WO1997025644A2

WO1997025644A2 - Near-field light source

Info

Publication number: WO1997025644A2
Application number: PCT/DE1997/000059
Authority: WO
Inventors: Gerhard Müller; Jürgen BEUTHAN
Original assignee: Laser- Und Medizin-Technologie Gmbh, Berlin
Priority date: 1996-01-13
Filing date: 1997-01-10
Publication date: 1997-07-17
Also published as: DE19601109A1; WO1997025644A3

Abstract

The invention concerns a near-field light source, especially for background illumination of a probe (4) in a microscope, with a support member (1) with a hollow channel (2) which essentially runs parallel to the direction of light emission and is at least partly filled with an excitonically active material (3) as well as with a radiation source (6) which is on the observe side from the sample for exciting the excitonically active material (3) to emit light. The support member (1) exhibits a number of contiguous hollow channels (2) which run essentially parallel to the direction of light emission and which are at least partly filled with an excitonically active material (3).

Description

Near field light source

description

The invention relates to a near-field light source, in particular for backlighting a sample in a microscope according to the preamble of claim 1.

It is known in near field microscopy to use ultrathin optical fibers for object illumination which form a point light source, the fibers being able to be moved piezoelectrically in order to illuminate different areas. The disadvantage here is that mechanically moving parts are required.

Furthermore, the so-called nano light source according to Prof. Aaron Lewis is known, which consists of a glass capillary which is conically extended to 50 nm and which is filled with anthracite as exciton-active material, whereby the anthracene is emitted by an argon laser is excited. The small illumination field is disadvantageous here.

The invention is therefore based on the object of creating a near-field light source, in particular for near-field microscopy, which has the largest possible illumination field and has as few moving parts as possible.

Starting from a near-field light source according to the preamble of the claim, the object is achieved by the characterizing features of claim 1.

The invention includes the technical teaching of arranging a large number of near-field light sources next to one another in a grid and to excite the individual near-field light sources together or in succession. The individual near-field light sources each consist of a hollow channel in a carrier element which preferably consists of semiconductor material, the individual hollow channels being at least partially filled with an exciton-active material. The term hollow channel is to be understood here and in the following generally and is not restricted to continuous channels, but also includes cavities in the carrier element. The only decisive factor for the function according to the invention is that exciton-active material can be introduced into the carrier element and the exciton-active material is then accessible for excitation by a laser or electron beam, for which purpose a radiation source is provided which is provided the side of the carrier element facing away from the sample is arranged.

The semiconductor plate preferably consists of a gallium arsenide semiconductor, but it is also possible to implement the near-field light source according to the invention with other semiconductor connections. Anthracene is particularly suitable as exciton-active material in the individual hollow channels, but the use of other excitone-active materials, such as amorphous or porous silicon, is also possible.

In a variant of the invention, the radiation source used to excite the exciton-active material is a laser, the radiation generated by the laser being passed on to the individual near-field light sources by means of an optical fiber bundle. The ends of the individual optical waveguides on the sample side each end in the region of a hollow channel, whereas the ends facing away from the sample are each connected to the laser. To improve the optical coupling of the individual light guides the light guide bundle is preferably tapped in such a way that the distal end is matched in cross section and can be placed on the carrier element. The excitation of the individual near-field light sources can take place jointly for all near-field light sources or sequentially by means of a laser scanner, which couples the light generated one after the other into the individual light guides of the light guide bundle.

In another variant of the invention, on the other hand, the excitation of the individual near-field light sources does not take place optically, but by means of an electron beam. For this purpose, an electron emitter is provided on the side of the carrier element facing away from the sample, a deflection device being arranged between the carrier element and the electron emitter, which deflects the electron beam one after the other at the individual near-field light sources. In one embodiment of this variant of the invention, the deflection device consists of capacitor plates, which are arranged in front of the electron emitter and deflect the electron beam on account of the electrical field existing between the capacitor plates, so that the deflection angle is caused by the electrical voltage to the Capacitor plates can be adjusted. In another embodiment, however, the deflection device has a coil which is arranged in front of the electron emitter and generates a magnetic field, so that the electron beam is deflected due to the Lorenz force.

