Device for measuring at least one dimension of an object and a method of operating said device

A device for measuring at least one dimension of an object, comprising a light source;

• an optical element for producing parallel light rays from said light source;
• optical means for the lateral deflection of light beyond the ray path of said optical element;
• a diaphragm having diaphragm apertures defining respectively the cross-sections of a first light channel into which the object to be measured is to be introduced and comprising rays derived directly from said optical element, and the cross-section of a second light channel comprising rays derived via said optical means and serving as a reference channel, the said diaphragm apertures being so dimensioned and arranged that the paths of light rays proceeding from said source to the respective channels are mutually exclusive;
• means for adjusting the relative quantities of light transmitted by said channels;
• a pair of photo-electric transducers arranged to be illuminated by the light transmitted by the said two channels, respectively;
• and a comparison circuit connected to the outputs of said transducers in order to compare the relationship between the intensities of illumination thereof.

A device for measuring at least one dimension of an object, comprising a light source;

• means defining a first light channel for light rays from said source and having a cross-section in the shape of a slit;
• means defining a second light channel of substantially smaller cross-section than the first;
• a diaphragm leaf mounted for movement in the direction of the major dimension of said first light channel;
• a micrometer coupled to said diaphragm leaf for effecting measured movement thereof;
• means for finely adjusting the cross-section of said second light channel;
• a pair of photo-electric transducers arranged to be illuminated by the light transmitted by the said two channels respectively;
• and a comparison circuit connected to the outputs of said transducers in order to compare the relationship between the intensities of illumination thereof.