Acoustic Rods or Buffer Rods are used in ultrasonic technology experiments for high temperature work, and in the investigation of small samples. Other common applications are reference standards, coupling devices and delay lines.
The buffer rod is usually a cylindrical rod with flat and parallel ends fabricated from crystal quartz or fused silica, which have low ultrasonic attenuation. We manufacture rods with ends flat to 1/10th wave and parallel to 2-6 arc seconds, and we will also fabricate rods from customer supplied materials, and to your specifications.
In a typical use, a transducer crystal is cemented to one end of the rod and the other end is cemented directly to the sample, as shown in Figure 1. For use with a small specimen, one end of the rod can be tapered, as shown in Figure 2.
In many experiments involving the measurement of ultrasonic attenuation and velocity in liquids, it is often desirable to have flat and parallel slabs of quartz or fused silica to use as reflector plates. These reflector plates can be polished flat and parallel to customer specifications.
Crystal quartz rods can be used in high frequency re-entrant type cavities as shown in Figure 3. High frequency electromagnetic waves are set up in cavity A, producing a high intensity periodic electric field sufficient to drive the quartz rod at frequencies as high as 25 x 109 MHz. Cavity B is used as a receiver to detect and measure the attenuation of the ultrasonic wave set up in the quartz rod.
|Material||Diameter (typical)||Length (typical)|
Z-cut single-crystal quartz, free of electrical and optical twinning,
Optical quality fused silica:
Shear velocity = 3.75 x 105 cm/sec
Compressional velocity = 5.90 x 105 cm/sec
0.500" - 1.000"
0.100" - 2.000"
0.100" - 5.000"
0.100" - 5.000"
Other diameters and lengths are available
Diameter Tolerance: +/- 0.003". Cylinder is diamond wheel finished. Clear polish available upon request.
Length Tolerance: +/- 0.005". Ends polished flat to 1/10th wave, parallel to 2-6 arc seconds. Crystal axis perpendicular to ends within 1/2° (30 minutes).
Ends may be flat, step-ground, or taper-ground.
Conductive coating of one end, both ends, or the entire rod is available.