HU226833B1 - Method and apparatus for quantitative measuring based on light intensity measurement - Google Patents

Abstract

The invention relates to a procedure for determining quantitative characteristics by measuring light intensity, in the course of which the sample to be examined is illuminated with measuring light, and the intensity of the light reflected from it or passing through it is measured, and in the interest of accurate measurement a sample reference of stable characteristics is also illuminated with measuring light via the same trace as the trace used in the case of the sample to be examined. The procedure is characterized that in the course of performing measurement(s) the measuring light is rotated in the circular space around the axis (t) of the circular space as an axis of rotation, or the circular space is rotated around as compared to the measuring light at a favourably speed. The invention also relates to equipment for determining quantitative characteristics by measuring light intensity.

Description

The present invention relates to a method and apparatus for quantitative measurement based on the measurement of light intensity. The solution is particularly useful for determining the quality characteristics of grain crops, such as cereals.

Optical instruments that measure a characteristic or component of a material by the spectra of its materials work by illuminating a sample with a single light source and measuring the intensity of light reflected or reflected by a light sensor unit at different wavelengths. The relationship between these data and the characteristic to be measured is used to determine the numerical value of that characteristic component based on the instrument calibration. In the case of instruments for quantitative measurements, both the wavelength and the intensity of the measuring light and the characteristics of the sensor (s) must be kept stable in order to obtain an adequate accuracy. Light of different wavelengths is produced with known monochromators, which in practice are usually periodically checked or corrected for wavelength stability. The proper stability of the measuring light and its sensing can be achieved either by using high quality components placed in a stabilized environment, or in the case of lower quality - less stable components - the error can be corrected or compensated by simultaneous measurement of a known constant reference material. This known solution is characterized by the use of two optical paths of the same size, containing the same elements, for measuring the sample and the reference material of constant property. The two optical paths alternate time with light to the sensor. The condition of proper compensation is that the two optical paths and their optical elements do not change over time. This known solution eliminates temporal changes in both the light source and the sensor, but it cannot eliminate the changes in the two optical paths or their optical elements.

The cross-section of the light channels should preferably be chosen such that the inhomogeneity of the test sample is negligible. In cases where this is not possible because it results in too large dimensions or an expensive construction, the light channel and the sample are moved relative to one another during measurement to compensate for the inhomogeneity by scanning the surface of the sample.

This function is usually accomplished by moving the sample, since it is easier to maintain constant optical conditions, i.e. stability.

US 4082464 discloses an optical arrangement in which the sample surface is illuminated perpendicular to the surface and the light reflected diffusively from the surface is detected by the detector (s) disposed at an angle of 45 ° to the plane of the sample surface.

US 4236076 discloses a solution in which light reflected from the illuminated sample surface is collected by an integrating sphere on the detector.

U. S. Patent No. 212 355 describes an optical arrangement comprising a light source, its light beam converting optical elements of different wavelengths into monochromatic measuring beams and reference beams, a detector connected to an electronic measuring and processing unit, and a detector.

A common disadvantage of these known solutions is that the sample reference change necessary to compensate for the instability of the measuring light and the sensor is performed by two optical paths, and thus they cannot eliminate changes in non-identical optical elements used in the optical paths during measurements. A further problem is the scanning of the sample to be tested, which requires complicated actuators.

The closest solution to the present invention is described in U.S. Pat. No. 5,020,909, which describes a spectrometric method and an apparatus assembly employing it. In this solution, a single optical path common to the test sample and reference material is used for compensation.

The light channel is chipped with a chopper disc so that one segment of the chopper disc is a transmission reference material (standard). In this known solution, the reference material is rotated, the light channel and the sample to be tested are composed. The spectrometer sample and spectrometer sample reference signals appearing on the detector are used as time-based convolutional spectra to compensate the sample spectrum to be measured, after deconvolution, by a mathematical method. This type of compensation is only applicable for special choppy disc light (containing reference material), the sample to be tested and reference material are not in the same motion state, so the sample and reference material cannot be measured under the same conditions. In addition, the frequency of chopping is determined by other measurement technology needs (such as maximum noise pressure) in addition to the frequency of compensation. In this known solution, a single optical path is used for compensation, but the test specimens and reference materials are not aligned.

