IL115206A - Method and apparatus for reception and processing of electromagnetic radiation signals - Google Patents

Description

ΓΓϋ];ΐΤ]"Πϋ]27Κ ΓΠΉΡ 7HJ ΌΙΝ 7121)1 ΠΌ7|2Π7 ΊΙϋΟΏΙ ΠΌΊ[ϋ METHOD AND APPARATUS FOR RECEPTION AND PROCESSING OF THE ELECTROMAGNETIC RADIATION SIGNALS METHOD AND APPARATUS FOR RECEPTION AND PROCESSING OF THE ELECTROMAGNETIC RADIATION SIGNALS Field of the Invention The invention relates to physics, in particular to optic measuring devices applied in various fields of human activities, and intended for spectrometric and colorimetric measurements, for measuring the density of an investigated object, measuring temperatures or distance of a radiation source, measuring the radiation wavelength etc.

Background of the Invention.

Many methods for reception and processing electromagnetic radiationsignals, as well as a plurality of various devices applied for carrying out these methods, are known. The known methods and devices may be schematically classified in following groups according to spectral characteristics of the optical system: a) Integral methods and devices based on the method's application.

The method provides for optical radiation reception over the entire band of wave lengths that can be handled by a specific optical system. This method is used in those cases where the radiation spectral pattern is non-essential, for solving measurement problems ( temperature-sensitive elements, logic cirquits, calorimeters) [L.Z.Kriksunov. Spravochnik po osnovam infrakrasnoi techniki. Moscow, "Sovetskoe radio", 1978] . Such is the method and device on its basis disclosed in U.S. Pat. # 5,264,925, U.S. CI. 358-44.

The spectral characteristics of such a method are represented in a diagram shown in Fig. 1. The main drawback of this method is in a complete abscence of any information on the radiation spectral pattern. b) Methods and devices for performing measurements in a narrow spectral band.

These methods are applied when it is necessary to separate a radiation of the certain wavelength from a total electromagnetic radiation spectrum (see diagram in Fig. 2). In this case the radiation source may be a monochromatic single frequency source. For the radiation source, operating on another wave length, it is necessary to select another filter, or use a more sophisticated device such as one disclosed in U.S. Pat. # 4,598,248, U.S. CI. 324-77R.

Among devices whose operation is based on such methods are various laser search and detector systems, lidars, range finders, etc. [R. Mezheris. Lasernoye distantsionnoye zondirovaniye. Moscow, "Mir", 1987.]. c) Methods and devices for measurements in two or several narrow bands.

Said methods are used in devices designed for comparing radiation in determined radiation ranges, or in determined points of continuous spectrum, such as the devices for determining ozone content in the atmosphere, and in differential absorption lidars, in devices for luminescence study, etc. [R.Mezheris Lasernoye distantsionnoye zondirovaniye. Moscow, "Mir", 1 87].

These methods provide information on certain spectrum areas, and make it possible to determine some radiation properties (Fig.3). Such a method and device on its basis are described in U.S. Pat. # 5,300,777, U.S . CI. 250-338.4.

The drawback of these methods is that for the evaluation of other than determined spectrum areas, or other radiation sources, it is necessary to use additional filters. d) Methods and devices for colorimetric measurements.

Methods for colorimetric measurements in three wide spectral bands are used to determine the radiation color, and applied in color television, color photography etc. An advantage of these methods is that they give integral information on the radiation spectrum which approximates the physiological sensitivity of a human eye.

This is, however, the main drawback of said methods, as spectral bands in the three ducts overlap. Therefore, the information becomes ambiguous and cannot be used for precise measurements [Fig. 4]. Moreover, for carrying out these methods, stringent requirements must be imposed for manufacturing and calibrating filters and receivers for each duct. Devices for colorimetric measurements are disclosed, for instance in U.S. Pat. # 5,363,197, U.S. CI. 356-405 and U.S. Pat. # 5,272,518, U.S. Cl.356-405. e) Spectrometric methods and devices.

