JPH07253306A - End face detector - Google Patents

Abstract

PURPOSE:To provide an end face detector which enables the measurement of the position of an end face at a higher accuracy depending on the shape and the nature of an object even when the gradient of the distribution of the brightness of the end face is gentle. CONSTITUTION:A photodetector on the outermost circumference suitable for the nature of an end face which is made up of a circular photodetector 5a and ring-like photodetectors 5b, 5c... and 5n arranged concentric on the outer circumference sequentially is selected and a quantity of light received of the photodetector on the outermost circumference is subtracted from the total of the quantity of light receive from the circular photodetector 5a to the second photodetector from the outermost circumference and the position at which the value obtained is zero is detected as the position of the end face.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は、端面検出装置に関する
ものである。更に詳しくは光学的寸法・形状測定機にお
ける被検物の端面位置を検出するための端面検出装置に
関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an end face detecting device. More specifically, the present invention relates to an end face detection device for detecting the end face position of a test object in an optical size / shape measuring machine.

【０００２】[0002]

【従来の技術】被検物の端面位置検出には、測定顕微鏡
や輪郭投影機のような光学的寸法・形状測定機に搭載さ
れた端面検出装置が使用されている。端面検出の原理
は、図１に示すように光源からの光Ｉが、対物レンズ１
の結像面におかれた細線状、スリット状の光電素子２に
入射しているとき、載物台３に載置された被検物４が測
定軸方向Ｘに移動し光Ｉを横切ると、端面の移動位置に
従い光電素子２の受光光量が変化するから、この変化を
測定し被検物の端面位置を検出するものである。光電素
子の代わりに、スリットとその後に光電素子を設けても
良い。2. Description of the Related Art To detect the position of an end surface of an object to be inspected, an end surface detection device mounted on an optical size / shape measuring machine such as a measuring microscope or a contour projector is used. The principle of end face detection is that the light I from the light source is transferred to the objective lens 1 as shown in FIG.
When the object 4 placed on the stage 3 moves in the measurement axis direction X and crosses the light I while it is incident on the thin-line or slit-shaped photoelectric element 2 placed on the image plane of Since the amount of light received by the photoelectric element 2 changes according to the movement position of the end face, this change is measured to detect the end face position of the test object. Instead of the photoelectric element, a slit and a photoelectric element may be provided after that.

【０００３】このような、端面検出の精度は被検物の端
面の形状、性状或いは測定方向や細線又はスリットと端
面のなす角度等により変化する。被検物の端面とスリッ
トのなす角度による検出精度の低下を避けるためには、
例えば特公昭５２−３１７４７号公報に開示された技術
がある。これは遮光板上の中心に円形窓及びこれの外周
に同心的な環状の窓が設けられ、スリットを通過した光
はそれぞれ窓ごとに独立に受光素子で光電変換される構
成である。そして中心の円形窓と外周の環状の窓とを透
過した光の受光信号出力を差動演算し、その差動演算の
出力信号が０レベルになったときに端面位置通過を示す
パルス信号を出力するものであった。The accuracy of such end face detection changes depending on the shape, property or measuring direction of the end face of the object to be inspected, the angle between the thin line or the slit and the end face, and the like. In order to avoid deterioration of detection accuracy due to the angle between the end surface of the object and the slit,
For example, there is a technique disclosed in Japanese Patent Publication No. 52-31747. In this structure, a circular window is provided at the center of the light shielding plate and a concentric annular window is provided on the outer periphery of the light shielding plate, and light passing through the slit is photoelectrically converted by a light receiving element for each window. Then, the light reception signal output of the light transmitted through the circular window at the center and the annular window at the outer periphery is differentially calculated, and when the output signal of the differential calculation becomes 0 level, a pulse signal indicating the passage of the end face position is output. It was something to do.

【０００４】[0004]

【発明が解決しようとする課題】しかし従来の特公昭５
２−３１７４７号公報に開示された技術では、被検物の
端面がスリットを横切る時の明度分布信号の傾斜が急な
場合と緩やかな場合とで測定精度が異なっていた。例え
ば、反射照明で測定を行った場合、被検物の面取りが行
われていない時は、明度分布信号の傾斜が急になる。ま
た、被検物の面取りが行われている時は、面取り部分で
も光が反射してしまい、明度分布信号の傾斜が緩やかに
なってしまう。明度分布信号の傾斜が急な場合は明確な
エッジ（すなわち、被検物に透過照明をあてた時、被検
物がない部分は明るく、被検物がある部分は暗くなる。
その明と暗の境界をいう）が得られ、緩やかな場合は精
度の悪いエッジとなるからである。対物レンズの倍率を
高くして像を大きくするときに分解能が伴わないと、点
像の強度分布がなだらかになり明度分布信号の傾斜が緩
やかになって、エッジがあいまいになる。エッジがあい
まいとは、上述した明と暗の境界がぼけることをいう。
特に落射照明を使用する場合に被検物の反射率が小さく
又は面取りされた緩い曲面の端面を有する場合等には信
号出力の振幅が小さく、端面検出の精度が低下し、正確
な端面位置計測が困難になるという問題点があった。However, the conventional Japanese Patent Publication Sho 5
In the technique disclosed in JP-A-2-31747, the measurement accuracy is different when the inclination of the lightness distribution signal when the end surface of the test object crosses the slit is steep and when the inclination is gentle. For example, when the measurement is performed with reflected illumination, the slope of the brightness distribution signal becomes steep when the test object is not chamfered. Further, when the test object is being chamfered, light is reflected even at the chamfered portion, and the inclination of the brightness distribution signal becomes gentle. When the slope of the lightness distribution signal is steep, a clear edge (that is, when transmitted light is applied to the test object, a part without the test object is bright and a part with the test object is dark.
This is because the boundary between light and dark is obtained, and when it is gentle, the edge has poor accuracy. If the resolution is not accompanied when the magnification of the objective lens is increased to enlarge the image, the intensity distribution of the point image becomes gentle, the inclination of the brightness distribution signal becomes gentle, and the edge becomes ambiguous. If the edge is obscure, it means that the above-mentioned boundary between light and dark is blurred.
Especially when epi-illumination is used, the signal output amplitude is small and the end face detection accuracy decreases, and the end face position measurement is accurate when the reflectance of the test object is small or when the end face is a chamfered curved surface. There was a problem that it became difficult.

