RU2148849C1 - Device for observation in visible and infrared spectra - Google Patents

Abstract

FIELD: optics. SUBSTANCE: device for observation in visible and infrared spectra includes photocathode, light-emitting cathode-luminescent screen with aluminum coat and microchannel plate. Spacing of channels in microchannel plate is equal or less than minimal working length of waves of photoelectrons emitted by photocathode. Photoelectrons emitted by photocathode hit channel of microchannel plate, bump against its walls causing emission of secondary electrons. Secondary electrons entrained by field inside each channel cause secondary emission as result of which current across output of channel exceeds current across input. As spacing of channels in microchannel plate does not exceed working length range of waves of photoelectrons emitted by photocathode direction of propagation of enhanced wave front is preserved which means that there will be no necessity whatsoever in employment of some optical aids. EFFECT: enhanced functional efficiency of device. 2 dwg

Description

 The invention relates to optical instrumentation and can be used in observation and aiming devices.

 Known electron-optical Converter, consisting of a microchannel plate (MCP), a ring with an internal conductive coating and a luminescent screen (US Pat. RU N 2005323 from 12.30.93). In this system, the image is converted and amplified to the required brightness.

 The disadvantage of this system is the inability to use the latter without various types of lenses and eyepieces, which leads to a significant increase in the dimensions and weight of the device.

 Also known is an optical-electronic device for night vision (US Pat. RU N 2037167 from 06/09/95), containing a mirror-lens optical system with field aberration compensator, an electron-optical converter, a wrapping system, a beam-splitting optical element and a mechanical system for pairing the operator’s helmet with synchronous rotation mechanism. The disadvantages of this device are the bulkiness, high weight and complexity of the design.

 Closest to the technical nature of the proposed is a flat electron-optical image converter according to US Pat. RU N 2020642 BI N 18 from 09.30.94, containing a photocathode, MCP and aluminized light-emitting cathodoluminescent screen from a single-crystal plate of yttrium aluminum garnet.

 The disadvantage of this system is the inability to use the latter without a different type of lenses and eyepieces, which leads to a significant increase in the dimensions and weight of the device.

 The task is to develop a device that eliminates the need for lenses and eyepieces, as well as reduce the size and weight.

 This object is achieved in that in a device for observing in the visible and infrared spectral regions containing a photocathode, a microchannel plate and a light-emitting cathodoluminescent screen with an aluminum coating on the side of the photocathode, according to the invention, the channel period of the microchannel plate (MCP) is equal to or less than the minimum working wavelength of the photocathode .

 An essential feature of the invention is the location of the MCP channels from each other at a distance equal to or less than the minimum working wavelength of the photocathode. In this case, the stimulated emission of elementary sections of the luminescent screen forms the same direction of light as at the input of the image intensifier tube, otherwise the direction of the front of the amplified light ceases to coincide with the original one, and thus, the resolution of the device deteriorates sharply.

 The invention is illustrated by drawings, where in FIG. 1 shows an optical diagram of a device for observation in the visible and infrared regions of the spectrum, and FIG. 2 - fragment of the MCP in a perspective view.

 The device contains a photocathode 1, a microchannel plate (MCP) 2, a light-emitting luminescent screen 3 made of a single-crystal plate of aluminum yttrium garnet, a mirror reflective film 4 of aluminum, a glass balloon 5. In the MCP 2, the channel period T is not more than the minimum working wavelength of photocathode 1.

 A device for observation in the visible and infrared regions of the spectrum operates as follows. The photoelectrons from photocathode 1, falling inside the MCP channel 2, hit its walls, causing the emission of secondary electrons. Secondary electrons, carried away by the field inside each channel, perform acts of secondary emission as the channel passes, as a result of which the current at the channel output exceeds the current at the input. From the output of the MCP 2, the image in the accelerating field is transferred to the single-crystal screen 3. Due to the fact that the period T of the microchannels of the MCP does not exceed the working range of the photocathode wavelengths, the propagation direction of the amplified wavefront is preserved. This eliminates the need for a lens and eyepiece.

Example. High image brightness and resolution of the image intensifier tube were obtained with a screen thickness of about 1 mm. Image intensifier tubes with single-crystal screens based on yttrium aluminum garnet emit in the yellow-green region (wavelength of the spectral maximum of radiation 544 nm), have a light output of more than 5 cd / W (at U = 5 kV) and afterglow duration t _e ≤3 • 10 ^-3 s . MCP had a period of 400 nm.

Claims (1)

 A device for observing in the visible and infrared spectral regions, comprising a photocathode, a microchannel plate and a light-emitting cathodoluminescent screen with an aluminum coating on the side of the photocathode, characterized in that the period of the channels in the microchannel plate is equal to or less than the minimum working wavelength of the photocathode.

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