Section 3: Probes Features are measured by probing points along the edge of the feature. Points are probed as part of either an explicit or automatic feature measurement using one of the M2 simple or optical edge crosshair probes. There are two main categories of probes: • Simple crosshair • Optical edge detection crosshairs o Manual edge detection o Auto edge detection M2 systems that support optical edge detection probes will display a probe menu providing access to the (from top to bottom): • Simple crosshair probe • Manual edge detection probe • Auto edge detection probe • Probe Teach (optical edge calibration) Systems without optical edge support will always be prepared to accept points entered manually using the simple crosshair. Simple Crosshair Probe Crosshair probes are used to measure a single point at a time by manually lining up the crosshair center with a point to be probed on the feature edge and then pressing the Enter button or pressing in the Measure Prompt screen. The The manual edge detection crosshair center must be aligned by the user but incorporates a relatively large area of edge detection that will detect a point on the feature edge automatically generating a tone as the crosshair center passes over the light/dark transition at a feature edge. The point location is retained by the system and must then be entered by pressing the Enter button or pressing in the Measure Prompt screen. The point location is retained by the system until the next edge is crossed. Manual edge detection increases measurement accuracy and reduces measurement time. The DRO stage position is updated only when a new edge is detected. Auto Edge Detection Probe Like the manual edge detection crosshair, the auto edge detection crosshair must be aligned with the part by the user and detects feature edges as explained above, but the detected point is entered automatically without the need for user interaction, further reducing measurement time. The DRO stage position is updated only when a new edge is detected. Points Required for Feature Measurements The minimum number of points required for each feature type and recommendations regarding probing are provided below. Probing more than the minimum required number of points increases measurement accuracy. Points Require one or more points. When more than one point is probed, a least squares fit is applied to the data cloud. Lines Require two or more points. When more than two points are probed, the data fit type specified in the Feature Detail screen is applied to the feature’s data cloud. Points should be evenly distributed along the line. DRO stage position is continually updated. Manual Edge Detection Probe
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