【０００５】本発明は上記の課題に鑑み、被検物の形状
や性状により、端面の明度分布の傾斜が緩やかな場合で
あっても、良好な精度で端面位置計測が行える端面検出
装置を提供することを目的とする。In view of the above problems, the present invention provides an end face detection device capable of measuring the end face position with good accuracy even when the inclination of the lightness distribution of the end face is gentle due to the shape and properties of the object to be inspected. The purpose is to do.

【０００６】[0006]

【課題を解決するための手段】対物レンズの結像面に配
置され、円形の受光素子及び円形の受光素子の外周に同
心的に順次多重に設けられたｎ周（ｎ≧２の整数）の環
形の受光素子とから形成され、前記受光素子ごとに受光
信号を出力する光電センサと、前記円形の受光素子か
ら、順次第ｍ周（ｍ≦ｎ−１の整数）の前記環形の受光
素子までの受光信号を合算して加算信号を出力する加算
回路と、前記加算信号と第（ｍ＋１）周の前記環形の受
光素子の受光信号との差を演算して差算信号を出力する
差算回路と、前記差算信号を検出し、前記差算信号が所
定値であるとき被検物の端面位置にあることを検出する
検出手段とを具備し、前記第ｍ周の環形の受光素子の数
ｍは、前記被検物の端面の性状により変更して設定可能
であるものである。A circular light receiving element is arranged on the image plane of an objective lens, and n rounds (an integer of n ≧ 2) are provided concentrically and sequentially on the outer circumference of the circular light receiving element. A photoelectric sensor that is formed of a ring-shaped light receiving element and outputs a light reception signal for each of the light receiving elements, and from the circular light receiving element to the ring-shaped light receiving element of the m-th circumference (m ≦ n−1) in order. Circuit for summing the received light signals of the above and outputting an added signal, and a difference circuit for calculating the difference between the added signal and the received light signal of the ring-shaped light receiving element of the (m + 1) th round and outputting a difference signal. And a detection means for detecting the difference signal and detecting that the difference signal is at the end face position of the test object when the difference signal has a predetermined value, and the number of ring-shaped light receiving elements in the m-th circumference. m can be changed and set according to the properties of the end surface of the test object.

【０００７】前記第ｍ周の前記環形の受光素子までの加
算信号の最大値と第（ｍ＋１）周の前記環形の受光素子
の受光信号の最大値は等しく設定され、前記差算信号の
前記所定値は０であることが望ましい。The maximum value of the summed signal up to the ring-shaped light receiving element on the m-th round and the maximum value of the light-receiving signal of the ring-shaped light receiving element on the (m + 1) th round are set equal to each other, and the predetermined value of the difference signal is set. The value is preferably 0.

【０００８】前記環形の受光素子の数ｎは２であること
が好ましい。The number n of the ring-shaped light receiving elements is preferably 2.

【０００９】前記円形の受光素子に代え、環形の受光素
子を有することが好ましい。It is preferable to have a ring-shaped light receiving element instead of the circular light receiving element.

【００１０】前記環形の受光素子の少なくも１個は、半
径方向に分割されて個別に受光信号を出力する少なくも
２個の分割受光素子から形成され、且つ前記少なくも２
個の分割受光素子の中、前記円形の受光素子の中心につ
いて対称の位置にある対を形成する２個の分割受光素子
の出力信号の最大出力は同一に設定されて、前記対を形
成する２個の分割受光素子の出力信号の差の絶対値を演
算して差・絶対値信号を出力する差・絶対値演算回路を
具備し、前記検出回路は、前記差・絶対値演算信号が０
でない有限値を有するとき、前記被検物の端面位置を検
出することが望ましい。At least one of the ring-shaped light receiving elements is formed by at least two divided light receiving elements which are divided in the radial direction and individually output light receiving signals, and the at least two light receiving elements are provided.
Of the divided light receiving elements, the maximum output signals of the two divided light receiving elements forming a pair symmetrically with respect to the center of the circular light receiving element are set to the same value to form the pair. The detection circuit includes a difference / absolute value calculation circuit that calculates the absolute value of the difference between the output signals of the divided light receiving elements and outputs the difference / absolute value signal.
When it has a finite value that is not, it is desirable to detect the end face position of the test object.

【００１１】前記環形の受光素子の少なくも１個は、半
径方向に等分に分割され、個別に受光信号を出力するた
４個の分割受光素子から形成され、且つ相対してそれぞ
れ対を形成する２個の分割受光素子の出力信号の最大出
力は同一に設定されて、前記それぞれ対を形成する２個
の前記分割受光素子の出力信号の差の絶対値を演算して
差・絶対値信号を出力する差・絶対値演算回路と、前記
２個の差・絶対値を加算演算して加算値信号を出力する
する加算演算回路とを具備し、前記検出回路は、前記加
算値信号が０でない有限値を有するとき、前記被検物の
端面位置を検出することが望ましい。At least one of the ring-shaped light receiving elements is divided into four equal parts in the radial direction and individually output light receiving signals, and each of the divided light receiving elements forms a pair. The maximum output of the output signals of the two divided light receiving elements is set to be the same, and the absolute value of the difference between the output signals of the two divided light receiving elements forming each pair is calculated to obtain a difference / absolute value signal. A difference / absolute value calculating circuit and an addition calculating circuit for adding and calculating the two difference / absolute values to output an added value signal, wherein the detection circuit detects that the added value signal is 0. When it has a finite value that is not, it is desirable to detect the end face position of the test object.

【００１２】[0012]

【作用】対物レンズの結像面に同心円状に形成された、
円形の受光素子及びその外周に同心的に順次設けられた
２周以上ｎ周の環形の受光素子から出力する受光信号の
加算と減算を反復し、被検物の端面の明度分布信号の傾
斜部分の範囲に合わせて、センサの寸法を切り換えて端
面検出を行う。第ｍ周の環形の受光素子までの加算信号
の最大値と第（ｍ＋１）周の環形の受光素子の受光信号
の最大値が等しく設定されたときは、両者に一様に（例
えば暗い時、又は明るい時）光があたった時に、差算信
号の所定値は０となる。[Operation] Concentric circles are formed on the image plane of the objective lens,
The addition and subtraction of the received light signals output from the circular light-receiving element and the ring-shaped light-receiving element having two or more rounds and n rounds, which are concentrically provided on the outer circumference of the circular light-receiving element, are repeatedly added and subtracted to obtain a sloped portion of the lightness distribution signal on the end surface of the test object. The edge size is detected by switching the sensor size according to the range. When the maximum value of the summed signal up to the ring-shaped light receiving element of the m-th round and the maximum value of the light-receiving signal of the ring-shaped light receiving element of the (m + 1) th round are set to be equal (for example, when dark, When bright (or bright), the predetermined value of the subtraction signal becomes 0.

