Infrared two-dimensional acoustooptic deflector using a tellurium crystal

Souilhac, Dominique Jacques; Billerey, D.; Gundjian, A.A.

doi:10.1364/ao.29.001798

Cited by 26 publications

(20 citation statements)

References 14 publications

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“…sin(a) = --. ('le (7 ) . cos( ) -n0 • cos(rd)) where a is the angle of the acoustic wave component that diffracts the extraordinary incident optical beam component entering at the angle into the diffracted beam component that closes '(j9 with the z axis.…”

Section: Acoustooptic Designmentioning

confidence: 99%

<title>Recent developments and results in 2D acousto-optic light deflection</title>

Maák

Jakab

Barócsi

et al. 1998

Advances in Optical Information Processing VIII

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A novel approach for one and two dimensional acoustooptic deflector design is presented. Two dimensional deflectors are optimally built of two adjacent Bragg cells in acoustically rotated configuration. The depleting effect of second order diffraction is compensated by a small change of the optical incidence angle. High bandwidth devices working below 100 MHz acoustic frequency and 1 W acoustic power are reported. . Several experimental results on deflectors for 633 nm and 1064 nm optical wavelengths are presented.

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Section: Acoustooptic Designmentioning

confidence: 99%

<title>Recent developments and results in 2D acousto-optic light deflection</title>

Maák

Jakab

Barócsi

et al. 1998

Advances in Optical Information Processing VIII

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“…A 50 MHz slow shear mode Tellurium (Te). Bragg cell is commercially available for this application from a number of sources with a time aperture of 25 ts (length = 15.5 mm) and an efficiency of 25 % (2) The Bragg cell, BC1 is used to compress the radar returns. It must support a bandwidth of 100 MHz.…”

Section: Tellurium Acousto-optic Sar Processor Performancementioning

confidence: 99%

“…The shot noise of the detector is given by : 'c (2e1 t f) 1/2 RT (2) For the measured values of I = 8.5 mA. and RT = 48 f the shot noise is determined to be.…”

Section: Shot Noisementioning

confidence: 99%

Infrared tellurium two-dimensional acousto-optic processor for synthetic aperture radar

Souilhac

Billerey

1991

SPIE Proceedings

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In this paper an infrared single element two-dimensional acoustooptic processor using a crystal of tellurium will be described, that can process to return echos of each pulse to form the image of the terrain illuminated by the SAR in real-time. This highly compact processor is designed to maintain a range and azimuth resolution of 2 m, will operate with an acoustic bandwith of 200 MHz for an acoustic drive-power of only 1 watt at the optic wavelength of 5 jim and will reach a dynamic range of the order of 40dB determined by the Hg Cd Te CCD array. This processor will control range and azimuth sidelobes below 40 dB, in a minimum detector integration time of 200 ms to resolve a 5 Hz Doppler frequency. INTRODUCTIONTo describe how synthetic aperture radar (SAR) works, let us take the example of Magellan's Venus orbiter. Any point in the radar map image can be located by using two measurements -the distance to the point (determined by the time it takes for the radar signals to return to Magellan), and the amount of Doppler shift in the signal (a shift in frequency caused by the spacecraft's motion along its orbit). However, two widely separated points (such as A and B shown in Fig 1 a) have the same delay and Doppler shift. Consequently, to avoid confusion between these two points, Magellan's SAR antenna will be pointed to the left of the orbital ground track to illuminate only one of these possible points (A as shown here, B will have already been mapped in a previous orbit's swath). The resulting radar map will therefore show only features to the left of the ground track. The portion of the Venusian surface shown here is a radar image form the Soviet Venera mission, and in Fig I b Nasa picture showing the stri king difference in resolution from a picture taken by the Arecibo radio-telescope and Magellan.With conventional radar, the resolution of an image depends on antenna size : the bigger the antenna, the better the resolution. A large antenna on a spacecraft, however, would be expensive and difficult to manipulate. To solve this problem, the signals from Magellan's synthetic aperture radar (SAR) are computer-processed on Earth so that they will imitate, or synthesize, the behavior of a large antenna on the spacecraft. Through this synthesis, the onboard radar sensor will operate as if it has a huge antenna and will produce high-resolution images, even though the antenna is only 3.7 meters (12 feet) in diameter. This computerized process of "aperture synthesis" is what gives SAR its resolving power as well as its name. As Magellan passes over the Venusian surface, its dish antenna will look downward and to the left side of the spacecraft's orbital path. For 37.2 minutes, the SAR antenna will emit several thousand radar pulses each second. Traveling at the speed of light, the pulses will strike and illuminate a 25-kilometer-wide (16-mile-wide) swath ot the planet's surface, and then will immediately bounce back and be received at the instrument. By recording the returned pulses, we can use two measurements on each ...

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“…Tl 3 AsSe 3 , calomel (Hg 2 Cl 2 ), mercurous bromide (Hg 2 Br 2 ) and iodide (Hg 2 I 2 ), have been used in modulators, deflectors and filters [4][5][6][7][8][9][10]. In the AO literature, the acoustic, optic and AO properties of Te have been examined in detail since the material was considered as one of the most promising for applications in the longer IR wavelengths [11][12][13][14][15][16][17][18][19][20][21][22]. In particular, we published a few papers in which we summarized results of our theoretical and experimental investigation of the anisotropic diffraction regime in Te crystal [17][18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

“…In this interaction geometry, the photoelastic coefficient p 41 is a key factor. In the literature, the value of this coefficient, p 41 was listed as 0.28, which is 1.5-2 times larger than the values for the other photoelastic constants in the crystal [13][14][15][16]. Therefore, use of a diffraction geometry dependent on the coefficient p 41 looked promising.…”

Section: Introductionmentioning

confidence: 99%

Optic, acoustic and acousto-optic properties of tellurium in close-to-axis regime of diffraction

et al. 2017

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We examined the optic, acoustic, photoelastic and acousto-optic (AO) properties of single crystal tellurium. We also determined the Bragg angle dependences on the acoustic frequency at 10.6 μm. The phenomenon of optical activity and its influence on the Bragg matching condition during anisotropic diffraction near the optic axis of the crystal are discussed in detail. Based on the results of our calculations, we designed, fabricated and characterized an AO cell to determine parameters of the anisotropic interaction with longitudinal acoustic waves propagating along the X axis in the crystal. In our experiments, we also measured the value of one of the important photoelastic coefficient in tellurium, p 41 =0.14±0.01 and demonstrated that this coefficient determines the efficiency of the anisotropic diffraction in the employed geometry.

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Infrared two-dimensional acoustooptic deflector using a tellurium crystal

Cited by 26 publications

References 14 publications

<title>Recent developments and results in 2D acousto-optic light deflection</title>

<title>Recent developments and results in 2D acousto-optic light deflection</title>

Infrared tellurium two-dimensional acousto-optic processor for synthetic aperture radar

Optic, acoustic and acousto-optic properties of tellurium in close-to-axis regime of diffraction

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