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
500 kHz kHz to amateur radio use. In Belgium, amateurs are allocated a 501 to 504 kHz on a secondary basis on January 15, 2008. Only CW may be used with a maximum ERP of 5 W. In Norway, the band 493–510 kHz was allocated to radio amateurs on November 6, 2009. Only radiotelegraphy is permitted. In New Zealand, the band of 505 to 515 kHz was allocated temporarily, pending an international frequency allocation. In the Netherlands Amateur radio operators have allocated the band from 501–505 kHz with a maximum of 100 watts PEP on January 1, 2012. 500 kHz The radio