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APPLICATION NOTEAll Sky Kite
Traditionally, Astronomers use CCD camera with a combination of cooling and low readout speed to achieve the long integration times necessary to detect faint objects. However, this approach has two limitations, the dynamic range is limited by the electron well depth of the pixel, and long exposure times are not suitable for tracking fast occurring events such as falling asteroids or space debris.
In addition, since where or when asteroids or debris will fall cannot be known, tracking these kind of objects requires a unique combination of wide fi eld of view, very high sensi-tivity and speed.
Driving CCD camera at 20 frames per second greatly reduces its sensitivity and the amount of collected photons. Only EMCCDs are capable of achieving fast frame rates required for this application, while maintaining good sensitivity levels thanks to the em-bedded on-chip Electron Multiplication (EM gain) which eliminates the readout noise. See Figure 1 and Figure 2, EMCCD allows a gain of sensitivity of up to 4 stellar magnitudes compared to a traditional CCD.
HDR IMAGING AND FAST EVEN TRACKING FOR ASTRONOMY
Figure 150ms exposure time
WITHOUT EM gain. 20mm, F/1 lens.
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APPLICATION NOTEAll Sky Kite
The removal of the readout noise and resulting added sensitivity can be used in two ways:
Lifting the limitation of the pixel well depth and obtain ultra-high dynamic range images. This is achieved through a combination of negligible readout noise and accumulation of short exposure images.Increasing acquisition frame rate in order to capture faint and fast transient events.
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Figure 250ms WITH EM gain
enabled. 20mm,F/1 lens.
SOLAR CELL INSPECTION
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APPLICATION NOTEAll Sky Kite
Ultra HDR with All-Sky Kite
Figure 3Single 100ms exposure time, EM gain
enabled, fi sheye lens f=1.8mm with Kite. Magnitude 3 stars can be detected
Figure 41500x 100ms exposure time fi sheye lens with Kite. Ultra HDR in only 2m30s!
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APPLICATION NOTEAll Sky Kite
Figure 3, shows how a single 100ms exposure allows the detection of stars down to stellar magnitude 3 with 16 bit dynamic range. Figure 4 shows a stack of 1500 images, equivalent to 2min30s cumulated exposure. The resulting image exhibits Ultra-High Dynamic Range (UHDR) from the windows house light and light pollution nearby to the horizon up to the faint Milky Way and many constellations.
Summing images without EM gain doesn’t result in the same increase in dynamic range or sensitivity because of the higher readout noise; see comparison on Figure 5 and Figure 6.
Figure 5500x 50ms exposure time WITHOUT EM gain, 20mm, f/1 lens with Kite
Figure 6500x 50ms exposure time WITH EM gain, 20mm, f/1 lens with Kite
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APPLICATION NOTEAll Sky Kite
With a little luck, the combination of wide angle lens, high sensitivity and fast frame rate detector, the capture of falling meteor into earth’s atmos-phere is possible. See Figure 7.
The camera high sensitivity allows detecting quick changes of the me-teor shape and the way it degrades throughout its entry into the earth’s atmosphere. Moreover, this kind of sequence can tell if meteor remains can be retrieved into the ground.
EM camera performance can also provide with this kind of time capture sequence, information on satellites reentry into earth’s atmosphere, and what and where can be recovered from it on the ground.
METEOR FALLING DETECTION
Figure 7Meteor, 100ms ex-
posure time, 10mm, f/1.8 lens with Kite.
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APPLICATION NOTEAll Sky Kite
CONCLUSION
Raptor Photonics’ Kite, Figure 8, and Alcor System’s All-Sky, Figure 9, com-bination offers the possibility to study random and fast occurring events in the earth’s atmosphere as well as obtaining ultra-high dynamic range im-ages within very short accumulated exposure, all within a proven compact and rugged package.
658 x 596, 10x10µm EMCCD sensor. Enables optimum image resolution in low light imaging applications.B/W EMCCD technology. Enables high sensitivity imaging with up to 1000x on-chip gain. 16 bit CameraLink output. Provides wide dynamic range.53% QE from Virtual Phase sensor. Optimum Photon collection.No Image intensifi er. Optimum B/W image sharpness in ALL light conditions.Interlined. No mechanical shutter required, vibration-less CCD readout.Realtime Imaging. Optimum image sharpness in ALL light conditions.XCAP software compatible. Ready-to-Run powerful Image Analysis Software.185°x185° fi sheye lense. Enables ultimate light collection over the widest possible fi eld of view Active dome defrost and camera auto-iris. Enable all night reliable data acquisitionAnodized aluminum casing, water tight box and connectors. To endure the harshest conditions maintenance free. Dedicated software. For easy automated acquisition and processing.
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Figure 9All-Sky camera
Raptor Photonics’ Kite, Figure 8, and Alcor System’s All-Sky, Figure 9, com-
Figure 8Kite EMCCD camera
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Raptor Photonics Limited is a global leader and manufacturer of high performance, industri-al-grade and extremely rugged ultra-low light digital & analogue cameras. Raptor specializes in complete cameras and core engine solutions using CCD, EMCCD, Scientifi c CMOS and SWIR sensor technology. The extreme low light capabil-ity of Raptor’s cameras makes them ideal for day/night surveillance, homeland security and scien-tifi c markets. Raptor Photonics Ltd is a registered ISO 9001:2008 company and is headquartered in Larne, Northern Ireland.
Raptor Photonics Limited. Willowbank business Park, Larne, Co Antrim, BT40 2SF, Northern Ire-land Registered in Northern Ireland No NI 60799, VAT Reg No: 906 1385 35
Raptor Photonics Ltd Telephone: +44 28 2827 [email protected] www.raptorphotonics.com
ABOUT RAPTOR PHOTONICS
Alcor System was created in 2009 to design and manufacture cutting edge software and instru-mentation for astronomical applications.
PRISM is a powerful software suit for auto-mated astronomical image acquisition and pro-cessing. The “ALL-SKY” outdoor camera range is designed to offer wide angle (180°x180°) contin-uous surveillance of the sky for a wide range of applications from fast meteors and slower sat-ellites tracking to the observation of aurora and nightglow. Alcor System has already delivered products and services to almost 500 customers including individuals (amateurs/professionals) as well as institutes such as ESO, CEA, IMCEE and many other worldwide class observatories.
Alcor System [email protected] www.alcor-system.com
ABOUT ALCOR SYSTEM
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