JPH0875980A

JPH0875980A - Automatic focus detector for microscope

Info

Publication number: JPH0875980A
Application number: JP20973494A
Authority: JP
Inventors: Takashi Yoneyama; 貴米山
Original assignee: Olympus Optical Co Ltd
Current assignee: Olympus Corp
Priority date: 1994-09-02
Filing date: 1994-09-02
Publication date: 1996-03-22
Anticipated expiration: 2018-07-28
Also published as: JP3431300B2

Abstract

PURPOSE: To restrain the low-contrast scanning to the minimum and to realize a high-speed AF. CONSTITUTION: The device detecting the focusing state of an imageformation optical system by obtaining a focusing degree evaluation value based on an output signal from a photodetector 13 which picks up the image of a subject being an observed object is equipped with a field diaphragm 11 arranged at a conjugate position to a subject image, a field diaphragm driving means 22 changing the diameter of the field diaphragm, a low contrast decision means judging whether or not the contrast value of the subject image is insufficient to detect focusing, a diaphragm diameter control means stopping the diaphragm diameter until the field diaphragm image is projected on the photodetector train 13 in the case where the contrast is insufficient, and a focusing direction detecting means detecting the focusing direction by comparing a 1st contrast value obtained in a state where the field diaphragm image is projected on the photodetector train 13 with a 2nd contarst value obtained after changing a relative distance between the subject and an objective lens 5.

Description

Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は、対象物の画像を光学的
に取得する光学機器に係り、特に顕微鏡における自動焦
点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 optical device for optically acquiring an image of an object, and more particularly to an automatic focus detecting device in a microscope.

【０００２】[0002]

【従来の技術】従来、物体像の焦点状態を検出して合焦
位置にステージ又はレンズを駆動する自動焦点検出装置
がある。かかる自動焦点検出装置のなかには、物体像の
コントラストが低く焦点検出が不能であるとき、レンズ
又はステージを移動しながら焦点検出可能なレンズ位置
又はステージ位置を探す方式（ローコンスキャン方式）
のものがある。2. Description of the Related Art Conventionally, there is an automatic focus detection device which detects a focus state of an object image and drives a stage or a lens to a focus position. Among such automatic focus detection devices, when the contrast of the object image is low and focus detection is impossible, a method for searching for a lens position or stage position where focus detection is possible while moving the lens or stage (low-conscan method)
There is one.

【０００３】例えば、特開平１−１８７５２０号には、
レンズセットが行なわれた直後かどうかを判定し、この
判定結果に基づいてローコンスキャンの方向および方法
を決定する装置が開示されている。この動作制御により
ローコンスキャンによる合焦時間の増大を抑制してい
る。また、この他にもローコンスキャン方式には様々な
方法が開発されている。For example, Japanese Patent Laid-Open No. 1-187520 discloses that
An apparatus is disclosed which determines whether or not a lens has been set immediately after, and determines the direction and method of low contrast scanning based on the determination result. This operation control suppresses an increase in focusing time due to low contrast scanning. In addition to this, various methods have been developed for the low contrast scan method.

【０００４】[0004]

【発明が解決しようとする課題】しかしながら、上述し
た従来の焦点検出技術は顕微鏡に適用することが困難で
ある。すなわち、顕微鏡では対物レンズのセット（装
着）および倍率交換に伴う対物レンズのセット（交換）
があるために物体像の合焦方向は必ずしも一定でない。
このため、レンズのセット直後かどうかの判定だけでは
ローコンスキャンの方向を決定することができない。However, it is difficult to apply the above-mentioned conventional focus detection technique to a microscope. That is, in a microscope, the objective lens is set (mounted) and the objective lens is set (exchanged) when the magnification is changed.
Therefore, the focusing direction of the object image is not always constant.
Therefore, the direction of low contrast scan cannot be determined only by determining whether or not the lens has just been set.

【０００５】また、顕微鏡は検鏡する試料の厚みが様々
であることから、試料のセット直後かどうかの判定によ
ってもローコンスキャンの方向を決定するのは困難であ
る。さらに、顕微鏡の対物レンズの焦点深度（被写体像
の観察が可能な範囲）は数〜数十［μｍ］である場合が
ほとんどであるから、ローコンスキャンを行う機会が非
常に多くなり、その度にこれまでのように双方向にロー
コンスキャンを行ったのでは焦点検出に要する時間は多
大なものとなり、合焦時間が長くなるという欠点があっ
た。Further, since the microscope has various thicknesses of the sample to be inspected, it is difficult to determine the direction of the low contrast scan by judging whether or not the sample has just been set. Furthermore, the depth of focus of the objective lens of the microscope (the range in which the subject image can be observed) is in the range of several to several tens [μm] in most cases. However, if the low-conscan is performed bidirectionally as in the past, the time required for focus detection becomes long and the focusing time becomes long.

【０００６】そこで、本発明の目的は、顕微鏡のローコ
ンスキャン制御において複雑なハードウェアを追加する
ことなく、物体像の合焦方向を短時間で察知し、全ての
範囲において焦点検出を短時間に行うことができる安価
な顕微鏡自動焦点検出装置を提供することにある。Therefore, an object of the present invention is to detect the focusing direction of an object image in a short time without adding complicated hardware in low-con scan control of a microscope, and focus detection in the entire range in a short time. An object of the present invention is to provide an inexpensive microscope automatic focus detection device that can be used for various purposes.

【０００７】[0007]

【課題を解決するための手段】本発明は、上記目的を達
成するために以下のような手段を講じた。請求項１に対
応する本発明は、観察対象の物体を照明光学系で照明す
ることにより対物レンズから入射した物体像を、結像光
学系により複数の受光素子からなる受光部上に投影し、
各受光素子から物体像の光強度分布に対応する出力信号
を取得し、これら出力信号を所定の評価関数に従って演
算処理して合焦度評価値を求め、その合焦度評価値に基
づいて前記物体に対する前記結像光学系の焦点状態を検
出する顕微鏡用自動焦点検出装置において、前記照明光
学系の光路上における前記物体像と共役な位置に、前記
物体像の空間周波数よりも十分小さな空間周波数を有す
る低周波像を発生させる低周波像発生手段と、前記受光
部から出力される出力信号から前記物体像のコントラス
ト値が合焦検出可能なレベルとなっているか否か判断す
るローコン判定手段と、前記ローコン判定手段で合焦検
出不可と判断されたならば、前記低周波像発生手段で発
生させた低周波像を前記受光部に投影させる低周波像投
影手段と、前記低周波像投影手段で低周波像を受光部上
に投影した状態で取得される低周波像の第１のコントラ
スト値と、前記低周波像を受光部上に投影したまま前記
物体と対物レンズとの相対距離を変化させた後に取得さ
れる第２のコントラスト値とを比較して合焦方向を検出
する合焦方向検出手段とを具備する構成とした。The present invention has taken the following means in order to achieve the above object. The present invention corresponding to claim 1 projects an object image incident from an objective lens by illuminating an object to be observed with an illumination optical system, onto a light receiving portion including a plurality of light receiving elements by an imaging optical system,
An output signal corresponding to the light intensity distribution of the object image is obtained from each light receiving element, a focus degree evaluation value is obtained by arithmetically processing these output signals according to a predetermined evaluation function, and the focus degree evaluation value is calculated based on the focus degree evaluation value. In an automatic focus detection device for a microscope that detects a focus state of the imaging optical system with respect to an object, a spatial frequency sufficiently smaller than a spatial frequency of the object image at a position conjugate with the object image on the optical path of the illumination optical system. A low-frequency image generating means for generating a low-frequency image, and a low-contrast determining means for determining whether or not the contrast value of the object image is at a focus detectable level based on the output signal output from the light receiving section. If the low contrast judging means judges that focusing cannot be detected, the low frequency image projecting means for projecting the low frequency image generated by the low frequency image generating means onto the light receiving section, and the low frequency image projecting means The first contrast value of the low-frequency image acquired in the state where the low-frequency image is projected on the light-receiving unit by the wave-image projection unit, and the object and the objective lens of the low-frequency image while the low-frequency image is projected on the light-receiving unit. A focusing direction detecting unit that detects a focusing direction by comparing the second contrast value obtained after changing the relative distance is provided.

