JP6645868B2 - Hole diameter measuring device and measuring method using the same - Google Patents

Description

  The present invention relates to a hole diameter measuring device and a measuring method using the same, and particularly to a hole diameter measuring device for measuring a hole diameter of a through hole having a small diameter by using a spectral spectrum and a measuring method using the same.

  For accurate measurement of the hole diameter, contact and non-contact measurement using a probe and measurement using an optical or electronic microscope are known. For example, in the measurement of the minute inner diameter described in Patent Document 1, a probe is inserted into a minute hole of an object to be measured, and the probe or the object to be measured is moved while the probe is inserted into the minute hole, and the probe comes into contact with the minute hole. The contact position at the time is stored. Then, the probe is brought into contact with the micropore at a plurality of locations, a circle is identified from information on three or more contact points, and the diameter of the micropore is calculated.

  Further, in Patent Document 2, a chromatic point sensor (CPS) is used to measure a geometric characteristic such as a hole diameter without rotating an optical pen. Specifically, the above CPS device having an optical pen provided with a beam splitting / deflecting element is provided, the optical pen is inserted into a hole, and measurement light is simultaneously irradiated in three measurement directions orthogonal to the central axis of the optical pen. The reflected light is received through a confocal aperture of the optical pen. The distance between the optical pen and the hole wall is determined from the spectrum of the received reflected light, and the geometrical characteristics such as the hole diameter are measured.

  Further, Patent Literature 3 describes that the outer diameter of a steel material is determined using a laser, not the hole diameter. In this publication, the outer diameter of the steel material is measured over the entire length while the steel material is being conveyed using a laser scanning type dimension measuring device including a light emitter and a light receiver. At that time, the optical axis of the dimension measuring instrument is arranged in two steps in the circumferential direction and in the vertical direction with respect to the flow direction of the steel material transfer table. Calculation processing is performed so that the outer diameter value on the circumference is obtained.

JP-A-2003-4433 JP-A-2015-114326 JP 2006-153545 A

  In the hole diameter measuring apparatus using the probe described in Patent Documents 1 and 2, the probe diameter is smaller than the hole diameter because the probe is inserted into the hole. Therefore, whether the probe is of the contact type or the non-contact type, the outer diameter of the probe is required to be more than a predetermined value to secure the rigidity of the probe and, in the case of the optical type, to irradiate light and to detect reflection. There are restrictions on the conversion. For example, in the measurement of a minute hole of an object to be measured of 1 mm or less or even sub-mm or less, in the case of a contact type, the probe diameter becomes too small, and there is a possibility that the rigidity is insufficient or the function is difficult to secure. Further, in the device described in Patent Document 3, the purpose of measuring the outer diameter is not considered, and therefore the measurement of the micropore diameter is not considered.

  On the other hand, if an attempt is made to measure the diameter of a minute hole using an optical microscope, the contrast must be increased in order to clarify the edge of the hole, which may cause problems such as halation. Further, the influence of diffraction cannot be ignored. Furthermore, since it is required that the measurement target be large enough to be mounted on a microscope or the like, the measurement target that can be used is limited. In the case of an electron microscope (SEM), it is necessary to further place an object to be measured in a vacuum vessel, and pretreatment of the object to be measured may be required.

  The present invention has been made in view of the above-described disadvantages of the related art, and has as its object to accurately measure a minute hole diameter of a measurement object having a minute through hole having a hole diameter of 1 mm or less. Another object of the present invention, in addition to the above objects, is to make it unnecessary to insert a probe into a hole for a micro hole in which it is difficult to insert a probe, and to further reduce the diameter of the micro hole without performing a pretreatment for measurement. Is to measure.

