JPH0786559B2 - Optical element and microscope using the same - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a composite optical element, and more specifically, to a combination of electromagnetic waves of different wavelength ranges, for example, visible light and ultraviolet rays or soft X-rays. The present invention relates to an optical element having an ultraviolet Fresnel zone plate or an X-ray Fresnel zone plate, which makes it easy to grasp the relative positional relationship with respect to electromagnetic waves, and an ultraviolet ray and X-ray microscope using the same.

2. Description of the Related Art An optical element in the ultraviolet ray range of 200 nm or less or in the soft X-ray region when exposed to ultraviolet light has a large absorption in the atmosphere of an electromagnetic wave having a wavelength to be used, and therefore needs to be handled in a vacuum. When handling an optical element in a vacuum, it is necessary to remotely control the alignment with respect to the optical axis of the electromagnetic wave to be used from the atmosphere in some way. In particular, with radiant light that can extract soft X-rays and vacuum ultraviolet rays with good directivity different from divergent light sources such as conventional ultraviolet lamps and X-ray tubes, the divergence angle of the radiation source is small and the area used by the radiation source is small. Since there is no simple monitoring method, when the optical axis of the optical element to be used is largely deviated from the optical axis of the radiation source, it is necessary to break the vacuum and perform realignment by trial and error. As a result, there is a disadvantage that it takes time to draw a vacuum and that the vacuum device is contaminated by breaking the vacuum.

Reflecting mirrors have been used as optical elements in the vacuum ultraviolet and X-ray regions, and Fresnel zone plates are used as optical elements that use the microfabrication technology developed in the semiconductor industry in recent years. It is being used as a child. Fresnel zone plate, radius r _n = (n
λf) ^1/2 (n is a natural number, λ is a wavelength, and f is a focal length) and is composed of a plurality of ring plates [r _n -r _n-1 ]. The characteristic of the condensing image forming element is proportional to the width of the outermost ring zone in terms of resolution. In addition, it is necessary that the plurality of ring zones are transparent or opaque to alternate electromagnetic waves used, and gold, tantalum, or the like is used as a material forming the opaque portion. And 1 μm
As a technique for selectively forming an opaque portion having the following line width, a technique for etching a semiconductor such as gold plating or tantalum is applied.

Actually, soft X-rays and vacuum UV zone plates are often used in vacuum, and in this case as well, the optical axis alignment is performed remotely from the atmosphere, so the operability is extremely poor and a huge amount of time is required for axis alignment. Will be spent.

SUMMARY OF THE INVENTION Therefore, the present invention is to provide an optical element in the ultraviolet ray or X-ray region that enables alignment in vacuum in the atmosphere in advance.

Furthermore, the present invention provides an ultraviolet microscope and an X-ray microscope which enable alignment in the atmosphere.

According to the present invention, a Fresnel zone plate for short wavelength and a Fresnel zone plate for visible light for electromagnetic waves having wavelengths belonging to a wavelength range including a soft X-ray range and an ultraviolet range are provided in the same unit. There is provided an optical element characterized by being juxtaposed with each other.

In the embodiment of the present invention, the short wavelength Fresnel zone plate and the visible light Fresnel zone plate are arranged concentrically, and in a preferred embodiment, the short wavelength Fresnel zone plate is inside the visible lens. The zones are located on the outside and are arranged concentrically. Also, a focal length at the wavelength of the short wavelength Fresnel zone plate,
It is preferable that the visible light Fresnel zone plate has an equal focal length with visible light of a given wavelength.

Further, according to the present invention, an optical system in which a Fresnel zone play for short wavelengths for an electromagnetic wave having a wavelength belonging to a wavelength range including a soft X-ray range and an ultraviolet range and a lens zone for visible light are juxtaposed in the same plane. There is provided a microscope in which an element is arranged in an optical path of an electromagnetic wave of the wavelength and a visible light inserting means for irradiating the optical element with visible light is provided.