【０００８】請求項２に対応する本発明は、観察対象の
物体を照明光学系で照明することにより対物レンズに入
射した物体像を、結像光学系により複数の受光素子から
なる受光部上に投影し、各受光素子から物体像の光強度
分布に対応する出力信号を取得し、これら出力信号を所
定の評価関数に従って演算処理して合焦度評価値を求
め、その合焦度評価値に基づいて前記物体に対する前記
結像光学系の焦点状態を検出する顕微鏡用自動焦点検出
装置において、前記照明光学系の光路上における前記物
体像と共役な位置に配置された視野絞りと、前記視野絞
りの絞り径を開閉制御指令に基づいて変化させる視野絞
り駆動手段と、前記受光部から出力される出力信号から
物体像のコントラスト値が合焦検出に不足しているか否
か判断するローコン判定手段と、前記ローコン判定手段
でコントラスト不足と判断されたならば、前記駆動手段
へ開閉制御指令を与えて視野絞り像が前記受光素子列上
に投影されるまで前記絞り径を絞る絞り径制御手段と、
前記絞り径制御手段により視野絞り像が前記受光素子列
上に投影された状態で取得される視野絞り像の第１のコ
ントラスト値と、前記絞り径制御手段で設定した絞り径
を維持したまま前記物体と対物レンズとの相対距離を変
化させた後に取得される第２のコントラスト値とを比較
して合焦方向を検出する合焦方向検出手段とを具備する
構成とした。According to the present invention corresponding to claim 2, an object image incident on an objective lens by illuminating an object to be observed with an illumination optical system is formed on a light receiving portion composed of a plurality of light receiving elements by an imaging optical system. Projecting, obtaining output signals corresponding to the light intensity distribution of the object image from each light receiving element, calculating the focusing degree evaluation value by arithmetically processing these output signals according to a predetermined evaluation function, and determining the focusing degree evaluation value. In an automatic focus detection device for a microscope that detects a focus state of the imaging optical system with respect to the object based on a field stop disposed at a position conjugate with the object image on the optical path of the illumination optical system, and the field stop. Field diaphragm driving means for changing the diaphragm diameter of the object on the basis of the opening / closing control command, and a low contrast for judging whether or not the contrast value of the object image is insufficient for focus detection from the output signal output from the light receiving section. If the contrast determining means and the low contrast determining means determine that the contrast is insufficient, an opening / closing control command is given to the driving means to reduce the diaphragm diameter until a field diaphragm image is projected on the light receiving element array. Means and
The first contrast value of the field diaphragm image acquired by the diaphragm diameter control means in a state where the field diaphragm image is projected on the light receiving element array, and the diaphragm diameter set by the diaphragm diameter control means are maintained. A focusing direction detecting unit that detects a focusing direction by comparing a second contrast value obtained after changing the relative distance between the object and the objective lens is configured.

【０００９】請求項３に対応する本発明は、観察対象の
物体を照明光学系で照明することにより対物レンズに入
射した物体像を、結像光学系により複数の受光素子から
なる受光部上に投影し、各受光素子から物体像の光強度
分布に対応する出力信号を取得し、これら出力信号を所
定の評価関数に従って演算処理して合焦度評価値を求
め、その合焦度評価値に基づいて前記物体に対する前記
結像光学系の焦点状態を検出する顕微鏡用自動焦点検出
装置において、前記照明光学系の光路上における前記物
体像と共役な位置に配置された視野絞りと、前記視野絞
りの絞り径を開閉制御指令に基づいて変化させる視野絞
り駆動手段と、前記受光部から出力される出力信号から
物体像のコントラスト値が合焦検出に不足しているか否
か判断するローコン判定手段と、外部から与えられる物
体像のコントラスト情報に基づいて物体像のコントラス
トが低いことを認識するローコン認識手段と、前記ロー
コン判定手段でコントラスト不足と判断した場合、又は
前記ローコン認識手段で低コントラストと認識している
場合に、前記駆動手段へ開閉制御指令を与えて視野絞り
像が前記受光素子列上に投影されるまで前記絞り径を絞
る絞り径制御手段と、前記絞り径制御手段により視野絞
り像が前記受光素子列上に投影された状態で取得される
視野絞り像の第１のコントラスト値と、前記絞り径制御
手段で設定した絞り径を維持したまま前記物体と対物レ
ンズとの相対距離を変化させた後に取得される第２のコ
ントラスト値とを比較して合焦方向を検出する合焦方向
検出手段とを具備する構成とした。According to a third aspect of the present invention, an object image incident on an objective lens by illuminating an object to be observed with an illumination optical system is formed on a light receiving section composed of a plurality of light receiving elements by an image forming optical system. Projecting, obtaining output signals corresponding to the light intensity distribution of the object image from each light receiving element, calculating the focusing degree evaluation value by arithmetically processing these output signals according to a predetermined evaluation function, and determining the focusing degree evaluation value. In an automatic focus detection device for a microscope that detects a focus state of the imaging optical system with respect to the object based on a field stop disposed at a position conjugate with the object image on the optical path of the illumination optical system, and the field stop. Field diaphragm driving means for changing the diaphragm diameter of the object on the basis of the opening / closing control command, and a low contrast for judging whether or not the contrast value of the object image is insufficient for focus detection from the output signal output from the light receiving section. Determining means, low contrast recognizing means for recognizing that the contrast of the object image is low on the basis of contrast information of the object image given from the outside, and low contrast deciding means for judging that the contrast is insufficient, or low contrast recognizing means When the contrast is recognized, an opening / closing control command is given to the driving means to reduce the diaphragm diameter until the field diaphragm image is projected on the light receiving element array, and the diaphragm diameter control means The first contrast value of the field diaphragm image acquired in the state where the field diaphragm image is projected on the light receiving element array, and the object and the objective lens while maintaining the diaphragm diameter set by the diaphragm diameter control means are maintained. A focusing direction detecting unit that detects a focusing direction by comparing the second contrast value obtained after changing the relative distance is provided.