These are methods for measurements in a great number of spectral ducts [A.N.Zaidel, G.V.Ostrovskaya, Yu.N.Ostrovsky. Technika i praktika spectroskopiyi. Moscow, "Nauka", 1976] that give in total a most comprehensive idea on an oncoming radiation spectral distribution [Fig. 5]. Such methods and devices are described in U.S. Pat. # 5,253,302, U.S.Cl. 382-1; U.S. Pat. # 5,311,293, U.S.Cl. 356-421.

The drawbacks of these methods are high costs, device bulkness, complexity of operation and information processing, and in many cases excessive amount of information.

Summary of the Invention An object of the present invention is a method and device to obtain some characteristic of electromagnetic radiation, described the general features of spectrum, through measuring optical radiation in two ducts, each by itself possess of spectral characteristics, given beforhand (one of which posses non-selective spectral sensitivity, and the other - linearly dependent spectral sensitivity) (Fig. 6). Such general features of spectrum can be effective wavelength of radiation.

The claimed method comprises several successive steps including delivering the investigated radiation stream to a means for radiation, reception with the following division of the radiation stream into two spectrally 'equal halves, delivering one half of said radiation stream to a first duct for photoelectric information reception, said first duct having linearly dependent spectral characteristics, and delivering the second half of said radiation stream to the second duct for photoelectric information reception, said second duct having non-selective spectral characteristics.

Then the obtained photoelectric information from said first and second ducts is recorded in pre-determined band and converted into electric signals, said signals are amplified and processed, and the electric signals obtained from the first and second ducfs are processed and compared using a certain algorithm. Thereafter, on the basis of comparing of said electric signals, the required electromagnetic radiation ranges are determined and presented as: i) effective wavelength (center of gravity) of radiation, effective wavelength (center of gravity) of an unknown added amount of radiation or effective wavelength (center of gravity) of spectrum representing a combination of several radiation sources, or ii) relative color density of the investigated object.

Operating parameters and conditions of said first duct for photometric information reception are selected beforehand in such a way that electric signals, emitted therefrom, satisfy the expression: J λ /( λ ) dX λ, were: /( λ ) - is the function of spectral distribution of radiation; λ is the radiation wavelength.

Operating parameters and conditions of said second duct for photometric information reception are selected beforehand in such a way that electric signals, emitted therefrom, satisfy the expression: Ι /( λ ) (!λ where: /( λ ) - is the function of spectral distribution of radiation; λ - is the radiation wavelength.

Electric signals, carried in first and second ducts, are received and compared according to the equation: λ . | λ /( λ ) άλ ί ί( λ ) άλ where: λββ· . is the effective wavelength or the center of gravity of investigated radiation signal; \f( X ) dX - is the integral radiation value in a given band obtained within non-selective first duct; λ ) <ϋλ - is the integral radiation value in a given band obtained within the linearly dependent second duct.

The claimed method is carried utilizing the claimed apparatus for reception and processing electromagnetic radiation signals comprising a means for collecting and concentrating the radiation stream, a means for dividing the radiation stream in two, at least one optical filter, a first duct for photometric information reception having non-selective spectral characteristics, a second duct for photometric information reception having linear spectral characteristics, at least one means for converting photometric information into electric signals, at least one duct for processing electric signals and, at last, a means for comparing electric signals obtained from said first and second ducts, as well as an electronic or computer system for information processing.

Said means for photometric information reception comprises at least one radiation receiver and at least one optical filter.

Said means for dividing the light stream in two may comprise a light dividing block or plate, a light guide or modulator.

A more detailed disclosure of the claimed invention is presented and illustrated in the following sections of the current specification.