  The feature of the present invention for achieving the above object is a hole diameter measuring device for measuring the hole of a measurement object having a small through hole, a white light source having a continuous spectrum, and a white light emitted from the light source. A prism for refraction, mounting means for mounting the object to be measured, positioning means for positioning the light refracted by the prism near the hole of the object to be measured, and a positioning means arranged on the back side of the mounting means. The light detection means for detecting the light passing through the hole, the upper limit wavelength and the lower limit wavelength of the light passed through the hole from the signal detected by the light detection means, and using the obtained upper limit wavelength and lower limit wavelength, Calculating means for calculating the hole diameter of the hole. The hole diameter measuring device of the present invention can measure a minute through hole having an inner diameter of 1 mm or less, and is suitable for measuring such a minute through hole.

  In this feature, it is preferable that a mask having an opening having a larger diameter than the hole of the measurement target is disposed on the lower surface side of the measurement target on the upper surface of the placing means, and holds the prism. It is preferable that a mechanism having a holding means and maintaining a constant distance between the holding means and the object to be measured is provided in the holding means or the positioning means.

  Further, between the prism and the object to be measured, a parallel light lens and a slit plate are arranged in order from the prism side, and the slit plate can be moved in a direction perpendicular to the optical axis of the parallel light lens. The light detecting means may be any one of a CMOS, a CCD, a direct image sensor, and a color separation photodiode, and a parallel light lens is provided between the prism and the object to be measured in order from the prism side. Disposing a slit plate, disposing a condenser lens between the placing means and the light detecting means, enabling the slit plate to move in a direction perpendicular to the optical axis of the parallel light lens, May be a photomultiplier tube.

Further, in the above features, the upper limit wavelength used for measuring the light refracted by the prism is λa, the lower limit wavelength is λb, and the spread width of the light exiting the prism at a position corresponding to the upper surface of the measurement target is D. When the upper limit wavelength of the light detected by the light detection unit is λa ′ and the lower limit wavelength is λb ′, the calculation unit sets the diameter d of the hole to:
d = D × (λa′−λb ′) / (λa−λb) (Equation 1)
It is better to get from.

Another feature of the present invention that achieves the above object is a method of measuring a hole diameter of a through hole having a hole diameter of 1.0 mm or less, wherein white light emitted from a light source having a continuous spectrum is refracted by a prism. In the case of irradiating the object to be measured, the spread range of the light exiting the prism when the reference height, which is the distance between the upper surface of the mounting means for mounting the object to be measured and the prism, is H. D, a calibration step for obtaining an upper limit wavelength λa and a lower limit wavelength λb at that time, and mounting the measurement target on the mounting means, and determining a distance between an upper surface of the measurement target and the prism as a reference height H. And a calculating step of calculating a hole diameter d of the hole from the obtained values by the following equation from the obtained upper limit wavelength λa ′ and lower limit wavelength λb ′ of the light passing through the hole.
d = D × (λa′−λb ′) / (λa−λb) (Equation 1)

  In this aspect, in the measurement step, the slit plate interposed between the prism and the measurement target may be moved in a direction substantially parallel to an upper surface of the measurement target.

  According to the present invention, light that has been dispersed enters a minute hole having a diameter of 1 mm or less, which is an object to be measured, and the wavelength of the light passing through the hole is detected to measure the minute hole diameter. The diameter of the minute hole can be measured. In addition, for a minute hole in which it is difficult to insert a probe, it is not necessary to insert the probe into the hole, and the diameter of the minute hole can be easily measured without performing a pretreatment or the like for measurement.

It is a front sectional view of one example of a hole diameter measuring device concerning the present invention, (a) shows a state at the time of calibration, and (b) shows a state at the time of measurement. It is a figure explaining the measurement principle of a minute hole diameter, (a) is an outline of an apparatus, (b) is a figure showing an example of a spectrum range, and (c) showing an example of a gain of a detecting means. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining Example 1 of this invention, (a) is a schematic front view, (b) is a figure which shows the detail of a mask part. It is a front sectional view of the modification of the hole diameter measuring device concerning the present invention. It is a front sectional view of other modification of a hole diameter measuring device concerning the present invention.