【００１０】請求項４に対応する本発明は、観察対象の
物体を照明光学系で照明することにより対物レンズに入
射した物体像を、結像光学系により複数の受光素子から
なる受光部上に投影し、各受光素子から物体像の光強度
分布に対応する出力信号を取得し、これら出力信号を所
定の評価関数に従って演算処理して合焦度評価値を求
め、その合焦度評価値に基づいて前記物体に対する前記
結像光学系の焦点状態を検出する顕微鏡用自動焦点検出
装置において、前記照明光学系の光路上における前記物
体像と共役な位置に配置された視野絞りと、前記視野絞
りの絞り径を開閉制御指令に基づいて変化させる視野絞
り駆動手段と、前記照明光学系の光路上に設けられ、当
該照明光学系の開口数を変化させる開口絞りと、前記開
口絞りの絞り径を開閉制御指令に基づいて変化させる開
口絞り駆動手段と、前記受光部から出力される出力信号
から物体像のコントラスト値が合焦検出に不足している
か否か判断する第１のローコン判定手段と、前記第１ロ
ーコン判定手段でコントラスト不足と判断されたなら
ば、前記開口絞り駆動手段へ開閉制御指令を与えて開口
絞りを絞る開口絞り径制御手段と、前記開口絞り径制御
手段で開口径を絞った状態において再び物体像のコント
ラスト値が合焦検出に不足しているか否か判断する第２
ローコン判定手段と、前記第２ローコン判定手段でコン
トラスト不足と判断されたならば、前記視野絞り駆動手
段へ開閉制御指令を与えて視野絞り像が受光部上に投影
されるまで視野絞り径を絞る視野絞り径制御手段と、前
記絞り径制御手段により視野絞り像が前記受光素子列上
に投影された状態で取得される視野絞り像の第１のコン
トラスト値と、前記絞り径制御手段で設定した絞り径を
維持したまま前記物体と対物レンズとの相対距離を変化
させた後に取得される第２のコントラスト値とを比較し
て合焦方向を検出する合焦方向検出手段とを具備する構
成とした。According to a fourth aspect of the present invention, an object image incident on an objective lens by illuminating an object to be observed with an illumination optical system is formed on a light receiving section composed of a plurality of light receiving elements by an image forming optical system. Projecting, obtaining output signals corresponding to the light intensity distribution of the object image from each light receiving element, calculating the focusing degree evaluation value by arithmetically processing these output signals according to a predetermined evaluation function, and determining the focusing degree evaluation value. In an automatic focus detection device for a microscope that detects a focus state of the imaging optical system with respect to the object based on a field stop disposed at a position conjugate with the object image on the optical path of the illumination optical system, and the field stop. The field stop driving means for changing the stop diameter of the aperture based on the opening / closing control command, the aperture stop provided on the optical path of the illumination optical system for changing the numerical aperture of the illumination optical system, and the aperture diameter of the aperture stop. Open An aperture stop driving means for changing it based on a control command; a first low contrast judging means for judging whether or not a contrast value of an object image is insufficient for focus detection from an output signal output from the light receiving section; If the first low contrast determination means determines that the contrast is insufficient, an aperture stop diameter control means for giving an opening / closing control command to the aperture stop drive means to reduce the aperture stop and an aperture stop diameter control means for reducing the aperture diameter. In the state, it is determined again whether the contrast value of the object image is insufficient for focus detection.
When the contrast is judged to be insufficient by the low contrast judging means and the second low contrast judging means, an opening / closing control command is given to the field diaphragm driving means to narrow the field diaphragm diameter until the field diaphragm image is projected on the light receiving portion. The field stop diameter control means, the first contrast value of the field stop image acquired by the stop diameter control means in a state where the field stop image is projected onto the light receiving element array, and the first stop value are set by the stop diameter control means. A focusing direction detecting means for detecting a focusing direction by comparing a second contrast value obtained after changing the relative distance between the object and the objective lens while maintaining the diaphragm diameter; did.

【００１１】[0011]

【作用】本発明は、以上のような手段を講じたことによ
り次のような作用を奏する。請求項１に対応する本発明
によれば、物体像が投影された受光素子の出力信号から
物体像のコントラスト値が合焦検出可能なレベルとなっ
ているか否かローコン判定手段により判断される。その
判断で合焦検出不可と判断されたならば、低周波像発生
手段で物体像と共役位置に発生させた低周波像が低周波
像投影手段により受光部上に投影される。The present invention has the following effects by taking the above measures. According to the first aspect of the present invention, the low contrast determining means determines whether or not the contrast value of the object image is at a level at which focus detection is possible based on the output signal of the light receiving element onto which the object image is projected. If it is determined that the focus cannot be detected by the determination, the low-frequency image generated by the low-frequency image generating means at the conjugate position is projected onto the light receiving portion by the low-frequency image projection means.

【００１２】ここで、低周波像はその空間周波数が物体
像に比べて十分小さな値に設定されているので、デフォ
ーカス量がローコン状態となる程に大きくても、デフォ
ーカス量の変化に対応して十分に検出可能なパワースペ
クトル変化がある。Here, since the spatial frequency of the low-frequency image is set to a value sufficiently smaller than that of the object image, even if the defocus amount is large enough to be in the low contrast state, it corresponds to the change of the defocus amount. Then there is a sufficiently detectable change in the power spectrum.

【００１３】従って、低周波像投影手段で低周波像を受
光部上に投影した状態で取得される低周波像の第１のコ
ントラスト値と、低周波像を受光部上に投影したまま物
体と対物レンズとの相対距離を変化させた後に取得され
る第２のコントラスト値とを比較することにより、いわ
ゆる山登り方式または光路差方式の合焦位置検出が可能
になる。Therefore, the first contrast value of the low-frequency image acquired in a state where the low-frequency image is projected onto the light-receiving portion by the low-frequency image projecting means, and the low-frequency image is projected onto the light-receiving portion as an object. By comparing the second contrast value obtained after changing the relative distance with the objective lens, it is possible to detect the in-focus position by a so-called hill climbing method or an optical path difference method.

【００１４】その結果、ローコン状態の場合であっても
双方向のローコンスキャンを行うことなく、低周波像の
受光部への投影と第２のコントラスト値の検出及びコン
トラスト比較だけで正確に合焦方向を検出できるので、
ローコン時の合焦位置検出に要する時間を短縮できる。As a result, even in the low contrast state, the bidirectional low contrast scan is not performed, and only the projection of the low frequency image onto the light receiving portion, the detection of the second contrast value, and the contrast comparison are performed to achieve accurate matching. Since the focus direction can be detected,
The time required to detect the in-focus position during low contrast can be shortened.

【００１５】請求項２に対応する本発明によれば、照明
光学系で照明された物体の物体像が、対物レンズから入
射して結像光学系に導かれて受光素子列上に投影され
る。それら各受光素子の出力信号に基づいてローコン判
定手段がコントラスト不足か否か判断する。ローコン判
定手段でコントラスト不足と判断されたならば、絞り径
制御手段から駆動手段へ開閉制御指令が与えられて視野
絞り像が受光素子列上に投影されるまで絞り径が絞めら
れる。According to the present invention corresponding to claim 2, an object image of an object illuminated by the illumination optical system enters from the objective lens, is guided to the imaging optical system, and is projected on the light receiving element array. . Based on the output signals of the respective light receiving elements, the low contrast judging means judges whether or not the contrast is insufficient. If the contrast is judged to be insufficient by the low contrast judging means, an opening / closing control command is given from the diaphragm diameter control means to the driving means and the diaphragm diameter is narrowed down until a field diaphragm image is projected onto the light receiving element array.