【００１３】[0013]

【実施例】本発明の一実施例を図２〜図５により説明す
る。図２及び図３は本実施例にかかるセンサ及び電気回
路を示す図である。円形の光電素子５ａの周囲には、光
電素子５ａと同一の中心Ｏを有する環形の光電素子５
ｂ、５ｃが、それぞれの間に不感帯６ａ、６ｂを介して
電気的に独立して設けられている。これらの光電素子は
フォトダイオードなどの光電変換素子である。尚不感帯
６ａ、６ｂは幅が狭い程好ましく（理想的には不感帯が
ない方が良い）、これは不感帯の幅に応じて演算して得
られる結果も異なるからである。電流電圧変換器５ｄ、
５ｅ、５ｆはそれぞれ光電素子５ａ、５ｂ、５ｃで光電
変換して出力した電流を電圧に変換し増幅する変換器で
ある。DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 2 and 3 are diagrams showing a sensor and an electric circuit according to this embodiment. Around the circular photoelectric element 5a, a ring-shaped photoelectric element 5 having the same center O as the photoelectric element 5a.
b and 5c are electrically independent from each other via dead zones 6a and 6b. These photoelectric elements are photoelectric conversion elements such as photodiodes. The dead zones 6a and 6b are preferably as narrow as possible (ideally, it is better that there is no dead zone), because the results obtained by calculation depending on the width of the dead zones are different. Current-voltage converter 5d,
Reference numerals 5e and 5f are converters for converting the currents, which are photoelectrically converted by the photoelectric elements 5a, 5b, and 5c and output, into voltages and amplifying them.

【００１４】差動増幅器５ｇは電流電圧変換器５ｄの出
力信号ａから電流電圧変換器５ｅの出力信号ｂを減算し
て差信号（ａ−ｂ）を出力する回路、加算演算器５ｈは
出力信号ａと出力信号ｂを加算して、和信号（ａ＋ｂ）
を出力する回路、差動増幅器５ｉは和信号（ａ＋ｂ）か
ら電流電圧変換器５ｆの出力信号ｃを減算して差信号
（ａ＋ｂ−ｃ）を出力する回路である。The differential amplifier 5g is a circuit for subtracting the output signal b of the current-voltage converter 5e from the output signal a of the current-voltage converter 5d to output a difference signal (ab), and the addition calculator 5h is an output signal. sum signal (a + b) by adding a and output signal b
The differential amplifier 5i is a circuit that subtracts the output signal c of the current-voltage converter 5f from the sum signal (a + b) and outputs a difference signal (a + b-c).

【００１５】次に動作について、図１に示す載物台３の
上に被検物４が載置され、矢印Ｘ方向に移動する場合を
図４により説明する。図４の上部にはセンサ５と端面４
ａとの関係を光軸方向から見た状況が示されている。円
形の受光素子５ａの中心Ｏと同心的に受光素子５ｂ及び
受光素子５ｃが配置されている。図中左側からセンサに
光が入射して明の状態、右側は入射せず暗の状態であ
る。端面４ａは順次、受光素子５ｂの点７Ａ、７Ｂ、受
光素子５ａの点７Ｃ、７Ｄ、受光素子５ｂの点７Ｅ、７
Ｆを通過し、明暗の境界が移動する。Next, the operation will be described with reference to FIG. 4 when the object 4 to be inspected is placed on the stage 3 shown in FIG. 1 and moves in the direction of arrow X. In the upper part of FIG.
The situation where the relationship with a is viewed from the optical axis direction is shown. The light receiving element 5b and the light receiving element 5c are arranged concentrically with the center O of the circular light receiving element 5a. Light enters the sensor from the left side in the figure and is in a bright state, and right side is a state in which no light is incident and is in a dark state. The end face 4a is sequentially provided with points 7A and 7B of the light receiving element 5b, points 7C and 7D of the light receiving element 5a, and points 7E and 7 of the light receiving element 5b.
Passing F, the boundary of light and dark moves.

【００１６】図４（ａ）、（ｂ）、（ｃ）はそれぞれ端
面４ａと受光素子５ａ、５ｂ及び５ｃから出力する出力
信号ａ、５ｂ及び５ｃの強度との関係である明度分布を
示す図である。出力信号ａは、図４（ａ）に示すように
点７Ｃまで０、点７Ｃで立ち上がり点７Ｄで一定値Ｉａ
となる。出力信号ｂは、図４（ｂ）に示すように点７Ｂ
まで０、点７Ｂで立ち上がり点７Ｂで緩やかになり、点
７Ｄで再び急になり点Ｅで一定値Ｉｂとなる。出力信号
ｃは、図４（ｃ）に示すように点７Ａまで０、点７Ａで
立ち上がり点７Ｂで緩やかになり、点７Ｅで再び急にな
り点７Ｆで一定値Ｉｃとなる。4 (a), (b) and (c) show the lightness distribution which is the relationship between the intensity of the output signals a, 5b and 5c output from the end face 4a and the light receiving elements 5a, 5b and 5c, respectively. Is. As shown in FIG. 4A, the output signal a is 0 up to the point 7C, and the constant value Ia at the rising point 7D at the point 7C.
Becomes The output signal b is at the point 7B as shown in FIG.
Up to 0, the point 7B becomes gentle at the rising point 7B, becomes steep again at the point 7D, and becomes a constant value Ib at the point E. As shown in FIG. 4C, the output signal c is 0 until the point 7A, becomes gentle at the rising point 7B at the point 7A, becomes sharp again at the point 7E, and becomes a constant value Ic at the point 7F.

