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Browse Prior Art Database

Batch Processing of Acousto Optic Modulators

IP.com Disclosure Number: IPCOM000088583D
Original Publication Date: 1977-Jul-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 3 page(s) / 60K

Publishing Venue

IBM

Related People

Call, LG: AUTHOR [+4]

Abstract

In the fabrication of acousto-optic modulators, two specially designed fixtures are disclosed which provide semiautomation of transducer thinning and deflector base angle lapping. One fixture, in conjunction with a potting technique, allows batch processing while achieving tolerances of m flatness and 30 arc seconds in parallelism in the thinning operation. The other fixture, also in conjunction with a potting technique, allows base angles to be lapped accurately, quickly and in large quantities.

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Batch Processing of Acousto Optic Modulators

In the fabrication of acousto-optic modulators, two specially designed fixtures are disclosed which provide semiautomation of transducer thinning and deflector base angle lapping. One fixture, in conjunction with a potting technique, allows batch processing while achieving tolerances of m flatness and 30 arc seconds in parallelism in the thinning operation. The other fixture, also in conjunction with a potting technique, allows base angles to be lapped accurately, quickly and in large quantities.

Referring to Fig. 1, the frequency at which piezoelectric transducer 12 of acousto-optic modulator 10 vibrates is dependent upon the material used and its final thickness. For example, if the material used is LiNbO(3), the frequency of vibration will be 80 MHz when the final thickness is 41.25 mum. However, during the bonding process (i.e., the bonding of piezoelectric transducer 12 to deflector crystal 14) piezoelectric transducer 12 must be considerably thicker than the final thickness because of handling considerations. Accordingly, it must be thinned to the previously mentioned final thickness while controlling flatness and a parallelism to 0.30 mum and 30 seconds of arc, respectively. To achieve these tolerances previously, each crystal was hand-lapped with a fixture utilizing a mounting plate capable of angular adjustment. With the fixture depicted in Fig. 2, lapping large quantities of acousto-optic modulators, while maintaining a flatness tolerance of .30 mum and a parallelism tolerance of 30 seconds of arc, is possible.

Referring to Fig. 2a, set gage 16, having a top surface 16a flat to .60 mum, has a cavity machined therein approximately the size of piezoelectric transducer
12. Acousto-optic modulator 10 is placed onto set gage 16 with piezoelectric transducer 12 within the aforementioned cavity. Since deflector crystal 14 is larger than piezoelectric transducer 12, the bonding surface therebetween (flat to
0.10 mum) is supported by top surface 16a, thereby completely covering the cavity.

Referring now to Fig. 2b, potting fixture 1B, having a bottom surface 18a also flat to 0.60 mum, also has a cavity machined therein large enough to accommodate deflector crystal 14. In this cavity is disposed rigid mounting pad 20 connected to set screw 22 via a ball joint. Set screw 22 is connected to potting fixture 18 via threads therein. Pressure is applied to deflector crystal 14 by rigid mounting pad 20 to prevent acousto-optic modulator 10 from moving during the next step in the process.

The next step in the process is potting. Accordingly, potting fixture 18 has therein wax port 24 extending from the top surface thereof to the cavity in which acousto-optic modulator 10 is disposed. A low melting point wax, such as QUARTZ TYPE STICKY WAX (Corning Rubber Company, Inc.), is then injected i...