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ASCENT & ALTA: SHARED FEATURES ASCENT & ALTA: SHARED FEATURES

Interline transfer CCDs ï¬� rst shift charge from the photodiode in each pixel to the masked storage diode, and then march the charge through the storage diodes to the serial register. Acquisition of a new image in the photodiodes during readout of the previous image is called “progressive scan.” Alta and Ascent cameras both support progressive scan with interline CCDs. Alta and Ascent cameras support readout of an arbitrary sub-section of the array in order to speed up frame rate. Reading half the array, for example, does not increase the frame rate by two because of overhead required in discarding unwanted pixels. The Alta and Ascent camera systems accept external hardware trigger signals through their camera I/O ports for a number of purposes. Software and hardware triggers can be used together. For example, a software or hardware trigger may be used to initiate a single exposure or a sequence of exposures of a speciï¬� c duration and speciï¬� c delay between exposures. Alternatively, a software trigger may be used to start a sequence, and the external trigger can be used to trigger each subsequent image in the sequence. In addition, the external trigger can be used to trigger row shifts for time-delayed integration, or can be used to trigger block shifts for kinetic imaging.

ASCENT & ALTA: SPECIAL MODES OF OPERATION ASCENT & ALTA: SPECIAL MODES OF OPERATION

INTERNAL INTERNAL MEMORY MEMORY PROGRAMMABLE PROGRAMMABLE LEDs LEDs EXTERNAL EXTERNAL TRIGGERING TRIGGERING
TIME-DELAYED TIME-DELAYED INTEGRATION INTEGRATION KINETICS KINETICS MODE MODE IMAGE IMAGE SEQUENCES SEQUENCES
32 Mbytes of SDRAM image memory is included in the Alta U Series and Ascent camera heads. 24 Mbytes of image memory is included in the Alta E Series camera head. Local memory serves some important functions:First, with any network connection and even USB2.0 connection, consistency in download rates cannot be guaranteed. Some manufacturers go to great lengths to attempt to lock Windows Image sequences of up to 65535 images can be acquired and transferred to camera / computer memory automatically. A delay may be programmed between images from 327 microseconds to 21.43 seconds. (This does not mean you can acquire images every 327 microseconds; it means you can program a delay of 327 microseconds between the end of a readout and the start of the next exposure.) The Ascent and Alta platforms allow for three types of image sequencing:Application-Driven Sequencing: Fast back to back sequencing This is a special form of precision back to back sequencing designed for a fi xed <1 microsecond spacing between a pair of interline CCD exposures. The caveat with this mode is that the exposure times for each image must be greater than the readout time for the image. For example, if using the A2000, the readout time for a full frame is about 0.2 seconds so your exposure would need to be in excess of 0.2 seconds. (Ratio Imaging - Interlines only) Precision back to back sequencing Alta and Ascent incorporate a fi rmware controlled back to back image sequencing mode suitable for image-image intervals from 327uS to a maximum of 21.43 seconds in 327uS intervals. This provides for precision spacing of images in a sequence where windows applications cannot respond. Two LEDs on the side can be programmed to show status of a variety of the camera functions, such as the camera has reached the set temperature, the shutter is open, or the camera is waiting for an external trigger. Alternatively, the LEDs can be turned off if you are concerned about stray light. The E Series cameras also have two green LEDs that indicate status of the network connection. This is the most common form of image sequencing. The application merely takes a specifi ed number of successive images. This type of sequencing is suitable when the time between image acquisitions is not short and where slight differences in timing from image to image are not important. ® up during downloads to ensure that no pattern noise results from breaks in the digitization process, but such a lockup is not possible with network interfaces. The Alta and Ascent systems buffer the image transfer to protect from noise-producing interruptions.Second, on heavily loaded USB2 ports, slower USB1.1 applications, loaded networks, or slower TCP/IP transfers, the maximum digitization rate could be limited without a local buffer. Local image memory allows very fast digitization of image sequences up to the limit of the internal camera. The maximum