Biomedical subjects
Publications and source records attributed to V Hyvärinen.
A method and a sensor device were developed to detect dynamic laser speckle pattern for monitoring of deformation of pharmaceutical tablets after compression. Temporal variations in optical signal revealed local surface deformation of the ibuprofen and the starch acetate tablets as well as anisotropy of tablet surfaces at the inspection location.
Optical inspection techniques for estimation of surface roughness and surface quality of flat punches, which are used in the pharmaceutical industry for tablet compression, were studied. It was observed that a simple specular reflection technique is useful for surface roughness assessment of flat punches. A diffractive element based sensor was used for the surface quality detection, such as mirror property or flatness, with the aid of image information of a test pattern. It was observed that a new punch may have a poorer surface quality than a used one.
Optical surface quality of concave shaped punches was investigated with a diffractive optical element based sensor. Image information of the present sensor was studied for the purpose of surface roughness and reflectance inspection. The robust sensor is proposed for off-line optical inspection of concave punches.
Optical surface roughness of starch acetate compacts was investigated by specular reflection of a laser beam as a function of angle of incidence. The intensity data was fitted using the model of Gaussian and Lorentzian curves to solve numerical values for optical surface roughness which was observed to be order of 1 microm with the present samples.