JP3138193U - Ultra-high vacuum flange with optical window - Google Patents

Abstract

The present invention provides a flange with a thin optical window for allowing vacuum ultraviolet light using an ultra-high purity material and a thin window material to be incident on an ultra-high vacuum chamber with high efficiency.
Various optical windows containing thin ultra-high purity crystals are attached to an ultra-high vacuum double-sided flange to allow vacuum ultraviolet light to enter the ultra-high vacuum chamber with high efficiency, and a steady pressure difference of 1 atm. As a structure that can withstand sudden pressure changes of 1 atm, the crystal is supported from both sides by a support grid 7 made of a rigid metal or a material having equivalent characteristics, and deformation due to pressure changes is reduced. The material used is a material that is stable to heating and cooling up to 200 ° C.
[Selection] Figure 1

Description

  The present invention relates to a thin flange with an optical window for making vacuum ultraviolet light incident on an ultra-high vacuum chamber with high efficiency.

Conventionally, LiF, CaF ₂ , MgF ₂ , BaF ₂ , SrF ₂ , sapphire, and the like have been used as ultra-high vacuum windows for vacuum ultraviolet light. These windows need to be able to withstand a steady pressure difference of 1 atm because they can be placed between ultra-high vacuum and the atmosphere. In addition, there are many cases where the equipment connected to the ultra-high vacuum chamber through this window is also evacuated. In that case, the window is suddenly damaged by 1 atm due to a vacuum leak on one side, and the window is damaged. There is a possibility that the vacuum leaks. For this reason, when a transmission region having a diameter of several tens of mm is provided, a window material having a thickness of about 4 mm is often used.

  In recent years, the need to use Ar, Kr, and Xe steady-state vacuum ultraviolet light sources with ultra-high energy resolution has increased, but in order to guide these lights into the vacuum with maximum intensity, the above-mentioned flange with an optical window is required. is there. Similarly, as the wavelength of a vacuum ultraviolet laser that can be used in the future approaches the transmission edge wavelength of these optical windows (about 1050 A in the case of LiF), a vacuum optical window having a transmittance as high as possible in that wavelength region is required. I came. However, in the wavelength region near the transmission edge of these crystals, the thickness of the window increases and the available transmitted light intensity decreases drastically.

  The present invention devised a structure in which a thin optical crystal is attached to an ultra-high vacuum flange and has a strength capable of withstanding the above environment in order to achieve high light transmittance. For this purpose, a structure is adopted in which the crystal is supported from both sides by a highly rigid lattice-like metal or a lattice of an equivalent material. The metal support lattice is in close contact with the crystal, and suppresses the crystal from being distorted or vacuum leaked by pressure or heating. The surface of the metal support grid that adheres to the sample is flat, but the part that begins to contact the optical window at the outermost periphery of the metal support grid has a structure that makes a smooth contact with the optical window by providing a certain curvature. Even in this case, the structure is to prevent the pain. In addition, since convergent light is often incident, the width of the grating on the rear side of the light is set so that the light is reflected on the side walls of the grating and spreads in an unexpected direction to become stray light. It is assumed to be smaller than the width of. The central portion is a round hole having a diameter of 5 mm or more so as to allow laser light to pass through, and the region outside the center portion has a structure that provides a transmittance as high as possible by 50% or more. It is desirable that the shadow of the lattice in front of the crystal and the lattice in the rear of the crystal overlap as much as possible.

  As described above, in the ultra-high vacuum thin flanged optical window flange according to the present invention, the crystal thickness can be set to 2 mm or less, 1 mm or 0.5 mm, and the light transmittance of the crystal near the transmission end can be increased. It is useful to set the transmittance for incident light as high as possible even when considering that the shadow of the grating is set to 80% or more.

  The metal support lattice is a material having high rigidity such as stainless steel, a composite material in which copper is bonded to stainless steel, Cr copper, or Be copper, and a material having high thermal conductivity is used as necessary. The lattice is processed by a tapered drill, chemical etching, electrolytic polishing, or the like. The metal support grid is mechanically fixed to the flange.

  An embodiment will be described below with reference to the accompanying drawings. Fig. 1 shows a cross-sectional structure of a flange with an ultra-high vacuum thin optical window. FIG. 2 shows an enlarged view of the mutual relationship between the light transmitting portion and the metal support grating. The thin optical window material 3 is supported from both sides by metal support grids 4 and 7. The metal supporting grids 4 and 7 are hollowed out with a lot of light transmitting areas. The light-transmitting thin optical window material 3 is ultra-high vacuum sealed on the left CF flange. 3 is suppressed by Viton O-ring 6 from 2 on the right. The flange 1 is an ultra-high vacuum double-sided flange and is directly connected to the right device. Light enters from the right side of FIG.

  FIG.   Thin optical window material mounting part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ultra high vacuum double-sided flange body 2 Metal member which holds thin optical window with Viton O-ring 3 Thin optical window material 4 Metal support grid 5 Metal support grid press 6 Viton O-ring 7 Metal support grid 8 Metal support grid press 9 Connection screw

Claims (6)

  A structure that can withstand a pressure difference of 1 atm using as thin a crystal as the optical window of an ultra-high vacuum container.   The flange that attaches the optical window is a double-sided flange, and two ultrahigh vacuum systems can be directly connected through this window.   Of the vacuum systems connected to both sides of this optical window, the structure is such that window breakage and vacuum leakage are less likely to occur even when sudden leakage from one of the vacuum systems to the atmosphere occurs.   The optical window is a structure that is fixed by a metal support grating from both sides, and this metal support grating is not only a structure that does not reflect convergent incident light on the side of the grating, but also the end of the contact surface with the optical crystal has a certain curvature. This structure makes it difficult to break even in the case of single crystal optical windows.   The window can withstand a pressure difference of 1 atm and has a transmission area and transmittance as large as possible, has a relatively large diameter transmission area in the center, and a peripheral area as large as possible over a relatively large area. Structure with high average transmittance.   Even with baking or cooling up to 200C, the temperature of the optical window changes uniformly, and by using a material that does not contaminate the optical window, it can be used due to deterioration of transmission characteristics and vacuum characteristics with respect to temperature changes. The structure should not cause the above problems.

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