The arrangement of the near-field light source according to the invention in the beam path of an inverse laser scan microscope is particularly advantageous, the excitation of the individual near-field light sources being effected by the laser. In the preferred embodiment of the invention of the invention, the carrier element also serves to receive the sample and is flat on the sample side so that the sample can be applied directly to the carrier element serving as a slide.

Other advantageous developments of the invention are characterized in the subclaims or are shown in more detail below together with the description of the preferred embodiment of the invention with reference to the figures. Show it:

1 as a preferred exemplary embodiment of the invention, a near-field light source for backlighting in a microscope with an electron beam for excitation of the individual near-field light sources in a perspective view,

FIG. 2 shows another near-field light source according to the invention with a laser and a deflection device for sequential excitation of the individual near-field light sources, likewise in a perspective view,

FIG. 3 shows a near-field light source according to the invention with a laser for excitation of the individual light sources and an optical fiber bundle for the common excitation of the individual near-field light sources and

FIG. 4 shows a cross-section of a near-field light source of one of the above-mentioned exemplary embodiments.

FIG. 1 shows a semiconductor plate 1 made of gallium arsenide as a carrier element for a large number of near-field light sources, which are shown in detail in FIG. For the Taking the individual near-field light sources, the semiconductor plate 1 has a multiplicity of continuous hollow channels 2, which are partially filled with anthracene 3 as exciton-active material. To produce the arrangement shown, a photochemical etching process is first carried out on a solid semiconductor plate 1 using laser-induced electromagnetic surface waves (SEW). In the presence of He / CH ₃ Br as the etching gas, s- or p-polarized UV laser light is emitted onto the semiconductor plate 1 at an angle suitable for imaging via holographic gratings. This results in a large number of depressions in the semiconductor plate 1, which are arranged in a grid shape in the semiconductor plate 1, the grid dimension being 335 nm and the recess depth being 200 nm. This is followed by a plane-parallel micro-grinding of the semiconductor plate 1 from the inverse side until the Atz-trough cut is realized. The trough cut through the plane-parallel micro-grinding is guided into the depth until the hollow channels 2 have formed in the semiconductor plate 1 and the desired aperture has been reached with a diameter trough opening of 100 nm. Anthracene 3 is then introduced into the individual hollow channels 2 as excitone-active material by solvent evaporation. The plane-parallel micro-grinding simultaneously creates an microscopic slide, so that a sample 4 to be examined microscopically can be applied directly to the semiconductor plate.

The individual near-field light sources are excited by an electron beam 5, which is emitted by an electron emitter 6 arranged on the side of the semiconductor plate 1 facing away from the sample. For clarification The electron emitter 6 is shown here on a different imaging scale than the semiconductor plate 1 with the individual near-field light sources. The semiconductor plate 1 thus appears greatly enlarged in relation to the electron emitter 6.

A deflection device is also arranged between the electron emitter 6 and the semiconductor plate 1, which deflects the electron beam 5 sequentially in the direction of the individual near-field light sources. For this purpose, the deflection device has two pairs of capacitor plates 7.1, 7.2, 8.1, 8.2, which each surround the electron beam 5 in pairs and deflect due to the electric field between the capacitor plates 7.1, 7.2, 8.1, 8.2. The deflection angle of the electron beam 5 can therefore be adjusted by the capacitor voltage. The two pairs of capacitor plates 7.1, 7.2, 8.1, 8.2 are oriented differently and are controlled separately in order to be able to deflect the electron beam 5 in different directions.

The light generated by the individual near-field light sources then passes through the sample 4 and is fed via a lens 10, which is only shown schematically, to a detector array 11, which thus takes an image of the sample 4.

