Method and apparatus for measuring depth and hardness

A method of measuring a characteristic at the surface of a sample, comprising:

• moving a sample surface into engagement with the sample surface penetrator which is connected to a load cell, the load cell generating signals proportional to a force being exerted on the load cell by the penetrator;
• moving the sample surface with respect to the penetrator until a preselected force is reached between the penetrator as measured by the load cell, and the sample surface, the preselected force being sufficiently high so that the penetrator produces an indentation in the sample surface;
• and
• measuring the indentation in the sample surface as a measurement of the characteristic by providing a surface contactor adjacent the penetrator, the surface contactor being connected to a further load cell, moving the sample so that it is in contact with both the penetrator and the surface contactor, and measuring the indentation as a function of a difference between signals from the first mentioned and further load cells.

An apparatus for measuring the surface characteristic of a sample comprising:

• a penetrator adapted for engaging and penetrating a sample surface;
• a load cell connected to said penetrator:
• a movable table means for carrying a sample with a sample surface facing the penetrator;
• first drive means operatively connected to move the table means with respect to the penetrator;
• a movable stage, for positioning the specimen to be tested, mounted on said table means
• a second drive means operatively connected to said table means for positioning said stage;
• and
• signal processing means connected to and controlling the first and second drive means to cause the table means to move the sample into contact with the penetrator to stop said movement when a preselected force sufficient to cause the penetrator to make an indentation in the sample surface has been reached;
• to remove the surface of the sample from the perpetrator and to move said stage so that the sample will be positioned to allow the resulting indentation to be optically measured.

An apparatus

• for measuring the surface characteristic of a sample comprising:
• a load cell;
• a penetrator connected to the load cell and adapted for engaging and penetrating a sample surface;
• table means for carrying a sample with a sample surface facing the penetrator;
• drive means operatively connected to move the table means with respect to the penetrator for engaging the penetrator with the sample surface;
• signal processing means connected to the drive means for moving the table means with respect to the penetrator until a preselected force sufficient to cause the penetrator to make an indentation in the sample surface, has been reached;
• a second load cell,
• a surface contactor connected to the second load cell and positioned adjacent the penetrator for engagement of the sample surface by both the penetrator and the contactor when the table means is moved with respect to the penetrator,
• the signal processing means including means for taking a difference between a signal of the first mentioned and the second load cells as a measurement of the indentation.