Optical: systems and elements – Compound lens system – Microscope
Reexamination Certificate
2000-11-09
2002-04-16
Nguyen, Thong (Department: 2872)
Optical: systems and elements
Compound lens system
Microscope
C359S368000, C359S388000, C359S381000
Reexamination Certificate
active
06373626
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a bright and dark field switching device and a microscope. More particularly, the invention relates to a bright and dark field switching device which is provided on an optical path of an illuminating optical system and can switch bright field illumination and dark field illumination, and a microscope which can switch bright field illumination and dark field illumination.
2. Description of the Related Art
In order to carry out observation through a microscope, bright field illumination is used for checking a comparatively rough portion of an object upon a workpiece, and dark field illumination is required for checking a comparatively fine portion of the object upon a workpiece, for example, a circuit pattern of an IC to determine the presence of a flaw.
Therefore, there has been known a microscope comprising a bright and dark field switching device capable of switching the bright field illumination and the dark field illumination.
The related art bright and dark field switching device has switched the bright field illumination and the dark field illumination by using a slide unit
100
shown in FIG.
9
.
The slide unit
100
includes a rectangular body portion
101
and an operation knob
102
. The body portion
101
has three kinds of filters, specifically, a filter
103
for bright field observation (which will hereinafter be referred to “bright field filter”), a glare-proof filter
104
and a filter
105
for dark field observation (which will hereinafter be referred to “dark field filter”) which are provided rectilinearly.
In use, the slide unit
100
is inserted in the illuminating optical path of the microscope and the amount of push-in (or pull-out) of the slide unit
100
is changed so as to selectively position, on the illuminating optical path, either of the bright field filter
103
and the dark field filter
105
which are provided on the slide unit
100
. Thus, the observation is carried out. In this case, when switching from the dark field filter
105
to the bright field filter
103
is to be carried out, the countermeasures are taken such that dazzling is not caused even if the dark field observation is switched into the bright field observation. More specifically, the glare-proof filter
104
is provided in the middle between the bright filed filter
103
and the dark field filter
105
.
With the above-mentioned related art structure, however, the amount of movement of the slide unit
100
is increased with the switching. When the amount of pull-out is the greatest, the filter
105
close to the operation knob
102
gets out of the microscope body. Consequently, a refuse or dust sticks to a filter surface.
If the slide unit
100
is to be pulled out most greatly such that the filter
105
does not get out of the microscope body, the size of the microscope body should be increased. For this reason, a cost is increased and operability is lacking.
For such a problem, it is also proposed that a unit having a bright field filter and a dark field filter and a unit having a glare-proof filter should be provided separately from each other and should be operated independently, respectively.
With such a structure, however, the two units should be operated in separate positions from each other. Therefore, an alternate holding operation is required so that the operability is more deteriorated.
SUMMARY OF THE INVENTION
In order to solve the problems, it is an object of the invention to provide a bright and dark field switching device and a microscope which can carry out switching into three states of the bright field illumination, the dark field illumination and the glare-proof illumination with a reduction in a size and high operability.
In order to achieve the object, the bright and dark field switching device and a microscope according to the invention employ the following structure.
A bright and dark field switching device for a microscope provided on an optical path of an illuminating optical system, according to the present invention, comprises:
a glare-proof optical part for limiting the amount of light illuminated form the illuminating optical system;
an optical part for dark field observation;
a guide mechanism for holding the glare-proof optical part and the optical part for dark field observation such that they can be moved to the optical path and can be returned from the optical path; and
a switching mechanism for moving the glare-proof optical part and the optical part for dark field observation to the optical path and returning them from the optical path, and for moving the glare-proof optical part together and positioning the glare-proof optical part on the optical path only when returning the optical part for dark field observation from the optical path,
wherein the glare-proof optical part and the optical part for dark field observation are provided on both sides with the optical path of the illuminating optical system interposed therebetween.
The optical part for dark field observation indicates a condenser lens for a dark field (will hereinafter be referred to “condenser lens”), a filter for a dark field or a metallic shielding mask.
According to such a structure, the glare-proof optical part and the optical part for dark field observation are provided through the guide mechanism on both sides with the optical path of the illuminating optical system interposed therebetween such that they can be moved to the optical path and can be returned from the optical path. The movement and return are carried out by the switching mechanism. Therefore, a smaller amount of movement is enough as compared with the structure of a slide unit having three kinds of related art filters provided rectilinearly. Therefore, even if the size of the device itself is not increased, the filter does not get out of the body. Accordingly, a reduction in the size of the device can be maintained.
Moreover, the switching mechanism can move the glare-proof optical part and the optical part for dark field observation to the optical path and can return them from the optical path. Also the switching mechanism can move the glare-proof optical part together and can position the same on the optical path only when returning the optical part for dark field observation from the optical path. Therefore, also when the switching is to be carried out from the dark field observation to the bright field observation, the glare-proof optical part is once positioned on the optical path. Consequently, an observer is not dazzled. Accordingly, the observer does not need to keep his (or her) eyes off from an eyepiece when carrying out the switching from the dark field observation to the bright field observation. Therefore, it is possible to carry out the switching from the bright field illumination to the dark field illumination without damaging operability.
In the above-mentioned the bright and dark field switching device, it is preferable that the guide mechanism includes:
a first slider having the glare-proof optical part and disposed on a microscope body of the microscope movably in a direction parallel with movement and return of the glare-proof optical part and the optical part for dark field observation;
a second slider having the optical part for dark field observation and disposed on the microscope body of the microscope movably in the direction parallel with movement and return of the glare-proof optical part and the optical part for dark field observation; and
a positioning mechanism for positioning the first and second sliders in a position where the glare-proof optical part and the optical part for dark field observation are moved onto the optical path and a position where they are returned from the optical path.
According to such a structure, the glare-proof optical part and the optical part for dark field observation are held in the first and second sliders provided movably in the direction parallel with the directions of the movement and return of the optical parts. Therefore, the moving and returning operatio
Isobe Hitoshi
Sano Hidekazu
Tanaka Shoichi
Mitutoyo Corporation
Nguyen Thong
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