Immersion objective lens, fluorometric analyzer, and inverted microscope

An immersion objective lens includes a front lens, a lens frame which supports the front lens, and a liquid preventive frame which is attached around the lens frame. The liquid preventive frame includes a liquid bulb holding wall which holds a liquid supplied onto the front lens. A distal end of the liquid bulb holding wall is located more inner in the front lens in a direction parallel to a center axis of the front lens than a distal end face of the front lens.

This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2004-001201, filed Jan. 6, 2004, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an immersion objective lens. The present invention also relates to an inverted microscope comprising an immersion objective lens, and an optical analyzer including such an inverted microscope.

2. Description of the Related Art

Japanese Pat. Appln. KOKAI Publication No. 5-60981 discloses an immersion objective lens which comprises a recessed liquid holding portion around a front lens. In this immersion objective lens, the liquid holding portion is formed between a lens barrel and an annular waterproof member which is fixed around the lens barrel.

Japanese Pat. Appln. KOKAI Publication No. 7-77657 discloses a liquid immersion device comprising an elastic container which contains a liquid and a holder which holds the elastic container. The holder has an operation hole for pressing the elastic container through it. The liquid immersion device is detachably mounted on a revolver in the same manner as an objective lens.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to an immersion objective lens. An immersion objective lens according to the present invention comprises a front lens, a lens frame which supports the front lens, and a liquid preventive frame which is attached around the lens frame. The liquid preventive frame includes a liquid bulb holding wall which holds a liquid supplied onto the front lens. A distal end of the liquid bulb holding wall is located more inner in the front lens in a direction parallel to a center axis of the front lens than a distal end face of the front lens.

The present invention is also directed to an optical analyzer. An optical analyzer according to the present invention comprises a light source to irradiate a specimen with light, an inverted microscope, a photoelectrical signal converter which converts light obtained by the inverted microscope into an electrical signal, and a data processor which obtains various types of characteristics of the specimen on the basis of the electrical signal which has been converted by the photoelectrical signal converter. The inverted microscope includes an immersion objective lens and a liquid supply device which supplies a liquid onto the immersion objective lens. The immersion objective lens includes a front lens, a lens frame which supports the front lens, and a liquid preventive frame which is attached around the lens frame. The liquid preventive frame includes a liquid bulb holding wall which holds the liquid supplied onto the front lens. A distal end of the liquid bulb holding wall is located more inner in the front lens in a direction parallel to a center axis of the front lens than a distal end face of the front lens.

The present invention is also directed to an inverted microscope. An inverted microscope according to the present invention comprises an immersion objective lens and a liquid supply device which supplies a liquid onto the immersion objective lens. The immersion objective lens includes a front lens, a lens frame which supports the front lens, and a liquid preventive frame which is attached around the lens frame. The liquid preventive frame includes a liquid bulb holding wall which holds the liquid supplied onto the front lens. A distal end of the liquid bulb holding wall is located more inner in the front lens in a direction parallel to a center axis of the front lens than a distal end face of the front lens.

DETAILED DESCRIPTION OF THE INVENTION

First Embodiment

This embodiment is directed to a fluorometric analyzer.FIG. 2schematically shows the arrangement of a fluorometric analyzer according to the first embodiment of the present invention.

As shown inFIG. 2, a fluorometric analyzer10comprises a light source5, an inverted fluorescence microscope1which uses a confocal optical system, a photoelectrical signal converter2which acquires fluorescence emitted by a sample labeled with fluorescence and converts it into an electrical signal, a data processor3which obtains the characteristics of a sample (not shown) on the basis of measurement data obtained by the photoelectrical signal converter2, and a display4which displays the various types of characteristics of the sample obtained by the data processor3. The fluorometric analyzer10also has a controller6(seeFIG. 4) which controls the units described above.

The light source5comprises, e.g., a laser beam generator, although not limited to it. The photoelectrical signal converter2comprises, e.g., a photomultiplier or avalanche diode, although is not limited to them.

The inverted fluorescence microscope1has an immersion objective lens11, a stage13which supports a sample plate12, a liquid supply device14which supplies a liquid to between the immersion objective lens11and sample plate12, a light channel16which guides light generated by the light source5to the immersion objective lens11, and a light channel17which guides light obtained by the immersion objective lens11to the photoelectrical signal converter2.

