Patent Description:
A vessel not loaded with cargo sails while being loaded with ballast water to make it stable, and discharges the ballast water in a sea area where cargo is loaded onto the vessel.

Ballast water is usually discharged in a sea area different from a sea area where the ballast water has been loaded. Therefore, microorganisms, such as plankton and bacteria, contained in the ballast water are carried to a sea area other than the native habitat of the microorganisms, and thus may damage the ecosystem.

To address such a problem, an international rule about the regulation of ballast water has been established. Specifically, the "International Convention for the Control and Management of Ships' Ballast Water and Sediments (Ballast Water Management Convention)" has been enacted and has entered into force.

In "Guidelines for ballast water sampling (G2)" related to the aforementioned Ballast Water Management Convention, "Ballast Water Performance Standard (D-<NUM>)" specifies the allowable limits for the number of live microorganisms contained in ballast water discharged from vessels based on the minimum size (i.e., minimum diameter) of the microorganisms. For example, the standard specifies that vessels shall discharge less than <NUM> organisms/m<NUM> regarding organisms with a minimum size (i.e., minimum diameter) of <NUM> or greater (hereinafter referred to as "L-size organisms") and less than <NUM> organisms/ml regarding microorganisms with a minimum size (i.e., minimum diameter) of <NUM> or greater and less than <NUM> (hereinafter referred to as "S-size organisms").

As a method for confirming if the aforementioned discharge standard is met during the discharge of the ballast water, there is known a method of passing sea water, which has been pumped with a conveying pump, through a flow cell and performing measurement based on an image (for example, Patent Literature <NUM>). As another means, there is also known a method of passing sea water, which has been pumped with a conveying pump, through a filter unit including filters with different apertures, and causing microorganisms on the filters to emit light, and then counting the number of the microorganisms (for example, Patent Literature <NUM>). As further another means, there is also known a microorganism inspection apparatus for inspecting the number of microorganisms using a batch-type measurement cell (for example, Patent Literature <NUM>).

A microorganism inspection apparatus described in Patent Literature <NUM> above includes a staining unit for staining organisms having live cells existing in a flowing liquid specimen, a concentration unit for increasing the concentration of the organisms in the flow of a stained specimen, an individual measuring unit for acquiring image information on the individuals containing the organisms in the concentrated specimen, and a control unit for measuring the organisms based on the image information on the individuals output from the individual measuring unit.

Accordingly, it is possible to perform flow cytometry inclusive of the step of staining organisms in a liquid specimen, the step of increasing the concentration of the organisms in the liquid, and the step of acquiring information on the organisms in the liquid, for example. Therefore, in comparison with a method of performing each step through a batch process, it is possible to significantly reduce the standby time for part of a specimen, which has undergone one step, to proceed to a next step, or set the standby time to zero, and thus acquire stable information about whether the organisms are alive or dead in the sense that degradation of the organisms in the stained state during the standby time can be prevented.

In addition, a microorganism inspection apparatus described in Patent Literature <NUM> above includes a step of passing sea water through a filter unit in which three types of filters with different apertures are arranged in series, a step of causing live microorganisms trapped by the filters to exhibit a color, emit light, or emit fluorescence, and a step of detecting one of the exhibited color, emitted light, and emitted fluorescence, and performing image analysis to count the number of microorganisms in the ballast water or the sea water.

Accordingly, it is possible to trap microorganisms of each size in stages, and thus quickly measure if the standard regulating the allowable residual microorganisms of each size is met.

Further, a microorganism inspection apparatus described in Patent Literature <NUM> above is adapted to add a sample and a fluorescent staining reagent into a batch-type sample container formed of a light-transmitting material, and stir and mix the sample solution, and then irradiate the sample solution with a light beam from a light source so as to calculate the number of microorganisms contained in a sample of the sample solution.

A microorganism inspection apparatus of Patent Literature <NUM> has a sample container for holding a sample and a fluorescent staining reagent, a stirring and mixing means, an excitation light source and a light receiving means.

Accordingly, it is possible to easily detect and measure the number of microorganisms in ballast water in a short time with high accuracy.

The microorganism inspection apparatus described in Patent Literature <NUM> is adapted to sequentially pass sea water, which has been pumped with a conveying pump, through each step. Thus, the apparatus is large and the production cost may become high. In addition, although the sea water is sequentially passed through each step to shorten the standby time, it may take at least several hours to complete the measurement.

