Principle of Depth Measurement
The micrometer optically measures the depth, or difference in height, of one surface to another. Focus sharply on a good surface near a scratch or pit and set display to "0.0000", then carefully focus into bottom of scratch or pit and read depth on digital display.

Clearance - Height of Objective Lens Above Surface
The "working distance" refers to how far the objective lens is from a surface when in focus. The working distance for the 10X lens is .250", for 4x lens, 1.275" above surface. (This means that .250" and 1.275" are the maximum scratch depths that could be observed, in theory, without the lens "bumping into" the surface). The 4X objective provides the most clearance, and is thus used for larger features and for transparencies, where the near and far sides can be focused upon without lens interference.

Transparencies - Use 4X Objective Lens
The 4X objective lens is ideal for transparencies. The wide field of view allows observation of more and larger features, and the long working distance prevents the lens from contacting surface - even when focusing on the far side of a thick transparency (up to 1.9"). Accuracy is not compromised by using the 4X objective.

Rugged and portable
The 8400K was designed for use in the field. The sealed, non-magnetic case is dustproof and shockresistant to withstand everyday shop use. The hardwood instrument case also contains adapters and lenses for use on convex, concave, or any combination of these surfaces.

Real cost savings
With the 8400K, damage can be measured optically in a fraction of the time needed for other methods such as "blend-out." Spending time on a part that may need replacement is costly, and in many cases, the 8400K can be used to inspect parts while on an aircraft, whereas removal is often necessary using other methods.

Serial port for PC access
In addition to the clear LCD readout "floating zero" and other features, the 8400K's digital display also has an RS232 serial port for data export to the optional processor/printer.

How the RENE optical micrometer works
First, focus on a smooth surface next to a scratch. Then, zero out the digital display (you can choose a readout in either inches or millimeters). Next, focus on the bottom of the scratch. The digital display shows depth relative to the surface.