The liquid supply device14has a supply nozzle19for supplying a liquid to between the sample plate12and immersion objective lens11and a liquid quantity adjusting device20which adjusts the quantity of liquid to be supplied from the supply nozzle19. The supply nozzle19and liquid quantity adjusting device20are in fluid connection with each other.

The sample plate12is supported by the stage13and arranged above the immersion objective lens11. The supply nozzle19for supplying the liquid is arranged near the immersion objective lens11. The liquid to be supplied from the supply nozzle19includes, for example, a solution having the refractive index adjusted by some agent, water, etc., and preferably have appropriate surface tension and do not contain an impurity that scatters light. The sample plate12includes, for example, a plate where the sample is to be placed flat, a microplate which has a plurality of recesses to accommodate samples, etc., and preferably transmits light from the light source5well.

FIG. 1shows a longitudinal section of the immersion objective lens shown inFIG. 2. As shown inFIG. 1, the immersion objective lens11has a front lens31, a lens frame32which supports the front lens31, and a liquid preventive frame33which is attached around the lens frame32. The lens frame32has a curved surface32alike a side surface of a frustum of circular cone which declines in the radial direction. The liquid preventive frame33is for preventing the liquid supplied onto the front lens31from flowing into the details of the immersion objective lens11or into a device under the immersion objective lens11. The liquid preventive frame33has a liquid bulb holding wall35on its inner side (a side closest to the center axis of the lens) and a liquid receiving portion33aon its outer side. An O-ring34is attached between the lens frame32and liquid preventive frame33. The O-ring34prevents the liquid from moving from the gap between the lens frame32and liquid preventive frame33into the details of the immersion objective lens11. The distal end35aof the liquid bulb holding wall35is located in front of an outer circumference of the curved surface32aof the lens frame32, so that an inner side surface of the liquid bulb holding wall35and the curved surface32aof the lens frame32form a recess32b.

As shown inFIG. 3, a distal end35aof the liquid bulb holding wall35is located more inner in the immersion objective lens11in a direction parallel to the center axis of the front lens31than a distal end face31aof the front lens31. In other words, the distal end35aof the liquid bulb holding wall35is located behind the distal end face31aof the front lens31along the center axis of the front lens31. More specifically, when the immersion objective lens11is set so that the front lens31comes to the upper side and the center axis of the front lens31extends in the vertical direction, the distal end35aof the liquid bulb holding wall35is at a position lower than the distal end face31aof the front lens31.

The volume of a liquid bulb36formed by supplying the liquid inside the liquid bulb holding wall35is smaller than that of a liquid bulb36cformed by supplying the liquid inside a liquid bulb holding wall with a distal end35cwhich is located on the same plane as the distal end face31aof the front lens31. Thus, the liquid bulb36is held stably. In other words, the immersion objective lens11can stably hold the liquid bulb36. Particularly, the distal end of the liquid bulb holding wall35is preferably at a position lower than the distal end face31aof the front lens31by 0.5 mm.

Furthermore, it is more preferable if a side surface35bon the inner side of the liquid bulb holding wall35is parallel to the vertical direction. The volume of the liquid bulb36formed by the liquid bulb holding wall35having such a vertical side surface35bis smaller than that of a liquid bulb36dwhich is formed by a liquid bulb holding wall having an inclined side surface35d. Thus, the liquid bulb is held more stably. Namely, such an immersion objective lens11can hold the liquid bulb36stably.

FIG. 4shows the controller6of the fluorometric analyzer10shown inFIG. 2. As shown inFIG. 4, the controller6has a light source, optical system controller7which controls the light source5and the optical systems of the light channels16and17, a stage controller8which controls the movement of the stage13, a liquid supply controller9which controls the liquid supply device14, an objective lens controller28which controls the movement and focusing of the immersion objective lens11, and a central controller29which supplies instructions to the respective controllers7,8,9, and28in accordance with the predetermined operation procedure (seeFIG. 5) of the fluorometric analyzer10.

FIG. 5shows the flow of the operation procedure of the fluorometric analyzer10shown inFIG. 2. The operation procedure of the fluorometric analyzer10will be described with reference toFIG. 5.

