Patent ID: 9057695
Filing Date: 2015-06-16
Classification: A61B,G01N,G03H

Abstract:
1. An apparatus comprising: a first irradiation unit configured to irradiate a medium with a incident wave; a first photodetector arranged to monitor an intensity of the incident wave before being irradiated on the medium; an ultrasound device configured to focus an ultrasound wave onto a position in the medium such that the incident wave is modulated into a frequency-shifted wave at the position where the ultrasound wave is focused by the ultrasound device; a holographic material; a second irradiation unit configured to irradiate the holographic material with a reference wave, a frequency difference between the reference wave and the incident wave being exactly or approximately equal to a frequency of the ultrasound wave focused by the ultrasound device, and to record information corresponding to an interference pattern formed by interference between the frequency-shifted wave and the reference wave by the holographic material; a second photodetector configured to detect light from the holographic material while the holographic material records the information corresponding to the interference pattern; a third irradiation unit, after the information is recorded on the holographic material, configured to irradiate the holographic material with a reading wave substantially in a direction opposite to a direction of the reference wave so that the holographic material generates a reconstructed wave to irradiate the medium to retrace trajectory of the frequency-shifted wave to the position where the ultrasound wave is focused by the ultrasound device; and a control unit configured to control the first irradiation unit and the third irradiation unit so that an intensity of the reading wave generated from the third irradiation unit is different from an intensity of the incident wave generated from the first irradiation unit, wherein the control unit is configured to control the first irradiation unit based on an output of the first photodetector so that the intensity of the incident wave keeps below a predetermined exposure and is configured to control the third irradiation unit so that the intensity of the reading wave is lower than the intensity of the incident wave.