Microscope including monochromatic light emitting diode and removable phosphor filter

A microscope includes: a stage on which a specimen is placed; an illumination optical system that includes a monochromatic light LED chip and a phosphor filter, which is arranged to be insertable and removable on and from an illumination optical path and is excited by light having a specific wavelength band irradiated from the monochromatic light LED chip to emit fluorescence having a longer wavelength relative to the light, the illumination optical system being configured to irradiate the specimen with illumination light; and an observation optical system that includes an absorption filter which is insertable and removable on and from an observation optical path and selectively takes fluorescence having a predetermined wavelength from the fluorescence emitted from the specimen.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2016-156749, filed on Aug. 9, 2016, the entire contents of which are incorporated herein by reference.

BACKGROUND

1. Technical Field

The disclosure relates to a microscope capable of bright-field observation and fluorescence observation with a single illumination optical system.

2. Related Art

Conventionally, a microscope, capable of observation by switching between an epi-illumination optical system and a transmitted-light illumination optical system according to various observation methods and observation specimens, has been used.

In recent years, microscopes using a white light emitting diode (LED), instead of a halogen lamp, as a light source of the transmitted-light illumination optical system have increased. For example, proposed is a microscope provided with a transmitted-light illumination optical system, which includes a white LED in which a phosphor of yellow or the like closely adheres on a monochromatic LED element of blue or the like, and an epi-illumination optical system which includes a fluorescence observation filter unit in which the fluorescence observation filter unit of the epi-illumination optical system is inserted and removed on and from an observation optical path by an optical path switching knob (for example, see U.S. Pat. No. 8,040,598).

In U.S. Pat. No. 8,040,598, switching between transmission bright-field observation and epifluorescence observation and switching on and off of each light source are performed by one operation of the optical path switching knob, and thus, it is easy to perform a switching operation of an observation method. However, a part of excitation light from epi-illumination with which a specimen is irradiated is transmitted through the specimen and is incident to the white LED which is the light source of the transmitting illumination optical system at the time of performing the epifluorescence observation so that the phosphor is excited and emits fluorescence, and thus, there is a problem that the fluorescence is detected as noise.

In order to solve this problem, proposed is a microscope in which a correction filter including a spectral transmission profile is insertable and removable into and from a transmitted-light illumination optical system (for example, see JP 2013-29836 A). The spectral transmission profile minimizes transmission of light having a wavelength, in which sensitivity of a spectrum is maximized, irradiated from a white light LED including a blue LED and a yellow phosphor.

SUMMARY

In some embodiments, a microscope includes: a stage on which a specimen is placed; an illumination optical system that includes a monochromatic light LED chip and a phosphor filter, which is arranged to be insertable and removable on and from an illumination optical path and is excited by light having a specific wavelength band irradiated from the monochromatic light LED chip to emit fluorescence having a longer wavelength relative to the light, the illumination optical system being configured to irradiate the specimen with illumination light; and an observation optical system that includes an absorption filter which is insertable and removable on and from an observation optical path and selectively takes fluorescence having a predetermined wavelength from the fluorescence emitted from the specimen.

DETAILED DESCRIPTION

Hereinafter, a preferred embodiment (hereinafter, referred to as the “embodiment”) of the disclosure will be described in detail with reference to the drawings. Incidentally, the disclosure is not limited to this embodiment. In addition, the same reference signs will be attached to the same parts in the description of the drawings.

Embodiment

FIG. 1is a schematic diagram illustrating the entire configuration of an upright microscope1according to an embodiment of the disclosure (at the time of bright-field observation).FIG. 2is a schematic view of the upright microscope1ofFIG. 1at the time of fluorescence observation. The upright microscope1according to the embodiment of the disclosure includes a microscope body2, an illumination optical system3, and an observation optical system4.

The microscope body2includes a base portion2a, a pillar portion2berected on a back surface side of the base portion2a, and an arm portion2csupported by the pillar portion2band extending toward a front surface side. The base portion2ais a portion directly placed on a place such as a desk where the microscope1is installed, and the illumination optical system3is arranged inside the base portion2a. The pillar portion2bis erected on the back surface side (back side) of the base portion2aand integrated with the base portion2aat a lower end portion. The pillar portion2bholds a stage5via a stage holding portion5a. A specimen S is placed on the stage5. The arm portion2cextends from an upper end of the pillar portion2btoward the front surface side of the microscope1, and an intermediate lens-barrel7, which allows a filter holder6on which an absorption filter6ato be described later is mounted to be insertable and removable on and from an observation optical path L1, is attached at an upper side of the arm portion2c. In addition, an objective lens8is attached onto the observation optical path L1on a lower side of the arm portion2c. In the present specification, the front surface side of the upright microscope1is a side on which an observer is positioned, and the back surface side is a side facing the front surface side.

The specimen S is moved together with the stage5in a front-rear direction, and the specimen S is moved in a lateral direction via a clip (not illustrated) by operating an operation handle9attached to the stage5. A focusing handle10is arranged on a side surface of the microscope body2and is connected to the stage5by a rack and pinion mechanism (not illustrated) built in the microscope body2. The stage5is raised and lowered in an optical path direction via the rack and pinion mechanism using a rotation operation of the focusing handle10.

