ISO 25178-603:2013 幾何学的製品仕様（GPS）—表面テクスチャ：面積—パート603：非接触（位相シフト干渉顕微鏡）機器の公称特性 | ページ 5

2.1.1

areal reference

component of the instrument that generates a reference surface with respect to which the surface topography is measured

2.1.2

coordinate system of the instrument

Note 1 to entry: Normally, the x-axis is the tracing axis and the y-axis is the stepping axis. (This note is valid for instruments that scan in the horizontal plane.)

Note 2 to entry: See also “specification coordinate system” [ISO 25178‑2:2012, 3.1.2] and “measurement coordinate system” [ISO 25178‑6:2010, 3.1.1].

SEE: Figure 1.

Figure 1—Coordinate system and measurement loop of the instrument

Key

1	coordinate system of the instrument
2	measurement loop

Note 3 to entry:

2.1.3

measurement loop

closed chain which comprises all components connecting the workpiece and the probe, e.g. the means of positioning, the work holding fixture, the measuring stand, the drive unit, the probing system

Note 1 to entry: The measurement loop will be subjected to external and internal disturbances that influence the measurement uncertainty.

SEE: Figure 1.

2.1.4

real surface of a workpiece

set of features which physically exist and separate the entire workpiece from the surrounding medium

Note 1 to entry: The real surface is a mathematical representation of the surface that is independent of the measurement process.

Note 2 to entry: See also “mechanical surface” [ISO 25178‑2:2012, 3.1.1.1 or ISO 14406:2010, 3.1.1] and “electromagnetic surface” [ISO 25178‑2:2012, 3.1.1.2 or ISO 14406:2010, 3.1.2].

Note 3 to entry: The electromagnetic surface considered for one type of optical instrument may be different from the electromagnetic surface for other types of optical instruments.

2.1.5

surface probe

device that converts the surface height into a signal during measurement

Note 1 to entry: In earlier standards, this was termed “transducer”.

2.1.6

measuring volume

range of the instrument stated in terms of the limits on all three coordinates measured by the instrument

Note 1 to entry: For areal surface texture measuring instruments, the measuring volume is defined by the measuring range of the x- and y- drive units, and the measuring range of the z-probing system.

[SOURCE:ISO 25178‑601:2010, 3.4.1]

2.1.7

response curve

F_x, F_y, F_z

graphical representation of the function that describes the relation between the actual quantity and the measured quantity

Note 1 to entry: An actual quantity in x (respectively yorz) corresponds to a measured quantity x_M (respectively y_Morz_M).

Note 2 to entry: The response curve can be used for adjustments and error corrections.

SEE: Figure 2

Figure 2—Example of a nonlinear response curve

Key

1	response curve	3	measured quantities
2	assessment of the linearity deviation by polynomial approximation	4	input quantities

[ISO 25178‑601:2010, 3.4.2]

2.1.8

amplification coefficient

α_x, α_y, α_z

slope of the linear regression curve obtained from the response curve (2.1.7)

Note 1 to entry: There will be amplification coefficients applicable to the x, y and z quantities.

Note 2 to entry: The ideal response is a straight line with a slope equal to 1 which means that the values of the measurand are equal to the values of the input quantities.

Note 3 to entry: See also “sensitivity of a measuring system” (ISO/IEC Guide 99:2007, 4.12)^[1].

SEE: Figure 3

Figure 3—Example of the linearization of a response curve

Key

1	measured quantities	4	linearization of the response curve of Figure 2
2	input quantities	5	line from which the amplification coefficient α is derived
3	ideal response curve	6	local residual correction error before adjustment

[ISO 25178‑601:2010, 3.4.3, modified — Note 3 to entry has been added.]

2.1.9

instrument noise

N_I

internal noise added to the output signal caused by the instrument if ideally placed in a noise-free environment

Note 1 to entry: Internal noise can be due to electronic noise, as e.g. amplifiers, or to optical noise, as e.g. stray light.

Note 2 to entry: This noise typically has high frequencies and it limits the ability of the instrument to detect small scale spatial wavelengths of the surface texture.

Note 3 to entry: The S-filter according ISO 25178‑3 may reduce this noise.

Note 4 to entry: For some instruments, instrument noise cannot be estimated because the instrument only takes data while moving.

2.1.10

measurement noise

N_M

noise added to the output signal occurring during the normal use of the instrument

Note 1 to entry: Notes 2 and 3 of 2.1.9 apply as well to this definition.

Note 2 to entry: Measurement noise includes instrument noise (2.1.9) .

