8. Measurement Strategy KineMic systems are available with either 6.5:1 zoom optics with adjustable magnification from 0.47X to 3.0X, with 12:1 zoom optics with adjustable magnification from 0.4X to 4.7X, or with any of six telecentric lenses with a fixed magnification of 0.30X, 0.50X, 0.80X, 1.0X, 2.0X or 4.0X. As used here, magnification is the image size at the camera CCD detector place divided by the object size. Since the CCD size is fixed, each magnification has a corresponding field of view (FOV), which is the CCD size divided by magnification. The higher the magnification, the higher the resolution, but also the smaller the field of view. 8.1 Zoom Optics Measurement Strategy While the zoom optics can provide the same field of view (FOV) as four of the telecentric lenses, they do not offer the ultra-low optical distortion that is required for purely optical measurements across the entire FOV. However, they can be more accurate than telecentric lenses when used at high magnification in combination with stage motion, where reading accuracy is based on the system’s calibrated linear encoders. Select zoom optics to measure large parts which would not fit into a single FOV, also to measure smaller parts where extremely high magnification is required. The lowest zoom magnification set- ting accommodates parts up to 11.2 x 9.4 mm (0.44" x 0.37") in the FOV. To measure large parts, locate the edge of interest at minimum magnification, then take the actual measurement at maxi- mum magnification using the system's crosshairs. The zoom optics’ parcentricity feature ensures that a feature will remain at the optical center of the video image throughout the magnification range. In general, higher magnification provides greater resolution and accuracy; however, not all features should be inspected at the highest available magnification. Too high a magnification may make it difficult to discern edges by exaggerating edge defects such as burrs or chips. Try decreasing the magnification until the edge is more clearly identifiable. Also consider factors such as tolerance requirements, manufacturing processes, functional requirements and optical characteristics of the part. Features with loose tolerances may not need to be inspected at high magnification. Select the magnification best suited for the requirements. 8.2 Telecentric Lens Measurement Strategy Select telecentric optics to perform high accuracy, high throughput field-of-view (FOV) measure- ments. If all measurements are to be in the FOV, select the highest magnification lens whose FOV encompasses the entire part. The 0.30X lens accommodates parts up to 24 x 18 mm (2.0” x 1.5”). If the entire part cannot fit into the FOV, no problem. Simply move the stage by up to 200 mm (4”) for the KineMic200 or 300 mm (12") for the KineMic300, and the M3 software will seamlessly integrate FOV measurements with encoder readings from stage motion. 8.3 Illumination Strategy Once the image has been properly focused and magnification has been set, adjust light levels as necessary using your systems manual adjustment knobs or the slider controls in 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 may 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.
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