The most important requirements for lens cementing are: 1- The lenses must be perfectly aligned, with no air gaps between them. 2- The work must be carried out in a dedicated cementing booth. 3- The ambient temperature (workroom temperature) must be appropriate. 4- It is recommended that the equipment be tested with precision instruments to measure the curvature using a number of Newton's rings (N = less than 5). 5. The focal point between the two lenses must be less than 100 microns to eliminate aberrations. 6. The lenses can only be separated using high torque settings exceeding 200C Cementing involves joining two or more lenses, depending on the desired design,made from two different materials, with a smooth finish( 14) and under high pressure between the optical surfaces, ensuring high cleanliness. 3 pes centimeters. University of Al-Mustaqbal – The First and Leading Private University