Brief description of the Drawings The invention is illustrated by drawings in which: Fig. 1- shows optical system characteristics of an apparatus that uses the integral method for electromagnetic radiation reception and processing; Fig. 2 -shows optical system characteristics of an apparatus that orecives and processes a signal coming in a narrow spectral band; Fig. 3 - shows optical system characteristics of an apparatus that recives processes a signal coming in two or several narrow spectral bands; Fig. 4 - shows optical system characteristics of an apparatus for colorimetric measurements; Fig. 5 - shows optical system characteristics of an apparatus for spectrometry measurements; Fig. 6 - shows optical system characteristics of the claimed apparatus; Fig. 7 - shows a schematic diagram of the claimed apparatus; Fig. 8 - shows a diagram of one of the claimed apparatus embodiments designed as an astronomic RGB-photometer.

Specific description The claimed method is carried out by the claimed apparatus for reception and processing electromagnetic radiation signals (Fig. 7).

The apparatus comprises a means for photometric information reception which includes a means for collecting and concentrating the radiation stream (radiation receiver) formed as a lens (1 ), a means for dividing the radiation stream into two formed as a light dividing block (2), an optical filter (3), a radiation receiver of the first duct (4) for photometric information reception with a filter (5), a radiation receiver of the second duct (6) for photometric information reception with a filter (7), a means (8) for converting photometric information into electric signals, at least one duct (9) for electric signals processing and, at last, a means (10) (an electronic circuit) for comparing electric signals obtained from said first and second ducts (4) and (6), and a computer system (11 ) for information processing.

As a light dividing device in the claimed apparatus instead of the light dividing block (2) a light dividing plate or light guides may be used (not shown in the drawings).

The claimed method is carried out by the claimed apparatus as follows: The investigated radiation stream gets via the lens (1 ) and filter (3) to the means for radiation reception. Therein it is divided by the light dividing block (2) into two spectrally equal halves, one of which is transmitted through the filter (5) to the first duct (4) for photometric information reception, and the second half is transmitted through the filter (7) to the second duct (6) for photometric information reception.

Further the obtained photometric information is recorded in the given band by said first and second ducts (4) and (6) and converted into electric signals. Said electric signals are amplified and processed in the means (9). Then electric signals obtained from the first and second ducts (4) and (6) are jointly processed and compared by the given expression using the computer system (11 ).

Thereafter, on the basis of comparing said electric signals, the required electromagnetic radiation signals are determined and represented as: i) one radiation effective wavelength (center of gravity), effective wavelength (center of gravity) of an unknown value of added amount of radiation or center of gravity of several spectrums of , or ii) relative density of the investigated object.

According to the claimed method parameters of said first and second ducts (4) and (6) are selected beforehand in such a way that electric signals emitted therefrom comply with the numerator and denominator of said expression. (Page 8, Lines 15-20) Then, the two ducts ratio corresponds to effective wavelength (^eff) of radiation spectrum.

The claimed method embodiments on the basis of the claimed apparatus Embodiment 1. Astronomic RGB-photometer.

The apparatus includes an inlet aperture (21 ) (Fig. 8), a lens (22), modulator (23), lens (24), two photoreceivers (25) and (26) one of which is spectrally non-selective and the second bears linear spectral dependence.

It further includes a processing and recording system (27). For continuously tracking of an astronomic object, the circuit includes a semitransparent mirror (28) and viewfinder with cross lines (29). For separating of a spectral band, a filter (30) is provided.

The apparatus operates as follows.

The oncoming radiation passes through the apparatus window, and is focused by the lens (22) on the modulator (23) which transmits the astronomic object's radiation from one photoreceiver to the other. Half of the time of each period during which the astronomic object radiation falls onto the receiver (25), receiver (26) accepts background radiation. The second half of said period, the receiver (26) accepts the astronomic object radiation, while receiver (25) - the background radiation.

The recording system (27) subtracts the background signal from the effective signal within each duct, determines the effective wavelength and projects the obtained result on the display.

Embodiment 2. Apparatus for controlling the wavelength and radiation force of the arrangeable monochromatic radiation source.

The apparatus diagram is similar to the schematic diagram of the claimed apparatus, which is shown in Fig. 7. A peculiarity of this embodiment is that the spectral sensitivity band of the two ducts is selected according to the band of spectral rearrangement of a laser. In this case the wavelength is calculated as the effective wavelength from an equation: ί λ /( λ ) άλ s = - ί/( λ )άλ λ, Radiation intensity is determined from readings within the spectrally non-selective duct.