【００１７】図４（ｄ）、（ｅ）はそれぞれ差動増幅器
５ｇから出力する差信号（ａ−ｂ）及び差動増幅器５ｉ
から出力する和信号（ａ＋ｂ−ｃ）の強度を示してい
る。本実施例ではＩａ＝Ｉｂ、Ｉｃ×２＝Ｉａ＋Ｉｂに
成るように構成してある。図４（ｄ）に示すように点Ｂ
まで０、点Ｂで立ち下がるが点Ｃ付近で増大し、点Ｏで
０となり、点Ｄ付近で減少に変じ、点Ｅで０となる。そ
して０となる点Ｏは点Ｃと点Ｄの中間点、受光素子５ａ
の中心Ｏに相当する点である。図４（ｅ）に示すように
点Ａまで０、点Ａで立ち立ち下がるが点Ｃ付近で増大
し、点Ｏで０となり、点Ｄ付近で減少に変じ、点Ｆで０
となる。FIGS. 4D and 4E show the difference signal (ab) output from the differential amplifier 5g and the differential amplifier 5i, respectively.
It shows the intensity of the sum signal (a + b-c) output from. In this embodiment, Ia = Ib and Ic × 2 = Ia + Ib. As shown in FIG. 4D, point B
0, and it falls at point B, but increases near point C, becomes 0 at point O, decreases to near point D, and becomes 0 at point E. The point O that becomes 0 is an intermediate point between the points C and D, the light receiving element 5a.
Is a point corresponding to the center O of. As shown in FIG. 4 (e), it reaches 0 at point A and falls at point A, but increases near point C, becomes 0 at point O, decreases to 0 at point D, and becomes 0 at point F.
Becomes

【００１８】このようにして順次繰り返し得られた差信
号は、被検物の移動に従って受光素子５ａの中心Ｏに相
当する点で０となるから、差信号０の位置が端面位置と
して検出される。The difference signal thus repeatedly obtained becomes 0 at the point corresponding to the center O of the light receiving element 5a according to the movement of the object to be detected, so that the position of the difference signal 0 is detected as the end face position. .

【００１９】ここで明度分布信号の傾斜の度合いに応じ
て、受光センサの直径を変更することについて説明す
る。図５に端面４ａの移動に伴う受光強度の変化、即ち
明度分布を示す。曲線１は、例えば、透過照明を使用
し、対物レンズの倍率が低くて充分な分解能をもち、又
被検物の反射率が大きく、端面形状が鋭い場合等に得ら
れる明度分布を示し、受光強度が大きく、且つ曲線の傾
斜は急である。このようなときは明確なエッジが得られ
る。曲線２は、例えば、落射照明を使用し、対物レンズ
の倍率が高くて充分な分解能をもたず、又は被検物の反
射率が小さく、端面形状が緩い曲面の場合等に得られる
明度分布を示し、受光強度が小さく、且つ曲線の傾斜が
なだらかである。このようなときはあいまいなエッジと
なる。Here, changing the diameter of the light receiving sensor according to the degree of inclination of the lightness distribution signal will be described. FIG. 5 shows a change in received light intensity with the movement of the end surface 4a, that is, a brightness distribution. Curve 1 shows the lightness distribution obtained when, for example, transmissive illumination is used, the objective lens has a low magnification and sufficient resolution, the reflectance of the test object is large, and the end face shape is sharp. The intensity is high and the slope of the curve is steep. In such a case, a clear edge can be obtained. Curve 2 is, for example, a brightness distribution obtained when epi-illumination is used, the objective lens has a high magnification and does not have sufficient resolution, or the reflectance of the test object is small and the end face shape is a curved surface. Shows that the received light intensity is low and the slope of the curve is gentle. In such a case, it becomes an ambiguous edge.

【００２０】そして、曲線１の場合は、受光センサの直
径Ｄ１が小さくても、充分な光量ΔＩが得られ、且つ光
量の変化を敏感に検知し、端面位置検出は精度良く行う
ことができるが、曲線２の場合はこれに反し、受光セン
サの直径Ｄ２を大きくしないと、同様な充分な光量ΔＩ
が得られず、且つ光量の変化を敏感に検知できず、端面
位置検出の精度が不十分となる。In the case of the curve 1, even if the diameter D1 of the light receiving sensor is small, a sufficient light quantity ΔI can be obtained, and the change in the light quantity can be detected sensitively, and the end face position can be detected with high accuracy. On the contrary, in the case of the curve 2, if the diameter D2 of the light receiving sensor is not increased, a similar sufficient light amount ΔI is obtained.
Is not obtained, and the change in light quantity cannot be detected sensitively, resulting in insufficient accuracy of end face position detection.

【００２１】従って、被検物の端面の明度分布信号の傾
斜が急な場合及び微細な被検物、例えばＩＣパターンの
ようなものの端面検出には、受光素子５ａと受光素子５
ｂとを使用する。又落射照明を使用する場合に被検物の
反射率が小さく又は緩い曲面の端面を有して被検物の端
面の明度分布信号の傾斜が緩やかであれば、受光素子５
ａと受光素子５ｂに加えて受光素子５ｃを使用する。こ
のようにして、１個のセンサで両方の場合に適切に対応
することができる。Therefore, the light receiving element 5a and the light receiving element 5 are used when the brightness distribution signal on the end surface of the test object has a steep slope and when detecting the end surface of a fine test object such as an IC pattern.
Use b and. Further, when epi-illumination is used, if the reflectance of the test object is small or has a gentle curved end surface and the slope of the brightness distribution signal on the end surface of the test object is gentle, the light receiving element 5
In addition to a and the light receiving element 5b, the light receiving element 5c is used. In this way, one sensor can adequately handle both cases.

【００２２】次に他の実施例を説明する。上記した一実
施例と同様な部分についての説明の詳述は省略する。図
６において、中心に円形の光電素子８ａ、その外周に扇
形の光電素子８ｂ、８ｃ、８ｄ、８ｅの４個の光電素子
が配置されている。光電素子８ｂ、８ｃ、８ｄ、８ｅは
互いに同形で、全体で光電素子８ａと同心的な環となっ
て、第１周に相当する中間周を構成している。さらに中
間周の外周には、扇形の光電素子８ｆ、８ｇ、８ｈ、８
ｉの４個の光電素子が配置されている。光電素子８ｆ、
８ｇ、８ｈ、８ｉは互いに同形で、全体で光電素子８ａ
と同心的な環となって、この４個の光電素子で第２周に
相当する最外周を構成し、全体として中心の円形の光電
素子８ａを２周の環が囲む３群構成のセンサとして構成
されている。Next, another embodiment will be described. Detailed description of the same parts as those in the above-described embodiment will be omitted. In FIG. 6, a circular photoelectric element 8a is arranged in the center, and four photoelectric elements 8b, 8c, 8d, and 8e in a fan shape are arranged on the outer periphery thereof. The photoelectric elements 8b, 8c, 8d, and 8e have the same shape, and form a ring concentric with the photoelectric element 8a as a whole to form an intermediate circumference corresponding to the first circumference. Further, fan-shaped photoelectric elements 8f, 8g, 8h, 8 are provided on the outer periphery of the intermediate circumference.
Four photoelectric elements of i are arranged. Photoelectric element 8f,
8g, 8h, and 8i have the same shape, and the photoelectric device 8a as a whole.
As a concentric ring, the four photoelectric elements constitute the outermost circumference corresponding to the second circumference, and as a sensor of a three-group configuration in which the central circular photoelectric element 8a is surrounded by a ring of two circumferences. It is configured.