  Hereinafter, several embodiments of the hole diameter measuring device for micro holes according to the present invention will be described with reference to the drawings. In the following examples, the hole diameter of the target minute hole is 1 mm or less, and the hole is a through hole. In the present invention, the light spectrum is used for measuring the hole diameter.

  FIG. 1 is a front sectional view of one embodiment of a hole diameter measuring device 100 according to the present invention. FIG. 1A shows a state of the hole diameter measuring device 100 at the time of calibration, and FIG. This figure shows a state when a hole diameter d of a hole 71 (also referred to as a measurement hole or a measurement target hole) formed in the object 70 is measured. First, the state at the time of calibration will be described with reference to FIG.

  The hole diameter measuring apparatus 100 includes a white light source 12 having a continuous spectrum, a prism 14 that refracts light emitted from the white light source 12 to generate a light spectrum, and a positional relationship between the white light source 12 and the prism 14. And a casing 16 for accommodating and holding the prism. The white light source 12 includes a deuterium lamp having a continuous spectrum from about 180 nm to 400 nm, a tungsten light having a continuous spectrum from about 350 nm to 300 nm, or a xenon lamp having a continuous spectrum from about 185 nm to 2000 nm. And so on. As the prism 14, a prism made of normal dispersion glass having a refractive index of about 15 is used, but the prism is not limited to this, and various prisms can be used.

  In the present embodiment, the white light source 12 is disposed on the upper left of the casing 16 and emits white light from the upper left to the lower right. The radiated light 81 emitted from the white light source 12 enters the prism 14 disposed below the white light source 12, the refraction of the prism 14 changes according to the wavelength thereof, and the lower limit side refracted light 82 on the short wavelength side A light spectrum is formed between the light and the upper limit side refracted light 83 on the long wavelength side.

  On the other hand, in order to place the measuring object 70, a table-like placing means 60 is arranged below the prism holding means 10. The mounting means 60 is divided into a right part for measurement, in which the prism holding means 10 covers the upper part, and a left part, in which the positioning means 20 for moving the prism holding means 10 in the vertical direction are arranged. . An opening 61 having a diameter sufficiently larger than the measurement target hole 71 formed in the measurement target 70 is formed in the measurement portion of the mounting means 60.

  The opening 61 is left as an opening or a transparent plate is fitted therein so that the spectrum of light that has exited the prism 14, which will be described in detail later, can be detected. The mask 30 in which the opening 32 having a diameter substantially the same as or slightly smaller than that of the opening 61 formed in the measurement portion of the mounting means 60 is disposed on the upper surface of the opening 61. The mask 30 is used to determine a light spectrum that is a reference of the hole diameter measuring device 100.

  The positioning means 20 includes a base 25 mounted on the mounting means 60, a rail 22 extending vertically upward from the base 25, and a slider 21 fitted to the rail 22. The rail 22 and the slider 21 may be linear motion means such as a ball spline or a linear motor, and the slider 21 or the rail 22 may be configured to be driven by a stepping motor or the like, or may be manually moved vertically in the vertical direction. You may make it do. When the slider 21 is moved manually, the rotation knob 23 attached to the slider 21 is rotated. The rotation knob 23 is also used to stop and hold the slider 21.

  The slider 21 is connected to the casing 16 of the prism holding means 10 by a support arm 24. When the slider 21 moves up and down, the prism 14 moves up and down together with the slider 21. A contact 18 is provided at a position on the lower surface of the prism holding means 10 and opposed to the upper surface of the mask 30, and the height from the upper surface of the mask 30 to the radiation position of the light exiting the prism 14 during calibration. H can be kept constant. In the present embodiment, the height H from the upper surface of the mask 30 to the position where the refracted light is emitted from the prism 14 is fixed at the time of calibration using the contact 18, but measurement is performed instead of the contact 18. It goes without saying that it is also possible to provide a distance device and use it to keep the height H constant.

