Strain Measuring Method, Strain Measuring Device and Program

A strain measuring device comprising:

• minute region extracting device for extracting a surface height distribution of a minute region a containing a point A in a predetermined region and a surface height distribution of a minute region b containing a point B in the predetermined region from an initial surface height distribution obtained by measuring a surface height of the predetermined region on a surface of a measurement-target object;
• matching device for comparing respective surface height distributions of the minute regions a and b with a time-advanced surface height distribution obtained by measuring a surface height of the predetermined region of the measurement-target object after a time has advanced, and obtaining a minute region a′ over the time-advanced surface height distribution most similar to the surface height distribution of the minute region a and a minute region b′ over the time-advanced surface height distribution most similar to the surface height distribution of the minute region b;
• coordinate calculating device for calculating coordinates of points A′ and B′ in the minute regions a′ and b′ corresponding to the points A and B in the minute regions a and b, respectively;
• and
• strain calculating device for substituting a length l of an initial line AB and a length l′ of a time-advanced line A′B′ into a following formula to calculate a strain c in a direction of the line AB.
• ɛ
• =
• l
• ′
• -
• l
• l
• [
• Formula
• 
• 
• 2
• ]

A program which is installed in a computer and which causes the computer as a strain measuring device that functions as:

• minute region extracting device for extracting a surface height distribution of a minute region a containing a point A in a predetermined region and a surface height distribution of a minute region b containing a point B in the predetermined region from an initial surface height distribution obtained by measuring a surface height of the predetermined region on a surface of a measurement-target object;
• matching device for comparing respective surface height distributions of the minute regions a and b with a time-advanced surface height distribution obtained by measuring a surface height of the predetermined region of the measurement-target object after a time has advanced, and obtaining a minute region a′ over the time-advanced surface height distribution most similar to the surface height distribution of the minute region a and a minute region b′ over the time-advanced surface height distribution most similar to the surface height distribution of the minute region b;
• coordinate calculating device for calculating coordinates of points A′ and B′ in the minute regions a′ and b′ corresponding to the points A and B in the minute regions a and b, respectively;
• and
• strain calculating device for substituting a length l of an initial line AB and a length 1′ of a time-advanced line A′B′ into a following formula to calculate a strains in a direction of the line AB.
• ɛ
• =
• l
• ′
• -
• l
• l
• [
• Formula
• 
• 
• 3
• ]