With polarization filters which enable detection of foreign bodies by making them clearly visible in the dark area. This device is intended especially for hospital use and for manufacturers of infusion bottles. Its design is the same as No. 1352, however, it can be used from two sides which leads to quicker completion of work arising.

The testing device consists of the light housing (1) with 3 fluorescent lamps (2) and the light scattering opal glass plate (3). As the polarization filters used should not be overheated exceeding a temperature of 70°C during uninterrupted use if possible, the filter (4) is fastened in front of the light housing by means of an insulation ring. The second filter (5) which is held in a metallic mount (6) being right in front of the magnifying lens (7) permitting 2-fold magnification renders it possible that a rotary motion of 90 degrees is being realized out of the polarization plane. The metallic mount (6) is displaceable in the longitudinal direction to adjust the desired enlargement. Testing of the filled white bottles shall be carried out in a room not being too bright, if possible. Prior to the latter the polarization filter (5) needs being adjusted by means of buttons (8) to the maximum polarization degree, i. e. to the almost entire darkening of the visiual field. If there are foreign bodies

in the bottles positioned between both filters, they are illuminated in the polarized light and are very clearly visible. The bottles are supported by two axes and are turnable by means of 3 rollers (9) each. The method of testing does not overstrain the eyes of the operator so that even over long periods no signs of tiredness arise. Both filters have a diameter of 250 mm, the magnifying lens is 300 mm in diameter. For brown bottles a cold light device can be installed, for which an extra price is charged.