  On the lower surface side of the mounting means 60, at a portion of the opening 61 provided in the mounting means 60, a light detecting means 40 for detecting light passing through the opening 32 of the mask 30 at the time of calibration is provided. As the light detecting means 40, a photodiode 41 (described in FIG. 4A) such as a CCD or CMOS, a direct image sensor, a color separation photodiode, or a FOVEON manufactured by FOVEON, USA can be used. The detection signal of the light detecting means 40 is sent to the calculating means 50.

  At the time of calibration of the hole diameter measuring apparatus 100 configured as described above, first, the mask 30 is positioned so that the opening 32 is positioned above the opening 61 of the mounting means 60. Next, the contact 18 provided on the lower surface of the prism holding means 10 is brought into contact with a portion other than the opening 32 of the mask 30, and the distance from the refracted light emission surface of the prism 14 to the upper surface of the mask 30 is determined in advance. Set to the determined height H. Next, the light detection means 40 detects the spectrum of the light originating from the white light source 12 passing through the opening 32 of the mask 30 and the opening 61 of the mounting means 60. At this time, the light detection means 40 determines the wavelength λb and the length of the lower limit side refracted light 82 on the short wavelength side of the spectrum passing through the opening 32 of the mask 30 having the inner diameter or the width D, that is, the limit of the white light source blocked by the mask 30. The wavelength λa of the upper-limit refracted light 83 on the wavelength side is detected. This completes the calibration.

  Next, the inner diameter of the hole (measurement object hole) 71 actually formed in the measurement object 70 is measured. In the same state as at the time of calibration, the prism holding means 10 is moved upward, and the measurement target 70 is placed on the upper surface of the mask 30. At this time, the hole 71 of the measurement target 70 is located within the opening 32 of the mask 30. Next, the contact 18 attached to the lower surface of the prism holding means 10 using the positioning means 20 is brought into contact with the upper surface of the measuring object 70. Thereby, the height H from the refracted light emission position of the prism 14 to the upper surface of the measurement object 70 can be made to match the height H at the time of calibration.

  When light having a continuous spectrum is emitted from the white light source 12 in this state, the emitted light 81 enters the prism 14 and is refracted to form a light spectrum. The emitted light 81 passes through the prism 14 and spreads in the same wavelength range between the lower limit refracted light 82 and the upper limit refracted light 83 as in calibration, but the spectrum of the light passing through the measurement hole 71 of the measurement target 70 is , The wavelength range between the hole entrance lower limit light 85 and the hole entrance upper limit light 86. The light detecting means 40 arranged on the lower surface of the placing means 60 detects the wavelength λb ′ of the hole entering lower limit light 85 and the wavelength λa ′ of the hole entering upper limit light 86.

Since the data λa, λb, and D at the time of calibration are stored in the arithmetic means 50, the measurement hole of the measuring object 70 is obtained by using the data and the wavelengths λb ′ and λa ′ obtained by the current measurement. The inner diameter d of 71 is obtained by the following equation.
d = D × (λa′−λb ′) / (λa−λb) (Equation 1)

  The above measurement principle will be further described with reference to FIG. FIG. 2A is a diagram illustrating a main part of the hole diameter measuring device 100 extracted therefrom. FIG. 2B is a diagram illustrating a spectrum of light generated by the prism 14 and measurement of a measurement target 70 on the spectrum. FIG. 3 is a diagram schematically showing a position 110 of a hole 71. FIG. 2C is a diagram schematically showing the amplitude Amp of the detection signal detected by the light detection means 40 as the vertical axis and the horizontal axis as the wavelength λ. In FIG. 2A, the mask 30 is omitted. In the case of calibration without using the mask 30, the reference position of the reference height H is the upper surface of the mounting means 60, and the internal diameter of the opening 61 of the mounting means 60 is D instead of the internal diameter of the opening 32 of the mask 30. By using, the above equation can be applied.

  When the light source 12 is a white light source having a continuous spectrum, the spectrum of the light refracted by the prism 14 and passed through the opening 62 formed in the mounting means 60 is, for example, as shown in FIG. If a xenon lamp is used as the light source 12, the light from the ultraviolet light λb to the infrared light λa is included. That is, in addition to the visible light region, the region outside the visible light is included. In short, it is only required that a continuous spectrum from short wavelength to long wavelength can be used. This corresponds to the gain 112 detected by the light detection means 40 at the time of calibration.

