FI116240B - Method and apparatus for measuring the density of wood materials using a laser optical sensor - Google Patents

Description

-1-116240

Method and apparatus for determining the density of wood by a laser optical sensor

The present invention relates to a device and method for determining the density of a tree based on a laser optical sensor.

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There are several prior art methods for determining wood density. The most traditional method of determining the density of wood is to weigh the sample and determine its volume. The density of a piece can be calculated from the ratio of the weight of the piece to the volume.

This assay yields an average density of wood but does not provide detailed density information, for example, on annual rings. The same is true for methods based on the use of particulate radiation. Nowadays, the use of X-ray based methods and devices for determining the density of wood has become more widespread, and suitable devices are commercially available.

The development of the method and apparatus according to the invention has been motivated by the fact that the use of X-rays in measuring instruments imposes limitations on the devices and their implementation, which complicates the structures. In addition, proper radiation training is required to operate the device. As a result, the general aim was to develop a laser optical method for measuring the density of the wood and a device that does not require any special radiation. In addition, it was a general requirement that the method achieve a resolution of • · 1 class of wood sample structures as with known X-ray illumination devices.

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! In addition to the above, the following patents are known: 1) WO 97/04299 (G01N

i t i!.! 25 21/17), the content of which is to be considered as known for measuring the density or density profile of a wood-based board using e.g. transmissionspektrometrimenetelmää.

. , Spectrum formation here refers to the division of light into wavelength components by a prism or lattice. 2) DE 19543134 (B07C 5/342) using a lattice or prism.

The radiation is detected by a row detector, whereby the light components are divided into groups according to the detector elements 30. 3) US 5530551 (G01B 11/00), wherein the light guiding element is • 1 * · ·. 1 bundle of optical fibers and as detector a CCD array to which the laser beams can be directed:; : into their own groups of fiber bundle fibers, respectively. 4) DE 19609045 (G01N 21/25) and 5) -2-1166240 WO 98/49545 (GOIN 21/89), in which the scattered radiation is directed into groups by mirrors, and the image signal of the camera row detectors is used for measuring the density of the wood. 6) DE 4410596 (GO 1N 21/84) and 7) US 3566121 (GO 1T 1/16), in which the density distribution of wood can be measured by transmitted optical radiation using a camera lens to refract the light components 5 onto the photosensitive detector of the CCD camera.

In order to overcome the shortcomings of the above methods and devices and to achieve a faster and simpler analysis of the density of wood, a laser-based method and device have been developed, the features of which are disclosed in the appended claims.

The invention will now be described in more detail with reference to the figures in the accompanying figure. In the method, the laser beam directed from the laser 1 at the lens 2 is directed to the sample 3. The laser light components scattered through the wood sample are directed to a computer-generated light-bending element 5 by a guide 4, typically a mirror 15, whose function differs from the prism in the mirror. The element divides the laser light components proportional to the density and order of the wood into their respective groups for the photosensitive detector 6 of the electro-optical camera. Measurement and analysis of the number of light components is performed by means of a computer 7 connected to the detector.

The method differs from the normal extinction assays in that the sensor includes, as part of a computer-generated light-bending element 5, that separates the light components proportional to the density and order of the structure of the wood into individual groups. The density values of the wood obtained by the apparatus and method are comparable to the density values obtained by methods and apparatuses based on X-ray scanning. In addition: 25 methods and devices provide information on the organization of woody structures (anisotropy). 1 »> <

Claims (4)

116240 -3- A method for determining the density of wood using a laser optical sensor, characterized in that the laser light components scattered through the wood sample 3 are controlled by the reflector 4 and the laser light components reflected by the wood sample 5 by the reflector 8 into groups of the electro-optical camera. Apparatus for implementing the method of claim 1, wherein laser light components scattered through the wood sample and reflected from the wood sample are guided together by the same light-bending element 5 to a photosensitive detector of the same electro-optical camera, characterized in that laser scattered measure simultaneously. Device according to Claim 2, characterized in that separate lens lenses are not used in connection with the bending element 5. Device according to claim 2, characterized in that the components scattered through or reflected from the wood sample are produced from the same sample site. 4, 116240