Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
Mechanical vibration effects in the biospeckle laser technique for portable equipment application
Submission Author:
Daniel Bernardes de Castro , SP
Co-Authors:
Daniel Bernardes de Castro, José Eduardo Silva Gomes, Roberto Braga, Henrique Silveira
Presenter: Daniel Bernardes de Castro
doi://10.26678/ABCM.COBEM2021.COB2021-0013
Abstract
The dynamic laser speckle and biospeckle laser are techniques developed based on the processing of optical interference patterns formed when a laser light strikes a dynamic surface, such as a paint drying, or biological, like seeds, leaves, or fruits. These non-destructive and non-invasive image processing techniques are used to quantify the activity level of biological or non-biological samples. Several studies were already developed in different areas, from Agriculture to Medicine. It has been observed in recent years an increase in the number of applications and publications about the use of the technique. Despite the expressive results, such studies, in general, are developed in a laboratory environment. The on-site application is necessary for the advancement of the technique in the commercial scope since it is not always feasible to move biological samples to a laboratory to be analyzed. However, there are limitations in the use of the technique in the field. Obtaining an integrated and compact experimental configuration, a laser and power supply stability, and also prevents external noise interference, such as luminosity and vibration mainly, are challenges that the technique needs to face regarding portability. Few studies have been carried out in this sense. Studies display that the biospeckle laser technique is sensitive to external vibrations, and aiming to understand the level of these interferences as well as to propose ways to mitigate them, in this work it was developed a portable prototype for dynamic laser speckle analysis. This equipment was subjected to various vibration tests, such as experimental modal analysis and transmissibility. Dynamic laser speckle tests were performed in parallel. The prototype’s natural frequencies were obtained. It was evaluated how the optical technique behaves when excited at these and other frequencies, in a range from 0 to 1000 Hz. It was discovered that the biospeckle laser is more sensitive to low frequencies, close to 5 Hz. In the transmissibility tests, where the vibration transmissibility of 11 vibration isolators was analyzed, it was found that the isolator with the lower stiffness presented the best characteristics of vibration isolation for the proposed purposes, making possible the portability of the prototype from the isolation of ordinary external mechanical vibrations.
Keywords
Dynamic speckle, Portability, Vibration, modal analysis, Transmissibility
