Optical: systems and elements – Compound lens system – Microscope
Reexamination Certificate
2001-02-28
2003-06-24
Nguyen, Thong (Department: 2872)
Optical: systems and elements
Compound lens system
Microscope
C359S368000, C359S380000, C359S385000
Reexamination Certificate
active
06583928
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a microscope such as an industrial microscope or the like.
2. Related Background Art
With an increased demand for optical microscopes of high resolving power in recent years, shortening of a wavelength to be used has progressed.
Constitution of a conventional microscope is simply explained as follows. An illumination light emitted from a light source is transmitted through an illuminating lens, and then made incident on a half mirror. A part of the illumination light made incident on the half mirror, which has been reflected by the half mirror, is transmitted through an objective lens to illuminate a sample placed on a stage. Assuming that a direction of an optical axis is Z and two directions orthogonal to each other on a plane are X and Y, the plane being orthogonal to the Z direction, the stage can be moved in the X, Y and Z directions by a stage driving system.
An observed light reflected on the sample is transmitted through the objective lens, and then made incident on the half mirror. After having passed through the half mirror, the observed light is transmitted through an image-forming lens to form an image on an image sensor. An output signal from the image sensor is converted into a video signal by a video signal processing circuit, and then transferred to a monitor. Thus, an image of the sample is displayed on the monitor.
In such a conventional microscope, when an observer watched the image of the sample placed nearly in a static state for a long time, the sample was continuously irradiated with illumination lights, and damage such as deformation, discoloration or the like occurred in the sample. The damage can be attributed to a gradual increase in energy of a light projected to the sample. Such a phenomenon was especially conspicuous in a laser-scanning microscope for converging illumination lights in a very small spot.
Light energy on the sample, i.e., a quantity of an illumination light to be projected, can be obtained by a product of illuminance and irradiation time. A damage degree of the sample has a correlation with this quantity of the illumination light to be projected. In other words, with an increase in the quantity of an illumination light to be projected, a damage of the sample is larger. With a reduction in the quantity of the same, a damage is smaller. If a damage of the sample is large, not only reproducibility will be reduced when the sample is observed again and measured but also a quality of the sample as a product will be reduced. If the sample is a living being such as a microorganism, the living being may die.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a microscope capable of reducing damage such as deformation, discoloration or the like given to a sample.
In accordance with a first aspect of the invention, a microscope is disclosed, which comprises: a light source; an illumination optical system for irradiating a sample with an illumination light emitted from the light source; a stage for placing the sample; an image-forming optical system for collecting an observed light exiting from the sample; a detector for detecting the observed light passing through the image-forming optical system; a processing unit for processing a signal from the detector; a display for displaying an image of the sample based on a video signal from the processing unit; and an illuminance reducing unit for reducing illuminance of the illumination light on the sample to be lower than a specified value enough for observation by the display. With this microscope, by operating the illuminance reducing unit at a specified timing according to conditions including a movement of the stage or the like, it is possible to prevent inconveniences such as damage given to the sample by an excessive quantity of illumination light made incident on the same.
In accordance with a second aspect of the invention, a microscope is disclosed, which comprises: a light source; an illumination optical system for irradiating a sample with an illumination light emitted from the light source; a stage for placing the sample; a stage driving system for driving the stage; an image-forming optical system for collecting an observed light exiting from the sample; a detector for detecting the observed light passing through the image-forming optical system; a processing unit for processing a signal from the detector; and a monitor for displaying an image of the sample based on a video signal from the processing unit. The microscope further comprises illuminance reducing means for reducing illuminance of the illumination light on the sample, and is characterized in that assuming that a time width where illuminance is at a level enough for displaying an image of the sample is T
F
, and a time width where illuminance is lower than the level for displaying an image of the sample is T
N
, and a value a is as follows:
&agr;=T
F
/(
T
F
+T
N
) (1)
the value &agr; is changed by the illuminance reducing means according to a velocity of the stage, and the monitor (or display) displays a still picture of the sample for a period of T
N
, the still picture being one before the time width T
N
.
In this case, the illumination reducing means can set the value &agr; to 0 while the stage is stopped, and to 1 while the stage is on the move.
With the foregoing constitution, since the irradiation quantity of illumination light in the same sample face is reduced, damage given to the sample is reduced. Next, an operation of the microscope of the invention will be described in detail. Generally, a sample placed on the stage of the microscope such as an industrial microscope is a static object. In other words, the sample unless a microorganism or the like never moves around itself.
Thus, while the stage where the sample has been placed is stopped, no change occurs in an image of the sample displayed on the monitor. Even while the stage is not completely stopped, if a velocity of a movement thereof is relatively low, a latest still picture may be displayed on the monitor while updating the same. In this way, a state is realized, which is nearly the same as that of displaying a motion picture (live image) of the sample in real time.
For example, consideration is given to a case where while the stage is in a stopped state, in other words while a stage velocity is 0, a monitor screen is frozen (fixed) without displaying the motion picture of the sample on the monitor, and the still picture of the sample is displayed. In this case, the stage is stopped and, at the instant of the stoppage thereof or after the passage of specified time, illuminance of an illumination light reaching the sample is reduced. As a result, damage given to the sample can be prevented.
On the monitor (or display), an image immediately before reduction of the illuminance is displayed as a still picture. In other words, the monitor screen is made frozen. Thus, no inconveniences occur for observation or measuring.
On the other hand, if the movement of the stage is started again, the illuminance of the illumination light reaching the sample is immediately restored to a normal value, and a motion picture of the sample is displayed on the monitor.
Here, the stopped state of the stage means that no displacement occurs in the stage not only in directions (X, and Y directions) orthogonal to an optical axis but also in a direction of the optical axis (Z direction). Thus, since the stage is not in a stopped state in a step of searching a desired position on the sample (moving step in X and Y directions) or in a step of adjusting a focus position (moving step in Z direction), the motion picture is displayed on the monitor. After the above operations are finished, then the stage is placed in a stopped state for the first time, and the still picture is displayed on the monitor.
Displacement of the stage can be easily detected by using a displacement gauge such as an encoder, an interferometer or the like. Also, in the case of using a
Kadomatsu Yuji
Ogino Katsumi
Ooki Hiroshi
Nguyen Thong
Nikon Corporation
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