  On the other hand, at the time of measurement, since it can be visually confirmed, the position 110 of the hole 71 of the measurement object 70 is set to be within the visible light range of the spectrum. In this embodiment, the short wavelength side is a purple range and the long wavelength side is a yellow range. At this time, in the gain 111 of the light detecting means 40, λb ′ is about 450 nm, and λa ′ is about 550 nm.

  Next, a more specific example will be described in Example 1 with reference to FIG. FIG. 3A is a schematic front view of the measuring device, and FIG. 3B is a diagram showing only the mask portion.

  As the white light source 12, a tungsten light source or a light source capable of emitting daylight is used. The light source 12 emits continuous light including a spectrum i-line (365.01 nm) on the short wavelength side to a spectrum t-line (1013.98 nm) on the long wavelength side. As the prism 14, a product equivalent to HOYA-C7 (trade name), which is a reference of the normal dispersion glass, is used. The apex angle μ between the entrance side surface 1 and the exit side surface 2 of the prism 14 is μ = 60 °.

First, the mask 30 having a known opening diameter or slit width is calibrated. The opening diameter or the aperture width of the mask 30 is _{D 1,} the three-dimensional measurement or the like using a _probe, which is D 1 = 2 mm. When the radiated light 81 from the light source 12 incident on the prism 14 at the incident angle θ ₁ passes through the prism 14, due to the difference in the refractive index n of the light spectrum, the ultraviolet (lower limit) refracted light 5 and the infrared ( The light is split between the refracted lights 6. The spectrum of the split light is emitted from the prism 14 as a spectrum between the lower limit refracted light 82 (λa = 365.01 nm) and the upper limit refracted light 83 (λb = 1013.98 nm). The height H from the emission side surface 2 of the prism 14 to the upper surface of the mask 30 is H = 80 mm. Since the refractive index n of each spectrum of the prism 14 is known, the argument ε in each spectrum can be obtained by (Equation 2) from Snell's law or the like.
Therefore, the difference [Delta] [epsilon] of the deflection angle epsilon ₁ of declination epsilon ₂ and lower side refracted light 82 of the upper side refracted light 83 is obtained in Δε = ε ₁ -ε _2. Since the reference width D is a function D = f (Δε, H) of the deviation angle Δε and the height H, the calibration is completed by comparing the reference width D with the reference width D obtained by (Equation 3). The reference width D was D = 2.776854 mm.

D ₁ = D × (λa ₁ −λb ₁ ) / (λa−λb) (Equation 3)
When the spectrum of the light that has passed through the opening 32 of the mask 30 is 455.086 nm to 923.903 nm, the light detection unit 40 detects the spectrum, so that D ₁ = 2.00 mm is obtained.

  Next, the measurement object 70 having the hole 71 formed thereon is set on the mask 30 with the height H from the prism 14 to the upper surface set to 80 mm. As in the case of the measurement of the mask 30, the emitted light 81 is emitted from the light source 12 to the prism 14, and the light detecting means 40 arranged on the back side of the mask 30 detects the light passing through the hole 71 and the opening 32 of the mask 30. Detect the spectrum. At this time, the wavelength λa ′ of the hole entrance lower limit light 85 was λa ′ = 500 nm, and the wavelength λb ′ of the hole entrance upper limit light 86 was λb ′ = 680 nm. Using (Equation 1), the diameter d of the hole 71 is obtained as d = 0.969 mm.

In this connection, the measurement error in the width _{D 1} of the opening 32 of the mask 30, if there is an error of ± 0.05 mm, when performing the above calculations, the error [Delta] d of the hole diameter d is there at about Δd = ± 0.0187mm Was. Therefore, it was confirmed that the micropore diameter can be measured with high accuracy by the method of this example.

