SU1679215A1 - Multichannel spectrofotometer - Google Patents

Abstract

This invention relates to optical spectral instrumentation. The purpose of the invention is to improve the measurement accuracy by increasing the light transmission. The radiation is reflected from the scanning mirror 1 and is fed to a set of autonomous lenses 2. At the focus of each of the lenses 2, one of the zones of the multizone field diaphragm 4 is placed. Next, the radiation passes the light filter 5 in each channel and is recorded by the photodetector 6. Between each autonomous lens 2 and the aperture zone 4 posted rhombic prism. A multichannel spectrophotometer allows radiation to be measured in one field simultaneously by several spectral channels. 3 il. S 7 solar radiation SL с о 3 N5 SP

Description

An object

1

The invention relates to the field of optical spectral instrumentation.

The purpose of the invention is to improve the measurement accuracy by increasing the light transmission.

Figures 1 and 2 show the optical layout of a multichannel spectrophotometer (in Fig. 1, two measuring channels and a calibration channel; in Fig. 2, view A in Fig. 1, which shows the branching (as an example) of eight optical measuring channels); on FIG. 3 - the image of three field diaphragms in the object space.

The spectrophotometer contains a scanning mirror 1, autonomous lenses 2, rhombic prisms 3, field diaphragms (zones) 4, band-pass light filters 5, photodetectors 6, diffuser 7, diaphragm 8, lens 9, swivel mirror 10, axis 11 symmetry.

 Scanning mirror 1 is made uniform for all measuring channels and installed at an angle of 45 ° to the optical axes of autonomous lenses with the possibility of rotation through 360 ° around the axis 11 of symmetry. Each measuring channel includes an autonomous lens 2, a rhombic prism 3, a field diaphragm 4, a band-pass filter 5 and a photodetector 6. The autonomous lenses are installed close to each other in the form of a honeycomb structure with mutually parallel optical axes.

After each lens 2, rhombic prisms 3 are radially mounted, the reflecting faces of which are at an angle of 45 ° to the optical axes of the lenses. The length of the prisms 3 is chosen based on the size of the photodetectors. Field diaphragms 4 are installed directly after the rhombic prisms in the focal plane of the lenses 2. Field diaphragms 4 together with the lenses 2 form an instantaneous field of view of the optical system where dn is the diameter of the wash, equal to

f ° i

left diaphragm 4; f0 focal

lens distance 2. Band-pass filters 5 are placed after field diaphragms 4 in front of photo detectors 6. The calibration channel is built according to a collimator scheme and includes a solar radiation diffuser 7, aperture 8 installed in the focal plane of the lens 9, a swivel mirror 10 at an angle of 45 ° to the optical axis of the collimator and the axis of rotation 11 of the mirror. The diameter d of the diaphragm 8 and the diameter dn of the field diaphragm 4

connected by the ratio dn / dn / fo1, where (k1 is the focal length of the lens 9 of the collimator.

Spectrophotometer works in two

modes: measurement and calibration as follows,

In the measurement mode, the luminous flux comes from the object under study, for example, the upper layers of the Earth’s atmosphere (Fig. 1),

the scanning mirror 1 and it is directed to all autonomous lenses 2, where, after passing through rhombic prisms 3, it concentrates on field diaphragms 4, and then the interference light filters 5 arrive at the diffuse beam and fall on the photodetectors 6. In each channel, the interference light filters are separated from the test stream monochromatic light in a narrow spectral range, which is converted by the photodetector into an electrical signal. The electrical signal is amplified, converted into a digital code and fed to a block of the control system, the collection and processing of information (not shown). Each photodetector b has its own registration channel. The signal levels of the multichannel spectrophotometer are recorded periodically at intervals of d dp / v, where

dn is the diameter of the image of the field diaphragm 4; v is its scanning speed. The spectral channels are interrogated all at the same time, and their signals, after conversion, are sent to the long-term memory block. Scanning mirror 1 changes the beam path during various instrument operation modes and provides scanning of images of field diaphragms 4 across the flight path of the spacecraft.

The viewing angle can be any one, for example, 96 °, which allows exploring the vast area of the Earth’s atmosphere at different zenith angles of the Sun.

In calibration mode scan

mirror 1 is rotated 180 ° and fixed. Calibration commences at the moment when the instrument velocity vector is directed toward the sun. Luminous flux from the Sun falls on the diffuser 7, passes

part of it, and the diaphragm 8, enters the lens 9, where it is collimated by it and guided by the rotating and scanning mirrors. in all measuring channels. Photodetectors 6 generate electrical signals, which then serve to compare with signals received from an object.

I will explore the relative output signals from the direct solar

radiation and the reflected atmosphere of the earth, one can judge, for example, the quantitative total ozone content in the atmosphere, and the relative change in signals in the spectral channels allows one to judge the distribution of ozone at different levels of the atmosphere. A multichannel spectrophotometer makes it possible to measure solar radiation reflected at different heights of the atmosphere (in depth) in one field and at the same time by eight spectral channels. Thus, the spectrophotometer allows you to globally investigate the dynamics of the distribution of ozone in the atmosphere at its various levels, and by replacing narrow-band optical filters in the instrument, you can investigate the content and distribution of other chemical elements in the atmosphere.

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five

Claims (1)

Claims of the invention A multichannel spectrophotometer comprising an optically coupled scanning mirror, a lens, a multi-field field stop located in the focal plane of the lens, an optical splitter, band-pass filters and photodetectors, characterized in that, in order to improve measurement accuracy by increasing the light transmission, the lens is made in the form of a set of autonomous lenses, in the focus of each of which is placed one zone of a multi-zone field stop, the optical splitter is performed in the form of rhombic prisms, each of which is located along the beam path between a lens and an autonomous zone multizone field diaphragm. Vida Fy Fi.Z