SUMMARY OF THE INVENTION The object of the present invention is to provide a solution which eliminates the disadvantages of the prior art and provides a sufficiently reliable measurement solution, can be implemented by conventional optical elements, so that they are easy to adjust and economical to produce the apparatus of the invention.

SUMMARY OF THE INVENTION The present invention is based on the recognition that when a sample to be examined is illuminated and the reflected or transmitted light is measured, and to increase the accuracy of the measurement, the optical path used for the sample is known to have a constant optical path. The reference substance with characteristic B is also illuminated and the intensity of the reflected or transmitted light is also measured to compensate, and the sample (s) to be examined and the reference substance (s) with constant property are placed in the same plane2

EN 226 833 Β1, the measurement light (s) shall be placed at an angle to the axis of rotation of the annular space as the axis of rotation, or the annular space shall be rotated with respect to the annular space and available in the annular space. place not only a single sample and a constant reference substance, but also several samples and a constant reference substance to be tested, and if either the measuring light is rotated in the annular space or the annular space is rotated at a suitable speed relative to the measuring light, the change time constant of the optical elements is negligible, thus, by selecting the appropriate rotational speed, the accuracy of the measurement can be clearly increased, since the sample measurement and the reference measurement needed to compensate for the error very fast, practically at the same time, and thus, even with relatively fast changes in time, that is to say, of poor quality, the rate of change of the used elements is negligible, and such poor quality elements are found to be stable during measurement. accomplishes the objectives of a method and apparatus for quantitative measurement based on the measurement of luminous intensity according to.

The present invention relates to a method of quantitative measurement based on the measurement of luminous intensity by illuminating a sample to be examined with a measuring light and measuring the reflected or passing light, and to increase the accuracy of measurement by an optical path identical to the measuring light. reference material of known constant property is also illuminated and the intensity of the light reflected from or passing through is also measured to compensate. The method involves placing their test specimens and your constant reference material in an annular space in the same plane, measuring the circular space around the axis of the annular space as an axis of rotation, or the annular space is rotated with respect to the measuring light.

In a preferred embodiment of the method, the measuring light is produced by a light source disposed off the axis of rotation, but it may also be desirable to produce the light as an optical axis light displaced from the axis of rotation by a light source positioned in the axis of rotation.

According to our solution, the measurement can also be evaluated preferably by measuring the intensity of light reflected from or passing through the sample (s) and reference substance (s) outside the axis of rotation, or by measuring the sample ( k) the optical axis of light reflected from or passing through it and its reference materials is returned to the axis of rotation by further optical path-changing optics, where the light intensity is measured.

In the process, a prism, pair of mirrors, or optical fiber (s) are used as the luminous pathway optics and further luminous pathway optics.

Preferably, a monochromator producing light of a specific wavelength is used to form the metering light, or the light intensity is measured using a spectrometer detecting light of a specific wavelength.

According to our solution, rotation is performed by rotating the annular space containing the sample (s) and reference material (s) to be tested, or by rotating the optics and / or further optics.

The present invention also relates to an apparatus for quantitative measurement based on the measurement of luminous intensity having a sample to be examined by a first optical path in the path of light emitted by a light source, a second optical path of the same optical path and a common light sensor. provided, the first and second optical paths are formed as a single optical path. The apparatus is characterized in that the sample (s) to be examined and the reference substance (s) of constant property are arranged in the same circumference as an annular shape, and during measurement (s), the measuring light is angled about the axis of rotation. in the annular space, or rotated in the annular space. Accordingly, the present invention relates to an apparatus for effecting the exchange of sample reference material required to compensate for instability of a measuring light and a photodetection unit and the necessary scanning of a sample to be tested in a completely new and common way.

In a preferred embodiment of the apparatus, the optical axis of the light source is disposed in the axis of the annular space. In this case, it is possible that a light path modification optic is inserted between the light source and the annular space containing the sample (s) to be tested and the reference material (s) to create a metering light disposed off the axis. The measurement may be evaluated by positioning the optical axis of the light sensor unit in the axis of the annular space, between the annular space containing the sample (s) and reference material (s) to be tested and the reference material. additional optical path-changing optics are incorporated into the optical axis of the light reflected or passing through it (s).