【００２３】電流電圧変換器９Ａ、９Ｂ、９Ｃ、９Ｄ、
９Ｅ、９Ｆ、９Ｇ、９Ｈ、９Ｉは、光電素子８ａ、８
ｂ、８ｃ、８ｄ、８ｅ、８ｆ、８ｇ、８ｈ、８ｉからの
電流をそれぞれ電圧に変換する。その結果、電流電圧変
換器９Ａが変換して出力する電圧はＡ、電流電圧変換器
９Ｂが変換して出力する電圧はＢ、電流電圧変換器９Ｃ
が変換して出力する電圧はＣ、電流電圧変換器９Ｄが変
換して出力する電圧はＤ、電流電圧変換器９Ｅが変換し
て出力する電圧はＥ、電流電圧変換器９Ｆが変換して出
力する電圧はＦ、電流電圧変換器９Ｇが変換して出力す
る電圧はＧ、電流電圧変換器９Ｈが変換して出力する電
圧はＨ、電流電圧変換器９Ｉが変換して出力する電圧は
Ｉとなっている。Current-voltage converters 9A, 9B, 9C, 9D,
9E, 9F, 9G, 9H, and 9I are photoelectric elements 8a and 8
The currents from b, 8c, 8d, 8e, 8f, 8g, 8h and 8i are converted into voltages, respectively. As a result, the voltage that the current-voltage converter 9A converts and outputs is A, the voltage that the current-voltage converter 9B converts and outputs is B, and the current-voltage converter 9C.
Is C, the voltage output by the current-voltage converter 9D is D, the voltage output by the current-voltage converter 9D is D, the voltage output by the current-voltage converter 9E is E, and the voltage output by the current-voltage converter 9F is output. The voltage to be applied is F, the voltage converted and output by the current-voltage converter 9G is G, the voltage converted and output by the current-voltage converter 9H is H, and the voltage converted and output by the current-voltage converter 9I is I. Has become.

【００２４】図７は上に述べたセンサの信号処理回路を
示している。回路２１ａは中間周の４個の光電素子８
ｂ、８ｃ、８ｄ、８ｅの出力を全て加算する回路、回路
２１ｂは最外周の４個の光電素子８ｆ、８ｇ、８ｈ、８
ｉの出力を全て加算する回路、回路２２ａ、２２ｂはそ
れぞれ中間周の対称位置にある対の光電素子８ｂ、８
ｃ、及び対の光電素子８ｄ、８ｅの出力信号の差動演算
と絶対値演算を行う回路、回路２２ｃ、２２ｄはそれぞ
れ最外周の対称位置にある対の光電素子８ｆ、８ｇ、及
び対の光電素子８ｈ、８ｉの出力信号の差動演算と絶対
値演算を行う回路、回路２３ａ、２３ｂはこの差動絶対
値演算の出力を中間周及び最外周でそれぞれ加算する回
路、回路２４は中心の光電素子の出力と中間周のすべて
光電素子８ｂ、８ｃ、８ｄ、８ｅの加算出力とを加算す
る回路、回路２５ａは中心の光電素子８ａの出力と回路
２１ａで加算された中間周の４個の光電素子８ｂ、８
ｃ、８ｄ、８ｅの加算出力との差動演算を行う回路、回
路２５ｂは回路２４の出力と回路２１ｂの出力との差動
演算をする回路である。FIG. 7 shows the signal processing circuit of the sensor described above. The circuit 21a includes four photoelectric elements 8 in the middle circumference.
The circuit 21b is a circuit that adds all the outputs of b, 8c, 8d, and 8e, and the four photoelectric elements 8f, 8g, 8h, and 8 at the outermost periphery are provided.
The circuits for adding all the outputs of i, the circuits 22a and 22b, respectively, are a pair of photoelectric elements 8b and 8 at symmetrical positions on the intermediate circumference.
c, a circuit for performing differential calculation and absolute value calculation of the output signals of the pair of photoelectric elements 8d and 8e, and circuits 22c and 22d are the pair of photoelectric elements 8f and 8g and the pair of photoelectric elements located at symmetrical positions on the outermost periphery, respectively. Circuits that perform differential calculation and absolute value calculation of the output signals of the elements 8h and 8i. Circuits 23a and 23b add the outputs of this differential absolute value calculation at the middle and outermost circumferences respectively. A circuit for adding the output of the element and the summed outputs of all the photoelectric elements 8b, 8c, 8d, 8e in the intermediate cycle, the circuit 25a is the output of the central photoelectric element 8a and four photoelectric cells in the intermediate cycle added by the circuit 21a. Elements 8b, 8
The circuit 25b is a circuit for performing a differential operation with the added outputs of c, 8d, and 8e, and the circuit 25b is a circuit for performing a differential operation with the output of the circuit 24 and the output of the circuit 21b.

【００２５】スイッチ２８ａ、２８ｂは中心と中間周の
光電素子を使用する明確なエッジに用の小さいセンサの
場合と、中心と中間周の光電素子に加えて最外周の光電
素子を使用するあいまいなエッジ用の大きいセンサの場
合との切換を行うスイッチである。パルス発生回路２７
は回路２５ａ又は回路２５ｂの出力によりパルスを発生
する回路である。比較器２６は回路２３ａ又は２３ｂの
出力と基準信号２９とを比較してパルス発生回路２７の
ゲート端子に入力させる回路である。検出回路３０は発
生回路２７で発生したパルスのエッジを検出する回路で
ある。The switches 28a, 28b are small sensors for clear edges that use the center and middle photoelements, and ambiguous using the outermost photoelements in addition to the center and middle photoelements. This is a switch for switching to the case of a large edge sensor. Pulse generation circuit 27
Is a circuit for generating a pulse by the output of the circuit 25a or the circuit 25b. The comparator 26 is a circuit that compares the output of the circuit 23a or 23b with the reference signal 29 and inputs the reference signal 29 to the gate terminal of the pulse generation circuit 27. The detection circuit 30 is a circuit that detects the edge of the pulse generated by the generation circuit 27.