【００１６】そして、絞り径制御手段により視野絞り像
が受光素子列上に投影された状態で受光素子から出力信
号が取り込まれ、その視野絞り像のコントラスト値が求
められる。また、絞り径制御手段で設定した絞り径を維
持したまま物体と対物レンズとの相対距離が変化せしめ
られた後にもう一度受光素子の出力信号が取り込まれ、
その視野絞り像のコントラスト値が求められる。合焦方
向検出手段では、前者を第１のコントラスト値とし、後
者を第２のコントラスト値として両者の比較が行われ、
その比較結果に基づいて合焦方向が検出される。Then, an output signal is fetched from the light-receiving element in a state where the field-diameter image is projected on the light-receiving element array by the aperture diameter control means, and the contrast value of the field-iris image is obtained. Further, after the relative distance between the object and the objective lens is changed while maintaining the diaphragm diameter set by the diaphragm diameter control means, the output signal of the light receiving element is captured again,
The contrast value of the field stop image is obtained. In the focusing direction detection means, the former is used as the first contrast value and the latter is used as the second contrast value, and both are compared,
The focusing direction is detected based on the comparison result.

【００１７】請求項３に対応する本発明によれば、低コ
ントラストの物体を観察対象とする場合などは、外部か
ら物体像のコントラスト情報が与えられローコン認識手
段により物体像のコントラストが低いことが認識され
る。According to the present invention corresponding to claim 3, when an object having a low contrast is to be observed, the contrast information of the object image is given from the outside and the contrast of the object image is low by the low contrast recognition means. Be recognized.

【００１８】ローコン判定手段でローコン状態を検出し
た場合、及び又はローコン認識手段で物体が低コントラ
ストであると認識している場合には、絞り径制御手段が
駆動手段へ開閉制御指令を与えて視野絞り像が受光素子
列上に投影されるまで絞り径を絞ることになる。このよ
うにして視野絞り像が受光素子列上に投影された状態で
受光素子の出力信号を取り込み視野絞り像の第１のコン
トラスト値を求める。また、絞り径制御手段で設定した
絞り径を維持したまま物体と対物レンズとの相対距離が
変化せしめられた後にもう一度受光素子の出力信号が取
り込まれ、その視野絞り像のコントラスト値が求められ
る。そして、双方のコントラスト値を比較して合焦方向
が検出される。When the low contrast judging means detects the low contrast state and / or when the low contrast recognizing means recognizes that the object has a low contrast, the diaphragm diameter control means gives an opening / closing control command to the driving means to control the visual field. The aperture diameter is reduced until the aperture image is projected on the light receiving element array. In this way, the first contrast value of the field stop image is obtained by taking in the output signal of the light receiving element with the field stop image projected on the light receiving element array. Further, after the relative distance between the object and the objective lens is changed while maintaining the diaphragm diameter set by the diaphragm diameter control means, the output signal of the light receiving element is again taken in and the contrast value of the field diaphragm image is obtained. Then, the in-focus direction is detected by comparing the contrast values of both.

【００１９】請求項４に対応する本発明によれば、受光
部から出力される出力信号から物体像のコントラスト値
が合焦検出に不足しているか否か第１のローコン判定手
段で判断される。第１ローコン判定手段でコントラスト
不足と判断されると、開口絞り径制御手段から開口絞り
駆動手段へ開閉制御指令が与えられ開口絞りが絞められ
る。このような状態において再び物体像のコントラスト
値が合焦検出に不足しているか否か第２ローコン判定手
段によって判断される。第２ローコン判定手段でコント
ラスト不足と判断されたならば、視野絞り径制御手段か
ら視野絞り駆動手段へ開閉制御指令が与えられて視野絞
り像が受光部上に投影されるまで視野絞り径が絞られ
る。According to the present invention corresponding to claim 4, the first low contrast judging means judges from the output signal output from the light receiving section whether or not the contrast value of the object image is insufficient for focus detection. . When the first low contrast determination means determines that the contrast is insufficient, the aperture stop diameter control means gives an opening / closing control command to the aperture stop drive means to narrow the aperture stop. In such a state, the second low contrast determining means determines again whether or not the contrast value of the object image is insufficient for focus detection. If the second low contrast judging means judges that the contrast is insufficient, the visual field diaphragm diameter controlling means gives an open / close control command to the visual field diaphragm driving means to narrow the visual field diaphragm diameter until the field diaphragm image is projected on the light receiving part. To be

【００２０】そして、絞り径制御手段により視野絞り像
が受光素子列上に投影された状態で各受光素子からの出
力信号が取り込まれて視野絞り像の第１のコントラスト
値が求められる。また、絞り径制御手段で設定した絞り
径を維持したまま物体と対物レンズとの相対距離が変化
せしめられた後に各受光素子からの出力信号が取り込ま
れ視野絞り像の第２のコントラスト値が求められる。そ
して、合焦方向検出手段で第１のコントラスト値と第２
のコントラスト値とが比較され、その比較結果に応じて
合焦方向が検出される。Then, with the aperture diameter control means projecting the field diaphragm image on the light receiving element array, the output signals from the respective light receiving elements are taken in to obtain the first contrast value of the field diaphragm image. Further, after the relative distance between the object and the objective lens is changed while maintaining the diaphragm diameter set by the diaphragm diameter control means, the output signal from each light receiving element is taken in and the second contrast value of the field diaphragm image is obtained. To be Then, the focusing direction detection means detects the first contrast value and the second contrast value.
Is compared with the contrast value of, and the focusing direction is detected according to the comparison result.

【００２１】[0021]

【実施例】以下、本発明の実施例について説明する。図
１は、落射観察用顕微鏡に本発明に係る自動焦点検出装
置を適用した実施例を示す図である。同図に示す落射観
察用顕微鏡は、顕微鏡本体の胴部１に対してステージ保
持部材２が上下方向へ摺動自在に取り付けられ、そのス
テージ保持部材２にステージ３が取り付けられている。
ステージ３の上方に位置する胴部１の先端部にはレボル
バ４が回転自在に取り付けられており、所定の対物レン
ズ５を光軸上に配置するようになっている。光軸上に配
置された対物レンズ５の光軸上には接眼鏡筒８が設けら
れており、光軸を接眼レンズ７側と撮影ユニット８側と
に分岐している。また、レボルバ４と接眼鏡筒８との間
には落射蛍光投光管９の一端部が挿入されている。投光
管９の他端部には光源ボックス１０が取付けられてい
る。投光管９内に形成されている光路上には視野絞り
（ＦＳ）１１、及び開口絞り（ＡＳ）１２が配置されて
いる。Embodiments of the present invention will be described below. FIG. 1 is a diagram showing an embodiment in which an automatic focus detection device according to the present invention is applied to an epi-illumination observation microscope. In the epi-illumination observation microscope shown in the figure, a stage holding member 2 is attached to a body portion 1 of a microscope main body so as to be vertically slidable, and a stage 3 is attached to the stage holding member 2.
A revolver 4 is rotatably attached to the tip of the body 1 located above the stage 3, and a predetermined objective lens 5 is arranged on the optical axis. An eyepiece tube 8 is provided on the optical axis of the objective lens 5 arranged on the optical axis, and the optical axis is branched into the eyepiece 7 side and the photographing unit 8 side. An end portion of an epi-illumination fluorescent light projection tube 9 is inserted between the revolver 4 and the eyepiece tube 8. A light source box 10 is attached to the other end of the light projecting tube 9. A field stop (FS) 11 and an aperture stop (AS) 12 are arranged on the optical path formed in the light projecting tube 9.

【００２２】ステージ保持部材２は、顕微鏡本体の胴部
１に組み込まれた伝達機構を介してステージ駆動装置２
１に結合されている。ステージ駆動装置２１から発生さ
せる駆動力が伝達機構によりステージ保持部材２を上下
動させる力に変換される。The stage holding member 2 is a stage driving device 2 via a transmission mechanism incorporated in the body portion 1 of the microscope body.
Is bound to 1. The driving force generated by the stage driving device 21 is converted into a force for vertically moving the stage holding member 2 by the transmission mechanism.