When the sample plate12is set on the stage13, the controller6instructs the stage controller8to move the stage13to a predetermined position. In response to the instruction, the stage controller8drives the stage13(step40).

Before measurement, the central controller29instructs the liquid supply controller9to supply the liquid to between the immersion objective lens11and sample plate12. In response to the instruction, the liquid supply controller9drives the liquid quantity adjusting device20to supply a predetermined quantity of liquid inside the liquid bulb holding wall35(step41).

As a result, the liquid bulb36is formed on the immersion objective lens11. The liquid bulb36is stably held by the immersion objective lens11. Thus, the flow can advance to the next step without replenishing or supplying again the liquid inside the liquid bulb holding wall35. When supplying the liquid inside the liquid bulb holding wall35(step41), assume that the liquid is supplied in a larger quantity than the quantity allowed by the liquid bulb holding wall35. The liquid in a quantity that cannot be completely held by the liquid bulb holding wall35may move to the liquid receiving portion33aoutside the liquid bulb holding wall35, but the liquid bulb36with an appropriate quantity is stably formed on the immersion objective lens11. Therefore, the supply quantity of the liquid need not be adjusted strictly, so that the operation of the fluorometric analyzer can be controlled easily.

The central controller29instructs the objective lens controller28to move and focus the immersion objective lens11, and the light source, optical system controller7to supply light. In response to the instruction, the objective lens controller28moves the immersion objective lens11close to the sample plate12(moves it upward on the surface of the sheet of drawing ofFIG. 2) (step42). When the light source, optical system controller7supplies a laser beam to the light source5for a predetermined period of time, the objective lens controller28performs focusing simultaneously (step43).

When moving the immersion objective lens11close to the sample plate12(step42), the liquid is squeezed from the liquid bulb36outside the liquid bulb holding wall35. As the liquid bulb holding wall35stably holds the liquid bulb36, the gap between the immersion objective lens11and a bottom surface18of the sample plate12is kept filled with a sufficient liquid, as shown inFIG. 6.

Therefore, light irradiation to the sample and fluorescence measurement can be performed immediately without replenishing the liquid inside the liquid bulb holding wall35. As the gap between the immersion objective lens11and sample plate12is filled with the liquid, the immersion objective lens11can be focused highly accurately. Thus, the sample can be irradiated at the focal point with light efficiently. As fluorescence that enters the immersion objective lens11is not lost between the immersion objective lens11and sample plate12, the photoelectrical signal converter2can obtain highly accurate fluorescence measurement data.

The central controller29then instructs the data processor3to start data processing. In response to the instruction, the data processor3processes data (step44).

The central controller29then instructs the stage controller8to move the sample plate12to the next measurement position. In response to the instruction, the stage controller8moves the sample plate12in the horizontal direction (step45).

When the sample plate12is to be moved in the horizontal direction, the liquid does not flow out because it is stably held by the liquid bulb holding wall35. Therefore, next optical analysis can be started immediately without replenishing the liquid bulb holding wall35with the liquid.

The central controller29instructs the objective lens controller28to focus the immersion objective lens11again. In response to the instruction, the objective lens controller28performs focusing (step43). Movement of the sample plate12, focusing, and measurement are repeated until measurement at the scheduled position is ended (step46).

When measurement at the scheduled position is ended, the central controller29instructs the objective lens controller28to move the immersion objective lens11away from the sample plate12. In response to the instruction, the objective lens controller28moves the immersion objective lens11away from the sample plate12(to move it downward on the sheet of drawing ofFIG. 2) (step47).

After that, the measured sample plate12is removed from the stage13by the operator.

According to the fluorometric analyzer10of the present embodiment, the liquid bulb36is stably held on the front lens31. Even when the sample plate12is moved in the horizontal direction, the liquid does not flow out from between the immersion objective lens11and sample plate12. Hence, the liquid need not be replenished or supplied again inside the liquid bulb holding wall35, so that optical analysis can be performed quickly. Also, the immersion objective lens11can be focused highly accurately. This enables light irradiation of the sample at the focal point efficiently.