【００２６】次に動作について説明する。先ず、端面が
面取りされているか否か、又は落射照明のとき、反射率
が小さいものかどうか等につき測定者が被検物の状態を
確認する。即ち、被検物の性状の状態を見て、センサを
切り換える。小さいセンサを使用する時は、以下のよう
な時である。明度分布信号の傾斜が急な時、微細な凹凸
（被検物）を測定する時、面取りがされていない又は面
取りが非常に小さくとられている場合に使用する。大き
いセンサは、落射照明で使用するときに被検物の反射率
が小さい時、面取りが比較的大きい時、粗い凹凸（被検
物）を測定する時に使用する。そしてこのセンサを小さ
いセンサとして使用するか大きいセンサとして使用する
か選定する。小さいセンサとして使用する場合、スイッ
チ２８ａを回路２５ａがパルス発生回路２７に接続し、
スイッチ２８ｂを回路２３ａが比較器２６に接続するよ
うに設定する。すると回路２５ａの出力を用いて明確な
エッジが得られる被検物４の端面位置検出を行う。Next, the operation will be described. First, the measurer confirms the condition of the test object such as whether the end surface is chamfered or whether the reflectance is small in the case of epi-illumination. That is, the sensor is switched depending on the condition of the property of the test object. When using a small sensor: It is used when the slope of the brightness distribution signal is steep, when measuring fine irregularities (inspection object), when chamfering is not performed or when chamfering is very small. A large sensor is used when the reflectance of the test object is small when used in epi-illumination, when the chamfering is relatively large, and when rough unevenness (test object) is measured. Then, it is selected whether this sensor is used as a small sensor or a large sensor. When used as a small sensor, the circuit 25a connects the switch 28a to the pulse generation circuit 27,
Switch 28b is set so that circuit 23a connects to comparator 26. Then, the output of the circuit 25a is used to detect the position of the end surface of the object 4 to be tested, which produces a clear edge.

【００２７】被検物４が光路に入ってその端面４ａが光
電素子８ａの中心Ｏを横切り、回路２５ａの出力信号が
負から正に変わる時、パルス発生回路２７からパルスが
発生し端面位置が検出される。この時、回路２３ａの出
力が基準信号２９と比較器２６で比較されパルス発生回
路２７のゲート端子に入力し、エッジとエッジ以外、す
なわち、光の強度分布に変化がない被検物の端面以外と
が区別される。When the object 4 enters the optical path and its end face 4a crosses the center O of the photoelectric element 8a and the output signal of the circuit 25a changes from negative to positive, a pulse is generated from the pulse generating circuit 27 and the end face position is changed. To be detected. At this time, the output of the circuit 23a is compared with the reference signal 29 by the comparator 26 and is input to the gate terminal of the pulse generating circuit 27, and is different from edge to edge, that is, other than the end surface of the object whose light intensity distribution does not change. Is distinguished from.

【００２８】又、被検物４の端面が面取りされている場
合、大きいセンサとして使用し、スイッチ２８ａを回路
２５ｂがパルス発生回路２７に接続し、スイッチ２８ｂ
を回路２３ｂが比較器２６に接続するように設定する。
すると回路２５ｂの出力を用いてあいまいなエッジが得
られる面取りされた被検物４の端面位置検出を行う。When the end surface of the object to be inspected 4 is chamfered, it is used as a large sensor, the switch 28a is connected to the pulse generating circuit 27 by the circuit 25b, and the switch 28b is connected.
Is set so that the circuit 23b is connected to the comparator 26.
Then, the output of the circuit 25b is used to detect the position of the end surface of the chamfered test object 4 in which an ambiguous edge is obtained.

【００２９】被検物４が光路に入って、回路２５ｂの出
力信号が負から正に変わる時、パルス発生回路２７から
パルスが発生し端面位置が検出される。この時、回路２
３ｂの出力が基準信号２９と比較器２６で比較されパル
ス発生回路２７のゲート端子に入力し、エッジとエッジ
以外とが区別される。When the inspection object 4 enters the optical path and the output signal of the circuit 25b changes from negative to positive, a pulse is generated from the pulse generation circuit 27 and the end face position is detected. At this time, circuit 2
The output of 3b is compared with the reference signal 29 by the comparator 26 and input to the gate terminal of the pulse generating circuit 27, and the edge and the other than the edge are distinguished.

【００３０】次にエッジとエッジ以外を区別することに
ついて説明する。図において被検物４の端面４ａの像が
光電素子８ｂ、光電素子８ａ、光電素子８ｃと順次移動
するとき、順次、端面４ａは受光素子８ｂの点Ｋ、Ｌ、
受光素子８ａの点Ｍ、Ｎ、受光素子８ｃの点Ｐ、Ｑを通
過する。受光素子８ｂからの出力信号９Ｂと受光素子８
ｃからの出力信号９Ｃの強度変化を図８（ａ）、
（ｂ）、（ｃ）に示す。出力信号９Ｂは、図８（ａ）に
示すように点Ｋまで０、点Ｋで立ち上がり点Ｌで一定値
Ｉとなる。出力信号９Ｃは、図８（ｂ）に示すように点
Ｐまで０、点Ｐで立ち上がり点Ｑでで一定値Ｉとなる。
差動増幅器２２ａが出力する差・絶対値信号（Ｂ−Ｃ）
は、図８（ｃ）に示すように点Ｋまで０、点Ｋで立ち上
がり、点Ｐで０となる。即ち点Ｋと点Ｐの間で有限の値
をとる。この間、光電素子８ｄと光電素子８ｅの間の差
・絶対値信号（Ｄ−Ｅ）は０である。Next, the distinction between edges and non-edges will be described. In the figure, when the image of the end surface 4a of the test object 4 moves sequentially with the photoelectric element 8b, the photoelectric element 8a, and the photoelectric element 8c, the end surface 4a is sequentially arranged with the points K, L of the light receiving element 8b.
The light passes through points M and N of the light receiving element 8a and points P and Q of the light receiving element 8c. Output signal 9B from light receiving element 8b and light receiving element 8
8A shows the intensity change of the output signal 9C from c.
Shown in (b) and (c). As shown in FIG. 8A, the output signal 9B has a constant value I at 0 at the point K and a rising point L at the point K. As shown in FIG. 8B, the output signal 9C has a constant value I at the point P and a constant value I at the rising point Q.
Difference / absolute value signal (BC) output from the differential amplifier 22a
8 is 0 up to the point K, rises at the point K, and becomes 0 at the point P as shown in FIG. 8C. That is, a finite value is set between the points K and P. During this period, the difference / absolute value signal (D−E) between the photoelectric element 8d and the photoelectric element 8e is 0.