FIG. 2 shows a further exemplary embodiment of a near-field light source according to the invention, which largely corresponds to the exemplary embodiment described above, so that — as in the following — for details that are identical in construction and function, are identified by the same reference numerals. Here, the semiconductor plate 1 is - as already shown in FIG. 1 - greatly enlarged compared to the remaining details of the drawing.

In contrast to the exemplary embodiment described above, the individual near-field light sources are excited by a laser beam 12, which is generated by an argon ion laser 13 arranged on the side of the semiconductor plate 1 facing away from the sample. The excitation of the individual near-field light sources by the laser beam 12 also takes place sequentially, in that the laser beam 12 is deflected one after the other by a deflection device in the direction of the individual near-field light sources. The deflection device essentially consists of a mirror 14 which can be adjusted by means of stepper motors, which is arranged in the beam path of the laser 13 and deflects the laser beam 12 onto one of the near-field light sources depending on the position of the mirror 14.

FIG. 3 finally shows a further exemplary embodiment of the invention, in which the excitation of the individual light sources also takes place with a laser 15. The semiconductor board 1 is again the other components

- As shown in Figures 1 and 2 - shows greatly enlarged. In contrast to the exemplary embodiments described above, the excitation of the individual near field light sources does not take place sequentially, but simultaneously. For this purpose, an optical fiber bundle 16 is provided, the individual fibers 16.1 to 16.6 of which each guide the light generated by the laser 15 to one of the near-field light sources.

The embodiment of the invention is not limited to the preferred exemplary embodiments described above. le. Rather, a number of variants are conceivable which make use of the solution shown even in the case of fundamentally different types.

Claims

Expectations

1. Near-field light source, in particular for background illumination of a sample (4) in a microscope, with a carrier element (1) with a hollow channel (2) which runs essentially parallel to the light exit direction and which is at least partially filled with an exciton-active material (3) and a radiation source (6, 13, 15) arranged on the side of the carrier element (1) facing away from the sample for excitation of the exciton-active material (3) for emitting light, characterized in that the carrier element (1) for enlarging the illumination field has a multiplicity of has hollow channels (2) which are arranged next to one another and run essentially parallel to the light exit direction and which are at least partially filled with an exciton-active material (3).

2. Near-field light source according to claim 1, characterized gekenn¬ characterized in that the carrier element (1) is plate-shaped.

3. Near field light source according to claim 1 or 2, characterized in that the carrier element (1) consists of a semiconductor material.

4. Near field light source according to one of the preceding claims, characterized in that the radiation source used to excite the exciton-active material (3)

REPLACEMENT BLAπ (RULE 26) A laser (15) is provided and for forwarding the radiation emitted by the laser (15) to the individual hollow channels (2) one of the hollow channels (2) ends and the ends of the individual light guides (16.1 to 16.6) facing away from the sample face the radiation source (15).

5. Near-field light source according to claim 4, characterized gekenn¬ characterized in that for optical coupling of the optical fiber bundle (16) to the hollow channels (2) em taper coupler

6. Near-field light source according to one of claims 1 to 3, characterized in that the radiation source is em electron beam (6) or em laser (13) and for deflecting the electron beam (5) or the laser beam (12) on the Different hollow channels (2) between the electron emitter (6) or the laser (13) and the support element (1) a deflection device (7.1, 7.2, 8.1, 8.2 or 14) is arranged.

7. Near-field light source according to one of the preceding claims, characterized in that the carrier element (1) for direct application of the sample (4) is at least flat on the sample side.

8. Near field light source according to one of the preceding claims, characterized in that the hollow channels (2) in the carrier element (1) are arranged in the form of a grid with a predetermined grid dimension.

9. Near field light source according to one of the preceding claims, characterized in that the cross section of the individual hollow channels (2) decreases in the light exit direction.

10. Near field light source according to one of the preceding claims, characterized in that the excitone-active material (3) is amorphous or porous silicon or anthracene.

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