digitization-to- memory rates for 100baseT systems is 1.4 megapixels per second, while the maximum digitization-to-memory rates for Alta USB systems is 11 megapixels per second, and Ascent is 20 megapixels/second..There is a fundamental difference in the way the Alta USB2 and network image buffers function. The USB2 image buffer is capable of transferring data to the host while digitization of the CCD is active. As long as the USB2 transfer speed is greater than the digitization rate, the memory buffer will never ï¬� ll. The network memory buffer requires the image digitization to complete prior to transfer across the network. More formally known in astronomy as time-delay integration (TDI), this technique is a powerful tool for applications requring the scan of an area larger than the CCD’s ï¬� eld of view. The image is clocked down the CCD in syncronization with the object’s movement. The CCD must be precisely aligned with the movement of the scene.The simplest way to illustrate TDI is an astronomical application. The telescope is kept stationary, and the CCD is precisely aligned with the sky. As the Earth rotates and the sky drifts, the image on the CCD is precisely clocked to continue building the image. When the image reaches the last row, it is read to the host computer and added to a continuous strip of sky. The TDI capability utilizes a 25 MHz time base (Ascents use a 48 MHz time base) and local memory to achieve consistent high resolution performance. TDI mode allows the user to adjust the row shift rate. Timing may be adjusted in 5.12 microsecond increments to a maximum of 336 milliseconds per row shift. The minimum TDI shift time is the digitization time for one row. TDI cannot be done with cameras using interline CCDs, such as the U2000 and U4000. SOFTWARE SOFTWARE
SEALED SEALED INNER CHAMBERS INNER CHAMBERS MaxIm DL/CCD software is standard with every Alta, as well as an ActiveX driver that is universal to all Apogee Alta and Ascent cameras, as well as legacy AP and KX cameras. If you write custom code for an Apogee camera, you won’t have to change it later if you change models. Our cameras are also supported by other programs like CCDSoft. A Linux and Mac OS X drivers are also available. The sensors for Alta and Ascent cameras are sealed into an inner chamber ï¬� lled with argon. The chamber has a lifetime guarantee against condensation. PROGRESSIVE PROGRESSIVE SCAN SCAN (CONTINUOUS IMAGING) (CONTINUOUS IMAGING) UPGRADEABLE UPGRADEABLE FIRMWARE FIRMWARE
When the number of desired exposures has been reached, or the CCD has been fi lled (whichever comes fi rst), the entire array is read out and digitized. If you want to use the entire CCD including the exposed area, then the light source needs to be shuttered after the fi nal exposure (externally, electronically, or electromechanically). or using an electromechanical shutter). The image in the exposed area is shifted to the masked area per software command, pre- set shift frequency, or external trigger. The number of rows per section is predetermined and constant. Kinetics Mode assumes that the user has optically masked off all but the top most section of the CCD. This exposed section is illuminated, shifted by x rows, then exposed again until the user has exposed the entire surface of the CCD with y image slices. The Alta and Ascent systems load all camera operating code on camera start. These confi guration fi les can be updated via the web as we add features and make improvements. Each camera head has coded information identifying the type of system, its confi guration, and type of CCD used, as well as the fi rmware revision in use. This allows automatic confi guration of the camera in the fi eld and better customer support from our offi ces. SUBARRAY SUBARRAY READOUT READOUT HARDWARE HARDWARE BINNING BINNING
Every Alta and Ascent camera supports hardware binning up to 8 in the horizontal direction and up to the height of the CCD in the vertical direction. Binning can be used to increase frame rate, dynamic range, or apparent sensitivity by collecting more light into a superpixel. See additional detail under CCD University on our website. TWO-YEAR TWO-YEAR WARRANTY WARRANTY
All Apogee cameras have a standard two-year warranty and a lifetime guarantee against condensation in the camera. Image courtesy of Prof. Dale Hunter, Tufts University, MARaman image and spectrum acquired using KestrelSpec TM software from Catalina Scienti� c (www.catalinasci.com)

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Speci� cations subject to change without notice. Speci� cations subject to change without notice.