mechanism are well understood and can be calculated precisely, several losses still had been excessive and needed to be minimized. The AIM program is based on the SADA I cryocooler, which now is optimized to carry 4.3 W net heat load at 77K. As this program will lead into applications on a space platform, in a next step AIM is introducing flexure bearings and in a final step, an advanced pulse tube cold head will be implemented. The performance of the SADA II cooler is also improved by using the same tools and methods than used for the performance increase of the SADA I cooler by a factor of two. The main features are summarized together with measured or calculated performance data.
The last 10 years of engineering and production at AEG INFRAROT-MODULE GmbH (AIM) resulted in continued improvements in performance, yield and reliability of IR modules and cryocoolers. For the optimizing of engineering, production and testing over the complete scope, from semiconductor material growth, FPA fabrication, cryo packaging data processing and software, cooling, etc. up to the camera level, AIM has all critical technologies under one roof. This paper demonstrates how such results were achieved, which criteria are to be met for performance, yield and cost improvements and how contemporary IR modules from AIM reflect these achievements.
Conference Committee Involvement (3)
Infrared Technology and Applications XXXII
17 April 2006 | Orlando (Kissimmee), Florida, United States
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