The microorganism inspection apparatus described in Patent Literature <NUM> is also adapted to sequentially pass sea water, which has been pumped with a conveying pump, through each step as with the technique described in Patent Literature <NUM>. Thus, the apparatus is large and the production cost may become high.

In the microorganism inspection apparatus described in Patent Literature <NUM>, a light-receiving unit is provided such that its light-receiving surface is arranged at an angle perpendicular to an excitation light beam. Thus, a number of optical components, such as a means for converting a light beam into a collimated light beam, a relay lens, a slit, and a condensing lens, are used. In addition, since a light source unit is provided on the lateral face side of the sample container, and the light-receiving unit is provided on the front face side or the rear face side of the sample container, the area for disposing the light source unit and the light-receiving unit as seen in plan view is large, which may result in a large body of the inspection apparatus.

It is a technical object of the present invention to provide a microorganism inspection apparatus with a reduced number of components and a reduced production cost, and also with a reduced size, and in which irradiation unevenness of an excitation light beam from a light source unit can be suppressed and thus inspection accuracy can be improved.

To solve the aforementioned problems, the present invention provides as a technical means a microorganism inspection apparatus for measuring the number of microorganisms in a sample as set out in the appended set of claims.

In addition, the excitation light source may be arranged above or below the sample container. Further, a reflective member may be provided in the sample container, the excitation light source may be arranged on a lateral side of the sample container, and an excitation light beam emitted from the excitation light source may irradiate the irradiation plane in the vertical direction by being reflected by the reflective member.

In addition, the microorganism inspection apparatus may further include an optical guide bar between the excitation light source and the irradiation plane.

Further, the microorganism inspection apparatus may further include a shielding plate on a side opposite to the excitation light source across the irradiation plane.

Accordingly, in comparison with an apparatus that performs measurement by leaving a sample solution to stand without stirring it, it is possible to allow microorganisms to emit bright light in an extremely short time and thus easily measure the number of microorganisms in ballast water in a short time. In addition, since the apparatus of the present invention uses a batch-type sample container, the size of the apparatus can be reduced, and the production cost can also be reduced. Further, since the number of optical members and the like can be reduced in comparison with that of the conventional art, the size of the apparatus can be further reduced, and the production cost can be further reduced. Furthermore, since excitation light beam irradiation is performed in a direction perpendicular to the water flow of the sample solution, the influence of the water flow can be reduced, and detection accuracy can be improved with suppressed irradiation unevenness.

In addition, since the excitation light source is arranged above or below the sample container, it is possible to reduce the number of members arranged around the sample container and the measurement unit as seen in plan view, and thus reduce the size of the apparatus and reduce the production cost.

Further, since the excitation light source is arranged on the lateral side of the sample container, the flexibility of the arrangement of the excitation light source can be increased. Furthermore, since excitation light beam irradiation is performed in a direction perpendicular to the water flow of the sample solution, the influence of the water flow can be reduced, and detection accuracy can be improved with suppressed irradiation unevenness.

In addition, since the optical guide bar is provided between the excitation light source and the irradiation plane, it is possible to allow an excitation light beam from the excitation light source to reliably irradiate the irradiation plane, and thus further improve detection accuracy.

Further, even when a lid and the like are not provided, it is possible to perform measurement without the operator feeling dazzling. Furthermore, the measurement range of microorganisms, including its vicinity, can be reliably irradiated with an excitation light beam.

According to the present invention, it is possible to reduce the number of components and reduce the production cost, and also reduce the size of an inspection apparatus, and further suppress irradiation unevenness of an excitation light beam from a light source unit, and thus improve inspection accuracy.

To describe the characteristics of the invention of the present application, a summary of conventional art described in Patent Literature <NUM> will be described first. <FIG> is a schematic planar cross-sectional view of a measurement unit of the conventional art.

An inspection apparatus of the conventional art includes a batch-type sample container <NUM> formed of a light-transmitting, transparent material (for example, glass, quartz, or acrylic resin), and a measurement unit <NUM> that optically counts the number of microorganisms in the sample container <NUM>. The sample container <NUM> includes a rotor <NUM> to stir a sample solution S in the sample container <NUM>. The rotor <NUM> is configured to be rotationally driven by a stirrer provided in a body (not illustrated).