In a preferred embodiment of the apparatus, the optical axis of the light source is disposed from the axis of the annular space. The measurement may be either as described above or in such a way that the optical axis of the light-sensing unit is out of the axis of the annular space reflecting or passing through the sample (s) and the reference material (s). placed.

In a very preferred embodiment of the apparatus, the light source is also provided with a monochromator or the light sensing unit comprises a spectrometer. invention

According to EN 226 833 1, the optical grid in the monochromator or spectrometer is located at an optically large distance from the light source, sample (s) to be tested, or reference material (s), preferably 10-20 times the focal length of the spherical mirror located behind the optical grid. .

It is highly desirable to arrange the apparatus in which a monochromator or spectrometer is fitted with a luminous optic between the light source or sample (s) to be tested and the reference materials and the optical grid.

The device according to the invention is a possible example. Fig. 1 shows one possible embodiment of the transmission principle apparatus, Fig. 2 shows a preferred embodiment of the reflection apparatus apparatus, and Fig. 3 shows another embodiment of the transmission principle apparatus, Figure 5 is a schematic diagram of a conventional two-slot spectrometer / monochromator; Figure 6 is a schematic detail of Figure 5; Figure 7 is a schematic diagram of the spectrometer / monochromator of the present invention; Figure 8 illustrates one possible embodiment of light path enhancement.

The apparatus of the present invention, shown in Figure 1, is provided with a S sample to be examined by a first optical path in the path of the ML measuring light emitted by the LS light source. A second optical path of the same size as the first optical path contains reference material R. In accordance with the present invention, the first and second optical paths are formed in the apparatus as a single common optical path, wherein the S sample (s) to be tested and the reference substance (s) R are arranged in a planar annular ring at a same distance from a given T axis. During the measurement (s), the measuring light ML is formed around the axis T of the annular space as a rotation axis, or is rotated around the annular space. At the end of the common optical path, the device is equipped with an LDS light sensor unit.

Figure 1 illustrates an embodiment of the apparatus wherein the optical axis of the light source LS is disposed in the T axis of the annular space. In this embodiment, a TMO light path modifying optic generating an optical axis ML from the T axis is inserted between the LS light source and the annular space containing the S sample (s) to be examined and the reference substance (s) R. The TMO luminosity modifying optic creates a ML measuring light with an optical axis out of the incident light IL in the T axis.

The apparatus of Fig. 1 operates on the transmission principle, i.e., the light transmitted by the ML measuring light passes through the sample S to be examined. The optical axis of the LDS light sensor unit is located in the T axis of the annular space as shown in the figure, therefore, the optical transmission of light transmitted between the annular space and the LDS light sensor unit on sample S (s) to be tested and reference substance (s) TL A further TMO luminaire optic is inserted into the T-axis. Thus, the optical axis of the light output from the further TMO optic pathway optics OL is again in the T axis of the annular space.

Figure 2 illustrates a preferred embodiment of the apparatus according to the invention which operates on a reflection principle. The LS light source located in the T axis of the annular space as well as the LDS light detector unit are also included. The role and placement of the TMO luminescent optics and other TMO luminescent optics are similar to those described in Figure 1. The only difference is in the measurement principle, where the ML light with optical axis ML out of the T axis is reflected from the S sample (s) to be examined and the reference substance (s) R, and the additional TMO optic pathway optics thus reflect the reflected light RL. axis, the LDS light sensor unit.

Figure 3 illustrates a possible embodiment of the apparatus operating on another transmission principle in which both the LS light source and the optical axis of the LDS light sensor unit are disposed from the T axis of the annular space, and the LS light source and the LDS light sensor unit It is located off the T axis.

Figure 4 schematically illustrates another preferred embodiment of the present invention based on the reflection principle. Again, the LS light source and the LDS light sensor unit are located outside the T axis of the annular space.

In practice, a major problem with transmission measurements is that the intensity of TL transmitted light is often very low. In the wavelength range that can be used in practice, for example, when measuring grain, the light transmitted by TL is very low. Commonly used so-called dual slit optical grid spectrometers / monochromators, which provide sufficient brightness and wavelength resolution for transmission measurements, are very expensive and require sophisticated, high technology.