The illumination optical system3is an optical element configured to perform transmission observation. The illumination optical system3includes a monochromatic light LED chip11, a filter unit12including a phosphor filter12aand an excitation filter12b, a collector lens13, and a condenser lens14. The filter unit12is attached to be insertable and removable into and from the base portion2aof the microscope body2such that an excitation filter12bis inserted on an illumination optical path L2in the case of performing the fluorescence observation and a phosphor filter12ais inserted on the illumination optical path L2in the case of performing bright-field observation.

The monochromatic light LED chip11irradiates light having a specific wavelength band within a wavelength range of 380 nm to 495 nm.

The phosphor filter12ais excited by light having the wavelength range of 380 nm to 495 nm irradiated from the monochromatic light LED chip11to emit fluorescence having a longer wavelength relative to the irradiated light. It is possible to use the phosphor filter12aincluding a yellow phosphor or red and green phosphors in the case of using a blue LED as the monochromatic light LED chip11, and to use the phosphor filter12aincluding red, green and blue phosphors in the case of using a purple LED. The monochromatic light LED chip11and the phosphor filter12afunction as the white LED when being combined, and the specimen S is irradiated with white light irradiated from the white LED using the collector lens13and the condenser lens14.

The excitation filter12bextracts excitation light having a predetermined wavelength band from the light having the wavelength of 380 nm to 495 nm that is irradiated from the monochromatic light LED chip11. Only the excitation light having a necessary excitation wavelength irradiated from the monochromatic light LED chip11is transmitted through the excitation filter12band is emitted to the specimen S by the collector lens13and the condenser lens14.

The observation optical system4includes: the objective lens8; the filter holder6including the absorption filter6a; a lens barrel15in which a relay lens and a tube lens (not illustrated) are built; and an eyepiece16.

The absorption filter6aselectively takes fluorescence having a specific wavelength from the fluorescence emitted from the specimen S at the time of fluorescence observation. The filter holder6is mounted to be insertable and removable into and from the intermediate lens-barrel7such that the absorption filter6ais inserted and positioned on the observation optical path L1in the case of performing the fluorescence observation and the absorption filter6ais removed from the observation optical path L1in the case of performing the bright-field observation.

The bright-field observation is performed by irradiating the specimen S with the white light using the optical system for bright-field observation, that is, the monochromatic light LED chip11, the phosphor filter12a, the collector lens13, and the condenser lens14, and visually observing white light transmitted through the specimen S among the irradiated white light through the objective lens8, a relay lens and a tube lens (not illustrated), and the eyepiece16.

On the other hand, the fluorescence observation is performed by irradiating the specimen S with excitation light using the optical system for fluorescence observation, that is, the monochromatic light LED chip11, the excitation filter12b, the collector lens13, and the condenser lens14, and visually observing the fluorescence excited by the excitation light through the objective lens8, the absorption filter6a, the relay lens and the tube lens (not illustrated), and the eyepiece16.

In the upright microscope1according to the embodiment of the disclosure, it is possible to perform the bright-field observation and the fluorescence observation with the single illumination optical system3by inserting and removing the filter unit12and the filter holder6, and it is possible to perform the fluorescence observation without noise regardless of a type of the white LED to be used.

Incidentally, the filter unit12including the phosphor filter12aand the excitation filter12bis used in the above-described embodiment. However, it is also possible to configure a filter unit including only the phosphor filter12asuch that the phosphor filter12ais inserted on the illumination optical path L2at the time of bright-field observation and the phosphor filter12ais removed from the illumination optical path L2at the time of fluorescence observation. In addition, the filter holder6including the absorption filter6amay be configured to remain inserted on the observation optical path L1even at the time of bright-field observation without being configured to be removable.

Further, the filter unit12including the phosphor filter12aand the single excitation filter12bis used in the above-described embodiment. However, it is also possible to use a filter unit including a phosphor filter and two excitation filters that extract excitation light having different wavelengths.

Further, the description has been given regarding the upright microscope including the single transmitted-light illumination optical system in the above-described embodiment. However, the disclosure may be provided with an epi-illumination optical system that includes a monochromatic light LED chip and a phosphor filter which is insertable and removable on and from an illumination optical path and is excited by light having a specific wavelength band irradiated from the monochromatic light LED chip to emit fluorescence having a longer wavelength relative to the irradiated light. In addition, an inverted microscope provided with a single transmitted-light illumination optical system or a single epi-illumination optical system having the same configuration also can perform the bright-field observation and the fluorescence observation with the single illumination optical system, and can perform the fluorescence observation without noise regardless of the type of the white LED to be used.

The microscope of the disclosure is advantageous in clinical tests in which bright-field observation and fluorescence observation are switched to observe one specimen, for example, positive and negative diagnosis on tubercle bacillus, malaria, and the like using multiple staining solution, an asbestos test, and the like.

According to the disclosure, it is possible to perform fluorescence observation and bright-field observation with a single illumination optical system and to perform the fluorescence observation without noise regardless of a type of a white LED to be used. In addition, since it is possible to perform the fluorescence observation and the bright-field observation with the single illumination optical system, it is possible to provide a microscope with excellent cost performance.