The inspection apparatus illustrated in <FIG> is formed such that it has a width of <NUM>, a depth of <NUM>, a height of <NUM>, and a weight in the range of about <NUM> to <NUM>. Therefore, the inspection apparatus can be carried around while being put in a handheld trunk or a backpack (not illustrated), for example, and thus can perform measurement on a vessel or outside.

In addition, the batch-type sample container <NUM> formed of a light-transmitting, transparent material is formed in the shape of a prism having a bottom face with a size of <NUM> × <NUM> and a height of <NUM>, and has an internal volume set to <NUM> (milliliter) when the water level in the container is <NUM>. The shape of the sample container <NUM> is not limited to such a prism shape, and may be a cylindrical shape or a cubic shape as long as an internal volume of about <NUM> (milliliter) can be secured.

The measurement unit <NUM> includes a sample container housing unit <NUM> that houses and holds the sample container <NUM>, a light source unit <NUM> that emits an excitation light beam toward the sample container <NUM>, and a light-receiving unit <NUM> for observing microorganisms stained by a luminescence reagent and floating in the sample container <NUM> with the excitation light beam emitted from the light source unit <NUM>. The light-receiving unit <NUM> is electrically connected to a CPU (not illustrated) that counts the number of microorganisms in the sample solution S and performs an information processing operation or a statistical processing operation on the measurement results, for example.

The sample container housing unit <NUM> is formed with holding plates 108a and 108b surrounding at least two faces of the sample container <NUM>, and houses and holds the sample container <NUM> so as not to block a light beam emitted from the light source unit <NUM>.

In addition, as illustrated in <FIG>, the light source unit <NUM> is arranged so as to allow an excitation light beam to become incident on an irradiation plane G of the sample container <NUM> in the direction of the normal P to the irradiation plane G. The light source unit <NUM> includes an LED light source <NUM> arranged in the vicinity of the sample container housing unit <NUM>, a means <NUM> for converting a light beam into a collimated light beam, arranged on the front face side of the LED light source <NUM> and adapted to convert a diffused light beam into a collimated light beam, and an excitation filter <NUM> that irradiates the sample container <NUM> with an excitation light beam of a slit-collimated light beam.

<FIG> are schematic cross-sectional views each illustrating an embodiment of the means <NUM> for converting a light beam into a collimated light beam. In the example illustrated in <FIG>, a flat plate <NUM> with a predetermined thickness, which has a thread cutting hole <NUM> with a predetermined diameter drilled therein, is formed as the means <NUM> for converting a light beam into a collimated light beam, and the thickness L of the flat plate <NUM> and the diameter of the thread cutting hole are appropriately set in accordance with the optical path length. This allows a scattered light beam with an incidence angle θ emitted from the LED light source <NUM> to be converted into a collimated light beam while passing through the thread cutting hole <NUM>. In the example illustrated in <FIG>, the optimum conditions for θ and L are determined through a test of the SN ratio, and for example, provided that the thread cutting hole <NUM> has a size of M3 (the outside diameter of the threaded hole) × <NUM> (pitch), the optimum conditions are θ of <NUM>° and L of <NUM>.

The means <NUM> for converting a light beam into a collimated light beam illustrated in <FIG> is the LED light source <NUM> with a front face provided with a convex lens <NUM>. A scattered light beam emitted from the LED light source <NUM> is converted into a collimated light beam when output to the outside through the convex lens <NUM>.

The light-receiving unit <NUM> is provided such that its light-receiving surface F is arranged at an angle perpendicular to an excitation light beam in the direction of the normal P from the light source unit <NUM>. The light-receiving unit <NUM> includes a detector <NUM> arranged and configured to receive fluorescence along an optical axis perpendicular to an excitation light beam emitted from the LED light source <NUM> toward the sample container <NUM>, a light-receiving filter <NUM> arranged on the front face side of the detector <NUM>, a condensing lens <NUM> arranged on the front face side of the light-receiving filter <NUM>, a slit <NUM> arranged on the front face side of the condensing lens <NUM>, and a relay lens <NUM> arranged in the gap between the slit <NUM> and the sample container <NUM> and adapted to excite a fluorescent material contained in microorganisms and collect the resulting fluorescence emission to form an image.

