Surface characteristic measurement

Claim 1

A method for the measurement of surface characteristics which comprises the steps of: projecting an image of a rectangular wave pattern, which has been reflected from a surface to be tested, onto an image forming plane by means of an image forming optical system to form the image of the pattern on the image forming plane; transforming the spatial distribution of the intensity of light falling on the image plane according to the Fourier transformation; quantifying the distinctness-of-image glossiness of the surface to be tested according to the intensity of each of power spectra at particular spatial frequencies; and individually quantifying the degree of blurring of the image according to the intensity of one of the power spectra which have been obtained from the waveform of the formed image, said one of the power spectra being obtained at a fundamental spatial frequency, and the degree of distortion of the image according to the total sum of the intensity of another one of the power spectra which have been obtained from the waveforms of the image from which the base line intensity has been subtracted, said another one of the power spectra being obtained at the fundamental spatial frequency, plus intensities of the power spectra at plural frequencies which are an integer multiple thereof.

Claim 2

A method for the measurement of surface characteristics which comprises the steps of: projecting an image of a rectangular wave pattern, which has been reflected from a surface to be tested, onto an image forming plane by means of an image forming optical system to form the image of the pattern on the image forming plane; transforming the spatial distribution of the intensity of light falling on the image plane according to the Fourier transformation; quantifying the distinctness-of-image glossiness of the surface to be tested according to the intensity of each of power spectra at particular spatial frequencies; and individually quantifying the degree of blurring of the image according to the intensity of one of the power spectra which have been obtained from the waveform of the formed image, said one of the power spectra being obtained at a fundamental spatial frequency, and the degree of distortion of the image according to the total sum of the intensity of another one of the power spectra which have been obtained from the waveforms of the image from which the base line intensity has been subtracted, said another one of the power spectra being obtained at the fundamental spatial frequency, plus intensities of the power spectra at plural frequencies which are an integer multiple thereof.

Claim 3

A method of quantifying the distinctness-of-image glossiness of the sample surface by projecting an image of a rectangular wave pattern, which has been reflected from a surface to be tested, onto an image forming plane by means of an image forming optical system to form the image of the pattern on the image forming plane, and transforming the spatial distribution of the intensity of light falling on the image plane according to the Fourier transformation to enable the quantification of the distinctness-of-image glossiness in terms of the magnitude of the light power strength at a particular spatial frequency, which method is characterized in that the blurring of the image is quantified by the power strength at a fundamental spatial frequency and the degree of deformation of the image is quantified by a ratio of the sum of the power strengths at a plurality of frequencies which are an integer multiple of the fundamental spatial frequency relative to the power strength at the fundamental spatial frequency.

Claim 4

A method of quantifying the distinctness-of-image glossiness of the sample surface by projecting an image of a rectangular wave pattern, which has been reflected from a surface to be tested, onto an image forming plane by means of an image forming optical system to form the image of the pattern on the image forming plane, and transforming the spatial distribution of the intensity of light falling on the image plane according to the Fourier transformation to enable the quantification of the distinctness-of-image glossiness in terms of the magnitude of the light power strength at a particular spatial frequency, which method is characterized in that the blurring of the image is quantified by the power strength at a fundamental spatial frequency and the degree of deformation of the image is quantified by a ratio of the sum of the power strengths at a plurality of frequencies which are an integer multiple of the fundamental spatial frequency relative to the power strength at the fundamental spatial frequency.

Claim 5

A method of quantifying the distinctness-of-image glossiness of the sample surface by projecting an image of a rectangular wave pattern, which has been reflected from a surface to be tested, onto an image forming plane by means of an image forming optical system to form the image of the pattern on the image forming plane, and transforming the spatial distribution of the intensity of light falling on the image plane according to the Fourier transformation to enable the quantification of the distinctness-of-image glossiness in terms of the magnitude of the light power strength at a particular spatial frequency, which method is characterized in that the degree of blurring of the image is quantified by the power strength at a fundamental spatial frequency and the degree of deformation of the image is quantified by a ratio of the sum of the power strengths at a plurality of frequencies in the vicinity of the fundamental spatial frequency relative to the power strength at the fundamental spatial frequency.

Claim 6

A method of quantifying the distinctness-of-image glossiness of the sample surface by projecting an image of a rectangular wave pattern, which has been reflected from a surface to be tested, onto an image forming plane by means of an image forming optical system to form the image of the pattern on the image forming plane, and transforming the spatial distribution of the intensity of light falling on the image plane according to the Fourier transformation to enable the quantification of the distinctness-of-image glossiness in terms of the magnitude of the light power strength at a particular spatial frequency, which method is characterized in that the degree of blurring of the image is quantified by the power strength at a fundamental spatial frequency and the degree of deformation of the image is quantified by a ratio of the sum of the power strengths at a plurality of frequencies in the vicinity of the fundamental spatial frequency relative to the power strength at the fundamental spatial frequency.

Claim 10

The method as claimed in any of claims 1-3, wherein the rectangular wave pattern has a pitch within the range of 0.5 to 20 mm -1 when expressed in terms of the spatial frequency.