【００３１】同様に次に端面４ａが光電素子８ｄ、光電
素子８ａ、光電素子８ｅの方向に端面４ａが移動する
と、差・絶対値信号（Ｄ−Ｅ）は有限の値をとり、光電
素子８ｂと光電素子８ｃの間の差・絶対値信号（Ｂ−
Ｃ）は０である。従って、差・絶対値信号（Ｂ−Ｃ）と
差・絶対値信号（Ｄ−Ｅ）の和は、被検物４の端面４ａ
の像が光電素子８ａの中心Ｏを如何なる方向から通過す
るときでも０でない有限の値をとることとなる。Similarly, when the end face 4a next moves toward the photoelectric element 8d, the photoelectric element 8a, and the photoelectric element 8e, the difference / absolute value signal (D-E) takes a finite value, and the photoelectric element 8b. Difference / absolute value signal (B-
C) is 0. Therefore, the sum of the difference / absolute value signal (B-C) and the difference / absolute value signal (D-E) is the end surface 4a of the test object 4.
Image has a finite value other than 0 when it passes through the center O of the photoelectric element 8a from any direction.

【００３２】回路２３ａ、２３ｂからの信号が基準信号
２９と比較器２６で比較して大きいとき、回路２７は被
検物４の端面４ａの像が光電素子８ａの中心を通過する
ことを検知し、端面位置を検出する。因に、被検物４の
端面４ａの像がセンサ８の外部にあるときは、差・絶対
値信号（Ｂ−Ｃ）と差・絶対値信号（Ｄ−Ｅ）の和は０
となり、端面位置が検出されることはない。When the signals from the circuits 23a and 23b are larger than the reference signal 29 by the comparator 26, the circuit 27 detects that the image of the end face 4a of the object 4 passes through the center of the photoelectric element 8a. , Detect the end face position. Incidentally, when the image of the end surface 4a of the test object 4 is outside the sensor 8, the sum of the difference / absolute value signal (BC) and the difference / absolute value signal (DE) is 0.
Therefore, the end face position is not detected.

【００３３】本実施例により、被検物の端面の明度分布
信号の傾斜状態に合わせてセンサの直径を適切な大きさ
に切り換えることができるから、被検物の端面の明度分
布信号の傾斜が急な場合でも、傾斜が緩やかな場合でも
共に精度よく端面検出が行える。すなわち、センサの大
きさを切り換え、端面位置検出に必要な光量を得るよう
にしたものである。According to this embodiment, the diameter of the sensor can be switched to an appropriate size according to the inclination state of the brightness distribution signal of the end surface of the object to be inspected, so that the inclination of the lightness distribution signal of the end surface of the object to be inspected is changed. Both in a steep case and a gentle inclination, the end face can be accurately detected. That is, the size of the sensor is switched to obtain the light amount necessary for detecting the end face position.

【００３４】両実施例において、円形及び環形の受光素
子を使用しているが、四角形その他の形状を有しても、
端面の形状や、検出方向によっては使用可能であること
はいうまでもないし、中心の円形の受光素子を環形の受
光素子にしても良いことはいうまでもない。In both of the embodiments, the circular and ring-shaped light receiving elements are used.
It goes without saying that the light receiving element can be used depending on the shape of the end face and the detection direction, and the circular light receiving element in the center may be a ring light receiving element.

【００３５】[0035]

【発明の効果】本発明により、被検物の形状や性状によ
り、端面の明度分布の傾斜が緩やかな場合であっても、
良好な精度で端面位置計測が行える端面検出装置が提供
できる。EFFECTS OF THE INVENTION According to the present invention, even when the inclination of the lightness distribution on the end face is gentle due to the shape and properties of the test object,
An end face detection device that can measure the end face position with good accuracy can be provided.

【図面の簡単な説明】[Brief description of drawings]

【図１】光学的な端面検出の状況を示すための光学図で
ある。FIG. 1 is an optical diagram for showing a situation of optical end face detection.

【図２】本発明の一実施例にかかるセンサ及び電気回路
を示す図。FIG. 2 is a diagram showing a sensor and an electric circuit according to an embodiment of the present invention.

【図３】本発明の一実施例にかかるセンサ及び電気回路
を示す図。FIG. 3 is a diagram showing a sensor and an electric circuit according to an embodiment of the present invention.

【図４】本発明にかかる端面検出の動作原理を示す図。FIG. 4 is a diagram showing an operation principle of end face detection according to the present invention.

【図５】本発明にかかる鋭いエッジとあいまいなエッジ
とで光電素子の大きさを変更する事を説明するための光
強度図。FIG. 5 is a light intensity diagram for explaining that the size of a photoelectric element is changed between a sharp edge and an ambiguous edge according to the present invention.

【図６】本発明の他の実施例にかかるセンサ及び電気回
路を示す図。FIG. 6 is a diagram showing a sensor and an electric circuit according to another embodiment of the present invention.

【図７】本発明の他の実施例にかかる端面検出の演算原
理を示す図。FIG. 7 is a diagram showing a calculation principle of end face detection according to another embodiment of the present invention.

【図８】本発明の他の実施例にかかる端面検出の演算原
理を示す図。FIG. 8 is a diagram showing a calculation principle of end face detection according to another embodiment of the present invention.

