OPTONOR – Optical Testing And Methodology
This system is based on the technique of TV-holography (or ESPI - Electronic Speckle Pattern Interferometry). TV-holography is a laser based interferometric technique for full field, noncontact measurement of object surface vibrations (and semistatic deflections, see NDT section).The system is developed with a unique computer software which enables accurate measurements with a series of 2D and 3D display options. Object size may vary from sub millimeter up to several meters. Amplitudes down to a nanometer can be detected.
This system is an excellent tool when you want to:
- design your mechanical construction without vibrations and resonances, or - design with controlled vibrations and controlled resonances - avoid noise and fatique fracture - evaluate and control your FEM results - ensure correct funcionality of your designed structure
How the system works
The system is basically for laboratory use, but it can also be used in workshop environments or even outdoor when the measurement is properly arranged. In laboratory environments, no special vibration isolation is required, but rotating machinery and other noise sources should be avoided close to the measurement site. Object surface preparation is normally not required. Specular surfaces, however, can be covered with powder (removable), while large surfaces should be covered with retroreflective paint of tape to get enough ligth reflected from the surface when the standard 5 mW laser is used. The system lets you yse object vibrations at one single frequency at a time. The system PC may control the object excitation by use of a built-in generator and by use of an excitation unit like a pzt, shaker, loudspeaker etc. The operates in two different modes, as described below.
Real time mode:
The PC lets you scan trough all required frequencies while you watch the object vibration real time on the PC monitor. You can very easily see resonance frequencies and their vibration modes with nodal line distribution and amplitude peaks, and you can see the frequency width of different vibration modes (Q-factors). You can also do small changes to your object, like e.g. putting small bits of clay onto the object surface (on an amplitude peak area) or even touch the object by hand, just to see how the vibration mode is dramatically changed or dampened. In the real time mode, you can yze object amplitudes ranging from appr. 30 nanometers up to a few micrometers. Using the VibroMap 1000 with the real time mode is an excellent way of getting really familiar with the dynamic responce of your design structure.
Qualitative mode:
When you see a vibration mode which you want to yze in detail, you start a quantitative recording routine. The PC uses a couple of minutes to calculate the phase and amplitude distribution on your object surface for the selected frequency. Afterwards, you can use the graphical tools to display the amplitude, phase or surface deflection in 2D or 3D displays. You can also see an animated display of the vibration mode. (Please note: The quality of the animated GIF examples shown in this WEB is very much reduced compared to the quality of the original display.) The vibration data (amplitude and phase) can be exported to be used with other commercial softwares, for instance when the data should be compared to data from a simulation software.
In the quanitative mode, you can yze object amplitudes up to 80 nanometer p-p. Experience shows that the linear dynamic responce of nearly all kinds of objects (from microstructures to car bodies) allows you to yze objects with amplitudes below 80 nanometers, even if the real life amplitudes of the object is tens of microns or more.
Some typical vibration measurement applications :
Engine components Turbine blades Propellers Car bodies Electronic components Microstructures Loudspeakers Transducers Cabinettes Underwater applications (through window)
Deformation measurements and NDT applications
The computer software has a simple standard routine for object deformation ysis. For more advanced deformation ysis, for example in connection to Nondestructive Testing applications, Optonor AS delivers special deformation ysis softwares, see the separate NDT section.
Specifications, standard system
Size of optical head : 525x230x100 mm (LxWxH) Weigth of optical head: 7 kg Imaging system : Zooming lens 12.5 - 75 mm (standard) Frame grabber : Matrox Operating system : Windows 98 or others Laser class : III a Laser :5/7 mW HeNe standard. Up to 200 mW or more non standard. Minimum vibration frequency: < 30 Hz Maximum vibration frequency: Unlimited for qualitative ysis 25-50 kHz (or higher) for quantitative ysis Minimum object size : Appr. 0.15x0.15 mm (microscopic) Maximum object size : Appr. 2x2 meters (retroreflective tape required) Object surface : Surface preparation is normally not required. Specular surfaces should be covered with powder (removable). Very large surfaces should be covered with retroreflective paint of tape to get enough ligth reflected from the surface when standard laser is used. Environments : Normal laboratory environments, no vibration isolation required No rotating machnery or noise sources should be allowed near by testing site.
