Laser microscope

Details Laser microscope Laser microscope

1999-12-01

2001-03-20

Nguyen, Thong (Department: 2872)

Optical: systems and elements

Compound lens system

Microscope

C359S363000, C359S368000, C359S370000

Reexamination Certificate

active

06204964

ABSTRACT:

INCORPORATION BY REFERENCE
The disclosure of the following priority application is incorporated herein by reference: Japanese Patent Application No. 11-38130 filed Feb. 17, 1999.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a microscope, and more particularly to a laser microscope using a TV monitor for observing images.
2. Description of the Related Art
FIG. 1
is a schematic view showing construction of a conventional microscope. In the conventional microscope, illumination light emanated from a white light source
1
such as halogen lamp is reflected by a semi-transparent mirror
2
and illuminates an object
4
through an objective lens
3
. An image of the illuminated object is formed on an image plane
6
by the objective lens
3
and a second objective lens
5
. An image-taking plane of a TV camera is arranged to coincide with the image plane. A light image formed on the image-taking plane is transformed into an electric signal and an observation image is displayed on a TV monitor.
FIG. 2
is a schematic view showing a conceptual diagram of an image-forming optical system of a conventional microscope. As shown in
FIG. 2
, the image-forming optical system of a conventional microscope is a telecentric system at the object side. However, no telecentric system at the image side is used. In
FIG. 2
, a reference number
7
denotes an aperture diaphragm.
If the light source is replaced with a laser source in the conventional microscope, a laser microscope can be constructed. However, when reflectance of the object is high, an interference pattern shown in
FIG. 3
may be produced on the TV monitor.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a laser microscope free from producing interference pattern on the image to be observed.
A laser microscope according to the present invention comprises; a laser illumination light source, an image-forming optical system which is substantially telecentric at at least image side, leading illumination light emanated from said laser illumination light source to an object and forming an image of reflected light from said object on an image plane, and a photoelectric conversion device having an image-taking plane which receives reflected light forming the image on the image plane, and which converts the light into electric signal. The image-taking plane of the photoelectric conversion device is tilted relative to the image plane in order to avoid interference of rays incident on the image-taking plane. Therefore, aforementioned object is hereby attained. In other words, since no interference of rays takes place on the image-taking plane of the photoelectric conversion device even if reflectance of the object is high, no interference pattern is produced on the image to be observed on the display monitor.
The tilt angle between the image-taking plane of the photoelectric conversion device and the image plane can be determined to satisfy the condition set out below:
sin
−1
(
NA
)<&thgr;<(½)·sin
−1
(&lgr;/
P
)−sin
−1
(
NA
)
where,
&thgr;: a tilt angle of the image-taking plane of the photoelectric conversion device relative to the image plane;
NA: a numerical aperture at the image side of the image-forming optical system;
&lgr;: a wavelength of the illumination light to be used; and
P: a period of a periodical structure of the photoelectric conversion device
The image-forming optical system includes a first objective lens located at the object side and a second objective lens located at the image side. The second objective lens can be substantially telecentric at the image side.
A semi-transparent mirror is arranged between the first and second objective lenses. Light emanated from a laser illumination light source is led to illuminate an object through the semi-transparent mirror. Reflected light from the object is incident to the photoelectric conversion device through the first objective lens, the semi-transparent mirror, and the second objective lens. In this case, an aperture diaphragm is arranged between the semi-transparent mirror and the first objective lens, and NA mentioned in the above condition is a numerical aperture of the aperture diaphragm. An imaging device such as CCD can be used as the photoelectric conversion device. P mentioned in the above condition is a pixel pitch of the imaging device such as CCD.


REFERENCES:
patent: 5633721 (1997-05-01), Mizutani
patent: 666 054 (1995-01-01), None
patent: 2 305 710 (1975-03-01), None
patent: 3-236699 (1991-10-01), None
patent: 6-133311 (1994-05-01), None
patent: 8-320525 (1996-12-01), None

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