2.1.11

surface topography repeatability

repeatability of topography map in successive measurements of the same surface under the same conditions of measurement

Note 1 to entry: Surface topography repeatability provides a measure of the likely agreement between repeated measurements normally expressed as a standard deviation.

Note 2 to entry: See ISO/IEC Guide 99:2007^[1] , 2.15 and 2.21, for a general discussion of repeatability and related concepts.

Note 3 to entry: Evaluation of surface topography repeatability is a common method for determining the measurement noise.

2.1.12

sampling interval in x

D_x

distance between two adjacent measured points along the x-axis

Note 1 to entry: In many microscopy systems, the sampling interval is determined by the distance between sensor elements in a camera, called pixels. For such systems, the terms pixel pitch and pixel spacing are often used interchangeably with the term sampling interval. Another term, pixel width, indicates a length associated with one side (xory) of the sensitive area of a single pixel and is always smaller than the pixel spacing. Yet another term, sampling zone, may be used to indicate the length or region over which a height sample is determined. This quantity could either be larger or smaller than the sampling interval. See also A.3.

2.1.13

sampling interval in y

D_y

distance between two adjacent measured points along the y-axis

Note 1 to entry: In many microscopy systems the sampling interval is determined by the distance between sensor elements in a camera, called pixels. For such systems, the terms pixel pitch and pixel spacing are often used interchangeably with the term sampling interval. Another term, pixel width, indicates a length associated with one side (xory) of the sensitive area of a single pixel and is always smaller than the pixel spacing. Yet another term, sampling zone, may be used to indicate the length or region over which a height sample is determined. This quantity could either be larger or smaller than the sampling interval. See also A.3.

2.1.14

digitization step in z

D_Z

smallest height variation along the z-axis between two ordinates of the extracted surface

2.1.15

lateral resolution

R_l

smallest distance between two features which can be detected

[SOURCE:ISO 25178‑601:2010, 3.4.10, modified — The word “separation” has been removed before “distance”.]

2.1.16

width limit for full height transmission

W_l

width of the narrowest rectangular groove whose measured height remains unchanged by the measurement

Note 1 to entry: Instrument properties (such as the sampling interval in x and y, the digitization step in z, andthe short wavelength cutoff filter) should be chosen so that they do not influence the lateral resolution and the width limit for full height transmission.

Note 2 to entry: When determining this parameter by measurement, the depth of the rectangular groove should be close to that of the surface to be measured.

Figure 4—Examples of grids and their measurements

a) Grid with horizontal spacing where t is greater than or equal to Wl

b) Measurement of the grid in a) — The spacing and depth of the grid are measured correctly

c) Grid with horizontal spacing t' smaller than Wl

d) Measurement of the grid in c) — The spacing is measured correctly but the depth is smaller (d' < d )

[SOURCE:ISO 25178‑601:2010, 3.4.11, modified — The definition is identical. The notes, examples and figures are different.]

2.1.17

lateral period limit

D_LIM

spatial period of a sinusoidal profile at which the height response of an instrument falls to 50 %

Note 1 to entry: The lateral period limit is one metric for describing spatial or lateral resolution of a surface topography measuring instrument and its ability to distinguish and measure closely spaced surface features. Its value depends on the heights of surface features and on the method used to probe the surface. Maximum values for this parameter are listed in ISO 25178‑3: 2012, Table 3, in comparison with recommended values for short wavelength (s-) filters and sampling intervals.

Note 2 to entry:Spatial period is the same concept as spatial wavelength and is the inverse of spatial frequency.

Note 3 to entry: One factor related to the value of D_LIM for optical tools is the Rayleigh criterion (2.3.7). Another is the degree of focus of the objective on the surface.

Note 4 to entry: One factor related to the value of D_LIM for contact tools is the stylus tip radius, r_TIP (see 25178–601).

Note 5 to entry: Other terms related to lateral period limit are structural resolution and topographic spatial resolution

2.1.18

maximum local slope

greatest local slope of a surface feature that can be assessed by the probing system

Note 1 to entry: The term “local slope” is defined in ISO 4287:1997, 3.2.9.

2.1.19

instrument transfer function

ITF

f_ITF

function of spatial frequency describing how a surface topography measuring instrument responds to an object surface topography having a specific spatial frequency

Note 1 to entry: Ideally, the ITF tells us what the measured amplitude of a sinusoidal grating of a specified spatial frequency would be relative to the true amplitude of the grating.

