Sample evaluating method by using thermal expansion displacement

A method for sample evaluating by measuring thermal expansion displacement on the surface of the sample, which is produced by irradiating the sample with an excitation beam of which intensity is cyclically modulated at a frequency F, comprising the steps of:

• irradiating the surface of the sample which is subjected to thermal expansion by irradiation of the excitation beam with a measuring beam having an optical frequency F1 to produce a reflection beam;
• interfering the reflection beam with a reference beam having an optical frequency F2;
• photoelectrically converting the interference beam to electric signals E;
• obtaining beat wave signals E1 whose beat frequency Fb=F1-F2 from the electric signals E;
• binarizing the beat wave signals E1 and converting the binarized signals to binary signals E2 to prevent changes in reflectivity of said sample due to temperature change and plasma density change of said sample from influencing measurement of thermal expansion displacement;
• creating delay signals Eb, which are delayed from time .tau. from the binary signals E2;
• and
• obtaining a signal Vt by multiplying the binary signals E2 by the delay signals Eb, and extracting a signal component Va regarding the frequency F therefrom, thereby causing the sample to be evaluated according to the amplitude and phase of the signal component Va.

A method for sample evaluating by measuring thermal expansion displacement on the surface of the sample, which is produced by irradiating the sample with an excitation beam of which intensity is cyclically modulated at a frequency F, comprising the steps of:

• irradiating the surface of the sample which is subjected to thermal expansion by irradiation of the excitation beam with a measuring beam having an optical frequency F1, in order to produce a reflection beam;
• interfering the reflection beam with a reference beam having an optical frequency F2;
• photoelectrically converting the interference beam to electric signal E;
• obtaining beat wave signals E1 having beat frequency Fb=F1-F2 from electric signals E;
• binarizing the beat wave signals E1 in order to convert the beat wave signals to binary signals E2 to prevent changes in reflectivity of said sample due to temperature change and plasma density change of said sample from influencing measurement of thermal expansion displacement;
• multiplying the binary signals E2 by local oscillating signals Eb of frequency Fb to obtain a signal Vu;
• multiplying a signal E4 whose phase is different by 90.degree. from the signal E2 by the local oscillating signals Eb of frequency Fb to obtain a signal Vn;
• extracting a component Vs of the frequency F from the signal Vu and extracting a component Vc of frequency F from the signals Vn;
• and
• operating on the components Vs and Vc to produce an output Vo having a variable concerning only the phase change P(t) of the measuring beam on account of the thermal expansion displacement of the sample, whereby the sample is evaluated according to the output Vo.

A method for sample evaluating by measuring thermal expansion displacement on the surface of the sample, which is produced by irradiating the sample with an excitation beam of which intensity is cyclically modulated, comprising the steps of:

• irradiating a surface position of the sample which is subjected to thermal expansion by irradiation of the excitation beam with a measuring beam having an optical frequency F1 of which intensity is modulated with the frequency F to produce a reflection beam;
• interfering said reflection beam with a reference beam having an optical frequency F2;
• photoelectrically converting said interference beam to electric signals E;
• obtaining beat wave signals E1 of the electric signals E having a beat frequency Fb where Fb=F1-F2;
• binarizing the beat wave signals E1 and converting the beat wave signals E1 to binary signals E2;
• and
• extracting components of the frequency Fb-F or Fb+F from the binary signals E2, thereby causing the sample to be evaluated according to the amplitude and phase of the respective component.

A method for sample evaluating by measuring thermal expansion displacement on the surface of a sample, which is produced by irradiating thereto an excitation beam of which intensity is cyclically (frequency:

• F) modulated, comprising the steps of:
• irradiating a measuring beam having an optical frequency F1 of which intensity is modulated with the frequency F to produce a reflection beam;
• interfering said reflection beam with a reference beam having an optical frequency F2;
• photoelectrically converting said interference beam to electric signals E;
• obtaining beat wave signals E1 of electric signals E habign a beat frequency Fb where Fb=F1-F2;
• binarizing the beat wave signals E1 and converting the beat wave signals E1 to binary signals E2;
• creating delay signals Eb which are delayed by time .tau. from said binary signals E2;
• and
• obtaining a signal Vt by multiplying the binary signals E2 by the delay signals Eb, and extracting a signal component Va regarding the frequency F therefrom, thereby causing the sample to be evaluated according to the amplitude and phase of the signal component Va.

A method for sample evaluating by measuring thermal expansion displacement on the surface of a sample, which is produced by irradiating the sample with an excitation beam of which intensity is cyclically (frequency:

• F) modulated, comprising the steps of:
• irradiating a measuring beam having an optical frequency F1 of which intensity is modulated with the frequency F to produce a reflection beam;
• interfering said reflection beam with a reference beam having an optical frequency F2;
• photoelectrically converting the interference beam to electric signals E;
• obtaining beat wave signals E1 of the electric signals E having a beat frequency Fb where Fb=F1-F2;
• binarizing the beat wave signals E1 and converting the beat wave signals E1 to binary signals E2;
• multiplying the binary signals E2 by local oscillating signals Eb of frequency Fb to obtain a signal Vu;
• multiplying a signal E4 whose phase is different by 90.degree. from the signal E2 by the local oscillating signals Eb of frequency Fb to obtain a signal Vn;
• extracting a component Vs of the frequency F from the signal Vu and extracting a component Vc of frequency F from the signals Vn;
• and
• operating on the components Vs and Vc to produce an output Vo having a variable concerning only the phase change P(t) of the measuring beam on account of the thermal expansion displacement of the sample, whereby the sample is evaluated according to the output Vo.