Action As described above, when aligning the visible light zone plate with the optical axis of the Fresnel zone plate for short wavelengths for electromagnetic waves of wavelengths belonging to the wavelength range including the soft X-ray range and the ultraviolet range, the relative positional relationship of the visible light zone plate is clarified. By arranging them in parallel with each other, if alignment is performed in advance with a visible light zone plate in the atmosphere, alignment in vacuum becomes unnecessary or easy.

Embodiments Embodiments of an optical element according to the present invention and a microscope using the same will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic view of an optical element according to the present invention. First
In the figure, a region indicated by reference numeral "c" is a Fresnel zone plate for short wavelength for soft X-rays and ultraviolet rays, and a region indicated by reference numeral "d" is a Fresnel zone plate for visible light. . It should be noted that in FIG. 1, the drawing of the entire Fresnel zone ring becomes complicated, so the Fresnel zone plate for short wavelength "c" is drawn only on the inner two, and the Fresnel zone plate for visible light is drawn. "D" depicts only one inside.

It is to be noted that the use of gold, tantalum, or the like is suitable as a means for forming such an optical element. Gold, tantalum, etc. are opaque to soft X-rays and ultraviolet rays as well as visible light, and are actually soft X-rays. It is easy to fabricate an ultraviolet zone plate and a visible light zone plate on the same substrate.

Example 1. A plurality of ring plates [r _n -r _n-1 ] represented by radius r _n = (nλf) ^1/2 (n is a natural number, λ is wavelength, f is focal length) from the optical axis When using a Fresnel zone plate consisting of {n is an even or odd combination, r ₀ = 0}, the center is designed for soft X-rays and the outer periphery is He-Ne as shown in FIG.
Designed for laser light.

Zone X-ray for soft X-rays has a wavelength of 0K (2.33nm)
Assuming the use of, the design parameters of the central zone plate are as follows. The center radius r ₁ = 34.6 μm for the main focal length 513.8 mm, the width of the tenth ring zone is 3.72 μm,
The width of the 100th ring is 1.13 μm and the width of the 160th ring is 0.
It is 896 μm. The radius of the outermost ring zone is 570.6 μm.

A He—Ne laser light zone plate was arranged outside the soft X-ray zone plate. The design parameter of the zone plate for He-Ne laser light is that the radius of the first annular plate is 57
The width of 0.2 μm is 236.2 μm, which is almost equal to the outermost circumference of the zone plate for soft X-rays, the width of the 10th zone plate is 61.6 μm, the width of the 100th zone plate is 26.7 μm and the 500th zone plate. Width is 8.4
μm, and the radius of the outermost ring plate is 16.765 mm.

The zone plate designed in this way was manufactured by using an electron beam drawing method, which is one of the fine pattern forming methods, and a tantalum edging technique, which is a means for selectively forming fine portions. When the He-Ne laser beam expanded to a diameter of 35 mm by a collimator lens system was illuminated in the atmosphere using the prepared zo plate, the He-Ne laser beam from the zone plate surface was condensed by the condensing action of the zone plate arranged at the outer periphery. −Ne
The laser light was focused at a position 513.8 mm away from the laser light propagation direction. Next, when the synchrotron radiation tuned to a wavelength of 2.33 nm was illuminated in a vacuum, it was confirmed that the central zone plate focused light at the same position as in the case of He-Ne laser light.

Example 2 A 1 μm thick Be thin film (sample) having a 0.1 μm pitch grid-like gold pattern (thickness 0.1 μm) at the focal position of the Fresnel zone plate shown in Example 1 was prepared, and FIG. The measurement was carried out by an apparatus as shown in.

