Vibration measurement by projection of phase-modulated and amplitude-modulated structured light

• Barbosa, Eduardo Acedo ^[1] ; Gonçalves Dib, Luiz Felipe ; Henrique, Marlene Correa ; Saita, Marcelo Tadao
  1. [1] 1Unidade de Pós-Graduação, Extensão e Pesquisa, CEETEPS
• Localización: Journal of Applied Research and Technology, ISSN 1665-6423, ISSN-e 2448-6736, Vol. 21, Nº. 1, 2023, págs. 1-11
• Idioma: inglés
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• Resumen

  • 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.