SU1396009A1 - Device for measuring the reflection coefficient of speicmens - Google Patents

Abstract

The invention relates to the field of optical measurements and can be used to measure the reflection coefficient of samples from optical and other materials. The goal is to expand the spectral range of measurements towards ultraviolet radiation and simplify the design. To ensure the work in the field of vacuum ultraviolet, the vacuum photocell windows are made of magnesium fluoride, a translucent photocathode is deposited on the inner surface of the exit window, the anode is ring-shaped, the air gaps between the radiation source and the input window of the photocell, as well as the output window and sample surface are minimized. The signal is produced by the emission of electrons at the first incidence of radiation on the photocathode and after reflection from a test sample or reference. 1 il. from 9 (L

Description

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The invention relates to the field of optical measurements and can be used to measure the reflection coefficient of samples of optical and other materials.

The purpose of the invention is to expand the spectral range of measurements towards ultraviolet radiation and to prohibit the design of the device.

The drawing shows the proposed device.

The device consists of an illuminator, a supportive radiation source 1 and an optical system 2 (for example, a vacuum monochromator), a vacuum photocell 3 and a flat inlet window 4, which is perpendicular to the optical axis of the illuminator,. An annular anode 5 is installed inside the photocell (approximately half of its length). A translucent photocathode b is deposited, for example, by vacuum fusing onto the inner surface of an output window 7 parallel to the input. Immediately behind the exit window is placed a movable cassette 8, fixed in positions I and II (shown by a dotted line), in which the reflecting measured sample 9 and the reference sample 10 are fixed.

The device works as follows.

Radiation from source 1, polychromatic I. OR monochromatic (the monochromator is not shown in the drawing), h (optical cut out cHCTeiMrs - 2 is sent to the input window 4 of the vacuum photocell 3 and hits the photoframe 6 deposited on the inner surface of the output window 1, The input and output windows are made of magnesium fluoride.When placing the cassette in position I, some of the radiation is absorbed by the photocathode and causes electrons to be emitted to the anode 5, and some of them pass through the photocathode and the output window is reflected by the sample 9, again gets to the photo The cathode causes additional emission of electrons and, therefore, an increment of the photocell signal. When the cassette is placed in position II, the radiation transmitted by the photocathode is reflected by the reference sample 10 and the radiation falls on the photocathode.

read from ir ratio

Rt-

 II -

where ij and

1 - photocell signals

when placing the cassettes in positions I and II, respectively, p, –g are the reflection coefficient

reference sample.

The advantages of the proposed device (as compared with the known ones) are as follows:

the design of the device has been simplified since there is no structurally complex and non-technological element of the device - the integrating sphere;

The spectral range of measurements is extended to ultraviolet radiation with the capture of a vacuum ultraviolet (wavelength less than 180 m), since the measured and reference samples in the device are mounted close to the exit window of the vacuum photocell as well as the exit window of the vacuum monochro close to the entrance window of the photocell - matora, for example. BMP-1 or MgF-25 discharge lamp MgF. Thus, the air gaps absorbing UV-irradiation are minimized.

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Claims (1)

Invention Formula A device for measuring the reflection coefficient of samples, containing a radiation source, an optical system located along the radiation path, and a photodetector, made in the form of a vacuum photocell, containing an input and output window, a photocathode and an anode, in order to expand the spectrum. of the measurement range in the direction of ultraviolet radiation and simplify the design, insert a movable cassette into it, and a translucent photocathode deposited on the inner surface of the photocell output window, the anode is made in the form of a ring located parallel to the planes of the input and output windows between them, with the sub-cassette cassette located behind the output window of the photocell and provided with a locking mechanism in two positions and seats for the measured and reference sample with the possibility of their installation close to the window.