Laser vibrometer for vibration measurements

US5883715A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Siegbert Steinlechner · Leonberg, DE
• Pawel Drabarek · Tiefenbronn, DE
• Michael Van Keulen · Stuttgart, DE

Key dates

• Filing date: Feb 19, 1997
• Grant date: Mar 16, 1999
• Expiry date: Feb 19, 2017

Classification

• Technology area (CPC G): Physics
• CPC primary: G01H9/00
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A laser diode (1) of a laser vibrometer emits light which is guided onto a polarization beam splitter (3) by a lens 2. A portion of the beam is guided through directly to an imaging lens (4) and a second portion is deflected onto a mirror (5). Quarter-wave plates (6) and (7) are arranged between the polarization beam splitter and respectively the lens or the mirror. The beam which is reflected on the mirror is guided completely through the polarization beam splitter onto a photodetector unit (8). The beam reflected by the object (9) to be measured, which swings in the direction (14), is also deflected to the photodetector unit. The output signal of the photodetector unit, the interference signal generated from the superposition of the two reflected beams, is supplied to an electronic evaluation equipment (10). The latter is also supplied with a signal of a current modulator (11) which, on the other hand, supplies the laser diode with modulated injection current via line (12). The distance between the imaging lens and the object to be measured forms an optical detour (13) which is considerably lengthened compared to the reference arm.