【００２３】視野絞り１１及び開口絞り１２はＦＳ／Ａ
Ｓ駆動回路２２により絞り径がそれぞれ制御されるよう
になっている。撮影ユニット８は、イメージセンサ１３
と、そのイメージセンサ１３上に試料Ｓの像を結像させ
る結像レンズ１４と、試料像の照度をモニタするための
照度モニタ１５とを備えている。イメージセンサ１３
は、その電荷蓄積時間や読出しタイミングがイメージセ
ンサ駆動回路２３から制御される。The field stop 11 and the aperture stop 12 are FS / A.
The diaphragm diameter is controlled by the S drive circuit 22. The photographing unit 8 includes an image sensor 13
An image forming lens 14 for forming an image of the sample S on the image sensor 13 and an illuminance monitor 15 for monitoring the illuminance of the sample image. Image sensor 13
The charge storage time and read timing of the image sensor are controlled by the image sensor drive circuit 23.

【００２４】イメージセンサ１３の出力段にはアナログ
信号処理回路２４，評価関数演算器２５が直列に接続さ
れている。評価関数演算器２５による評価演算結果はＣ
ＰＵ２６に入力している。そしてＣＰＵ２６が評価演算
の結果を基にステージ駆動装置２１へ制御信号を送り、
ステージ３を上下方向に移動させることにより試料Ｓと
対物レンズ３５の相対的距離を調整し自動合焦を得る様
に構成されている。At the output stage of the image sensor 13, an analog signal processing circuit 24 and an evaluation function calculator 25 are connected in series. The evaluation calculation result by the evaluation function calculator 25 is C
Inputting to PU26. Then, the CPU 26 sends a control signal to the stage driving device 21 based on the result of the evaluation calculation,
By moving the stage 3 in the vertical direction, the relative distance between the sample S and the objective lens 35 is adjusted to obtain automatic focusing.

【００２５】また、ＣＰＵ２６に対して外部コントロー
ラ２７が接続されている。この外部コントローラ２７は
検鏡者が顕微鏡の電動部位を制御するために使用するス
イッチやジョグダイヤルを有する装置である。自動合焦
動作の開始、中断などの操作を検鏡者が外部コントロー
ラ２７を用いて行うとその情報をＣＰＵ２６に送り、そ
れに応答してＣＰＵ２６が操作に対応した動作を行う様
になっている。An external controller 27 is connected to the CPU 26. The external controller 27 is a device having a switch and a jog dial used by a spectroscope to control an electric part of the microscope. When the microscoper performs an operation such as starting or interrupting the automatic focusing operation using the external controller 27, the information is sent to the CPU 26, and in response thereto, the CPU 26 performs an operation corresponding to the operation.

【００２６】次に、以上のようにに構成された本実施例
の動作について説明する。光源ボックス１０から発した
照明光は、落射蛍光投光管９、対物レンズ５を通過して
試料Ｓへ照射される。試料Ｓから発した蛍光画像は、対
物レンズ５を通過し、一部は接眼レンズ７へ入射して検
鏡者に観察される。また、一部は焦点調整のためのイメ
ージセンサ１３へ投影される。Next, the operation of this embodiment configured as described above will be described. The illumination light emitted from the light source box 10 passes through the epi-illumination fluorescent light projection tube 9 and the objective lens 5 and is applied to the sample S. The fluorescence image emitted from the sample S passes through the objective lens 5, and a part of the fluorescence image is incident on the eyepiece lens 7 and is observed by a spectroscope. A part of the image is projected on the image sensor 13 for focus adjustment.

【００２７】イメージセンサ駆動回路２３は、ＣＰＵ２
６からの制御により、常に適正なタイミングでイメージ
センサ１３へ駆動パルスを出力する。イメージセンサ１
３は、受光した画像を入力駆動パルスに従ったタイミン
グで電気信号に変換する。イメージセンサ１３により電
気信号に変換された画像信号は、アナログ信号処理回路
２４で処理を受け、さらに評価関数演算器２５でＣＰＵ
２６から指定された演算式に従って評価演算が行われ
る。ＣＰＵ２６は評価演算の結果を基にステージ駆動装
置２１へ制御信号を送り試料Ｓと対物レンズ５との相対
的距離を調整して自動合焦を得る。The image sensor drive circuit 23 includes the CPU 2
By the control from 6, the driving pulse is always output to the image sensor 13 at proper timing. Image sensor 1
Reference numeral 3 converts the received image into an electric signal at a timing according to the input drive pulse. The image signal converted into an electric signal by the image sensor 13 is processed by the analog signal processing circuit 24, and is further processed by the evaluation function calculator 25 by the CPU.
The evaluation calculation is performed according to the calculation formula designated by 26. The CPU 26 sends a control signal to the stage drive device 21 based on the result of the evaluation calculation to adjust the relative distance between the sample S and the objective lens 5 to obtain automatic focusing.

【００２８】また、ＣＰＵ２６からＦＳ／ＡＳ駆動回路
２２に対して開閉制御信号を出力して必要に応じて視野
絞り１１、開口絞り１２を開閉する。以上のように構成
された本実施例の焦点検出動作について図２を用いて詳
細に説明する。Further, the CPU 26 outputs an open / close control signal to the FS / AS drive circuit 22 to open / close the field stop 11 and the aperture stop 12 as needed. The focus detection operation of this embodiment configured as described above will be described in detail with reference to FIG.

【００２９】自動合焦動作（以下、「ＡＦ」と呼ぶ）が
開始されると（Ｓ１）、イメージセンサ１３の出力を読
込み（Ｓ２）、イメージセンサ１３の出力がアナログ処
理回路２４のレンジに適しているかチェックする（Ｓ
３）。When the automatic focusing operation (hereinafter referred to as "AF") is started (S1), the output of the image sensor 13 is read (S2), and the output of the image sensor 13 is suitable for the range of the analog processing circuit 24. Check if there is (S
3).

【００３０】レンジが適合していない場合は、イメージ
センサ駆動回路２３にレンジが適合するような蓄積時間
とする指令をＣＰＵ２６から与える。この動作はイメー
ジセンサ１３の出力がアナログ処理回路２４のレンジに
適合するまで行われる。If the range is not compatible, the CPU 26 gives the image sensor drive circuit 23 a command to set the storage time so that the range is compatible. This operation is performed until the output of the image sensor 13 matches the range of the analog processing circuit 24.

【００３１】レンジが適合している場合は、イメージセ
ンサ１３から出力される試料Ｓの光像のコントラスト値
が、焦点検出可能なコントラスト値以上（いわゆるロー
コン）かどうか判断する（Ｓ５）。ステップＳ５におい
て、コントラストが低く焦点検出不可能であると判断さ
れた場合は、後述する図３のローコン処理を行う（Ｓ
６）。When the range is suitable, it is determined whether the contrast value of the optical image of the sample S output from the image sensor 13 is equal to or higher than the focus detectable contrast value (so-called low contrast) (S5). If it is determined in step S5 that the contrast is low and focus detection cannot be performed, the low contrast processing of FIG. 3 described later is performed (S).
6).