Second Embodiment

This embodiment is directed to another immersion objective lens that can replace the immersion objective lens of the first embodiment.FIG. 7shows a longitudinal sectional view of an immersion objective lens according to the second embodiment of the present invention. InFIG. 7, members that are denoted by the same reference numerals as those of the members shown inFIG. 1are identical members, and a detailed description thereof will be omitted.

As shown inFIG. 7, an immersion objective lens50according to this embodiment has a front lens31, a lens frame32which supports the front lens31, and a liquid preventive frame53which is attached around the lens frame32. Namely, the immersion objective lens50has the liquid preventive frame53in place of the liquid preventive frame33ofFIG. 1. The liquid preventive frame53has a liquid bulb holding wall55on its inner side (a side closer to the center axis of the lens) and a liquid receiving portion53aon its outer side.

A distal end55aof the liquid bulb holding wall55is located more inner in the immersion objective lens50in a direction parallel to the center axis of the front lens31than a distal end face31aof the front lens31. In other words, the distal end55aof the liquid bulb holding wall55is located behind the distal end face31aof the front lens31along the center axis of the front lens31. More specifically, when the immersion objective lens50is set so that the front lens31comes to the upper side and the center axis of the front lens31extends in the vertical direction, the distal end55aof the liquid bulb holding wall55is at a position lower than the distal end face31aof the front lens31.

Furthermore, a side surface55bon the inner side of the liquid bulb holding wall55is located on the outer side of the outermost circumference of the front lens31and on the inner side of the outermost circumference of the lens frame32. Namely, the inner diameter of the side surface55bis larger than the diameter of the front lens31and smaller than the diameter of the outermost circumference of the lens frame32.

The volume of a liquid bulb formed by supplying the liquid inside the liquid bulb holding wall55is smaller than that of, e.g., a liquid bulb formed by supplying the liquid inside the liquid bulb holding wall35the side surface35bof which is located on the outer side of the outermost circumference of the lens frame32, as shown inFIG. 3. Thus, the immersion objective lens50according to this embodiment can hold the liquid bulb more stably.

Third Embodiment

This embodiment is directed to another immersion objective lens that can replace the immersion objective lens of the first embodiment.FIG. 8shows a longitudinal section of an immersion objective lens according to the third embodiment of the present invention.

As shown inFIG. 8, an immersion objective lens60according to this embodiment has a front lens31, a lens frame62which supports the front lens31, and a liquid preventive frame63which is attached around the lens frame32. A distal end62aof the lens frame62is perpendicular to the center axis of the front lens31, that is, the distal end62aforms a flat surface. The liquid preventive frame63has a liquid bulb holding wall65on its inner side (a side closer to the center axis of the lens) and a liquid receiving portion63aon its outer side.

The liquid bulb holding wall65is located in front of a distal end62aof the lens frame62along the center axis of the front lens31. A side surface65bon the inner side of the liquid bulb holding wall65is located on the outer side of the outermost circumference of the front lens31and on the inner side of the outermost circumference of the lens frame32. In other words, the inner diameter of the side surface65bis larger than the diameter of the front lens31and smaller than the diameter of the outermost circumference of the lens frame62.

According to the immersion objective lens60of the present embodiment, a liquid bulb formed by supplying the liquid inside the liquid bulb holding wall65is stably held by the liquid bulb holding wall65. Even when a sample plate12is moved in the horizontal direction, the liquid does not flow out from between the immersion objective lens60and sample plate12.

FIG. 9shows a longitudinal section of an immersion objective lens according to a modification to an embodiment of the present invention.

As shown inFIG. 9, an immersion objective lens70according to this modification has a front lens31, a lens frame72which supports the front lens31, and a liquid preventive wall73which is attached around the lens frame72. A distal end72aof the lens frame72is high on the outer side and lowers toward the front lens31. A liquid bulb holding wall75is located in front of the distal end72aof the lens frame72along the center axis of the front lens31.

A side surface75bon the inner side of the liquid bulb holding wall75is located on the outer side of the outermost circumference of the front lens31and on the inner side of the outermost circumference of the lens frame32. In other words, the inner diameter of the side surface75bis larger than the diameter of the front lens31and smaller than the diameter of the outermost circumference of the lens frame72.

According to the immersion objective lens70of the present modification as well, a liquid bulb formed by supplying the liquid inside the liquid bulb holding wall75is stably held by the liquid bulb holding wall75.