Note 2 to entry: For several types of optical instruments, the ITF may be a nonlinear function of height except for heights much smaller than the optical wavelength.

2.1.20

hysteresis

x_HYS, y_HYS, z_HYS

property of measuring equipment or characteristic whereby the indication of the equipment or value of the characteristic depends on the orientation of the preceding stimuli

Note 1 to entry: Hysteresis can also depend, for example, on the distance travelled after the orientation of stimuli has changed.

Note 2 to entry: For lateral scanning systems, the hysteresis is mainly a repositioning error.

[SOURCE:ISO 14978:2006, 3.24, modified — Note 2 to entry and the symbols have been added.]

2.1.21

metrological characteristic

metrological characteristic of a measuring instrument

<measuring equipment> characteristic of measuring equipment, which may influence the results of measurement

Note 1 to entry: Calibration of metrological characteristics may be necessary.

Note 2 to entry: The metrological characteristics have an immediate contribution to measurement uncertainty.

[SOURCE:ISO 14978:2006, 3.12, modified — The notes are different and the table has been added.]

2.2.1

areal reference guide

component(s) of the instrument that generate(s) the reference surface, in which the probing system moves relative to the surface being measured according to a theoretically exact trajectory

Note 1 to entry: In the case of x- and y-scanning areal surface texture measuring instruments, the areal reference guide establishes a reference surface [ISO 25178‑2:2012, 3.1.8]. It can be achieved through the use of two linear and perpendicular reference guides [ISO 3274:1996, 3.3.2] or one reference surface guide.

2.2.2

lateral scanning system

system that performs the scanning of the surface to be measured in the (x,y) plane

Note 1 to entry: There are essentially four aspects to a surface texture scanning instrument system: the x-axis drive, the y-axis drive, the z-measurement probe and the surface to be measured. There are different ways in which these may be configured and thus there will be a difference between different configurations as explained in Table 2.

2.2.3

drive unit x

component of the instrument that moves the probing system or the surface being measured along the reference guide on the x-axis and returns the horizontal position of the measured point in terms of the lateral x-coordinate of the profile

2.2.4

drive unit y

component of the instrument that moves the probing system or the surface being measured along the reference guide on the y-axis and returns the horizontal position of the measured point in terms of the lateral y-coordinate of the profile

2.2.5

lateral position sensor

component of the drive unit that provides the lateral position of the measured point

Note 1 to entry: The lateral position can be measured or inferred by using, for example, a linear encoder, a laser interferometer, or a counting device coupled with a micrometer screw.

2.2.6

speed of measurement

V_x

speed of the probing system relative to the surface to be measured during the measurement along the x-axis

[SOURCE:ISO 25178‑601:2010, 3.4.13]

2.2.7

static noise

N_S

combination of the instrument and environmental noise on the output signal when the instrument is not scanning laterally

Note 1 to entry:Environmental noise is caused by e.g. seismic, sonic and external electromagnetic disturbances.

Note 2 to entry: Notes 2 and 3 in 2.1.9 apply to this definition.

Note 3 to entry: Static noise is included in measurement noise (2.1.10)

2.2.8

dynamic noise

N_D

noise occurring during the motion of the drive units on the output signal

Note 1 to entry: Notes 2 and 3 in 2.1.9 apply to this definition.

Note 2 to entry: Dynamic noise includes the static noise.

Note 3 to entry: Dynamic noise is included in measurement noise (2.1.10) .

2.3.1

light source

optical device emitting an appropriate range of wavelengths in a specified spectral region

2.3.2

measurement optical bandwidth

B_λ0

range of wavelengths of light used to measure a surface

Note 1 to entry: Instruments may be constructed with light sources with a limited optical bandwidth and/or with additional filter elements to further limit the optical bandwidth.

2.3.3

measurement optical wavelength

λ₀

effective value of the wavelength of the light used to measure a surface

Note 1 to entry: The measurement optical wavelength is affected by conditions such as the light source spectrum, spectral transmission of the optical components, and spectral response of the image sensor array (see Annex A).

2.3.4

angular aperture

angle of the cone of light entering an optical system from a point on the surface being measured

[SOURCE:ISO 25178‑602:2010, 3.3.3]

2.3.5

half aperture angle

α

one half of the angular aperture

Note 1 to entry: This angle is sometimes called the “half cone angle” (see Figure 5).

Figure 5—Half aperture angle

Key

L	lens or optical system
P	focal point
α	half aperture angle

2.3.6

numerical aperture

A_N

Note 1 to entry: In air for visible light, n ≅ 1.

