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Measurement of Bragg Angle

IP.com Disclosure Number: IPCOM000044350D
Original Publication Date: 1984-Dec-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Arnold, RC: AUTHOR

Abstract

An acousto-optic modulator using two RF frequencies and a helium-neon laser produce a diffracted beam at the Bragg angle. The relationship of the zero order beam to the first order beam of each of the frequencies can be measured with a degree of confidence. These angles will be a function of the type of material used for a crystal. The laser printers use an acousto-optic modulator (AOM) to control the laser beam. This device is used to split the laser beam into three beams. The zero order beam and the first order beam of each frequency of the RF are used to control the modulator. An ultrasonic wave is launched into an acoustic-wave-supporting material, usually a crystal, by means of a piezoelectric transducer. A laser beam is aligned with respect to the crystal so that one first order intensity is maximized.

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Measurement of Bragg Angle

An acousto-optic modulator using two RF frequencies and a helium-neon laser produce a diffracted beam at the Bragg angle. The relationship of the zero order beam to the first order beam of each of the frequencies can be measured with a degree of confidence. These angles will be a function of the type of material used for a crystal. The laser printers use an acousto-optic modulator (AOM) to control the laser beam. This device is used to split the laser beam into three beams. The zero order beam and the first order beam of each frequency of the RF are used to control the modulator. An ultrasonic wave is launched into an acoustic- wave-supporting material, usually a crystal, by means of a piezoelectric transducer. A laser beam is aligned with respect to the crystal so that one first order intensity is maximized. The angle of the incidence is the Bragg angle. The resulting angle is a function of the sound wave and the index of the material. The Bragg condition is satisfied by the equation:

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To determine the Bragg angle for a given frequency, measure the coordinates of the beam at several points along the beam relative to the zero order beam and use the following equation:

(Image Omitted)

The laser, the acousto-optic modulator, and the detector used are mounted on an optical rail which is secured to a vibration isolation table. The measurement is determined by taking the difference of two optical rail scale readings. The detec...