A He-Ne laser 3 that emits a laser beam 2 at a right angle to the optical path of the soft X-ray 1 that passes through the vacuum chamber 15 is provided, while it enters the optical path of the soft X-ray 1 and blocks the optical path of the soft X-ray 1. The mirror 4 for irradiating the laser beam instead of the soft X-ray is moved forward and backward by the mirror insertion mechanism 5. Behind the mirror 4, the optical element 8 according to the first embodiment is supported by the moving mechanism 14, the sample 6 is also supported by the moving mechanism 7, and the photodetector 16 is moved by the moving mechanism 17.
It is located supported by. A peep window 11 is provided at the end of the vacuum chamber 15.

First, in a state where the air is not removed from the vacuum chamber 15, that is, in the atmosphere, the mirror 4 is made to enter the optical path of the soft X-ray 1, and the He-Ne laser 2 is used to form a spectral pattern by the edge of the gold pattern of the sample 6. Observe from the peep window 11, He-
It was confirmed that the Ne laser light was focused on the gold pattern. After that, the mirror 4 is retracted and air is evacuated from the vacuum chamber 15 to create a vacuum, and a soft X-ray having the same wavelength as in Example 1 is applied to the sample 6 from the same direction as the He-Ne laser light.
Was irradiated. The sample 6 was moved in the plane by the moving mechanism 7 and the soft X-rays that passed through the sample were measured by the photodetector 16.

As a result, as shown in the graph of FIG. 2, the transmitted X-ray dose with respect to the moving distance of the sample was measured, which shows that the transmitted X-ray intensity is weak in the portion where the gold lattice is present. Thus, by arranging the optical elements that are aligned in the atmosphere in parallel, an X-ray microscope capable of analyzing a fine structure by soft X-rays that does not require an operation to find the focus of soft X-rays on a sample again in vacuum is constructed. it can.

Example 3 A carbon thin film (sample) having a thickness of 0.5 μm and having dot-like “A1” (thickness 500 Å) having a diameter of 5 μm and 0.05 μm was prepared, and measurement was carried out by an apparatus as shown in FIG. .

A He-Ne laser 3 that emits a laser beam 2 at a right angle to the optical path of the soft X-ray 1 that passes through the vacuum chamber 15 is provided, while it enters the optical path of the soft X-ray 1 and blocks the optical path of the soft X-ray 1. The mirror 4 for irradiating the laser beam instead of the soft X-ray is moved forward and backward by the mirror insertion mechanism 5. Up to this configuration
It is similar to the device shown in FIG.

Behind the mirror 4, the sample 6 is supported by the moving mechanism 7, and the optical element 8 according to the first embodiment is also supported by the moving mechanism 14 and positioned. Further, a microchannel plate 9 is arranged in front of the observation window 11 provided at the end of the vacuum chamber 15, and a power supply terminal 10 extends from the microchannel plate 9. A television camera 12 with a lens is arranged outside the peep window 11, and its output is connected to a monitor television 13.

First, in a state where air is not removed from the vacuum chamber 15, that is, in the atmosphere, the mirror 4 is moved forward to irradiate the sample 6 with the He—Ne laser light 2 and the transmitted He—Ne laser light is diffracted to 5 μm. An enlarged image of the image was formed by the Fresnel zone plate 8 of Example 1, photographed by the television camera 12, and observed by the monitor television 13.

Next, while the mirror 4 is retracted, the air in the vacuum chamber 15 is evacuated, and the soft X-ray of the wavelength is changed to He-Ne as in the second embodiment.
Irradiate the sample in the same direction as the laser beam in vacuum and diffracted the soft X-rays that have passed through it to 5 μm and 0.05 μm.
When a magnified image of A1 of m was formed on the Fresnel zone plate, the diameter was 5 on the same image plane as that of He-Ne laser light.
Magnified images of A1 with μm and 0.05 μm were obtained. By using an optical element that can be aligned in the atmosphere as described above, a magnifying X-ray microscope that does not require operations such as soft X-ray focusing and axis alignment in vacuum can be constructed. In this case, as a soft X-ray illuminating method, a brighter image can be obtained by irradiating the sample with X-rays condensed in advance by a zone plate or the like.