  Next, a modification of the above embodiment of the present invention will be described with reference to FIGS. The modification shown in FIG. 4 is significantly different from the above-described embodiment in that a slit plate 90 that can move in the horizontal direction with the parallel light lens 15 is provided between the prism 14 and the object 70 to be measured. In FIG. 4A, other components are the same as those in the embodiment shown in FIG. 1, but in FIG. 4B, a condenser lens 42 is further provided on the light detecting means 40 side.

  These are because the light separated by the prism 14 is guided to the measurement object 70 as parallel light, and only light having a predetermined spectrum is allowed to pass perpendicularly to the hole 71 so as to perform more accurate spectrum measurement. It is. Therefore, the slit plate 90 is provided with a slit 95 having only a spectral width. The width of the slit 95 is preferably as narrow as possible, but is about 50 μm in consideration of workability.

  In order to allow the slit plate 90 to move in the horizontal direction, the casing 16 is provided with a hole for moving the slit plate 90 and a slide bearing 17 that supports the slit plate 90 so as to be able to move directly. A rack 91 is attached to the outer side of the casing 16 of the slit plate 90 and meshes with a pinion 92 connected to a servomotor 93 (a stepping motor may be used instead of the servomotor). The movement of the slit plate 90 is controlled by controlling the servomotor 93. In this embodiment, the slit plate is moved by the servo motor. However, for example, a variable slit made by Sigma Kogyo may be provided below the condenser lens.

  In the light detecting means 40 of FIG. 4B, a casing 43 is provided below the mounting means 60 to hold the condenser lens 42 and the photomultiplier tube 44 for detecting the light passing through the condenser lens 42. ing. The spectrum of the light passing through the minute holes 71 is condensed by the condenser lens 42 and amplified by the photomultiplier 44 to improve the detection accuracy. 4A and 4B, the spectrum passing through the minute hole 71 is measured in synchronization with the movement of the slit plate 90.

  FIG. 5 shows the embodiment shown in FIG. 1 in which the light detecting means 40 is provided with a grating 47 and a line sensor 48. The traveling direction of the spectrum passing through the minute holes 71 is changed by a grating 47 and detected by a number of line sensors (photodiodes or the like) 48 arranged vertically. The hole entry lower limit light (short wavelength side) 45 is detected by a sensor above the line sensor 48, and the hole entry upper limit light (long wavelength side) 46 is detected by the sensor below the line sensor 48, thereby detecting each wavelength (spectrum). ), And the hole diameter can be measured. Instead of the light detection means 40 shown in this modification, for example, a spectroscope BW-T6 manufactured by Konica Minolta, Inc. having a similar function is detected by connecting an optical fiber to the rear side of the mounting means 60. You may do so.

  In short, in the present invention, the spectroscopic light enters the minute hole having a diameter of 1 mm or less, which is an object to be measured, and the diameter of the minute hole is accurately measured only by detecting the wavelength of the light passing through the hole. Yes, all embodiments based on the spirit of the invention are within the scope of the invention.

DESCRIPTION OF SYMBOLS 1 ... incident side surface, 2 ... outgoing side surface, 5 ... violet outside (lower limit side) refraction light, 6 ... infrared side (upper limit side) refraction light, 10 ... prism holding means, 12 ... white light source, 14 ... prism (refraction means) , 15: Parallel light lens, 16: Casing, 17: Slide bearing, 18: Contact, 20: Positioning means, 21: Slider, 22: Rail, 23: Rotary knob, 24: Support arm, 25: Base, 30 ... Mask, 32 aperture, 40 light detecting means, 41 CCD or CMOS, 42 condenser lens, 43 casing, 44 photomultiplier tube, 45 hole lower limit light, 46 hole upper limit light, 47 ... Grating, 48 ... Line sensor (photodiode), 50 ... Calculation means, 60 ... Placement means, 61 ... Opening or transparent part, 70 ... Measurement object, 71 ... Measurement hole (micro hole), 81 ... Emitted light , 82 ... Limited side refraction light, 83: Upper limit side refraction light, 85: Hole entry lower limit light, 86: Hole entry upper limit light, 90: Slit plate, 91: Rack, 92: Pinion, 93: Servo motor, 95: Slit, 100 ... diameter measuring device, 110 ... measured hole position, 111 ... gain of refracted light, 112 ... hole enters the light gain, d ... diameter, D ... reference width (spreading width), D 1 _... mask opening diameter or opening width, H: reference height, θ ₁ : incident angle, ε: declination, λ: wavelength, λa: upper limit wavelength of refracted light, λa ': upper limit wavelength of light entering hole, λb: lower wavelength of refracted light, λb': light entering hole Lower limit wavelength, μ ... Vertical angle

