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Hydrophone Handbook

         Choosing a Hydrophone

 2.5 Reflection Profile
 It is preferable to use a sensor that does not affect the
 parameter being measured, which depends on the nature of the
 acoustic field. Needle type hydrophones have a good reflection
 profile and are preferred for continuous wave fields. Pulsed
 fields, on the other hand, are more forgiving because the effect
 of reflections can be separated by time with the use of an
 oscilloscope.
 There are generally three types of hydrophone profiles:
 (1) needle, (2) capsule, and (3) membrane.

Needle            Capsule     Membrane

Using a schlieren system, it is possible to visually compare how
the acoustic reflections behave for different reflection profiles.

                  Transducer

     3.5 MHz
Pulsed Wave

                           Needle Hydrophone
                           (HN)

                             Mount

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