Embodiment 3. Remote temperature determination systems (pyrometers) In ordinary pyrometers the radiometric signal is measured in one wavelength range. This method suffers from three drawbacks: the radiometric signal depends on radiometer properties (geometrical factor G, spectral sensitivity of radiometer - η(λ)), on spectral transmission of atmosphere α(λ) and on the sample's emissivity ε(λ). Real materials are non-gray, i.e. the spectral emissivity ε varies with wavelength, with viewing angle and also may vary with the time A widely used method to determine the temperature of a surface uses dual spectral-bands radiometric techniques. This method is based on relating the radiometric signals from two measured spectral bands. In case where G, η(λ), α(λ) and ε(λ) are similar in the two wavelength bands, the ratio R of the spectral emission signals becomes only a function of temperature T.

A widely used method to determine the temperature of a surface uses dual spectral-bands radiometric techniques. This method is based on relating the radiometric signals from two measured different spectral bands.

The main disadvantage of two spectral-band pyrometers is that all parameters η(λ), α(λ) and ε(λ) may vary from band to band .

Unlike many other pyrometric devices, the proposed system could determine the true temperature of measured target in one spectral band with two channels for different spectral sensitivity λ where ί(λ)=Ρ(λ,Τ) - Planck distribution for a blackbody at temperature T.

The calculated dependence of λ eff from blackbody temperature T for two bandwidths of the wavelength is shown on Fig.9, 10.

The simplest application for this theory can be a fire alarm systems, which major drawback is that they measure the total emission instead of target temperature Embodiment 4 Apparatus for detecting the additional radiation amount in a total pattern within the absorption or reflection spectrum.

The apparatus diagram is similar to the schematic diagram of the claimed apparatus, shown in Fig. 7. in order to use this device, the standard calibration values of the main radiation spectrum, and an additional radiatin spectrum, are entered beforehand into the computer memory, said radiation values then registered by said first and second ducts. After the radiation values are measured the relative density of additional radiation is calculated from a set of linearly independent equations: where: In , I22 -are the first and second duct readings of the; total radiation value Ig!, Igi - are the first duct readings for a singular spectra within the main radiation value and the additional radiation value; Io2, Ig2 - are the second duct readings for a singular spectra within the main radiation value and the additional radiation value; Ci, C2 - is the density of the main radiation and the additional radiation in the total spectrum.

Otherwise, the design and operation of the apparatus do not differ from those of the apparatus shown in the diagram in Fig. 7.

Embodiment 5. Apparatus for determining the effective wavelength in impurities spectrum.

The apparatus diagram is similar of the schematic diagram of the claimed apparatus, which is shown in Fig. 7. Measurements are first performed in radiation of the basic substance with an impurity. The relation of readings difference in said first and second ducts gives the effective wavelength of impurity spectrum which is calculated from the expression: where: · 11.11 - are the first duct readings; 12, 12 - are the second duct readings; ίΐ , f!? - is distribution of the total and the impurities-free radiations values; Fim - is the impurities spectral distribution.

The claimed method Is highly effective and does not require much time for investigations. The applied apparatus is relatively in expencive, as it is assembled from the off-the-shelve components (computer, conventional lenses, filters, light dividing devices etc.). No high skill or special knowledge is required from the user.

An advantage of the claimed method is that it allows to perform, the colorimetric measurements using only two ducts, while such colorimetric measurements are now carried out with the methods that require using three ducts. Moreover, the claimed method permits to obtain more precise spectrum characteristics not limited by the eye physiologic sensitivity, so that said method can be used in precise measurements for scientific and engineering purposes, as well as for quality control. On the basis of the claimed method, the devices can be designed for control of television tubes, color printers, polygraphic equipment, as well as production of textiles, plastics, tiles dyestuffs etc. These apparatus can be as well used for automated production processes, sorting by color verious products ( by ripeness - vegetables and fruits, by color marking- electronic parts etc.).