According to these embodiments, the liquid preventive frame63(or liquid preventive wall73) is attached to the lens frame62(or lens frame72) by using the O-ring34. The liquid preventive frame63(or liquid preventive wall73) can be made of a flexible, elastic, and adhesive material such as silicone rubber and be attached to the lens frame62(or lens frame72) without using an O-ring. Such a liquid preventive frame can cope with lens frames having different shapes.

Fourth Embodiment

This embodiment is directed to still another immersion objective lens that can replace the immersion objective lens of the first embodiment.FIG. 10shows a longitudinal section of an immersion objective lens according to the fourth embodiment of the present invention.FIG. 11is a plan view seen from above the immersion objective lens shown inFIG. 10.

As shown inFIG. 10, an immersion objective lens80according to this embodiment has a front lens31, a lens frame32which supports the front lens31, and a liquid preventive frame83which is attached around the lens frame32. Namely, the immersion objective lens80has the liquid preventive frame83in place of the liquid preventive frame33ofFIG. 1.

The liquid preventive frame83has a liquid bulb holding wall85on its inner side (a side closer to the center axis of the lens) and a liquid receiving portion83aon its outer side. A distal end85aof the liquid bulb holding wall85is located more inner in the immersion objective lens80in a direction parallel to the center axis of the front lens31than a distal end face31aof the front lens31to. In other words, the distal end85aof the liquid bulb holding wall85is located behind the distal end face31aof the front lens31along the center axis of the front lens31.

Liquid drain channels83dwhich extend in the vertical direction are formed in the bottom of the liquid receiving portion83a. As shown inFIG. 11, the liquid drain channels83dare formed at three portions at an interval of 120° around the center axis of the front lens31.

As shown inFIGS. 10 and 11, the liquid preventive frame83further has a liquid supply channel83cwhich extends in it. The liquid supply channel83chas a circular channel portion about the center axis of the front lens31as the substantial center, a portion which extends from the circular channel portion and terminates on the outer surface of the liquid preventive frame83, and portions which extend from the circular channel portion and terminate on a side surface85bon the inner side of the liquid bulb holding wall85. Those portions which terminate on the side surface85bon the inner side are formed at three locations at an interval of 120° around the center axis of the front lens31, as shown inFIG. 11.

In the immersion objective lens80according to this embodiment, the liquid supply channel83cis connected to the liquid quantity adjusting device20(seeFIG. 2) through an open end in the outer surface of the liquid preventive frame83. The liquid supplied from the liquid quantity adjusting device20flows inside the liquid bulb holding wall85through the liquid supply channel83c. The liquid flowing inside the liquid bulb holding wall85forms a liquid bulb. The formed liquid bulb is stably held by the liquid bulb holding wall85.

The liquid drain channels83dare connected to a waste pipe (not shown). The liquid overflowing from the liquid bulb holding wall85runs through the liquid drain channels83dand the waste pipe and is discharged outside.

According to this embodiment, in addition to the advantages described in the first embodiment, the following advantages can be obtained. As the liquid is supplied from inside the liquid bulb holding wall85, the liquid bulb can be formed stably. As the liquid drain channels83dextend in a direction perpendicular to the bottom of the liquid receiving portion83a, the liquid does not overflow from the liquid receiving portion83abut can be readily discharged well.

This embodiment may be modified in various manners. For example, the liquid drain channels83dcan be formed to extend through the outer wall of the liquid receiving portion83ahorizontally. A pump for discharging the liquid can be connected to the liquid drain channels83dto discharge the liquid flowing into the liquid receiving portion83aoutside.

The number of open ends of the liquid supply channel83cformed in the side surface85binside the liquid bulb holding wall85can be one. Preferably, the liquid supply channel83chas a plurality of open ends. In this case, the liquid bulb can be formed more stably.

Although the embodiments of the present invention have been described so far with reference to the accompanying drawings, the present invention is not limited to these embodiments. Various changes and modifications may be made without departing from the scope of the present invention.

The embodiments described above exemplify immersion objective lenses which are assumed to be employed in a fluorometric analyzer. However, the immersion objective lenses of the respective embodiments can be employed in another device such as a fluorescence microscope.