Claims (8)

In a hole diameter measuring device for measuring the diameter of the hole of the measurement object having a through hole,
A white light source having a continuous spectrum;
A prism that refracts white light emitted from the light source,
Mounting means for mounting the measurement object,
Positioning means for positioning the light refracted by the prism in the vicinity of the hole of the measurement object,
Light detection means arranged on the back side of the placement means, for detecting light passing through the hole,
Calculating means for calculating an upper limit wavelength and a lower limit wavelength of light passing through the hole from the signal detected by the light detecting means, and calculating a hole diameter of the hole using the obtained upper limit wavelength and lower limit wavelength;
A hole diameter measuring device comprising:   The hole diameter measurement according to claim 1, wherein a mask having an opening having a larger diameter than the hole of the measurement object is arranged on an upper surface of the mounting means and on a lower surface side of the measurement object. apparatus.   3. The apparatus according to claim 1, further comprising a holding unit for holding the prism, wherein a mechanism for holding a distance between the holding unit and the object to be measured constant is provided in the holding unit or the positioning unit. The described hole diameter measuring device.   Between the prism and the object to be measured, in order from the prism side, a parallel light lens and a slit plate are arranged, and the slit plate is movable in a direction perpendicular to the optical axis of the parallel light lens, 4. The hole diameter measuring device according to claim 1, wherein the light detecting means is any one of a CMOS, a CCD, a direct image sensor, and a color separation photodiode.   Between the prism and the object to be measured, a parallel light lens and a slit plate are arranged in this order from the prism side, and a condenser lens is arranged between the placing means and the light detecting means, 4. The hole diameter measuring device according to claim 1, wherein the plate is movable in a direction perpendicular to the optical axis of the parallel light lens, and the light detecting means is a photomultiplier tube. apparatus. The upper limit wavelength used for the measurement of the light refracted by the prism is λa, the lower limit wavelength is λb, and the spread width of the refracted light at a position corresponding to the upper surface of the measurement target is D, and the light detection unit is When the upper limit wavelength of the detected light is λa ′ and the lower limit wavelength is λb ′, the calculating unit sets the hole diameter d of the hole to:
d = D × (λa′−λb ′) / (λa−λb)
The hole diameter measuring device according to any one of claims 1 to 5, wherein the hole diameter is determined from the following. A method of measuring the diameter of a through hole,
In what irradiates the measurement object by refracting white light emitted from a light source having a continuous spectrum with a prism,
With the distance between the upper surface of the mounting means for mounting the measurement object and the prism being H, the spread range D of the refracted light from the prism, and the upper limit wavelength λa and the lower limit wavelength λb at that time. The required calibration steps,
A measuring step of placing the object to be measured on the mounting means and determining an upper limit wavelength λa ′ and a lower limit wavelength λb ′ of light passing through the hole with a distance between the upper surface of the measurement object and the prism being H; ,
A calculating step of calculating the hole diameter of the hole from the obtained values according to the following equation:
d = D × (λa′−λb ′) / (λa−λb)   The hole diameter according to claim 7, wherein in the measuring step, a slit plate interposed between the prism and the measurement target is moved in a direction substantially parallel to an upper surface of the measurement target. Measurement method.