In such an inspection apparatus, since the rotor <NUM> rotates on the bottom face of the sample container <NUM> as illustrated in <FIG>, the sample solution S basically rotates in the direction along the plane of the bottom face. Usually, the measurement range is set vertically long in the vertical direction so as to allow for efficient detection of the number of microorganisms based on the direction of rotation of the sample solution S.

<FIG> is a view illustrating a detection method performed with the conventional inspection apparatus. A measurement range <NUM> is set vertically long to specifically allow for the detection of fluorescence emitted from organisms and passing through a region with a height of <NUM> and a width of <NUM>. Due to such a configuration, LED light sources <NUM> are arranged at three points in the conventional inspection apparatus to cover the entire measurement range <NUM> with a height of <NUM>. To detect a light beam from an intended observation point among light beams from the three points, the light-receiving unit includes optical components, such as the condensing lens <NUM>, the slit <NUM>, and the relay lens <NUM>. Therefore, in the conventional art, it is necessary to dispose the light source unit <NUM> and a number of optical components as the light-receiving unit <NUM> around the sample container <NUM>, which may result in an increased overall size of the inspection apparatus.

In view of the foregoing, an embodiment of the present invention will be described hereinafter. <FIG> is a perspective view illustrating the entire microorganism inspection apparatus according to an embodiment of the present invention.

An inspection apparatus <NUM> of the present embodiment includes a body unit <NUM> that incorporates a control mechanism, such as a CPU board, and performs an operation of processing measurement results, for example, an operation unit <NUM> that is arranged next to the body unit <NUM> and includes operation buttons, for example, and a display unit <NUM> for displaying the measurement results, for example. The display unit <NUM> includes a liquid crystal panel, for example. The operation unit <NUM> includes a power button 3a, a measurement start button 3b, an external output button 3c, and a setting button 3d. Pressing the power button 3a can control the on/off switching, and pressing the measurement start button 3b can start measurement. In addition, pressing the external output button 3c can transfer data to an external printer or personal computer, and pressing the setting button 3d can switch the type of measurement, such as the setting of the size of microorganisms as a measurement target, change the setting of a threshold, and change the setting of the measurement time.

The body unit <NUM> includes a measurement unit <NUM>. The measurement unit <NUM> houses a batch-type sample container <NUM> and optically counts the number of microorganisms in a sample solution S in the sample container <NUM>. The sample container <NUM> is formed of a transparent material, such as glass, quartz, or acrylic resin, for example, and thus is configured to transmit light. The sample container <NUM> houses a rotor <NUM>, and the rotor <NUM> stirs the sample solution S. The rotor <NUM> is housed in the sample container <NUM> together with the sample solution S and a luminescence reagent, and is closed with a lid <NUM>. In addition, the rotor <NUM> is configured to be, when the sample container <NUM> is housed in the measurement unit <NUM>, rotationally driven by a stirrer <NUM> incorporated in the measurement unit <NUM>.

The inspection apparatus <NUM> illustrated in <FIG> is dimensioned such that it can be carried around while being put in a handheld trunk, for example. Therefore, it is possible to perform measurement on a vessel or outside by carrying around the inspection apparatus.

The sample container <NUM> is formed in the shape of a prism having a bottom face with a size of <NUM> × <NUM> and a height of <NUM>, and has a volume set to about <NUM> when the water level in the container is <NUM>. Although the sample container <NUM> is formed in the shape of a prism in the present embodiment, the sample container <NUM> may have other shapes, such as a cylindrical shape. In such a case, however, the sample container <NUM> is desirably dimensioned to be able to secure a volume of about <NUM> to facilitate measurement.

Further, the electrical control configuration of the inspection apparatus <NUM> of the present embodiment will be described based on <FIG>. A CPU board <NUM>, which is supplied with power from an AC power supply <NUM> or a secondary battery <NUM>, is arranged in the center of a housing <NUM> forming the body unit <NUM>. The CPU board <NUM> analyzes an output signal obtained by converting a light beam into electricity with a detector <NUM>, determines if the luminance is greater than or equal to a given luminance level, counts pulses of a given luminance signal, and controls on/off of an LED light source <NUM>, for example. An AC/DC converter <NUM> is arranged between the AC power supply <NUM> and the CPU board <NUM>.

