Recording of position-specific wavelength absorption spectra
The invention relates to recording of position-specific optical measurements of substances such as foodstuff, building materials, combustion products etc. The invention provides online, in-situ recording of wavelength absorption spectra in substances, performed without removing a sample from the substance. In inhomogeneous products, the position correlated to each spectrum allows for extraction of both average values for larger regions as well as specific values characteristic for smaller individual portions. In a preferred embodiment, a probe with two elongate arms has light guiding and light collecting means for recording infrared absorption spectra of portions between them, as well as means for determining an insertion distance into the product. The invention may be applied to as different substances as diary products (cheese, cream, milk), fruit, berries, seeds, meat, vegetable and animal fat, animal feed, water, wine, beer, lemonades, oils, rubber and plastic materials, gypsum and plaster, cement and concrete mixes, paints, glues etc.
1. An apparatus for recording of wavelength absorption spectra in a substance, the apparatus comprising
a probe for penetrating into the substance, the probe having light transmitting means and light receiving means for receiving light transmitted from the light transmitting means, the light transmitting means and the light receiving means defining an optical path of light between the light transmitting means and the light receiving means, the probe being shaped so that when the probe is inserted into the substance an interior portion of the substance at a depth corresponding to the insertion depth of the probe will be received in the optical path
a means for determining the insertion depth of the probe in the substance, comprising a support for abutting an exterior portion of the substance and a stepping motor operating on the support, when the support abuts against the exterior portion of the surface, for extracting the probe from an inserted position, wherein the insertion depth is determined relative to the support during extraction of the probe;
a light source for providing infrared light of multiple wavelengths to the light emitting means and
a detecting unit for detecting wavelength spectra of light received by the light receiving means.
2. The apparatus according to claim 1 wherein the probe is a cutting probe with a sharp end portion for penetrating a surface of a product.
3. The apparatus according to claim 1 , further comprising a data processing unit for receiving detected wavelength absorption spectra and being configured to determine qualitative and/or quantitative parameters of the substance, the data processing unit comprising a memory for holding a database of wavelength spectra previously detected on similar substance portions with known qualitative and/or quantitative parameters, and means for comparing detected spectra with spectra from the database to identify at least approximate qualitative and/or quantitative parameters of corresponding interior portions of the substance.
4. The apparatus according to claim 3 , wherein the data processing unit is configured to provide the qualitative and/or quantitative parameters as a function of insertion depth.
5. The apparatus according to claim 3 , wherein the data processing unit comprises software configured to perform in-situ spectra-based grading of the substance.
6. The apparatus according to claim 1 , further comprising a data processing unit for receiving detected wavelength absorption spectra and being configured to determine a content of a predefined substance in the substance, the data processing unit comprising a memory for holding a database of wavelength spectra previously detected on similar substance portions with known contents of the predefined substance, and means for comparing detected spectra with spectra from the database to determine the content of the predefined substance in corresponding interior portions of the substance.
7. The apparatus according to claim 1 , wherein the apparatus is interfaced with a system configured to perform online spectra-based grading of the substance.
8. The apparatus according to claim 1 , further comprising a means to correlate a determined insertion depth or a change in insertion depth with a detected wavelength absorption spectrum and to trigger recording of a wavelength absorption spectrum for every extraction step of the probe.
9. The apparatus according to claim 1 , wherein a first surface part of the probe is an optical window through which light from the light transmitting means will exit the probe, and an opposite second surface part of the probe is an optical window through which light from the light emitting means will enter the probe to be received by the light receiving means.
10. The apparatus according to claim 9 , wherein the first and second surface parts are surface parts of the first and second knife, respectively, and wherein a distance between the optical windows of the first and second knives is at least substantially the same as a distance between the points of the first and second knives.
11. The apparatus according to claim 1 , wherein the probe comprises a first knife holding the light transmitting means and a second knife holding the light receiving means, the first and second knives extending in parallel from a common base and each having a point for penetrating a surface and a first cutting edge starting at the point.