Figure 5 shows a conventional two-slot Crossed Czerny-Turner spectrometer / monochromator. The light from the S sample or the light source LS is introduced into the gap S1 by means of imaging optics (not shown), from which the light is reflected to the optical grid G by reflection from the first spherical mirror SM1. By moving the optical grid G, light of different wavelengths is transmitted to the second spherical mirror SM2, from which it is reflected through the slit S2 and exits the spectrometer / monochromator. The required luminance is determined by the size of the optical grid G, the focal length L of the first spherical mirror SM1, the second spherical mirror SM2, and the angle of the light beam following the gap S1. The wavelength resolution, in the case of a given grid, depends on the ratio of the dimension d of the gap S1 to the focal length L of the first spherical mirror SM1.

HU 226 833 Β1

A strong LS light source or an appropriate light beam from the S sample is required to obtain the appropriate signal magnitude. Fig. 6 is a schematic diagram illustrating, in the case illustrated, a beam of light from a LS light source and a light emitting from the surface of the S sample via the CO imaging optic of the spectrometer / monochromator IS.

In order to carry out the principle scheme of Figure 6 in the apparatus according to the invention, the LS light source is preferably equipped with a special monochromator or a special spectrometer for the LDS light detector unit.

Figure 7 illustrates the basic structure of a special spectrometer / monochromator. Compared to the known two-slot arrangement of Figure 5, the spectrometer / monochromator of the present invention does not have an inlet S1 and an inlet SM1 first spherical mirror. Since there is no entry slot S1, no CO imaging optics are required. In the spectrometer / monochromator of the present invention, the parallelism of the light beam entering the optical grid G is achieved by optically spacing the optical grid G in the monochromator or spectrometer from the LS light source, the S samples, or reference substance (s) R, preferably 10 to 20 times the focal length L of the spherical mirror SM located after the optical grid G. The distance between the LS light source and the optical grid G is preferably 10-20 L focal length. Thus, in the present case, the spectrometer / monochromator has a single OS outlet, directly in front of the D detector.

Figure 8 illustrates a preferred embodiment of the spectrometer / monochromator of the present invention. In the spectrometer or monochromator, the S-beam optic LE is placed between the S sample (s) to be examined or the reference substance (s) R or the light source LS and the optical grid G. The LE pathway optics provide optically long distances, preferably by means of correctly positioned M mirrors, such that the light path is multiplied by these M mirrors. When using high quality M mirrors, this mode of light enhancement gives a very good efficiency of over 95% in practice with significant size reduction.

The use of the spectrometer / monochromator used in the apparatus of the invention has several advantages. A less powerful LS light source is required, can be implemented with conventional optical elements, making them easy to set up and making the equipment economically less expensive.

The simple construction of the device according to the invention by providing a rotational movement around the T-axis results in a simple and quick operation. For measurement, either the circular space containing the S sample (s) to be examined and the reference substance (s) R, or the rotational motion of the ML measuring light required for the measurement, may be generated. The desired movement of the ML gauge can be easily achieved by rotating the TMO luminosity optics. It is just as easy to do

Also, moving additional TMO luminous transducer optics to provide the LDS light sensor. Any combination of those described in the production of the ML metering light and the exemplary embodiments described in the sensing example may be implemented in the apparatus of the present invention.

An advantage of the present invention is that the sample reference change required to compensate for the instability of both the ML meter light and the LDS light sensor unit and the required scanning of the S sample to be tested are completely new in a single optical path, and accomplishes by positioning the constant reference substance (s) R in an annular space in the same plane, and forming a measuring light ML at an angle around the axis of the annular space as the axis of rotation. Since the optical elements used are common, perfect compensation can be achieved. From the rotational motion, the measurement of the S sample and the reference substance R is carried out very rapidly, practically simultaneously. Compared to this time difference, the time-varying speed of fast-changing - poor quality - components is negligible, so they seem stable in our solution.

The structure of the device according to the invention allows for a cheap construction and the design of the annular space results in a reduction of the size of the device. Further reduction in size is achieved by the use of luminous optics. The described properties provide a unique opportunity to realize a very advantageous, preferably portable, quantitative measuring arrangement for the present invention.

