Acoustic microscopy acoustic microscope (CSAM), and C-mode scanning acoustic microscope (C-SAM). More recently acoustic microscopes based around picosecond ultrasonics systems have demonstrated acoustic imaging in cells using sub-optical wavelengths working with ultrasonic frequencies into the multi-GHz. Since the vast majority of acoustic microscopes in use today are C-SAM type instruments, this discussion will be limited to these instruments. Ultrasound is broadly defined as any sound having a frequency above 20 kHz, which is approximately the highest frequency that can be detected by the human ear. However, the acoustic microscopes emit ultrasound ranging from 5 MHz to beyond 400 MHz so that micrometre
Bitcrusher the consequence that it is impossible to accurately record all frequencies right up to the Nyquist limit for a given sample rate. The solution is to increase the sample rate by an amount that accommodates the transition bands of the filters used both for sampling and for continuous-wave reconstruction; this is why, for example, Compact Discs use a sampling rate of 44.1 kHz to record audio that seldom exceeds 20 kHz, even though the Nyquist limit for this sample rate is 22.05 kHz. Another consideration is that for perfect reconstruction, the samples should be rendered as ideal impulses of infinitesimal