The CPU board <NUM> has electrically connected thereto the detector <NUM>, the LED light source <NUM>, a RAM <NUM> as a read/write memory portion, and a ROM <NUM> as a read-only memory portion.

Besides, the CPU board <NUM> has connected thereto the stirrer <NUM>, which rotates the rotor <NUM> with a magnetic force, the display unit <NUM> formed with a liquid crystal panel, for example, a cooling fan <NUM> for control devices, such as the CPU board <NUM>, and an external output terminal <NUM>, such as RS-232C.

Next, the configuration of the measurement unit <NUM> of the present embodiment will be described based on <FIG> is a side view of the measurement unit <NUM> of the present embodiment. The sample solution S and the rotor <NUM> are put in the sample container <NUM>, and the rotor <NUM> can be rotated by the stirrer <NUM> provided in the measurement unit <NUM>. A light source unit <NUM> is provided on the bottom face side of the sample container <NUM>, and an excitation filter <NUM> is provided on the front face side of the LED light source <NUM>, and further, a diaphragm <NUM> is provided on the front face side of the excitation filter <NUM>. As the excitation filter <NUM>, a bandpass filter can be used. The shape of the diaphragm will be described later. The light-receiving unit <NUM> is provided on the lateral face side of the sample container <NUM>, and includes the detector <NUM> and a light-receiving filter <NUM>. As the detector <NUM>, it is possible to use a photomultiplier, for example, that is arranged and configured to receive fluorescence emitted by microorganisms that have been irradiated with a light beam emitted from the light source unit <NUM> toward the sample solution S in the sample container <NUM>. As the color of the LED light source <NUM>, blue is preferably used.

The rotor <NUM> is arranged on the bottom face of the sample container <NUM>. Thus, when the rotor <NUM> is rotated by the stirrer <NUM>, the flow of water is stirred mainly in the horizontal direction along the bottom face. Therefore, although excitation light beam irradiation is performed in a direction parallel with the flow of water in the conventional art, in the present embodiment, excitation light beam irradiation is performed in a direction perpendicular to the flow of water. Therefore, the influence of the flow of water is reduced, and detection of the number of microorganisms can be performed with higher accuracy and with suppressed irradiation unevenness.

<FIG> illustrates exemplary shapes of the diaphragm <NUM>. A diaphragm A has a circular shape, a diaphragm B has a shape with arc-like portions, such as an elliptical shape, an elongated circular shape, or a rounded rectangular shape, a diaphragm C has a square shape, and a diaphragm D has a rectangular shape. Such diaphragms are selectively used according to the intended use.

An excitation light beam excited by the LED light source <NUM> passes through the excitation filter <NUM> so that unwanted wavelengths are filtered out, and then, the beam shape is adjusted by the diaphragm <NUM>. Accordingly, it is possible to reduce variation in the amount of fluorescence emitted by microorganisms depending on the portion through which an excitation light beam passes.

In the present embodiment, the number of optical members on the side of the light source unit <NUM> and the side of the light-receiving unit <NUM> can be reduced in comparison with that of the conventional art, and thus, the optical configuration can be simplified. Specifically, the number of the LED light sources <NUM> can be reduced from <NUM> to <NUM>, and the number of the excitation filters <NUM> can be reduced from <NUM> to <NUM>. The diameter of the LED light source <NUM> can also be reduced to half, specifically, from <NUM> to <NUM>. In addition, the number of pieces of cover glass provided on the excitation filter <NUM> can also be reduced from <NUM> to <NUM>, and the size of the cover glass can also be reduced.

Regarding the light source unit <NUM>, although the LED light source <NUM> is used as a light source, it is possible to use not only the LED light source <NUM> but also a collimated-light-beam LED light source capable of emitting a collimated light beam, a laser light source, or a light bulb as long as a fluorescent material contained in microorganisms can be excited.

Regarding the optical components on the side of the light-receiving unit <NUM>, there is no need to use a relay lens, a slit, or a cylindrical lens provided in the conventional art. In addition, regarding the light-receiving filter <NUM> and the detector <NUM>, a single light-receiving filter <NUM> and a single detector <NUM> may be provided.

In this manner, reducing the number of optical components on the side of the light source unit <NUM> and the side of the light-receiving unit <NUM> to simplify the configuration can reduce the overall size of the apparatus.

