JPS6111686Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an automatic focusing device for a phase contrast microscope.

Conventional automatic focusing devices for microscopes change the relative distance between the stage and the objective lens while the photoelectric means photoelectrically converts the sample image formed by the objective lens, detects the contrast of the image, and adjusts the relative distance so that the contrast is maximized. It was meant to control distance.

However, when the present inventor tried using this type of automatic focusing device together with a phase contrast microscope, he found that the relative distance controlled by this automatic focusing device as the in-focus state and the specimen image observed with the naked eye through the eyepiece. However, it was discovered that the above-mentioned relative distance does not match when manual focus adjustment is performed, that is, when the specimen image is observed with the naked eye under the automatic focusing control of the automatic focusing device, the specimen image is unclear. As described above, conventional automatic focusing devices of this type cannot be used in phase contrast microscopes.

Therefore, an object of the present invention is to provide an automatic focusing device that enables automatic focusing of a phase contrast microscope.

As a result of intensive research based on numerous experiments, the inventor of this invention found that the relative distance between the objective lens and the stage when photoelectrically detected is the maximum specimen image contrast.
It has been found that the relative distance differs by a certain value from the above-mentioned relative distance when manually adjusting the focus with the naked eye, and this value is a constant determined by the relationship between the phase contrast microscope and the specimen. Based on this, the gist of the present invention is that the automatic focusing device of the phase contrast microscope performs photoelectric conversion of the specimen image of the specimen by the objective lens while changing the relative distance between the objective lens of the phase contrast microscope and the specimen on the stage. a detection means for detecting the maximum contrast of a specimen image from the output of the photoelectric conversion means; an external introduction section for introducing a fixed correction distance determined by the relationship between the phase contrast microscope and the specimen by an external operation; a control means that determines a focusing distance by adding the correction coefficient to the relative distance between the specimen and the objective lens when the means detects the maximum contrast; and a control means that drives at least one of the stage and the objective lens to determine the distance between them. The present invention includes a driving means for automatically matching the focusing distance.

Next, the present invention will be explained in detail based on the embodiment shown in FIG. 1 is a camera incorporating a solid-state image sensor, 2
3 is a sample and hold circuit, and 3 is a scanning clock generation circuit. For example, a specimen such as a lymphocyte specimen is placed on a stage 11 and the distance from the camera 1 is varied by a drive device 10 connected to the stage and a control device 9 thereof. To measure the contrast of the image of the object to be inspected by the objective lens of this camera, it is sufficient to scan the image, extract the high-frequency components of the electrical signal obtained by photoelectric conversion, and examine the integrated result. Since an image sensor is used and sample-and-hold is performed at a constant clock, simply extracting high-frequency components has no effect. To explain in detail, when sampling, there is enough information to restore the information of the original signal in frequency components up to 1/2 of the sampling frequency, and information included in frequencies higher than 1/2 is a repetition of that information. Therefore, in order to extract the high frequency components of the original signal, it is necessary to extract only the high frequency components within frequencies that are 1/2 or less of the sampling frequency. A bandpass filter 4 is connected for this purpose. 5
6 is a rectifier circuit, 6 is an integrating circuit, 7 is a sample-and-hold circuit that holds the output of the integrating circuit 6 for a certain period of time, and 8 is a controller.

Next, this operation will be explained.

In response to commands from the controller 8, the control device 9 and the drive device 10 move the stage 11 from one end of its movement range in constant steps in the direction of the optical axis of the camera. The controller 8 examines the output P of the sample-and-hold circuit 7 for each step. When the stage 11 moves through its entire range of movement, the circuit 7 generates an output as shown in FIG. In FIG. 2, the horizontal axis represents the position x of the stage, and the vertical axis represents the output P of the circuit 7, that is, the contrast of the image. Controller 8 stores the stage position x _c that provides maximum contrast. A fixed correction distance x _d determined in advance from the combination of the object to be examined and the phase contrast microscope is introduced into the controller 8 from the external introduction section 12 . The controller 8 adds the aforementioned x _c and this x _d and generates an output of the added value (x _c +x _d ). Therefore, this added value (x _c +x _d ) represents the in-focus position of the stage. Control device 9 and drive device 10
Based on the output of this added value (x _c +x _d ), the stage 11 is driven to this (x _c +x _d ) position and focused. Such a controller 8 can be easily constructed by a combination of an A/D conversion circuit and a microcomputer, an analog comparator, an up/down counter, etc. That is, in this embodiment, a camera 1 incorporating a solid-state image sensor constitutes a photoelectric conversion means, and a sample-and-hold circuit 2, a scanning clock generation circuit 3, a bandpass filter 4, a rectification circuit 5, and an integration circuit 7 constitute a detection means. The controller 8 constitutes a control means, the control device 9 and the drive device 10
constitutes the driving means. Although the stage 11 is driven in this embodiment, the camera 1 may be moved in the direction of its optical axis.

Furthermore, the aforementioned (x _c +x _d ) output of the controller 8 can be supplied to the display 14 to display the in-focus position of the stage 11, and the operator can drive the stage 11 based on this displayed value. Note that the value of the output x _d of the external introduction section 12 is determined in advance by experiment for each test object.

As described above, according to the present invention, an automatic focusing device for a phase contrast microscope can be obtained very easily by using a conventional photoelectric conversion device for detecting a focal point position.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a graph showing the contrast of images when the relative distance of the objective lens to the object to be examined is changed. Explanation of symbols of main parts, 1...Photoelectric conversion means,
2, 3, 4, 5, 6, 7... detection means, 8... control means, 9, 10... drive means, 11... stage, 12... external introduction section.

Claims (1)

[Claims for Utility Model Registration] An automatic focusing device for a phase contrast microscope, which captures a sample image of the specimen by the objective lens while changing the relative distance between the objective lens of the phase contrast microscope and the specimen on a stage. a photoelectric conversion means for photoelectric conversion; a detection means for detecting the maximum contrast of the sample image from the output of the photoelectric conversion means; and a fixed correction distance determined by the relationship between the phase contrast microscope and the sample by an external operation. an external introduction section for introducing the object; a control means for determining a focusing distance by adding the correction distance to the relative distance between the specimen and the objective lens when the detection means detects the maximum contrast; an automatic focusing device for a phase contrast microscope, comprising: driving means for driving at least one of the two to automatically match the distance between the two to the focusing distance.