Method for determining film thickness, method for producing a film and device for producing a film

A method of producing a wet cellulose-based film, comprising:

• providing a continuous conveyor having a conveyor width,
• using a casting device for applying the wet cellulose-based film comprising a film forming component, which is distributed in a medium that is to be essentially removed, onto the conveyor, so as to solvent cast the wet cellulose-based film,
• determining a wet film thickness, or a wet film thickness distribution, or both by:
• providing a laser projection across the conveyor, the laser projection extending across a wet film edge,
• acquiring a series of images, each depicting an area of the conveyor, wherein the laser projection, a portion of the wet cellulose-based film, and a portion of an exposed conveyor surface are visible, wherein said wet cellulose-based film comprises at least 75% by weight of the medium when the series of images is acquired, and
• using at least some of said images to determine at least one of the wet film thickness and the wet film thickness distribution across the wet film width, and
• adjusting at least one casting parameter based on said determined wet film thickness, or said wet film thickness distribution, or both, so as to change the wet film thickness, the wet film thickness distribution, or both provided by the casting device.

A device for producing a wet cellulose-based film, comprising:

• a continuous conveyor having a conveyor width;
• a casting device for applying the wet cellulose-based film comprising a film forming component, which is distributed in a medium that is to be essentially removed, onto the conveyor, for solvent casting the wet cellulose-based film to provide a wet film width that is less than the conveyor width;
• a laser projection device configured to provide a laser projection across a wet film edge;
• an image capture device configured to acquire a series of images, each depicting an area of the conveyor, wherein the laser projection, a portion of the wet cellulose-based film, and a portion of an exposed conveyor surface are visible, the image capture device positioned at a location wherein said wet cellulose-based film comprises at least 75% by weight of the medium when the series of images is acquired;
• and
• a processing device, configured to use at least some of said images to determine at least one of a wet film thickness and a wet film thickness distribution across the wet film width.