Although the sample container <NUM> in the present embodiment is formed in the shape of a prism, the sample container <NUM> may be formed in a cylindrical shape. Further, the sample container <NUM> may also be formed in the shape of a polygonal prism, such as a triangular prism, a pentagonal prism, or a hexagonal prism.

Although an example in which a photomultiplier (PMT) is used as a light-receiving sensor of the light-receiving unit <NUM> has been illustrated, the present invention is not limited thereto, and it is possible to use various photodetectors, such as a silicon photodiode (SiPD) and an avalanche photodiode (APD), that can detect light emission of a fluorescent material contained in microorganisms as with a photomultiplier (PMT).

<FIG> is a flowchart illustrating a measurement flow. A measurement flow of each step will be described based on <FIG>.

The configuration of the measurement unit <NUM> according to another embodiment will be described based on <FIG>. The present embodiment differs from the previous embodiment in that the light source unit <NUM> is arranged above the sample container <NUM>. When light beam irradiation is performed from above as in the present embodiment, the light beam may not travel straight and may not reach the inside of the water due to ruffle generated at the boundary portion between the air and the water surface or due to the difference in refractive index between the air and the water if no measure is taken. Thus, an optical guide bar <NUM> is provided ahead of the diaphragm <NUM> of the light source unit <NUM>, and the optical guide bar <NUM> is arranged in a range including the air and the water. In the present embodiment, the lid <NUM> is preferably provided with a hole for passing the optical guide bar <NUM>. A light beam emitted from the LED light source <NUM> and transmitted through the excitation filter <NUM> and the diaphragm <NUM> passes through the optical guide bar <NUM>, and thus is guided to the vicinity of the measurement unit. The optical guide bar <NUM> is formed of transparent resin, such as acrylic resin, and guides a light beam utilizing internal reflection. Accordingly, the influence between the air and the water can be reduced, and a light beam from the light source unit <NUM> can be guided to the vicinity of the measurement unit for microorganisms. The other configurations of the light source unit <NUM> and the light-receiving unit <NUM> are similar to those of the previous embodiment. Thus, the description thereof is omitted herein.

The configuration of the measurement unit <NUM> according to further another embodiment will be described based on <FIG>. The present embodiment differs from the previous embodiments in that the light source unit <NUM> is arranged on the same side as the light-receiving unit <NUM> that is arranged on the lateral side of the sample container <NUM>. In the present embodiment, a mirror <NUM> is arranged in the sample solution S to allow microorganisms to be irradiated with a light beam from below. Specifically, the direction of a light beam from the light source unit <NUM> is switched to the vertical direction so that the light beam irradiates the microorganisms. The light-receiving unit <NUM> is arranged so as to receive a light beam which the microorganisms emit as fluorescence, which has become incident on the microorganisms in the vertical direction, at an angle perpendicular thereto. The other configurations of the light source unit <NUM> and the light-receiving unit <NUM> are similar to those of the previous embodiments. Thus, the description thereof is omitted herein. Although the mirror <NUM> is used to switch the direction of a light beam in the present embodiment, it is also possible to use other elements, such as a prism <NUM>, to switch the direction of a light beam. In the present embodiment, since the light source unit <NUM> and the light-receiving unit <NUM> are arranged on the same lateral side, the size of the inspection apparatus can be reduced.

The configuration of the measurement unit <NUM> according to still another embodiment will be described based on <FIG>. In the present embodiment, the light source unit <NUM> is arranged on the same side as the light-receiving unit <NUM> that is arranged on the lateral side of the sample container <NUM> as in the previous embodiment. In the present embodiment, the light source unit <NUM> is arranged at a position above the light-receiving unit <NUM>, and a mirror <NUM> is arranged in the sample solution S so as to allow microorganisms to be irradiated with a light beam from above. Specifically, the direction of a light beam from the light source unit <NUM> is switched to the vertical direction so that the light beam irradiates the microorganisms. The light-receiving unit <NUM> is arranged so as to receive a light beam which the microorganisms emit as fluorescence, which has become incident on the microorganisms in the vertical direction, at an angle perpendicular thereto. The other configurations of the light source unit <NUM> and the light-receiving unit <NUM> are similar to those of the previous embodiments. Thus, the description thereof is omitted herein. Although the mirror <NUM> is used to switch the direction of a light beam in the present embodiment, it is also possible to use other elements, such as a prism <NUM>, to switch the direction of a light beam. In the present embodiment, the light source unit <NUM> and the light-receiving unit <NUM> are also arranged on the same lateral side. Thus, the size of the inspection apparatus can be reduced.

