Most of the whole-field optical methods for vibration measurement have low sensitivity when the points of the studied surface vibrate with the same amplitude. Those techniques also usually require complex and/or expensive solutions which are difficult to implement in engineering processes when the vibration amplitudes are relatively high. In order to overcome those limitations we propose a method for out-of-plane vibration measurement which uses structured light projection. The vibrating surface is obliquely illuminated by straight and parallel interference fringes produced by a Twyman-Green interferometer with a 532-nm laser as light source. In order to enable fringe visualization two techniques were employed, namely, the phase modulation of the fringe pattern by using a vibrating mirror in the interferometer, and a stroboscopic illumination by using a Fabry-Perot etalon amplitude modulator. We demonstrated the technique by measuring the vibration amplitudes of small objects in the millimeter and submillimeter range.
Three-dimensional (3D) contouring has become very important in industry and in many other production systems. The optical techniques provide many attractive properties for such measurement due to their precision, reliability, accuracy and ability to measure small and fragile objects. In this work we report the study, the development and the performance of a low-cost optical device based on interferogram projection in order to measure the sub-millimetric relief of polymeric plates containing biomimetic textures used in the automotive industry. The interferogram was generated by a Twyman-Green interferometer illuminated by a 532-nm green laser. The measurement was performed by means of phase-shifting and phase-unwrapping procedures and the results were benchmarked with the ones obtained by a commercial device.
This work presents the development and implementation of a character recognition software of digital displays with serial communication for the automation of the readings, registry and transcription of measurement instrument’s indications during calibrations. The software proved to be flexible, allowing calibrations with automatic registry, reducing transcription errors, improving the work conditions and organizing the registers, besides allow remote calibrations.
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