Claims (20)

PATENT CLAIMS 1. A method of quantitative measurement based on the measurement of luminous intensity, comprising illuminating a sample to be examined with a measuring light and measuring the reflected or passing luminous intensity, and increasing the accuracy of the measurement by the optical path of the sample using the optical path of the sample. is also illuminated and the intensity of light reflected or transmitted is also measured to compensate, characterized by placing the test sample (s) and the constant reference substance (s) in an annular space in the same plane, during the measurement (s), the measuring light is angled about the axis of the annular space as an axis of rotation, or the annular space is rotated with respect to the measuring light. Method according to claim 1, characterized in that the measuring light is produced by a light source extending out of the axis of rotation. A method according to claim 1, characterized in that the measuring light is arranged in the light 5 in the axis of rotation. EN 226 833 Β1 by means of light-path-changing optics, as light with an optical axis offset from the axis of rotation. Method according to claim 2 or 3, characterized in that the measurement of the intensity of light reflected from or passing through the sample (s) and reference substance (s) to be tested is performed outside the axis of rotation. A method according to claim 2 or claim 3, characterized in that the optical axis of light reflected from or passing through the sample (s) and reference material (s) is returned to the axis of rotation by further light-transmitting optics, wherein: light intensity is measured. Method according to claim 3 or 5, characterized in that prism, pair of mirrors or optical fiber (s) are used as the light-path optics and further light-path optics. 7. A method according to any one of claims 1 to 3, characterized in that a monochromator generating light of a specific wavelength is used in the formation of the measuring light. 8. A method according to any one of claims 1 to 3, characterized in that the light intensity is measured with a light detecting spectrometer of a specific wavelength. 9. A method according to any one of claims 1 to 4, characterized in that the annular space containing the test sample (s) and the reference substance (s) is rotated. Method according to claim 3 or 5 or 6, characterized in that the optical path modifying optic and / or further optical path modifying optic are rotated. 11. Apparatus for quantitative measurement based on measurement of luminous intensity having a sample to be examined by a first optical path in the path of the light emitted by the light source, a second optical path of the same optical path having a constant property of reference and the remainder of the optical paths provided, the first and second optical paths being formed as a single common optical path, characterized in that the sample (s) (S) to be tested and the reference substance (s) of constant property (R) are in a plane at the same distance from a given axis (T) are arranged in a ring shape, and during the measurements, the measuring light (ML) is formed around the axis (T) of the ring-shaped space as a axis of rotation, or is rotated around the ring-shaped space. Apparatus according to claim 11, characterized in that the optical axis of the light source (LS) is disposed in the axis (T) of the annular space. Apparatus according to claim 11, characterized in that the optical axis of the light source (LS) is disposed from the axis (T) of the annular space. Apparatus according to claim 12, characterized in that between the light source (LS) and the annular space containing the sample (s) to be tested and the reference substance (s) (R), the axis (T) ) Optical Lens Modification (TMO) Optical Axis Light (ML) is installed. 15. A 11-14. Apparatus according to any one of claims 1 to 3, characterized in that the light source (LS) is also provided with a monochromator. 16. A 11-14. Apparatus according to any one of claims 1 to 3, characterized in that the light sensing unit (LDS) comprises a spectrometer. 17. A 13-16. Apparatus according to any one of claims 1 to 4, characterized in that the optical axis of the light-sensing unit (LDS) is disposed in the axis (T) of the annular space, the annular ring containing the sample (s) and reference substance (s) to be tested. additional light-path-changing optics (TMO) between the light-emitting unit (LDS) and the light sensor unit (S) reflected from or passing through the sample (s) and reference material (R) to the axis (T) is installed. 18. A 13-16. Apparatus according to any one of claims 1 to 3, characterized in that the optical axis of the light-sensing unit (LDS) is circular in shape, coincident with the optical axis of light reflected from or passing through the sample (s) and reference material (s). space out of axis (T). Apparatus according to claim 15 or 16, characterized in that the optical grid (G) in the monochromator or spectrometer is from the light source (LS), the sample (s) to be tested and the reference substance (s). ) is located at an optically large distance from (R), preferably 10-20 times the focal length (L) of the spherical mirror (SM) located after the optical grid (G). 20. Apparatus according to claim 19, characterized in that the monochromator or spectrometer comprises the light source (LS) or the sample (s) to be tested (S) or the reference substance (s) (R) and the optical grid (G). ) is equipped with Luminous Optics (LE).