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FMP300JR-52-5K1_Yageo

来源:LM317 Electronics Components编辑:Future Technology Devices International, Ltd.时间:2021-06-14 04:00:46

Itera may be partitioned into anywhere from 100 to 1,024 sub-arrays, which means it can undergo anywhere from 100 to 1,024 programming cycles.

The size of the hybridization bumps was calculated to ensure that the resonance cavity would be tuned to the wavelength to be absorbed. This cavity comprises the bolometer array, and a reflector, positioned over the CMOS circuit: this promotes maximum absorption of the incident wave, close to unity. Absorption occurs on metal deposited onto the array, exhibiting a surface impedance matching that of the vacuum.

Array’s twofold advantage The silicon bolometer array is suspended by way of very thin (≈ 2 mm), low-thermal-conductivity beams. This setup allows the tenuous absorbed radiation to induce a measurable rise in temperature. Finally, a doped-silicon thermometer, positioned at the center of the array, effects the measurement, making use of an exponential law, relating resistance to temperature. This exhibits a temperature coefficient close to 3,000%/K. Compared to a solid” surface, the array affords a twofold advantage: first, a lower heat capacity is exhibited, ensuring a swifter thermal response rate; second, it is less susceptible to the ionizing cosmic particles in the space environment. Obviously, the use of an array to absorb light may raise questions: would not such light get through” the gaps in the array? No, because light does not detect” details smaller than its own wavelength. All that is required is to fabricate an array with a pitch smaller than the wavelength to be detected.

FMP300JR-52-5K1_Yageo

As regards the 16×16-pixel modules, every one of them was individually evaluated, several years before launch of the mission and based on their performance, they were integrated into the focal planes, and calibrated a first time. Once the complete camera had been integrated into the PACS instrument – including its cryocooler, and flight electronics – final calibration was carried out. Early in 2008, the PACS instrument in turn was mounted on board the Herschel satellite, alongside SPIRE, and HIFI (Heterodyne Instrument for the Far Infrared). After the final adjustments, e.g. replacing faulty connectors and rerouting cables to preclude interference from the solar panels, the satellite was determined to be ready for service” in December 2008.

Currently, the development teams for this sub-millimeter camera are switching the thrust of their effort along two directions:

The first direction involves taking the PACS bolometer arrays to longer wavelengths, in order to fit them to large ground-based telescopes. Such an operation requires that these arrays are first adjusted to cater to the various atmospheric windows,” i.e. the various narrow spectral bands for which the atmosphere (at altitude) does not prove wholly opaque (200mm, 350mm, 450mm, 865mm). The benefit accruing from this development work has less to do with measurement sensitivity (there being no way of matching spaceborne performance) than with the use of very large telescopes (12–15 meters in diameter), affording far higher resolving power. Adjusting the arrays to the longer wavelengths will chiefly involve increasing the size of the hybridization bumps.

FMP300JR-52-5K1_Yageo

The other avenue is concerned with the development of far more sensitive detectors, intended for future space missions.

Currently, two projects are already benefiting from this development work. The ArTéMis (Architecture de bolomètres pour les télescopes submillimétriques au sol: Bolometer Architecture for Ground-based Submillimeter Telescopes) is a 5,000-pixel bolometer-array camera intended for the Atacama Pathfinder Experiment (APEX) Telescope, sited in Chile.  The PILOT (Polarized Instrument for Long-wavelength Observation of the Tenuous Interstellar Medium) is an experiment featuring two focal planes, carried by balloon, to measure the polarized radiation emission from the Milky Way.

FMP300JR-52-5K1_Yageo

Finally, bolometer optimization should also prove useful to a variety of very-low-background-flux applications. Such is the case in SPICA (Space Infrared Telescope for Cosmology and Astrophysics), a space mission conducted by the Japan Aerospace Exploration Agency (JAXA), in collaboration with the European Space Agency (ESA). Launch is scheduled for 2018. This space telescope will use the same mirror as Herschel, cooled however to –268°C. In order to optimize to the utmost this new configuration, researchers will need to raise detector sensitivity by a factor 100, at least. To achieve such sensitivity (background noise power of 10–18 watt), the silicon bolometer cooling will be enhanced, down to 0.05 Kelvin.

In order to meet the challenges set by this new mission, CEA has embarked on a preliminary study phase. For example, research scientists at CEA’s Low Temperatures Service are already working on the design of an adiabatic demagnetization cryocooler for space applications. SPICA should pave the way for other exciting projects, e.g. the spaceborne FIRI (Far-Infrared Interferometry) experiment, involving use of bolometers, or the BPOL (Cosmic Microwave Background Polarization) experiment, at 3 K.

Because most low power processor centric radio designs require a microcontroller to handle all the intelligence for the transceiver, the microcontroller needs to be awake the entire time, which requires additional power. Instead, by using a more energy efficient communication controller approach, the transceiver can transmit and receive the data independently from the microprocessor. Thus the microprocessor is only awakened and used when it is needed to further process the data. Synchronizing the wake ups means that the communications controller decides when to wake up and check for messages. The device can be off most of the entire time – thereby greatly reducing overall energy consumption. This is especially effective for the home's various environmental, security and location sensors. Because of the scheduler and synchronizer inside the communication controller, the system only wakes up for a brief moment to check to see if there are any messages and then goes back to sleep.

By using a hardware based scheduler and synchronizer within the chip itself, the radio only wakes up as needed to see if there is any data that needs to be sent. If not, it returns to sleep. If there is data to be sent, the controller then wakes up the microcontroller. The chip then communicates the information and then goes back to sleep until the next time it is scheduled to wake. 9999 times out of 10,000 – there is no message to be sent and the controller does not need to energize the microprocessor. Every time that data is sent, the chips also transmit a synchronization message to ensure that they all wake up together on the next duty cycle.

Figure 4 illustrates that by letting the communications controller decide when to wake up and check for messages, it is possible to greatly reduce overall energy consumption. Because of the scheduler and synchronizer inside the communication controller, the system only wakes up for a brief moment to check to see if there are any messages and goes back to sleep.

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