Encountered a relatively special mechanical processing part. The actual part is shown in the figure. The inner bottom is a spherical surface, and the diameter of the entrance is only 10mm. Such a part needs to measure the roughness of the inner spherical surface.

  Usually, a roughness tester can also be used for spherical surfaces, but because the spherical surface of this part is located at the bottom of a deep hole, conventional instruments cannot measure the roughness.

  If using a non-contact white light interferometer, the working distance of white light interferometers currently on the market is very short, and the image at the bottom cannot be observed, so it is not suitable for measuring the bottom of the hole.

  This time, we used our self-developed micro-nano profile measurement system, with a 10X Linnik interference objective lens and a working distance of 15mm. It can easily capture the image of the bottom. The roughness inside the spherical surface is calculated and analyzed through CRWLI software.

Measured part

Measured part

Using 10X Linnik interference objective lens measurement process

Acquired inner spherical interference fringes 1

Acquired inner spherical interference fringes 2

Acquired inner spherical interference fringes 3

Measurement report 1

Measurement report 2

Measurement report 3

  Measurement results: Ra values are 0.04997um, 0.05237um, 0.06109um respectively.