JPH09297266A - Microscope - Google Patents

Abstract

(57) Abstract: A dark field microscope is constructed with a simple illumination system, and a transparent sample and an opaque sample are observed by switching between bright field and dark field with a simple configuration. A lens for converting illumination light emitted from a light source into parallel light, and a reflected light obtained by reflecting the illumination light incident on the lens and reflecting the reflected illumination light on a sample. Of the above, a beam splitter that transmits reflected light whose polarization angle is different from the illumination light by a predetermined angle,
The illumination light output from the beam splitter is condensed and applied to a sample, and the reflected light is applied to the beam splitter. The objective lens is inserted between the beam splitter and the objective lens, and the illumination light and the reflected light are reflected. The optical phase space filter is provided with a hollow portion that allows light to pass therethrough, and an optical phase spatial filter that shifts the polarization angles of the illuminated light and reflected light by ½ wavelength.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microscope, and more particularly to an illumination system that can easily switch between a bright field and a dark field.

[0002]

2. Description of the Related Art A dark field microscope is one of the microscopes for observing the surface of an opaque sample such as a metallic material. In this dark field microscope, illumination light is vertically incident on the sample from the objective lens side, and observation is performed based on not the specularly reflected light from the sample but the scattered light scattered on the surface of the sample.

FIG. 2 is a diagram showing an example of the configuration of an optical system of a conventional dark-field microscope. Illumination light emitted from a light source is collimated by a collimator lens and collimated by a perforated mirror. The sample is irradiated through a ring-type condenser lens which is reflected and also has a hollowed central portion. In addition, the objective lens is arranged in the central part (hollowed part) of the ring-type condenser lens,
The reflected light obtained by reflecting the illumination light on the sample is captured by the objective lens and observed. Here, since the illumination light is applied to the sample from the outside of the objective lens, the specularly reflected light is not incident on the objective lens, and the reflected light incident on the objective lens is scattered on the surface of the sample. It becomes scattered light.

[0004]

However, when an attempt is made to observe a transparent sample with the above-mentioned microscope, a transmissive illumination facility for irradiating the sample with illumination light from the lower side is required in addition to the above-mentioned illumination. There is a problem that the structure is complicated and the cost is high. On the other hand, it is possible to observe a transparent sample by illuminating the sample with illumination light, but in this case a new dedicated objective lens must be provided, which complicates the structure and reduces the cost. It costs.

The present invention has been made in view of the above-mentioned problems, and has the following objects. (1) To provide a microscope capable of configuring a dark field microscope with a simple illumination system. (2) To provide a microscope capable of switching between bright field and dark field with a simple configuration. (3) To provide a microscope capable of observing a transparent sample and an opaque sample.

[0006]

In order to achieve the above object, as a first means, a lens for converting illumination light emitted from a light source into parallel light and an illumination light incident from the lens are reflected. Along with this, a beam splitter that transmits reflected light having a polarization angle different from the illumination light by a predetermined angle among the reflected light obtained by reflecting the reflected illumination light on the sample, and the illumination output from the beam splitter An objective lens that collects light and irradiates it on a sample, and irradiates the beam splitter with its reflected light, and a hollow part that is interposed between the beam splitter and the objective lens and allows illumination light and reflected light to pass therethrough. And an optical phase spatial filter that shifts the polarization angle of the illuminated illumination light and the reflected light by 1/2 wavelength.

As a second means, in the above-mentioned first means, an optical phase spatial filter or a 1/4 wavelength optical phase filter for shifting the polarization angles of the illumination light and the reflected light by 1/4 wavelength is alternatively used in the optical path. Means that are configured to insert are employed.

As a third means, in the first or second means, a means in which the optical phase spatial filter is formed in a ring shape is adopted.

As a fourth means, the means of any one of the first to fourth means is provided with a tube lens for condensing the reflected light transmitted through the beam splitter and irradiating it to the eyepiece.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a microscope according to the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 is a light source such as a lamp, which emits illumination light toward a collimator lens (lens) 2. The collimator lens 2 converts the illumination light into parallel light and irradiates the beam splitter 3 with it. The beam splitter 3 is of a polarization type and reflects illumination light to irradiate the optical phase spatial filter 4 and transmits reflected light whose polarization plane is, for example, orthogonal to the illumination light, out of the light emitted from the sample A to form a tube. Irradiate the lens 5.

The optical phase spatial filter 4 is a disc-shaped 1 /
A two-wave plate is formed by hollowing out the central portion to form a ring, and the polarization planes of the illumination light and the reflected light radiated to the half-wave plate portion (hereinafter referred to as the half-wave plate portion) are set to 1 / 2
The wavelength, that is, the polarization angle is changed by 180 ° and transmitted toward the objective lens 6.