【００３２】一方、ステップＳ５において焦点検出が可
能であると判断された場合は、評価関数演算器２５から
出力されるデフォーカス量に基づきステージ３を駆動す
る（Ｓ７）。このような一連のＡＦは試料Ｓが合焦位置
に来るまで繰り返され、評価関数演算器２５のデフォー
カス量が合焦状態となったところで終了する（Ｓ８，Ｓ
９）。On the other hand, if it is determined in step S5 that focus detection is possible, the stage 3 is driven based on the defocus amount output from the evaluation function calculator 25 (S7). Such a series of AF is repeated until the sample S reaches the in-focus position, and ends when the defocus amount of the evaluation function calculator 25 reaches the in-focus state (S8, S).
9).

【００３３】ここで、ローコン処理（ステップＳ６）に
ついて図３を参照して詳細に説明する。ステップＳ５に
おいてローコンであると判定されると、ＣＰＵ２６から
ＦＳ／ＡＳ駆動回路２２を制御して視野絞り１１の径を
所定量だけ絞る（Ｓ１０）。視野絞り１１の径が完全に
閉じた状態になったならば（ステップＳ１１）、視野絞
り１１の径をローコンと判定した時点の径まで戻してか
ら双方向スキャンを開始する（ステップＳ１２）。The low contrast processing (step S6) will be described in detail with reference to FIG. When it is determined in step S5 that it is a low contrast, the CPU 26 controls the FS / AS drive circuit 22 to reduce the diameter of the field stop 11 by a predetermined amount (S10). When the diameter of the field diaphragm 11 is completely closed (step S11), the diameter of the field diaphragm 11 is returned to the diameter at the time when it is determined to be low contrast, and then the bidirectional scanning is started (step S12).

【００３４】一方、視野絞り１１の径が全閉でない場合
は、イメージセンサ１３にＦＳ像が投影されているかど
うかを検出する（Ｓ１３）。この一連の絞り径の制御動
作はイメージセンサ１３にＦＳ像が投影されるまで繰り
返される。そして、イメージセンサ１３にＦＳ像が投影
された時点でのＦＳ像のコントラスト値をメモリし（ロ
ーコンであるため、ここで得られるコントラスト値はＦ
Ｓ像のものである）、ステージ駆動装置２１を制御して
ステージ３を所定量下降させる（Ｓ１４）。On the other hand, when the diameter of the field stop 11 is not fully closed, it is detected whether the FS image is projected on the image sensor 13 (S13). This series of control operations of the aperture diameter is repeated until the FS image is projected on the image sensor 13. Then, the contrast value of the FS image at the time when the FS image is projected on the image sensor 13 is stored in memory (because it is a low contrast, the contrast value obtained here is F
Then, the stage drive device 21 is controlled to lower the stage 3 by a predetermined amount (S14).

【００３５】次に、ステージ３を下降させ後のＦＳ像の
コントラスト値を検出し、先にメモリされたＦＳ像のコ
ントラスト値と比較する（Ｓ１５）。この比較の結果、
コントラスト値が上昇していた場合、試料ＳとＦＳ像は
共役関係にあるため試料Ｓの合焦位置は現在のステージ
位置より下方向であると判定する（Ｓ１６）。また、コ
ントラスト値が下降していた場合は、試料Ｓの合焦位置
は現在のステージ位置より上方向であると判断できる
（Ｓ１６′）。Next, the contrast value of the FS image after the stage 3 is lowered is detected and compared with the contrast value of the previously stored FS image (S15). As a result of this comparison,
If the contrast value is increased, it is determined that the focus position of the sample S is below the current stage position because the sample S and the FS image have a conjugate relationship (S16). If the contrast value has decreased, it can be determined that the focus position of the sample S is above the current stage position (S16 ').

【００３６】試料Ｓの合焦方向が確認されたならば、視
野絞り１１の径をローコン判定時の値に戻し（Ｓ１
７）、試料Ｓのサーチを開始する（Ｓ１８）。ここで、
ＦＳ像からサーチ可能な理由について説明する。一般に
結像光学系はセンサや目視などの受光系で識別可能な空
間周波数に限界がある。この周波数をカットオフ周波数
と呼んでいる。さらに、空間周波数とそのデフォーカス
特性は結像光学系によって定まっており、これをＭ−Ｄ
特性と呼んでいる。Ｍ−Ｄ特性において、ほとんどの空
間周波数はデフォーカス量の増大とともにそのパワース
ペクトルが低下する。しかし、空間周波数におけるデフ
ォーカス量の増大とパワースペクトルの低下量の関係
は、一般にカットオフ周波数に近づくに従ってデフォー
カス量の増大に応じたパワースペクトルの低下量は大き
くなり、受光系で識別しにくくなる。すなわち、空間周
波数が低くければデフォーカス量が大きくなってもパワ
ースペクトルの低下量が小さく受光系で識別しやすい。When the focusing direction of the sample S is confirmed, the diameter of the field stop 11 is returned to the value at the time of low contrast determination (S1
7) Then, the search for the sample S is started (S18). here,
The reason why the FS image can be searched will be described. Generally, the imaging optical system has a limit in the spatial frequency that can be identified by a sensor or a light receiving system such as visual inspection. This frequency is called the cutoff frequency. Furthermore, the spatial frequency and its defocus characteristics are determined by the imaging optical system, and this is
I call it a characteristic. In the MD characteristics, the power spectrum of most spatial frequencies decreases as the defocus amount increases. However, the relationship between the increase of the defocus amount and the decrease amount of the power spectrum at the spatial frequency is that the decrease amount of the power spectrum corresponding to the increase of the defocus amount becomes larger as the cutoff frequency is approached, and it is difficult to discriminate in the light receiving system. Become. That is, if the spatial frequency is low, the amount of decrease in the power spectrum is small even if the defocus amount is large, and it is easy to identify by the light receiving system.

【００３７】このモデルを示したものが図４である。図
４の横軸はデフォーカス量を表し、縦軸はパワースペク
トルを示している。同図（ａ）は空間周波数４００本／
ｍｍのＭ−Ｄ特性を表し、同図（ｂ）は５０本／ｍｍの
Ｍ−Ｄ特性を表している。ＦＳ像の空間周波数は非常に
低いためデフォーカス量がかなり大きくなっても検出が
可能である。従って、焦点深度外のローコン状態におい
てもＦＳ像によるサーチは可能である。FIG. 4 shows this model. The horizontal axis of FIG. 4 represents the defocus amount, and the vertical axis represents the power spectrum. In the figure (a), the spatial frequency is 400 lines /
The MD characteristic of mm is shown, and the figure (b) shows the MD characteristic of 50 lines / mm. Since the spatial frequency of the FS image is very low, it is possible to detect even if the defocus amount is considerably large. Therefore, it is possible to search by the FS image even in the low contrast state outside the depth of focus.

【００３８】この様に本発明によれば、試料Ｓが焦点深
度範囲外にあり、ローコン状態であっても空間周波数の
非常に小さいＦＳ像のコントラスト、すなわちＦＳ像の
エッジを検出することにより試料Ｓの合焦方向を検知す
るようにしたので、ローコンスキャンを最低限に抑える
ことができ高速なＡＦが可能となる。As described above, according to the present invention, even if the sample S is outside the depth of focus range and in the low contrast state, the contrast of the FS image having a very small spatial frequency, that is, the edge of the FS image is detected to detect the sample. Since the focus direction of S is detected, the low contrast scan can be suppressed to the minimum and high-speed AF can be performed.

