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Surface Profile Evaluation for Shim Rings / Non-contact 3D shape measurement using a laser microscope


A shim ring is used as a spacer to adjust height or spacing for products in various fields such as machinery components, automobiles, and structures. The thickness, size, and material of such rings differ widely, and one of the thinnest rings is about 5 μm thick. The rings are typically made of iron, stainless steel, aluminum, copper, and brass.
Shim rings are mainly required to adjust a gap between parts or stabilize contact resistance. One of the criteria for determining quality is the surface profile of the ring, which must be controlled during the manufacturing process. Manufacturers try to create rings that are as smooth as possible. The measurement of the surface profile is based on an evaluation of surface roughness instead of conventional line roughness.

The Olympus solution

Olympus' OLS4100 3D laser scanning microscope enables non-contact 3D shape measurement with high resolution and high precision. Users can accurately measure the profile of the depth (or height) of surface irregularities and surface roughness. Since the surface of the ring is uniform, non-contact and millimeter-based long-line roughness measurements can be used for length dimensions using the roughness mode. The roughness data of the long length dimension makes it possible to correlate the data with a contact-type roughness tester. In addition, the spot diameter of the laser is smaller than the diameter of the tip of a stylus, so users can accurately measure finer irregularities.

Surface of a shim ring


Objective lens 100X, Zoom 1X

Olympus IMS

Products used for this application


With the Olympus LEXT OLS5000 laser scanning confocal microscope, noncontact, nondestructive 3D observations and measurements are easy to produce. Simply by pushing the Start button, users can measure fine shapes at the submicron level. Ease of use is combined with leading-edge features to deliver an acquisition speed four times faster than our previous model. For customers with larger samples, LEXT long working distance objectives and an extended frame option allow the system to accommodate samples as large as 210 mm.
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