The objective lens 6 focuses the illumination light, which is parallel light, onto the surface of the sample and irradiates it, and also converts the reflected light from the sample into parallel light and irradiates it onto the optical phase spatial filter 4. Reference numeral 7 is an eyepiece lens, which forms an image X by the reflected light that has passed through the beam splitter 3 and is focused by the tube lens 5.

According to the microscope thus constructed, the illumination light transmitted through the ½ wavelength plate of the ring-shaped optical phase spatial filter 4 has its polarization angle shifted by ½ wavelength and the sample A
The specularly reflected light, which is specularly reflected by the sample A and is specularly reflected by the sample A, has its polarization angle shifted by 1/2 wavelength by the optical phase spatial filter 4. That is, the specularly reflected light is reflected toward the collimator lens 2 without passing through the beam splitter 3.

On the other hand, of the scattered light, the scattered light that passes through the hollowed-out center portion other than the half-wave plate portion and has a polarization angle orthogonal to the illumination light is transmitted through the beam splitter 3 to form an image. Image X. Therefore, since the image X is formed only by scattered light, the microscope is a dark field microscope. Since the scattering of the illumination light becomes intense at the edge of the sample or the part where dust or scratches are attached to the sample surface, such a dark-field microscope specularly reflects the outline of the transparent sample, dust or scratches. It can be detected accurately without being disturbed.

A flat quarter-wave plate (a quarter-wave optical phase filter) is used instead of the optical phase spatial filter 4 described above.
When the is inserted, the specularly reflected light that is specularly reflected by the sample A with respect to the illumination light emitted from the light source 1 passes through a ¼ wavelength plate.
Since it will pass twice, this specularly reflected light will pass through the beam splitter 3 and form an image X. in this case,
The microscope becomes a bright field microscope, and it becomes possible to observe an opaque sample, and the focus of the objective lens 6 can be accurately adjusted based on specular reflection light having high intensity.

[0017]

As described above, the microscope according to the present invention has the following effects. (1) Reflected light that reflects the illumination light incident from the lens and that has a polarization angle that differs from the illumination light by a predetermined angle among the reflected light obtained by irradiating the sample with the illumination light. A beam splitter that transmits light and a hollow portion that is interposed between the beam splitter and the sample and that allows illumination light and reflected light to pass therethrough, and an optical phase that shifts the polarization angle of the illumination light and reflected light by half a wavelength. Since the spatial filter is provided, the dark field microscope can be configured with a simple configuration. (2) Since either the optical phase spatial filter or the optical phase filter is formed to be selectively inserted in the optical path, it is possible to easily switch between the bright field and the dark field with a simple configuration. (3) It is possible to quickly observe a transparent sample and an opaque sample by switching between the bright field and the dark field.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of an optical system of a microscope according to the present invention.

FIG. 2 is a front view showing an example of an optical system of a conventional dark field microscope.

[Explanation of symbols]

 1 Light Source 2 Collimator Lens 3 Beam Splitter 4 Optical Phase Spatial Filter 5 Tube Lens 6 Objective Lens 7 Eyepiece A Sample X Image

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Shigeru Tachikawa 1-1-17 Kamiosaki, Shinagawa-ku, Tokyo Ishikawajima System Technology Co., Ltd.

Claims (4)

[Claims] 1. A lens for converting illumination light emitted from a light source into parallel light, reflecting the illumination light incident from the lens, and reflecting the reflected illumination light by a sample. A beam splitter that transmits reflected light having a polarization angle different from the illumination light by a predetermined angle with respect to the illumination light, condenses the illumination light output from the beam splitter and irradiates the sample with the reflected light. An objective lens for irradiating the splitter, and is inserted between the beam splitter and the objective lens,
A hollow portion is provided to allow the illumination light and the reflected light to pass through, and the polarization angle of the illuminated illumination light and the reflected light is reduced to 1/2.
An optical phase spatial filter that shifts the wavelength, and a microscope. 2. An optical phase spatial filter or a 1/4 wavelength optical phase filter that shifts the polarization angles of illumination light and reflected light by 1/4 wavelength is formed to be selectively inserted in the optical path. The microscope according to claim 1. 3. The microscope according to claim 1, wherein the optical phase spatial filter is formed in a ring shape. 4. The microscope according to claim 1, further comprising a tube lens that collects reflected light that has passed through the beam splitter and irradiates the reflected light onto an eyepiece lens.