The first one is Dark light measurement, simply said is to measure the O - ring shadow.We usually choose projector for this kind of measuring tool.In general, O-ring is to measure the size of its outside diameter and inside diameter. When measuring the size of O-ring, the diameter is measured by the top, bottom, left and right four points of the O-ring.The following methods are applicable to both the outer and inner diameters of the O-ring:

1. On the projector, adjust the multiple size of the lens according to the size of the product to make the lens clear.

2. Put the coordinates on one edge of the O-ring and close to the coordinate line of the projector;

3. Find the icon marked with a circle on the projector, press the icon, and then press the confirm button, so that you can find a point;4. Move the coordinate to the second point of the O-ring, and also close the coordinate line to the edge of the O-ring, and then press OK.And so on, so that after four points of the O-ring, a diameter is measured.

The second is light measurement, that is, the measurement of the O-ring itself.This kind of measuring tool we generally choose optical image measuring instrument.The method is basically the same as the projector.