Incident-light fluorescent illumination device and fluorescent microscope using the device

1. An incident-light fluorescent illumination device comprising:

a light source emitting illumination light;

a collector lens receiving the illumination light from the light source;

a fly-eye lens optical system receiving the illumination light from the collector lens;

an objective emitting the illumination light to a sample surface; and

a relay optical system arranged between the fly-eye lens optical system and the objective,

wherein:

the fly-eye lens optical system comprises a first fly-eye lens surface and a second fly-eye lens surface each having a plurality of lens elements; and

a conditional expression of

0.3 ≦D 0 /Lob ≦0.75

is satisfied where: D 0 indicates a distance between a conjugate position with the second fly-eye lens surface through the relay optical system and a pupil position of the objective, and Lob indicates a parfocalizing distance of the objective.

2. The device according to claim 1 , wherein:

the first fly-eye lens surface is conjugate with a front focal position of the objective; and

the second fly-eye lens surface is located at a back focal position of the fly-eye lens optical system.

3. The device according to claim 2 , wherein:

the collector lens converts the illumination light into substantially parallel light; and

the relay optical system relays an image S 1 of the light source, formed near the second fly-eye lens surface, to close to the conjugate position with the second fly-eye lens surface.

4. The device according to claim 1 , further comprising a field stop, wherein:

the relay optical system comprises sequentially from the light source side:

a first lens group comprising at least one meniscus lens, and having positive power entirely; and

a second lens group comprising a lens having negative power, and having positive power entirely;

the field stop is arranged between the first lens group and the second lens group and at a conjugate position with the sample surface;

the first lens group comprises a lens having negative power at a position closest to the field stop.

5. The device according to claim 1 , wherein:

the objective is selected from among a plurality of objectives including a first objective having a largest pupil diameter and a second objective having a smallest pupil diameter; and

conditional expressions of

0.6 <E×β/DL< 1.2

1 <DS /(β× P )<3

2 ≦DL/DS≦ 5

are satisfied where:β indicates a projection magnification at which the second fly-eye lens surface is projected onto the conjugate position with the second fly-eye lens surface; DL indicates a pupil diameter of the first objective; DS indicates a pupil diameter of the second objective; P indicates a pitch of the lens element of the second fly-eye lens surface; and E indicates an effective diameter of the second fly-eye lens.

6. The device according to claim 1 , further comprising a switch unit for switching between a first state in which a plurality of images of the light source near the second fly-eye lens surface are formed and a second state in which an image of the light source near the first fly-eye lens surface is formed.

7. The device according to claim 6 , wherein the switch unit changes a distance between the light source and the collector lens.

8. The device according to claim 6 , wherein:

the fly-eye lens optical system comprises sequentially from the light source side:

a first fly-eye lens comprising the first fly-eye lens surface and having positive power; and

a second fly-eye lens comprising the second fly-eye lens surface and having positive power; and

conditional expressions of

1.5 ≦H/P≦ 5

0.5≦2 ×F 2 ×NA 0 /P≦ 1

are satisfied where: H indicates a size of an image of the light source formed near the first fly-eye lens surface in the second state; P indicates a pitch of the lens element of the first fly-eye lens surface, NA 0 indicates a numerical aperture of the illumination light entering the first fly-eye lens surface; and F 2 indicates a focal distance of the second fly-eye lens.

9. A fluorescent microscope comprising the incident-light fluorescent illumination device according to claim 1 .