Digital imaging lenses are often made of multiple lens elements to achieve the required specifications. How are those lens elements made in mass production ? The answer to this question depends on the type of element chosen by the lens design engineer. Three types of lens elements are commonly used today. They are polished glass elements, molded plastic elements and molded glass elements. Each type of elements has its own unique process steps and capabilities. …
It is well-known that the magnification of an imaging lens changes with the object distance (distance from the object to the lens). However it is less known that the magnification changes with the field angle as well (i.e, where in the field the object is placed). Additionally the off-axis magnification can be asymmetric. In other words, the tangential and sagittal magnifications can be different. This causes shape deformation for off-axis objects. For example, a golf…
Lens distortion is a commonly used term in the general specification of lenses. The classic, textbook definition of distortion includes barrel and pincushion type distortions. These concepts are useful for photographic optics where the field of view of the lenses are not extreme. Lenses designed for machine or computer vision applications can have extreme field of views. Field of view greater than 100 degrees are common specifications for machine vision lenses. We need to develop…
“Scaling’ refers to a method where a known lens design is proportionally enlarged or reduced geometrically to meet a different image size requirement from what the lens was originally designed for. For example, say, we have a lens that was originally designed for a 1/3” format sensor with an image circle of 6mm, we can “scale” up that design to make the image circle 8mm. This new scaled-up design is now capable of supporting a…
