Laser Doppler vibrometer

About: Laser Doppler vibrometer is a research topic. Over the lifetime, 6319 publications have been published within this topic receiving 76068 citations.

Optical system with movable lens for ophthalmic surgical laser

Abstract: An eye-surgical laser system includes a laser source, to generate a laser beam, an XY scanner, to scan a focal spot of a received laser beam in an XY direction essentially transverse to an optical axis of the laser system, and a lens group, disposed in the optical path between the laser source and the XY scanner, to receive the laser beam generated by the laser source, to precompensate an aberration of the laser beam, and to forward the precompensated laser beam to the XY scanner, the lens group having a movable lens, movable in a Z direction along an optical axis.

Laser beam projection apparatus

Abstract: A laser beam projection apparatus is capable of supplying laser beams finely converged on an object at all times irrespective of a distance to the object. The laser beam projection apparatus has a laser beam generator, including a focus adjusting device, for supplying laser beams periodically swept within one plane and, at the same time, converged at a controllable distance, a light receiving element for receiving reflected laser beams from a predetermined object and generating an output signal, a distance calculating unit for calculating a distance to the object on the basis of the output signal and a controller for operating the focus adjusting device so that the swept laser beams are converged in a position corresponding to the calculated distance. The controller can change a sweep speed of the laser beam in accordance with a change in the calculated distance. The controller cna change a sweep speed of the laser beam in accordance with a change in the calculated distance.

Cantilever optical vibrometer using fiber Bragg grating

Abstract: A cantilever optical vibrometer using a fiber Bragg grating (FBG) is developed. The sensor head is made by attaching an FBG to a triangular beam to provide position-independent strain for the purpose of acceleration measurement. The vibrometer demonstrates a noise-limited acceleration resolution of 2.8×10 –4 √Hz with repeatability error of less than 2.4%.

Preliminary Assessment of Remote Photoelectric Excitation of an Actuator for a Hearing Implant

Abstract: Sound modulated infrared (IR) light, as an alternative signal (and energy) transmission method, was evaluated for remote powering of a hearing implant via an implanted photodiode receiver. One human cadaveric temporal bone was used to test this concept by locating an IR source (LED) in the ear canal 4 mm away from the eardrum and a photodiode in the middle ear cavity. The photodiode output was directly used to drive a piezo-ceramic disc actuator which was located externally for facilitating the test. The displacement frequency response of the actuator was measured by a laser vibrometer. It was found that, at a LED current of 8.6 mA, the actuator displacement was about 22.4 nm, equivalent to a stapes displacement from about 91 dB sound-pressure-level (SPL) stimulation at the eardrum. The IR light transmittance through the eardrum (compared to through an air path) was about 67%. The LED optical power was 0.77 mW (its maximal irradiance was about 3.95 mW/cm2) which is a safe to the human body. Current consumption can be reduced by a factor of 3-5 by using a more efficient LED and photodiode

First laser pulse amplitude modulation

Abstract: The initially high amplitude laser output pulses at the start of a string of pulses from a continuously pumped, repetitively, Q-switched Nd:YAG laser are reduced in amplitude by reducing the current to the krypton arc lamp pumping light source by about 5 amperes for a time of about one-half to about one millisecond prior to gating the Q-switch.