【符号の説明】[Explanation of symbols]

１・・・・対物レンズ ４・・・・被検物 ５ａ、５ｂ、５ｃ・・・・光電素子 ５ｄ、５ｅ、５ｆ・・・・電流電圧変換器 ５ｈ・・・・加算演算器 ５ｉ・・・・差動増幅器 ８ａ、８ｂ、８ｃ、８ｄ、８ｅ、８ｆ、８ｇ、８ｈ、８
ｉ・・・・光電素子 出力信号Ａ、Ｂ、Ｃ、Ｄ、Ｅ、Ｆ、Ｇ、Ｈ、Ｉ ９Ａ、９Ｂ、９Ｃ、９Ｄ、９Ｅ、９Ｆ、９Ｇ、９Ｈ、９
Ｉ・・・・電流電圧変換器1 ... Objective lens 4 ... Object to be inspected 5a, 5b, 5c ... Photoelectric element 5d, 5e, 5f ... Current-voltage converter 5h ... Addition calculator 5i ... ..Differential amplifiers 8a, 8b, 8c, 8d, 8e, 8f, 8g, 8h, 8
i ... Photoelectric element output signals A, B, C, D, E, F, G, H, I 9A, 9B, 9C, 9D, 9E, 9F, 9G, 9H, 9
I ... Current-voltage converter

Claims (6)

【特許請求の範囲】[Claims] 【請求項１】対物レンズの結像面に配置され、円形の受
光素子及び円形の受光素子の外周に同心的に順次多重に
設けられたｎ周（ｎ≧２の整数）の環形の受光素子とか
ら形成され、前記受光素子ごとに受光信号を出力する光
電センサと、前記円形の受光素子から、順次第ｍ周（ｍ
≦ｎ−１の整数）の前記環形の受光素子までの受光信号
を合算して加算信号を出力する加算回路と、前記加算信
号と第（ｍ＋１）周の前記環形の受光素子の受光信号と
の差を演算して差算信号を出力する差算回路と、前記差
算信号を検出し、前記差算信号が所定値であるとき被検
物の端面位置にあることを検出する検出手段とを具備
し、前記第ｍ周の環形の受光素子の数ｍは、前記被検物
の端面の性状により変更して設定可能であることを特徴
とする端面検出装置。1. A circular light-receiving element arranged on the image plane of an objective lens, and a ring-shaped light-receiving element of n rounds (an integer of n ≧ 2) which is concentrically and multiply provided on the outer circumference of the circular light-receiving element. And a photoelectric sensor that outputs a light reception signal for each of the light receiving elements, and from the circular light receiving element, the mth circumference (m
An integer circuit of (≦ n−1) up to the ring-shaped light-receiving element and outputting an addition signal, and the addition signal and the light-receiving signal of the ring-shaped light-receiving element on the (m + 1) th turn. A difference circuit that calculates a difference and outputs a difference signal; and a detection unit that detects the difference signal and detects that the difference signal is at the end face position of the test object when the difference signal has a predetermined value. The end face detection device is characterized in that the number m of the ring-shaped light receiving elements in the m-th circumference can be changed and set according to the properties of the end face of the object to be inspected. 【請求項２】前記第ｍ周の前記環形の受光素子までの加
算信号の最大値と第（ｍ＋１）周の前記環形の受光素子
の受光信号の最大値は等しく設定され、前記差算信号の
前記所定値は０であることを特徴とする請求項１に記載
の端面検出装置。2. The maximum value of the added signal up to the ring-shaped light receiving element in the m-th round and the maximum value of the light-receiving signal of the ring-shaped light receiving element in the (m + 1) th round are set to be equal to each other, and The end face detection device according to claim 1, wherein the predetermined value is 0. 【請求項３】前記環形の受光素子の数ｎは２であること
を特徴とする請求項１に記載の端面検出装置。3. The end face detecting device according to claim 1, wherein the number n of the ring-shaped light receiving elements is two. 【請求項４】前記円形の受光素子に代え、環形の受光素
子を有することを特徴とする請求項１に記載の端面検出
装置。4. The end face detection device according to claim 1, further comprising a ring-shaped light receiving element instead of the circular light receiving element. 【請求項５】前記環形の受光素子の少なくも１個は、半
径方向に分割されて個別に受光信号を出力する少なくも
２個の分割受光素子から形成され、且つ前記少なくも２
個の分割受光素子の中、前記円形の受光素子の中心につ
いて対称の位置にある対を形成する２個の分割受光素子
の出力信号の最大出力は同一に設定されて、前記対を形
成する２個の分割受光素子の出力信号の差の絶対値を演
算して差・絶対値信号を出力する差・絶対値演算回路を
具備し、前記検出回路は、前記差・絶対値演算信号が０
でない有限値を有するとき、前記被検物の端面位置を検
出することを特徴とする請求項１、２、３又は４に記載
の端面検出装置。5. At least one of the ring-shaped light receiving elements is formed from at least two divided light receiving elements which are divided in the radial direction and individually output light receiving signals, and the at least two light receiving elements are provided.
Of the divided light receiving elements, the maximum output signals of the two divided light receiving elements forming a pair symmetrically with respect to the center of the circular light receiving element are set to the same value to form the pair. The detection circuit includes a difference / absolute value calculation circuit that calculates the absolute value of the difference between the output signals of the divided light receiving elements and outputs the difference / absolute value signal.
The end surface detecting device according to claim 1, 2, 3 or 4, wherein the end surface position of the object is detected when the end surface position has a finite value that is not. 【請求項６】前記環形の受光素子の少なくも１個は、半
径方向に等分に分割され、個別に受光信号を出力するた
４個の分割受光素子から形成され、且つ相対してそれぞ
れ対を形成する２個の分割受光素子の出力信号の最大出
力は同一に設定されて、前記それぞれ対を形成する２個
の前記分割受光素子の出力信号の差の絶対値を演算して
差・絶対値信号を出力する差・絶対値演算回路と、前記
２個の差・絶対値を加算演算して加算値信号を出力する
する加算演算回路とを具備し、前記検出回路は、前記加
算値信号が０でない有限値を有するとき、前記被検物の
端面位置を検出することを特徴とする請求項１、２、３
又は４に記載の端面検出装置。6. At least one of the ring-shaped light-receiving elements is divided into four equal parts in the radial direction and is formed from four divided light-receiving elements which individually output light-receiving signals. The maximum outputs of the output signals of the two divided light receiving elements forming the pair are set to be the same, and the absolute value of the difference between the output signals of the two divided light receiving elements forming each pair is calculated to obtain the difference / absolute value. The detection circuit includes a difference / absolute value arithmetic circuit that outputs a value signal and an addition arithmetic circuit that performs an arithmetic operation on the two difference / absolute values and outputs an addition value signal, wherein the detection circuit is the addition value signal. The end face position of the test object is detected when has a finite value other than 0.
Alternatively, the end face detection device according to item 4.