AVX System User Guide
7.2.1 Measurement Accuracy and Depth of Field
Telecentric lenses have a large focus range, also known as depth of field. Within this range, the instrument is expected to measure with an accuracy of about ten microns or better for a one-inch artifact. However, the most repeatable results can be achieved by taking the time to adjust focus using digital zoom. To do this, digitally zoom in on an edge and adjust focus until the pixels appear on that edge. This will ensure the best and most repeatable measurements are obtained. Refer to the following images.
Poor Focus
Good Focus
7.3 Illumination Strategy Once the image has been properly focused and magnification has been set, adjust light levels as necessary using the slider controls in the M3 software. The right lighting is paramount to accurate measurement with any video-based measurement system. Lighting that is too dim will result in a dark, low-contrast image with indiscernible features. Lighting that is too bright might result in a washed-out image and blooming, or oversaturated bright regions that distort features. When adjusting lighting, start with light that is lower than desired, and then increase lighting while viewing the image on the monitor. Maintain constant lighting for consistent results. Always use the same light level while sampling points for a single feature – do not to change light levels during a measurement run. Depending on the part characteristics and the feature being measured, the right combination of lighting can aid in bringing out a particular feature. Take time to experiment by balancing the available light sources. Once the best illuminations settings have been found, illumination should be under full computer control along with CNC motion.
Light Options
The AVX system includes the following LED light options: ring light, substage light, coaxial light, dome light, quad ring light, and stepped dome light. The quad ring light and stepped dome light are available with height adjustment of 152 millimeters (6 inches).
46
1000 0074 Revision A
Made with FlippingBook - professional solution for displaying marketing and sales documents online