【００３９】なお、上記本実施例では、ローコン時の合
焦方向検出をＦＳ像によるいわゆる山登りサーチによっ
て行っているが、これを光路差光学系を用いて合焦方向
検出を行っても同様の効果を得ることができる。In the present embodiment, the focusing direction at the time of low contrast is detected by a so-called hill climbing search using the FS image. However, if the focusing direction is detected by using the optical path difference optical system, the same result is obtained. The effect can be obtained.

【００４０】また、本実施例ではローコン時の合焦方向
検出のみＦＳ像を用いているが、ＦＳ像自体に合焦させ
ても良く、その場合は、一旦、ＦＳに合焦させた後、Ｆ
Ｓを開いて標本画像に合焦させればさらに精度が良いＡ
Ｆを実現できる。Further, in the present embodiment, the FS image is used only for detecting the focusing direction at the time of low contrast, but it may be focused on the FS image itself. In that case, after focusing on the FS once, F
If S is opened and the sample image is focused, the accuracy is higher.
F can be realized.

【００４１】さらに、本実施例ではステージ駆動による
ＡＦ制御を行っているがこれを対物レンズ駆動としても
同様である。次に、本発明の第２実施例について説明す
る。Furthermore, in the present embodiment, the AF control is performed by driving the stage, but the same applies when driving the objective lens. Next, a second embodiment of the present invention will be described.

【００４２】本実施例は、光学系及びハードウエアの構
成は前述した第１実施例と同様であり、ＣＰＵ２６によ
る焦点検出動作のみが異なる。ここでは、本実施例の動
作について図５を用いて説明する。The optical system and the hardware of this embodiment are the same as those of the first embodiment, and only the focus detection operation by the CPU 26 is different. Here, the operation of this embodiment will be described with reference to FIG.

【００４３】本実施例では試料が液晶の様な低コントラ
ストの物である場合は、予め検鏡者から外部コントロー
ラ２７を介してＣＰＵ２６に対してローコンモードが指
示される。In the present embodiment, when the sample is a low-contrast material such as liquid crystal, the speculum operator instructs the CPU 26 in advance via the external controller 27 to the CPU 26.

【００４４】ＡＦが開始されると（Ｓ２０）、ＣＰＵ２
６が外部コントローラ２７からローコンモード指示が入
力されているか否か検知する（Ｓ２１）。ローコンモー
ドの指定がない場合には、第１実施例の様な通常ＡＦ制
御をＣＰＵ２６が行う（Ｓ２２）。When AF is started (S20), the CPU2
6 detects whether a low contrast mode instruction is input from the external controller 27 (S21). When the low contrast mode is not designated, the CPU 26 performs the normal AF control as in the first embodiment (S22).

【００４５】一方、ローコンモードの指定がされている
場合は、ＣＰＵ２６はＦＳ／ＡＳ駆動回路２２により視
野絞り１１を所定量だけ絞る（Ｓ２３）。そして、その
絞った視野絞り１１が閉じた状態になったならば、視野
絞り径を対物レンズ倍率に関連した所定の径としＦＳ像
が認識できるまで双方向スキャンを開始する（Ｓ２４，
Ｓ２５，Ｓ２６）。視野絞り径が全閉する前、また双方
向スキャンを行ってＦＳ像の検出が完了したら（Ｓ２
７）、ＦＳ像に合焦させる様にＦＳ像のデフォーカス量
に基づいてステージ駆動させる（Ｓ２８）。この合焦動
作はＦＳ像に合焦させるまで繰り返し行われる（Ｓ２
９）。ＦＳ像に合焦させた時点でＡＦ動作は終了する
（Ｓ３０）。On the other hand, when the low contrast mode is designated, the CPU 26 narrows the field stop 11 by a predetermined amount by the FS / AS drive circuit 22 (S23). When the narrowed field stop 11 is closed, the field stop diameter is set to a predetermined value related to the objective lens magnification and bidirectional scanning is started until the FS image can be recognized (S24,
S25, S26). Before detection of the FS image is completed by performing bidirectional scanning before the field stop diameter is fully closed (S2
7) The stage is driven based on the defocus amount of the FS image so as to focus on the FS image (S28). This focusing operation is repeated until the FS image is focused (S2).
9). The AF operation ends when the FS image is focused (S30).

【００４６】この様な本実施例によれば、通常のコント
ラスト法では合焦不能な被写体に対しても、高精度かつ
高速なＡＦが可能となる。また本実施ではＦＳ像を用い
てＡＦ動作を行っているが、焦点深度を深くし、被写体
像あるいはＦＳ像をサーチし易くする様に開口絞りを通
常より絞る制御を組み合わせれば、その相乗効果により
さらに高速なＡＦが可能となる。According to the present embodiment as described above, it is possible to perform high-precision and high-speed AF even for a subject that cannot be focused by the normal contrast method. Further, in the present embodiment, the AF operation is performed using the FS image. However, if the control of narrowing the aperture diaphragm than usual is combined so that the depth of focus is increased and the subject image or the FS image is easily searched for, the synergistic effect is obtained. This enables even faster AF.

【００４７】また本発明の実施例では落射顕微鏡システ
ムで説明を行っているがこれを透過顕微鏡システムに置
き換えても実施可能である。さらに本発明ではＦＳ像に
より、合焦制御を行っているが、他にスペースがある場
合には被写体像と共役な位置に極低周波の光像を投影さ
せてれば同様の効果を得ることができる。本発明は上記
実施例に限定されるものではなく、本発明の要旨を逸脱
しない範囲内で種々変形実施可能である。In the embodiment of the present invention, the epi-illumination microscope system has been described, but the present invention can be implemented by replacing it with a transmission microscope system. Further, in the present invention, the focusing control is performed by the FS image, but when there is another space, the same effect can be obtained by projecting an extremely low frequency optical image at a position conjugate with the subject image. You can The present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention.

【００４８】[0048]

【発明の効果】以上詳記したように本発明によれば、試
料が焦点深度範囲外にあり、ローコン状態でもローコン
スキャンを最低限に抑え、高速なＡＦが可能となる。本
発明によれば、試料が通常コントラスト法では不可能な
低コントラストなものであっても高精度かつ高速なＡＦ
が可能となる。As described in detail above, according to the present invention, even when the sample is out of the depth of focus range and the low-constant state, the low-constant scan is suppressed to the minimum, and high-speed AF is possible. According to the present invention, even if the sample has a low contrast that cannot be obtained by the usual contrast method, high-accuracy and high-speed AF is possible.
Becomes possible.

【００４９】本発明によれば、開口絞りにより焦点深度
を深くしても物体のサーチが不可能な場合にのみ視野絞
り像によるＡＦを行うことにより、より高速なＡＦが可
能となる。According to the present invention, higher speed AF is possible by performing AF using the field stop image only when the object cannot be searched even if the depth of focus is increased by the aperture stop.

[Brief description of drawings]

【図１】本発明の第１実施例に係る顕微鏡用自動焦点検
出装置の構成図である。FIG. 1 is a configuration diagram of an automatic focus detection device for a microscope according to a first embodiment of the present invention.

【図２】第１実施例に係る顕微鏡用自動焦点検出装置の
焦点検出動作を示すフローチャートである。FIG. 2 is a flowchart showing a focus detection operation of the microscope automatic focus detection apparatus according to the first embodiment.

【図３】焦点検出動作のうちのローコン処理のフローチ
ャートである。FIG. 3 is a flowchart of a low contrast process in the focus detection operation.

【図４】異なる空間周波数でのＭ−Ｄ特性を示す図であ
る。FIG. 4 is a diagram showing MD characteristics at different spatial frequencies.

