The concept of "Two lenses in contact" refers to the arrangement of two lenses that are placed in direct physical contact with each other, typically with the goal of manipulating the properties of light passing through both lenses.
The purpose of using two lenses in contact is to create a compound lens system with unique optical properties that cannot be achieved with a single lens. This can include magnifying or reducing the size of an image, correcting for lens aberrations, and changing the focal length or depth of field.
The combined power of two lenses in contact can be calculated by adding the individual powers of each lens. If the lenses have the same power, the combined power will be twice the power of one lens. If the lenses have different powers, the combined power can be calculated using the lensmaker's equation.
One potential drawback of using two lenses in contact is the possibility of introducing additional optical aberrations or distortions. Other factors to consider include the size and weight of the lens system, as well as the potential for increased cost and complexity.
The distance between the two lenses, also known as the lens separation, can affect the combined power of the lenses. Generally, a smaller lens separation will result in a higher combined power, while a larger separation will result in a lower combined power. However, the specific effect may vary depending on the individual properties of the lenses in contact.