Table 4.3: Pulsed ultrasonic transmission measurement cells. The two columns describe the 1-MHz and 10-MHz pulse cells. r_q is the radius and f_q the fundamental resonance frequency of the crystal transducers; f_n denotes the available measurement frequencies, f_max the maximum measurement frequency, τ the pulse length, x_min and x_max the minimum and maximum changes in transducer separation, and V the liquid volume of the cell. The table also specifies the delay-line configuration, optical displacement probes and axial positioning.

4.3.5 Errors of the ultrasonic transmission cells

• In both the 1-MHz and 10-MHz ultrasonic transmission cells, extremely accurate parallel alignment is essential. If the transmitter is not correctly aligned parallel to the receiver, unacceptable errors arise; in some cases the transmitted signal is not received at all.
• Temperature sensitivity is particularly important in ultrasonic transmission cells. The low-frequency measurement cell, in particular, is highly sensitive to any temperature fluctuations.

The errors of the cells used are given in Table 4.4. More detailed discussions can be found in [29], [30] and [32].