JPH03196000A - Beam splitter for soft x-ray - Google Patents

Abstract

PURPOSE:To enable splitting a soft X-ray beam in at least two directions, a strong reflected X-ray and a transmitted X-ray, on the whole, by forming a multi-layered film containing a Be or Al thin film of a specific thickness, on a metal mesh of a pitch through which the soft X-rays can pass. CONSTITUTION:On a metal mesh 1 of a pitch through which a soft X-ray can pass, a Be or A thin film 2 of 1000Angstrom to 1 mum thick, is formed. Moreover, on the thin film 2, a multilayer film 5 two kinds of materials 3 and 4 of which refraction indices differ one another, is formed. As materials 3 and 4, materials one of which complex refraction index is high and the other is low, are selected, and also it is much preferable that the difference of the two complex refraction indices is great, and those absorption factors are low. For example, as the material 3, one of Mo, W, Au, Pt, Rh and so on, is used, and as the material 4, one of C, Si, Be, Al and so on, is used. The soft X-rays is intensified by reflected X-rays from each layer of the multilayered film 5 and interference is induced and thereby a strong reflected X-ray can be obtained, on the whole, and, at the same time, transmitted X-rays which pass through the multilayered film 5 penetrate furthermore the thin film 2 and thereby the transmitted X-rays can be obtained. Consequently, the soft X-ray beam can be splitted in at least two directions.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) This invention is used as an optical system for soft X-rays such as X-ray phosphorography, X-ray microscopes, synchrotron radiation spectroscopy, and X-ray lasers. The present invention relates to a soft X-ray beam splitter.

(Prior Art) The following are conventionally known beam splitters that split light into two or more directions.

a. A semi-transparent mirror that has appropriate transmittance and reflectance by depositing a thin film of metal or the like on a transparent substrate such as glass. (Applicable to visible light)b.Things that utilize the transmission/reflection properties of polyethylene sheets, metal mesh, etc. (targets far infrared rays) c. A semi-transparent mirror that utilizes total internal reflection, consisting of two right-angled prisms facing each other with a slight distance between them.

However, the beam splitter mentioned above has a wavelength of several orders of magnitude Å~
In the soft X-ray region of one person, the reflectance of any material when incident perpendicularly becomes almost zero.
All wavelengths can only be applied to wavelengths from laser light to visible light.

In addition, high reflectivity optical elements that reflect soft X-rays, which target light with a wavelength of several angstroms to one person, are called soft X-rays.
For example, Japanese Patent Application Laid-Open No. 62-297800 is known. This includes a first layer containing one or more of the metals of platinum;
A second compound containing one or more elements among e, B, C and SL
layers are laminated alternately, and is characterized by a high reflectance even for X-rays with a wavelength of 80 to 120 people.

(Problems to be Solved by the Invention) However, since the above-described high reflectance optical element is a multilayer film laminated on a thick substrate, even if high reflectance is obtained, transmittance cannot be obtained.

This invention was made with attention to the above-mentioned circumstances, and its purpose is to target human light with a wavelength of 1 to 100 yen, and to split this soft X-ray into two or more. The object of the present invention is to provide a beam splitter for soft X-rays that can be used.

[Structure of the invention]

(Means and effects for solving the problem) In order to achieve the above object, the present invention forms a thin film of Be or AI with a thickness of 1000 Å to 1 μm on a metal mesh with intervals that allow soft X-rays to pass through. , is characterized in that a multilayer film made of two types of substances with mutually different refractive indexes is formed on this thin film.

When soft X-rays are incident on the beam splitter, the reflections Xwa from each layer of the multilayer film constructively interfere with each other, resulting in strong reflected X-rays as a whole. At the same time, the X-rays that have passed through the multilayer film also pass through the Be or Al thin film, yielding transmitted X-rays, and the soft X-rays can be split into at least two directions.

(Example) Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 shows a cross section of the beam splitter, and FIG. 2 shows the entire beam splitter. As shown in FIG.
A thin film 2 of Be or l of μm is formed. Further, on this thin film 2, two types of substances having mutually different refractive indexes, that is, a first substance 3... and a second substance 4... are laminated to form a multilayer film 5.