Claim 11

The method as claimed in any of claims 1-3, wherein the magnification of the formed image is within the range of 0.5 to 20 times.

Claim 12

The method as claimed in any of claims 1-3, wherein, in a plane generally perpendicular to the surface to be tested and containing an optical axis of the optical system, which includes an illuminating optical means, the rectangular wave pattern and the image forming optical means for projecting and forming the image of the rectangular wave pattern, and an optical axis of the photoelectric converting means for converting a spatial distribution of the intensity of light of the formed image waveform on the image forming plane into an electric signal, each of the angle of projection defined between the plane normal to the surface to be tested and the optical axis of the optical system containing the illuminating optical means and the rectangular wave pattern and the image forming optical means, and the light receiving angle defined between the plane normal to the surface to be tested and the photoelectric converting means for converting a spatial distribution of the intensity of light of the formed image waveform on the image forming plane into an electric signal is within the range of 20° to 80°.

Claim 13

The method as claimed in any of claims 1-3, wherein the distance between the principal point of an image forming lens included in the image forming optical means and the surface to be tested is within the range φ0.1 to 0.9 times the distance between the principal point of the image forming lens and the image forming plane.

Claim 14

An apparatus for measuring surface characteristics which comprises: an illuminating optical means for illuminating a rectangular wave pattern; an image forming optical system for projecting an image of the rectangular wave pattern, reflected from a surface to be tested, onto an image forming plane to form the image of the rectangular wave pattern on an image forming plane; a photoelectric converting means for converting a spatial distribution of the intensity of light of the formed image waveform on the image forming plane into an electric signal; and a data processing means for transforming a spatial light intensity distribution signal from the photoelectric converting means according to the Fourier transformation thereby to calculate the intensity of a power spectrum at a particular spatial frequency; said data processing means being operable to calculate the intensity of a power spectrum at a fundamental spatial frequency of the waveform of the formed image and also the sum of the intensity of the power spectrum at the fundamental spatial frequency of the waveform of the formed image from which the base line intensity has been substracted and the intensity of the power spectrum at plural spatial frequencies which are an integer multiple of the fundamental spatial frequency.

Claim 15

An apparatus for measuring surface characteristics which comprises: an illuminating optical means for illuminating a rectangular wave pattern; an image forming optical system for projecting an image of the rectangular wave pattern, reflected from a surface to be tested, onto an image forming plane to form the image of the rectangular wave pattern on an image forming plane; a photoelectric converting means for converting a spatial distribution of the intensity of light of the formed image waveform on the image forming plane into an electric signal; and a data processing means for transforming a spatial light intensity distribution signal from the photoelectric converting means according to the Fourier transformation thereby to calculate the intensity of a power spectrum at a particular spatial frequency; said data processing means being operable to calculate the intensity of a power spectrum at a fundamental spatial frequency of the waveform of the formed image and also the sum of the intensity of the power spectrum at the fundamental spatial frequency of the waveform of the formed image from which the base line intensity has been substracted and the intensity of the power spectrum at plural spatial frequencies which are an integer multiple of the fundamental spatial frequency.

Claim 16

An apparatus for measuring a surface characteristic which comprises an illuminating optical means for illuminating a rectangular wave pattern, an image forming optical system for projecting an image of the rectangular wave pattern, reflected from a surface to be tested, onto an image forming plane to form the image of the rectangular wave pattern on an image forming plane, a photoelectric converting means for converting a spatial distribution of the intensity of light of the formed image waveform on the image forming plane into an electric signal, and a data processing means for transforming a spatial light intensity distribution signal from the photoelectric converting means according to the Fourier transformation thereby to calculate the intensity of a power spectrum at a particular spatial frequency so that the surface characteristic can be measured from the power spectrum calculated by the data processing means, which apparatus is characterized in that there is provided a calculating means for calculating the power spectrum at a fundamental spatial frequency and also the sum of the power strengths at a plurality of frequencies which are an integer multiple of the fundamental spatial frequency relative to the power strength at the fundamental spatial frequency.

Claim 17

An apparatus for measuring a surface characteristic which comprises an illuminating optical means for illuminating a rectangular wave pattern, an image forming optical system for projecting an image of the rectangular wave pattern, reflected from a surface to be tested, onto an image forming plane to form the image of the rectangular wave pattern on an image forming plane, a photoelectric converting means for converting a spatial distribution of the intensity of light of the formed image waveform on the image forming plane into an electric signal, and a data processing means for transforming a spatial light intensity distribution signal from the photoelectric converting means according to the Fourier transformation thereby to calculate the intensity of a power spectrum at a particular spatial frequency so that the surface characteristic can be measured from the power spectrum calculated by the data processing means, which apparatus is characterized in that there is provided a calculating means for calculating the power spectrum at a fundamental spatial frequency and also the sum of the power strengths at a plurality of frequencies which are an integer multiple of the fundamental spatial frequency relative to the power strength at the fundamental spatial frequency.