Note 2 to entry: The numerical aperture is dependent on the wavelength of light. Typically, the numerical aperture is specified for the wavelength that is in the middle of the measurement optical bandwidth.

2.3.7

Rayleigh criterion

quantity characterizing the spatial resolution of an optical system given by the separation of two point sources at which the first diffraction minimum of the image of one point source coincides with the maximum of the other

Note 1 to entry: For a theoretically perfect, incoherent optical system with a filled objective pupil, the Rayleigh criterion of the optical system is equal to 0,61 λ₀/A_N.

Note 2 to entry: This parameter is useful for characterizing the instrument response to features with heights much less than λ₀ for optical 3D metrology instruments.

2.3.8

Sparrow criterion

quantity characterizing the spatial resolution of an optical system given by the separation of two point sources at which the second derivative of the intensity distribution vanishes between the two imaged points

Note 1 to entry: For a theoretically perfect, incoherent optical system with a filled objective pupil, the Sparrow criterion of the optical system is equal to 0,47 λ₀/A_N, approximately 0,77 times the Rayleigh criterion (2.3.7) .

Note 2 to entry: This parameter is useful for characterizing the instrument response to features with heights much less than λ₀ for optical 3D metrology instruments.

Note 3 to entry: Under the same measurement conditions as the notes above, the Sparrow criterion is nearly equal to the spatial period of 0,50 λ₀/A_N, for which the theoretical instrument response falls to zero.

2.4.1

surface film

material deposited onto another surface whose optical properties are different from that surface

Note 1 to entry: This concept may also be called “surface layer”.

2.4.2

thin film

film whose thickness is such that the top and bottom surfaces cannot be readily separated by the optical measuring system

Note 1 to entry: For some measurement systems with special properties and algorithms, the thicknesses of thin films may be derived.

2.4.3

thick film

film whose thickness is such that the top and bottom surfaces can be readily separated by the optical measuring system

2.4.4

optically smooth surface

surface from which the reflected light is primarily specular and scattered light is not significant

Note 1 to entry: An optically smooth surface behaves locally like a mirror.

Note 2 to entry: A surface that acts as optically smooth under certain conditions, such as wavelength range, numerical aperture, pixel resolution, etc., can act as optically rough when one or more of these conditions change.

2.4.5

optically rough surface

surface that does not behave as an optically smooth surface, i.e. where scattered light is significant

Note 1 to entry: A surface that acts as optically rough under certain conditions, such as wavelength range, numerical aperture, pixel resolution, etc., can act as optically smooth when one or more of these conditions change.

2.4.6

optically non-uniform material

sample with different optical properties in different regions

Note 1 to entry: An optically non-uniform material may result in measured phase differences across the field of view that can be erroneously interpreted as differences in surface height.

2.5.1

phase-shifting interferometric microscopy

PSI

surface topography measurement method whereby an optical microscope with illumination of a known effective wavelength is integrated with an interferometric attachment and produces multiple successive optical images with interferometric fringes from which the profile or areal surface topography image is calculated

Note 1 to entry: Phase-shifting interferometric (PSI) microscopes provide a non-contact measurement of surface texture for which the average roughness (Raorsa) is typically less than λ₀/10.

Note 2 to entry: Typical illumination sources include lasers, light emitting diodes (LED), narrow-band filtered white light sources, or spectral lamps.

[SOURCE:ISO 25178‑6:2010, 3.3.5]

2.5.2

phase-shifting measurement algorithm

algorithm that determines the number of phase shifted images to be acquired, the relative phase difference between images and the measurement equations used to calculate the texture

2.5.3

phase unwrapping algorithm

algorithm used to construct the measured surface given that the measured height at each point is a multivalued function and can be ambiguous by integral multiples of λ₀/2

Note 1 to entry: Phase unwrapping algorithms typically assume that the height difference of adjacent measured points is less than λ₀/4.

2.5.4

sample tilt

angle between the surface normal and the optical axis of the system during measurement

Note 1 to entry: Sample tilt is typically measured by the number of fringes in the field of view across an ideally flat sample (see Annex A).

2.5.5

reference root mean square variation

rms of the height deviations measured by the system when an ideally flat and smooth surface is measured

Note 1 to entry: The reference root mean square variation arises from several sources of error in the instrument including imperfections in the reference mirror and elsewhere in the optical system. The reference root mean square variation may be reduced by an appropriate averaging procedure as outlined in Annex A.

Note 2 to entry: The reference root mean square variation may be resolved into components, such as residual flatness and measurement noise.