【図５】第２実施例に係る顕微鏡用自動焦点検出装置の
焦点検出動作を示すフローチャートである。FIG. 5 is a flowchart showing focus detection operation of the microscope automatic focus detection apparatus according to the second embodiment.

[Explanation of symbols]

１…顕微鏡本体の胴部、３…ステージ、５…対物レン
ズ、７…接眼レンズ、８…撮影ユニット、１０…光源ボ
ックス、１１…視野絞り、１２…開口絞り、１３…イメ
ージセンサ、２１…ステージ駆動装置、２２…ＦＳ／Ａ
Ｓ駆動回路、２３…イメージセンサ駆動回路、２４…ア
ナログ信号処理回路、２５…評価関数演算器、２６…Ｃ
ＰＵ。DESCRIPTION OF SYMBOLS 1 ... Body part of microscope main body, 3 ... Stage, 5 ... Objective lens, 7 ... Eyepiece lens, 8 ... Imaging unit, 10 ... Light source box, 11 ... Field stop, 12 ... Aperture stop, 13 ... Image sensor, 21 ... Stage Drive device, 22 ... FS / A
S drive circuit, 23 ... Image sensor drive circuit, 24 ... Analog signal processing circuit, 25 ... Evaluation function calculator, 26 ... C
PU.

───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.⁶ 識別記号庁内整理番号ＦＩ技術表示箇所Ｇ０３Ｂ 3/00 Ａ ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G03B 3/00 A

Claims

[Claims]

1. An object image incident from an objective lens by illuminating an object to be observed with an illumination optical system is projected by an imaging optical system onto a light receiving section composed of a plurality of light receiving elements, and the object from each light receiving element is projected. An output signal corresponding to the light intensity distribution of the image is obtained, the output signals are arithmetically processed according to a predetermined evaluation function to obtain a focus degree evaluation value, and the image formation on the object is performed based on the focus degree evaluation value. In a microscope automatic focus detection device for detecting the focus state of an optical system, a low-frequency image having a spatial frequency sufficiently smaller than the spatial frequency of the object image at a position conjugate with the object image on the optical path of the illumination optical system. Low frequency image generating means, and low contrast determining means for determining whether or not the contrast value of the object image is at a level at which focus detection is possible based on the output signal output from the light receiving section. A low-frequency image projecting means for projecting the low-frequency image generated by the low-frequency image generating means onto the light-receiving part if the low-contrast determining means determines that focus detection is impossible; The first contrast value of the low-frequency image acquired in the state where the low-frequency image is projected on the light receiving unit by
Focusing direction detecting means for detecting a focusing direction by comparing with a second contrast value obtained after changing the relative distance between the object and the objective lens while projecting the low-frequency image on the light receiving unit. An automatic focus detection device for a microscope, comprising:

2. An object image incident on an objective lens by illuminating an object to be observed with an illumination optical system is projected by an imaging optical system onto a light receiving section composed of a plurality of light receiving elements, and the object from each light receiving element is projected. An output signal corresponding to the light intensity distribution of the image is obtained, the output signals are arithmetically processed according to a predetermined evaluation function to obtain a focus degree evaluation value, and the image formation on the object is performed based on the focus degree evaluation value. In an automatic focus detection device for a microscope that detects a focus state of an optical system, a field stop arranged at a position conjugate with the object image on the optical path of the illumination optical system, and a diaphragm diameter of the field stop as an opening / closing control command. A field diaphragm drive unit that changes based on the output signal; a low contrast determination unit that determines whether the contrast value of the object image is insufficient for focus detection from the output signal output from the light receiving unit; If the contrast means determines that the contrast is insufficient, an opening / closing control command is given to the driving means to reduce the diaphragm diameter until a field diaphragm image is projected onto the light receiving element array, and the diaphragm diameter. The first contrast value of the field stop image acquired by the control means while the field stop image is projected on the light receiving element array, and the object and the objective while maintaining the stop diameter set by the stop diameter control means. An automatic focus detection device for a microscope, comprising: a focusing direction detecting means for detecting a focusing direction by comparing with a second contrast value obtained after changing the relative distance to the lens.

3. An object image incident on an objective lens by illuminating an object to be observed with an illumination optical system is projected by an imaging optical system onto a light receiving section composed of a plurality of light receiving elements, and the object is received from each light receiving element. An output signal corresponding to the light intensity distribution of the image is obtained, the output signals are arithmetically processed according to a predetermined evaluation function to obtain a focus degree evaluation value, and the image formation on the object is performed based on the focus degree evaluation value. In an automatic focus detection device for a microscope that detects a focus state of an optical system, a field stop arranged at a position conjugate with the object image on the optical path of the illumination optical system, and a diaphragm diameter of the field stop as an opening / closing control command. A field diaphragm drive unit that changes based on the output signal, a low contrast determination unit that determines whether or not the contrast value of the object image is insufficient for focus detection from the output signal output from the light receiving unit, and an externally applied control unit. When a low contrast recognizing unit that recognizes that the contrast of the object image is low based on the contrast information of the object image is determined to be insufficient contrast, or when the low contrast recognizing unit recognizes that the contrast is low. And an aperture diameter control means for narrowing the aperture diameter until a field aperture image is projected onto the light-receiving element array by giving an opening / closing control command to the driving means, and the aperture diameter control means converts the field aperture image into the light-receiving elements. After changing the relative distance between the object and the objective lens while maintaining the first contrast value of the field diaphragm image obtained in a state of being projected on the column and the diaphragm diameter set by the diaphragm diameter control means. An automatic focus detection device for a microscope, comprising: a focus direction detection unit that detects a focus direction by comparing the acquired second contrast value.

4. An object image incident on an objective lens by illuminating an object to be observed with an illumination optical system is projected by an imaging optical system onto a light receiving section composed of a plurality of light receiving elements, and the object from each light receiving element is projected. An output signal corresponding to the light intensity distribution of the image is obtained, the output signals are arithmetically processed according to a predetermined evaluation function to obtain a focus degree evaluation value, and the image formation on the object is performed based on the focus degree evaluation value. In an automatic focus detection device for a microscope that detects a focus state of an optical system, a field stop arranged at a position conjugate with the object image on the optical path of the illumination optical system, and a diaphragm diameter of the field stop as an opening / closing control command. A field diaphragm drive unit that changes based on an opening / closing control command, and an aperture stop that is provided on the optical path of the illumination optical system and that changes the numerical aperture of the illumination optical system. An aperture stop drive means for a first contrast value of the object image from the output signal output from the light receiving unit determines whether or not the missing detection focus
And a first low contrast determining means, if the first low contrast determining means determines that the contrast is insufficient, an aperture stop diameter control means for giving an opening / closing control command to the aperture stop driving means to reduce the aperture stop, and the aperture stop diameter control Second contrast control means for determining whether or not the contrast value of the object image is insufficient for focus detection again when the aperture diameter is narrowed by the means, and if the second contrast control means determines that the contrast is insufficient. A field stop diameter control means for narrowing the field stop diameter until a field stop image is projected onto the light receiving part by giving an opening / closing control command to the field stop drive means; The object and the objective lens while maintaining the first contrast value of the field diaphragm image acquired in a state of being projected on the row and the diaphragm diameter set by the diaphragm diameter control means. And an in-focus direction detecting means for detecting an in-focus direction by comparing with a second contrast value acquired after changing the relative distance of the microscope automatic focus detection apparatus.