12. The apparatus according to claim 11 , wherein the cutting edges of the first and second knives can be projected onto the same straight line.
13. The apparatus according to claim 1 , wherein the probe is formed in a material composition and dimensioned to ensure a constant distance between the light emitting means and the light receiving means during insertion in the substance.
14. The apparatus according to claim 1 , wherein the detecting unit is configured to record a spectrum of infrared light received from the light receiving means at user determined intervals when the means for determining insertion depth of the probe indicates that there is no interior portion of a meat product in said optical path between the light emitting means and the light receiving means.
15. A method for recording infrared wavelength absorption spectra in a substance, the method comprising:
providing an apparatus comprising a probe for penetrating into the substance, the probe having light transmitting means for transmitting infrared light and light receiving means for receiving light transmitted from the light transmitting means, an optical path of light being defined between the light transmitting means and the light receiving means, the probe being shaped so that when the probe is inserted into the substance an interior portion of the substance at a depth corresponding to the insertion depth of the probe will be received in said optical path, the apparatus further having a support for abutting an exterior portion of the substance and a stepping motor operable on the support and configured to change the position of support relative to the probe;
inserting the probe into the substance to a first insertion depth so as to receive a first interior portion of the substance in said optical path and so that the support abuts an exterior portion of the substance;
operating, while the support abuts the exterior portion of the substance, the stepping motor to withdraw the probe from the substance so as to change the insertion depth of the probe in the substance to a second insertion depth so as to receive a second interior portion of the substance in said optical path
determining the second insertion depth of the probe as a distance relative to the support;
transmitting infrared light of multiple wavelengths from the light transmitting means;
receiving light transmitted from the light transmitting means; and
recording a wavelength absorption spectrum of light received by the light receiving means.
16. The method according to claim 15 , wherein the substance is a meat product.
17. The method according to claim 15 , wherein inserting the probe into the substance is performed in situ so that no sample is removed from the substance.
18. The method according to claim 15 , further comprising the step of performing an online grading of the substance based on the detected series of spectra.
19. The method according to claim 15 , wherein the step of changing an insertion depth of the probe is a stepwise reduction of the insertion depth so that spectra are stepwise detected during extraction of the probe from the substance.
20. The method according to claim 15 , further comprising the step of comparing detected wavelength absorption spectra with wavelength absorption spectra previously detected on substance portions with known qualitative and/or quantitative parameters to determine corresponding qualitative and/or quantitative parameters of the portion(s) used in the recording.
21. The method according to claim 15 , further comprising the step of comparing detected wavelength absorption spectra with wavelength absorption spectra previously detected on substance portions with known contents of a predefined substance to determine a content of the predefined substance in the portion(s) used in the recording.
22. The method according to claim 15 , further comprising the step of pre-processing detected wavelength absorption spectra to sort spectra into segments and merging, or forming mean values of, spectral data in a segment.
23. The method according to claim 22 , wherein each segment corresponds to one or more insertion depth intervals in the substance and wherein spectra are sorted according to their corresponding insertion depth.
24. The method according to claim 23 , further comprising the step of using qualitative and/or quantitative parameters from individual segments to determine a grading of the substance.
25. The method according to claim 22 , wherein corresponding qualitative and/or quantitative parameters are determined for individual segments.
26. An apparatus for recording a wavelength absorption spectra in a substance, comprising:
a housing that comprises a light source and a probe, which comprises a transparent window
an optical fibre that receives and transmits light from the light source to a collimator, which forms directional light deflected by a mirror and transmitted by said transparent window
a detecting unit, which detects absorption spectra received from the optical fibre
a support that abuts an exterior portion of the substance
a stepping motor operating on the support, which can extract the probe from an inserted position by pushing the support against the exterior portion of the substance and
a position calculation unit that determines the depth of the probe in said substance during extraction of the probe from the inserted position.