<FIG> illustrates the configuration of the measurement unit <NUM> according to yet another embodiment. The present embodiment differs from the other embodiments in the configuration of the light-receiving unit <NUM>. The light-receiving unit <NUM> according to the present embodiment is provided on the lateral face side of the sample container <NUM>, and includes the detector <NUM> and the light-receiving filter <NUM>. A condensing lens <NUM> is arranged on the front face side of the light-receiving filter <NUM>, and a slit <NUM> is arranged on the front face side of the lens <NUM>. In addition, a relay lens <NUM> is arranged between the slit <NUM> and the sample container <NUM>. The relay lens <NUM> has functions of exciting a fluorescent material contained in microorganisms, and collecting the resulting fluorescence emission to form an image.

The slit <NUM> is used to narrow the observation plane in a slit form. Using the slit <NUM> can narrow the light-receiving area of the light-receiving surface and can also narrow the area of the background fluorescence emission that would become noise. This improves the ratio of a signal of the fluorescence emission of microorganisms to the background fluorescence emission, and thus improves detection accuracy for the fluorescence emission of microorganisms.

The configuration of the measurement unit <NUM> according to yet another embodiment will be described based on <FIG>. In the present embodiment, the light source unit <NUM> is arranged below the sample container <NUM> so as to emit an excitation light beam vertically upward, but the present embodiment differs from the previous embodiment in that a light-shielding plate <NUM> is arranged in the vicinity of the water surface. Such a configuration allows a light beam, which has irradiated microorganisms and passed therethrough in the upward direction, to be shielded by the light-shielding plate <NUM>. Thus, even when the lid <NUM> is not provided, it is possible to perform measurement without the operator feeling dazzling. The other configurations of the light source unit <NUM> and the light-receiving unit <NUM> are similar to those of the previous embodiments. Thus, the description thereof is omitted herein.

The configuration of the measurement unit <NUM> according to yet another embodiment will be described based on <FIG>. The present embodiment differs from the previous embodiment in that the optical guide bar <NUM> is provided for excitation light beam irradiation in addition to the light-shielding plate <NUM> provided as in the previous embodiment so that an excitation light beam can be reliably transmitted from the bottom face of the sample container <NUM> to the vicinity of the measurement range of microorganisms. Such a configuration allows a light beam, which has irradiated the microorganisms and passed therethrough in the upward direction, to be shielded by the light-shielding plate <NUM>. Thus, even when the lid <NUM> is not provided, it is possible to perform measurement without the operator feeling dazzling. Further, the measurement range of microorganisms, including its vicinity, can be reliably irradiated with an excitation light beam. The other configurations of the light source unit <NUM> and the light-receiving unit <NUM> are similar to those of the previous embodiments. Thus, the description thereof is omitted herein.

Claim 1:
A microorganism inspection apparatus (<NUM>) for measuring the number of microorganisms in a sample solution, comprising:
a batch-type sample container formed of a light-transmitting material;
stirring/mixing means (<NUM>, <NUM>) for stirring/mixing a sample and a fluorescent staining reagent in the batch-type sample container (<NUM>) to form a sample solution;
an excitation light source (<NUM>) including a light source (<NUM>) that irradiates a horizontal irradiation plane of the sample container (<NUM>) with an excitation light beam in a vertical direction while the sample solution is stirred by the stirring/mixing means;
light-receiving means (<NUM>) arranged on a lateral face side of the sample container (<NUM>), the light-receiving means being configured to detect a fluorescence beam emitted in response to the excitation light beam from the excitation light source (<NUM>); and
control means (<NUM>) for converting the beam detected by the light-receiving means (<NUM>) into an electric signal to detect the number of light emissions, and calculating the number of microorganisms contained in the sample in the sample container (<NUM>) from the number of light emissions, wherein
the stirring/mixing means (<NUM>, <NUM>) and the excitation light source (<NUM>) are arranged such that a direction of the flow of the sample solution due to agitation by the stirring/mixing means and a direction of the irradiation of the excitation light beam from the excitation light source are perpendicular to each other.