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Non-contact Thickness Measurement Apparatus Disclosure Number: IPCOM000129033D
Publication Date: 2005-Sep-27
Document File: 3 page(s) / 697K

Publishing Venue

The Prior Art Database

Related People

James Cunnington: ATTORNEY [+3]


Apparatus for measuring the thickness of a material, in particular the thickness of a foamed material such as a foamed tobacco substitute material. The apparatus comprises a light source, a light refracting means such as a glass prism having a high optical quality, an image receiving means such as a camera and a sample holder which is suitably a glass slide. Depth or thickness of a sample of foamed material may be measured without contacting the sample, avoiding exerting a pressure on, and deforming, the sample.

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Non-contact Thickness Measurement Apparatus

The present disclosure relates to an apparatus for measuring thickness of a material, and in particular the thickness of a compressible material, such as a foamed material, including but not limited to a foamed tobacco substitute material. For example, the present apparatus is suitable for measuring the thickness, and related density, of a foamed smokable material as described in International Patent Publication WO 2005/044026.


Measuring the thickness of compressible materials using conventional apparatus, such as a conventional dual weight micrometer, is not possible as the pressure exerted by the micrometer deforms the material and results in inaccurate readings. This inaccuracy in determining the depth/thickness of a material results, in turn, in inaccuracies in the calculation of the density of the material. Accordingly, there is a need for an apparatus for measuring compressible materials without contacting the material.

An apparatus utilising the Maxtascan video measuring tool is described herein. In order to obtain accurate results the foam material has to be held flat, without distortion. As the Maxtascan is only able to measure on a horizontal plane an apparatus was designed to convert the Maxtascan from a horizontal to a vertical measurement tool. The diagram in Figure 1 below shows a side view of the device.

Figure 1

Summary of the Apparatus

The apparatus comprises a sample holder, a light source, a light refracting means and an image receiving means.

Preferably the sample holder comprises a glass slide, and ideally comprises two glass sides positioned either side of the material to be measured. The sample holder may be any suitable device that is able to provide a definite sharp contrast to an edge of the sample whilst not compressing or distorting the sample.

The refracting means is preferably a glass prism, having a high optical quality. The optical quality of the prism affects the accuracy of the measurement of the thickness of the sample. It is preferred that the refracting surface of the prism is at an angle of 45ยบ to the plane of the sample and the direction of the light source.

The image receiving means is suitably a camera, and may be a Maxtascan camera. It will be appreciated by a skilled person that any device that is capable of accurately measuring a distance between defined points provided by the sample holder would be suitable as the image receiving means and would allow the depth of a sample to be determined.

The apparatus also preferably comprises a support for the sample holder and the light refracting means. This support may suitably be made from steel, and is preferably coated with a black oxidant on a face in contact with the prism to reduce optical flaring.

Further features and specific details of the apparatus may be seen in Figure 1 and Figures 4-5.


In order to asses the level of effect the new method has on the measurement of compressible foamed...