As described above, when aligning an optical element for soft X-rays, an optical element that can be aligned with visible light is also provided side by side. Obviously, it is possible to construct an X-ray microscope that does not require or facilitates alignment in vacuum by combining such optical elements. In the embodiment, the central zone plate is designed so that soft X-rays are required. However, by preparing the ultraviolet zone plate in the central portion according to the design formula, the same action as in the case of Example 1-3 can be obtained even with ultraviolet rays. The effect was recognized.

EFFECTS OF THE INVENTION As described above, when an optical element is handled using a light source such as vacuum ultraviolet light or soft X-ray that cannot be directly visually observed and can be handled only in a vacuum, an optical element that can be aligned with visible light is provided in parallel. By doing so, if alignment is performed with visible light in the atmosphere in advance, alignment in a vacuum becomes easy. Therefore, when performing an optical experiment in a vacuum apparatus, there are advantages that work efficiency can be improved and contamination in the apparatus can be prevented.

Further, by combining the optical elements according to the present invention, it is not particularly necessary to perform alignment in a vacuum, and an ultraviolet and soft X-ray microscope having good operability can be constructed.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an optical element according to the present invention having a Fresnel zone plate for soft X-rays in the central portion and a Fresnel zone plate for He-Ne laser in the outer peripheral portion, and FIG. Soft X transmitted through the sample described in
Graph showing line intensity, FIG. 3 is a schematic configuration diagram of a microscope used for measurement in Example 2, and FIG. 4 is a schematic configuration of a microscope used for measurement in Example 3. It is a figure. [Main reference numbers] C ... Fresnel zone plate for soft X-ray d ... Full-nel zone plate for He-Ne laser 1 ... Soft X-ray 2 ... He-Ne laser light 4 ... Mirror, 6 ... Sample 8 …… Complex optical element 12 …… TV camera with lens, 16 …… Photodetector

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideki Maesawa, Room 2, No. 808, Azuma, Sakuramura, Shinji District, Ibaraki Prefecture, No. 1065 Room (72) Inventor, Sadao Aoki, Room No. 306, No. 306, Sakura Village, Shinji District, Ibaraki Prefecture (56) Room (56) Reference Document JP-A-60-66730 (JP, A)

Claims (8)

[Claims] 1. A Fresnel zone plate for short wavelength and a Fresnel zone plate for visible light for electromagnetic waves having wavelengths belonging to a wavelength range consisting of a soft X-ray region and an ultraviolet region are arranged side by side in the same plane. Optical element. 2. The optical element according to claim 1, wherein the Fresnel zone plate for short wavelength and the Fresnel zone plate for visible light are arranged concentrically. 3. The Fresnel zone plate for short wavelengths is located inside and the Fresnel zone plate for visible light is located outside, and is concentrically arranged. Alternatively, the optical element according to the item (2). 4. A focal length of the Fresnel zone plate for short wavelengths at the wavelength and a focal length of the Fresnel zone plate for visible light at visible light of a given wavelength are equal to each other. Range of (1) to (3)
The optical element according to claim 1. 5. An optical element comprising a Fresnel zone plate for short wavelengths for an electromagnetic wave having a wavelength belonging to a wavelength range consisting of a soft X-ray region and an ultraviolet region and a lens zone for visible light arranged side by side in the same plane, A microscope provided in the optical path of an electromagnetic wave of the wavelength and provided with visible light insertion means for irradiating the optical element with visible light. 6. The microscope according to claim 5, wherein the Fresnel zone plate for short wavelength and the Fresnel zone plate for visible light are arranged concentrically. 7. The Fresnel zone plate for visible light is located inside and the Fresnel zone plate for visible light is located outside, and is concentrically arranged. The microscope according to item (6). 8. The focal length of the Fresnel zone plate for short wavelengths at the wavelength is equal to the focal length of the Fresnel zone plate for visible light at visible light of a given wavelength. Range of (5) to (7)
The microscope according to any one of items 1 to 7.