Claim 18

An apparatus for measuring a surface characteristic which comprises an illuminating optical means for illuminating a rectangular wave pattern, an image forming optical system for projecting an image of the rectangular wave pattern, reflected from a surface to be tested, onto an image forming plane to form the image of the rectangular wave pattern on an image forming plane, a photoelectric converting means for converting a spatial distribution of the intensity of light of the formed image waveform on the image forming plane into an electric signal, and a data processing means for transforming a spatial light intensity distribution signal from the photoelectric converting means according to the Fourier transformation thereby to calculate the intensity of a power spectrum at a particular spatial frequency so that the surface characteristic can be measured from the power spectrum calculated by the data processing means, which apparatus is characterized in that there is provided a calculating means for calculating the power strength at a fundamental spatial frequency and the ratio of the sum of the power strengths at a plurality of frequencies in the vicinity of the fundamental spatial frequency relative to the power strength at the fundamental spatial frequency.

Claim 19

An apparatus for measuring a surface characteristic which comprises an illuminating optical means for illuminating a rectangular wave pattern, an image forming optical system for projecting an image of the rectangular wave pattern, reflected from a surface to be tested, onto an image forming plane to form the image of the rectangular wave pattern on an image forming plane, a photoelectric converting means for converting a spatial distribution of the intensity of light of the formed image waveform on the image forming plane into an electric signal, and a data processing means for transforming a spatial light intensity distribution signal from the photoelectric converting means according to the Fourier transformation thereby to calculate the intensity of a power spectrum at a particular spatial frequency so that the surface characteristic can be measured from the power spectrum calculated by the data processing means, which apparatus is characterized in that there is provided a calculating means for calculating the power strength at a fundamental spatial frequency and the ratio of the sum of the power strengths at a plurality of frequencies in the vicinity of the fundamental spatial frequency relative to the power strength at the fundamental spatial frequency.

Claim 23

The apparatus as claimed in any of claims 11-13, further comprising a control means for controlling the intensity of light of the illuminating optical means.

Claim 24

The apparatus as claimed in any of claims 11-13, wherein the rectangular wave pattern has a pitch within the range 0.5 to 20 mm -1 in terms of the spatial frequency.

Claim 25

The apparatus as claimed in any of claims 11-13, wherein the rectangular wave pattern comprises a substrate formed with rectangular wave patterns having different pitches.

Claim 26

The apparatus as claimed in any claims 11-13, further comprising a mechanism provided with a plurality of rectangular waver patterns of different pitches and operable to change the rectangular wave pattern used to project and form the image.

Claim 27

The apparatus as claimed in any of claims 11-13, wherein the magnification of the formed image is within the range of 0.5 to 20 times.

Claim 28

The apparatus as claimed in any of claims 11-13, further comprising a mechanism for adjusting the image forming magnification employed to form the image of the pattern on the image forming plane to a value within the range of 0.5 to x20.

Claim 29

The apparatus as claimed in any of claims 11-13, wherein the distance between the principal point of an image forming lens included in the image forming optical means and the surface to be tested is within the range of 0.1 to 0.9 times the distance between the principal point of the image forming lens and the image forming plane.

Claim 30

The apparatus as claimed in any of claims 11-13, further comprising means for adjusting the distance between the principal point of the image forming lens and the surface to be tested to a value within the range of 0.1 to 0.9 times the distance between the principal point of the image forming lens and the image forming plane.

Claim 31

The apparatus as claimed in any of claims 11-13, wherein, in a plane generally perpendicular to the surface to be tested and containing an optical axis of the optical system, which includes an illuminating optical means, the rectangular wave pattern and the image forming optical means, and an optical axis of the image of the rectangular wave pattern, each of the angle of projection defined between the plane normal to the surface to be tested and the optical axis of the optical system containing the illuminating optical means, the rectangular wave pattern and the image forming optical means, and the light receiving angle defined between the plane normal to the surface to be tested and the optical axis of the image of the rectangular wave pattern is within the range of 20° to 80°.

Claim 32

The apparatus as claimed in any of claims 11-13, further comprising a mechanism for adjusting the angle formed between the same optical axis on which the illuminating optical means and the image of the rectangular wave pattern are located and the direction perpendicular to the surface to be tested to a value within the range of 20° to 80°.

Claim 33

The apparatus as claimed in any of claims 11-13, wherein the photoelectric converting means is a single-cell photoelectric tranducing element provided with a perforated light shielding mask positioned in front of a light receiving surface thereof, said element being so designed as to mechanically scan the image forming plane.

Claim 34

The apparatus as claimed in any of claims 11-13, wherein the photoelectric converting means is a linear image sensor provided with a circuit for varying an electronically scanning speed.

Claim 35

The apparatus as claimed in any of claims 11-13, wherein the photoelectric converting means is comprised of a linear image sensor and a single-cell photoelectric tranducing element provided with a light shielding mask having an opening defined therein, said light shielding mask being positioned in front of a light receiving surface thereof.

Claim 36

The apparatus as claimed in any of claims 11-13, further comprising a mechanism for automatically adjusting one of the surface to be tested, the image forming optical means and the photoelectric element to a focused position.

Claim 37

The apparatus as claimed in any of claims 11-13, further comprising means for controlling any one of the temperatures, humidity and flow of air inside a space in which the surface to be tested is located.