Another advantage of the method is that it allows to solve some simple problems which can be handled only by the spectrometric method, such as determining the wavelength and intensity of monochromatic radiation, controlling the wavelength and intensity of tunable lasers and filters, identifying a luminescent substance by effective wavelength, active remote sounding etc.

Still another advantage of the claimed method and the claimed apparatus is that the same apparatus can be used for measuring different wavelengths without changing the filters.

This is especially important for monitoring Earth's surface from aircrafts when special requirements are imposed on the design simplicity and reliability, weight, and size of the radiation receivers.

In the description of the invention embodiments specific terms are used for the sake of clarity. However, the invention is not limited by the accepted specific terms and it should be clear that each term covers all the equivalent elements operating likewise and used to solve the same problems as the claimed invention.

Above the preferred embodiments of the present invention have been described. However, many improvements, changes and additions of equivalent elements may be introduced therein without depriving the invention of its advantages disclosed in the attached claims.

Claims (9)

CLAIMS I claim:

1. l. A method for reception and processing of the electromagnetic radiation signals comprising the steps of: a) delivering the investigated radiation stream to a means for radiation reception; b) dividing the radiation stream in said means for radiation reception into two spectrally equal halves; c) delivering one half of the radiation stream to a first duct for photometric information reception in said means for radiation reception, said duct being spectrally non-selective; d) delivering the second half of said radiation stream to a second duct for photometric information reception in said means for radiation reception, said duct having linearly depending spectral characteristics; e) recording the delivered photometric information in a predetermined band via said first and said second ducts and converting the latter into electric signals; f) amplifying and processing of electric signals obtained from the first and second ducts; g) simultaneous processing of electric signals obtained from the first and second ducts and their comparison according to a certain algorithm; h) determining, on the basis of said electric signals comparison, the required electromagnetic radiation parameters and presenting said parameters as: i) effective wave length (center of gravity) of one radiation source, effective wave length (center of gravity) of a unknown added radiation amount, or effective wave length (center of gravity) from several radiation sources, ii) relative density of the investigated object.

2. A method according to claim 1 wherein the parameters and operating conditions .of said first duct for photometric information reception are selected beforehand in such a way that electric signals emitted therefrom would satisfy the expression: where: /( λ ) - is the function of radiation spectral distribution; λ - is the radiation wave length.

3. A method according to claim 1 wherein the parameters and operating conditions of said second duct for photometric information reception are selected beforehand in such a way that electric signals emitted therefrom would satisfy the expression: λ» ί/( λ ) άλ where: /( λ ) - is the function of radiation spectral distribution; λ - the radiation wave length.

4. A method according to claim 1 wherein the electric signals eceptibn and comparison are performed by said first and second ucts according to the equation: ί λ /( λ ) άλ where: eff iS the effective weave length or the investigated radiation center of gravity; \ ί( λ ) άλ is the integral radiation in a given band obtained by the non-selective first duct; j λ /( λ ) άλ -is the integral radiation in a given band obtained by the linearly dependent second duct

5. An apparatus for reception and processing electromagnetic radiation signals comprising: - a means for obtaining photometric information including: - a means for collecting and concentrating the radiation stream; - a means for dividing the radiation stream into two; - at least one optical filter; - a first duct for photometric information reception being spectrally non-selective; - a second duct for photometric information reception bearing linear spectral dependence; - at least one means for converting photometric information into electric signals; - at least one duct for processing electric signals; - a means for comparing electric signals obtained from said first and .second ducts for photometric information eception and an electronic or computer system for information processing.

6. An apparatus according to claim 5 wherein said means for photometric information reception includes at least one radiation receiver and at least one optical filter.

7. An apparatus according to claim 5 wherein said means for dividing the light stream into two comprises a light dividing block or a plate.

8. An apparatus according to claim 5 wherein said means fordividing the light stream into two comprises a stream divider in a form of a light guide.

9. An apparatus according to claim 5 wherein said means for dividing the light stream into two comprises a stream divider in a form of a modulator.