Detection of pitch variations in lenticular material

Apparatus for forming a lenticular image product from a sheet of lenticular material having one side forming an array of cylindrical lenses having a pitch between lenses and a flat opposite side and a photographic emulsion coated on the flat side, said emulsion having a range of wavelength sensitivity comprising:

• means for scanning the flat side of the lenticular material with an intensity modulated first beam of light in a direction parallel to the long axes of the cylindrical lenses to form a latent lenticular image in the photographic emulsion;
• means for focusing a second beam of light having a wavelength outside of the range of sensitivity of the photographic emulsion into a spot smaller than the pitch of the cylindrical lenses onto the lenticular material;
• means for moving the lenticular material in a direction perpendicular to the axes of the cylindrical lenses to provide a page scan motion of the lenticular material and to modulate the angle of reflection or refraction of the second beam of light;
• and
• a position sensor for sensing the position but not the intensity of the angularly modulated second beam of light to control the motion of the lenticular material.