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A novel Shack-Hartmann high bandwidth two-dimensional wave front sensor was designed and tested, addressing high temporal bandwidth light aberrations due to light-fluid interaction. The new sensor's principles of operation and modifications are presented, and compared against a commercially-available two-dimensional wave front sensor with a 33x44 s...
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... H and H are calibration coefficients which are constant over a large area of the detector. The 68 detectors were mounted on a single substrate and arranged in a % diameter circular pattern (10x10 with removed corners) and % space between each two adjacent PSDs, see Fig. 4, left. The 272 analog voltage signals are sampled by a three data acquisition boards from Microstar Laboratories, Inc., controlled by a data acquisition computer, also used to post-process the acquired data. The sensor electronic design was improved by designing a single transimpedance amplifiers board, which decreases the number of ...
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... wires, and reducing the electronic rack size significantly, compared to the previous %I% wave front sensor 10,11 , were BNC cables were used to connect the system components and four transimpedance amplifiers breakout boxes were used, thus, simplifying the use of the system in different facilities. The new sensor with its electronics are shown in Fig. 4, left, a photo of the old electronic rack data acquisition system is shown in Fig. 4, right. Replacing the charge-coupled device (CCD) array with an array of analog PSDs offers an accurate spot position measurement, a high analog resolution, and a fast response time that could not be achieved with the commercially available wave front ...
Context 3
... %I% wave front sensor 10,11 , were BNC cables were used to connect the system components and four transimpedance amplifiers breakout boxes were used, thus, simplifying the use of the system in different facilities. The new sensor with its electronics are shown in Fig. 4, left, a photo of the old electronic rack data acquisition system is shown in Fig. 4, right. Replacing the charge-coupled device (CCD) array with an array of analog PSDs offers an accurate spot position measurement, a high analog resolution, and a fast response time that could not be achieved with the commercially available wave front sensors. Therefore, the time-consuming CCD data-reduction algorithm was replaced by a ...
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Citations
... This novel sensor can be used to address high temporal bandwidth aero-optical aberrated flows that cannot be addressed by the currently available state-of-art wave front sensors. Progress on the sensor was covered extensively in an earlier report [20] and has been documented in two papers [23,24]. The only portion of this work not previously reported is that the sensor has now been mounted in an enclosure and is now being used to record unsteady wavefront data. ...
This report covers the work performed under ONR Grant number N00014-07-1-0291, entitled "Aero-Optical Investigation of a Pod Directed Energy System." As described herein, the initial effort investigated approaches to using passive flow control to mitigate the presence of shocks over the exit pupil of a relatively large aperture laser beam projected from an underbody pod for an F/A-18 aircraft up to flight Mach numbers of Mach 0.8, and still provide a large field of regard. During the course of the investigation, the Grant Technical Manager redirected our efforts toward studying the aero-optical environment imposed on a laser beam projected from a turret placed underneath a helicopter. The results of both of these studies presented in this report.
Two-dimensional wavefronts were collected in the span-wise direction of a weakly-compressible two-dimensional shear layer. The measurements were made in an attempt to determine the character of the flow in the braid region between coherent structures of the convecting vortical structures. Multiple measurements were taken, including individual wavefront snapshots as well as temporally-resolved high-speed wavefronts. The individual wavefronts show the overall vertical profile of the shear layer, while the high-speed wavefront data capture the convection of the structures across the aperture.
A novel two-dimensional high-bandwidth Shack-Hartmann wavefront sensor was designed and tested, addressing the high temporal bandwidth of aero-optical aberrations caused by compressible flows. The principle of operation and modifications from an earlier version of the wavefront sensor are presented and compared with a commercially available wavefront sensor with a 33×44 subaperture spatial resolution. A two-dimensional wavefront reconstruction algorithm is presented. The comparison was performed over a two-dimensional, acoustically forced heated jet. The high temporal resolution and spatial resolution of the sensor are demonstrated. The results show good agreement between the two sensors.
