Greenwood Margaret Stautberg, Brodsky Anatol, Burgess Lloyd, Bond Leonard J, Hamad Mazen
Pacific Northwest National Laboratory, P.O. Box 999, Mailstop K5-26, Richland, WA 99352, USA.
Ultrasonics. 2004 Apr;42(1-9):531-6. doi: 10.1016/j.ultras.2004.01.030.
The ultrasonic diffraction grating is formed by machining triangular grooves, 300 microns apart, on a stainless steel surface. The grating surface is in contact with the liquid or slurry. The ultrasonic beam, traveling in the solid, strikes the back of the grating and produces a transmitted m=1 beam in the liquid. The angle of this beam in the liquid increases with decreasing frequency and the critical frequency FCR occurs when the angle is 90 degrees. At frequencies below FCR, this m=1 wave does not exist and its energy is shared with other types of waves. The signal of the reflected m=0 wave is observed and an increase is observed at FCR. This information yields the velocity of sound in the liquid and particle size.
超声衍射光栅是通过在不锈钢表面加工间距为300微米的三角形凹槽形成的。光栅表面与液体或浆料接触。在固体中传播的超声束撞击光栅背面，并在液体中产生透射的m = 1波束。该波束在液体中的角度随频率降低而增大，当角度为90度时会出现临界频率FCR。在低于FCR的频率下，这种m = 1波不存在，其能量会与其他类型的波共享。观察到反射的m = 0波的信号，并在FCR处观察到信号增强。这些信息可得出液体中的声速和颗粒尺寸。