The first substance 3 and the second substance 4 are selected to have a high complex refractive index and a low complex refractive index for soft X-rays so that the refractive index is different, and the difference is large and the absorption rate is low. For example, the first substance 3 is (Mo, W, Au
, P t, Rh), and the second substance 4 is (C, St,
Be, AN), etc.

The thickness of each of the layers may be alternately the same or the thickness may be changed, but the phenomenon of amplitude due to absorption of soft X-rays in each layer and reflection at the interface of each layer In consideration of both the reinforcement due to the overlapping of the phases of xIjl, it is desirable to set the thickness such that the overall reflectance in the multilayer film is the highest with a small number of layers and a thin film thickness. However, when forming a layer of different materials, interfacial diffusion occurs, so the thickness of one layer is preferably at least IOλ or more.

On the other hand, the reflectance theoretically increases as the number of layers increases, but
Transmittance must be considered at the same time as reflectance of the multilayer film.

Although reflectance and transmittance are contradictory, in order to satisfy both conditions of high reflectance and high transmittance, the number of laminated layers of the multilayer film 5 is desirably from several layers to several tens at most. Furthermore, Be or A
A thin film having a thickness of approximately 1000 Å to 1 μm is formed using II. The film formed on the metal mesh 1 is preferably a material with high X-ray transmittance. Furthermore, forming a thin film on the metal mesh 1 is effective in compensating for this drawback, since even if the Be or AI film and the multilayer film 5 are combined, the film thickness is extremely thin and cannot stand as a single unit.

The multilayer film 5 made of the Be film or the /l film and two types of substances is formed by a vacuum evaporation method, a snow ivy method, or the like. That is, the Be film or the l film is first deposited on the metal mesh 1. 2 is formed into a film, and then two types of substances are formed into a multilayer film alternately while controlling the film thickness with high precision.

When soft X@L is incident on the beam splitter configured as described above, the reflected X-rays from each layer of the multilayer film 5 constructively interfere with each other, resulting in a strong overall effect (1 reflection X@L,
is obtained. At the same time, the transmitted X-rays that have passed through the multilayer film 5 are further transmitted through the thin film of Be or AII to obtain transmitted X-rays L2, and the soft X and IL can be divided into at least two directions.

Note that the beam splitter configured as described above can also be used as a filter that reflects only a specific wavelength and transmits other wavelengths by appropriately setting the thickness of each layer of the multilayer film. That is, the multilayer film and Be layer or A1
If X-ray absorption within the layer or scattering at the interface is ignored, filter-like characteristics are obtained as shown in FIGS. 3 and 4. In addition, in FIG. 3 and FIG. 4, the solid line is the reflectance, and the broken line is the transmittance.

[Effects of the Invention] As explained above, according to the present invention, the reflected X-rays from each layer of the multilayer film constructively interfere with each other to obtain strong reflected X-rays as a whole, and at the same time, the multilayer film The transmitted X-rays further pass through the Be or Afi thin film to obtain transmitted X-rays, and the soft X-rays can be split into at least two directions. Therefore, the beam splitter required for the interference effect of soft X-rays having a shorter wavelength has the effect that a great leap forward can be expected in improving the illumination precision and resolution of the interferometer.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a beam splitter showing an embodiment of the present invention, Fig. 2 is a side view of the beam splitter, Fig. 3 is a characteristic diagram of a wideband filter, and Fig. 4 is a characteristic diagram of a narrowband filter. be. DESCRIPTION OF SYMBOLS 1... Metal mesh, 2... Thin film, 3... First substance, 4... Second substance, 5... Multilayer film.

Claims (1)

[Claims] 10 mm thick on a metal mesh with intervals that allow soft X-rays to pass through.
A beam splitter for soft X-rays, characterized in that a thin film of Be or Al with a thickness of 00 Å to 1 μm is formed, and a multilayer film made of two types of substances having mutually different refractive indexes is formed on this thin film.