26 Oct 2017
Telecentric lenses are particularly important when accurate measurements need to be made from parts that may pass in front of the camera at varying distances. This often happens in automated inspection systems since as objects move through the field of view of the imaging system their position is rarely perfectly repeatable. Unlike conventional lenses, telecentric lenses collimate the light ensuring that all objects appear at an equal magnification providing they are located within the depth of field of the lens. This means that no magnification compensation is needed.
The Vico DTCM series have the added benefit that they are bi-telecentric lenses. These have two components to not only collimate the light as it enters the lens but also as it leaves the lens to the camera sensor. This gives a significantly improved depth of field compared to standard telecentric lenses. Bi-telecentric lenses also ensure a very even illumination of the image sensor, and overall improve measurement accuracy.
Since telecentric lenses collimate the light, the aperture of the lens needs to be the same size as the field of view. The large number of lenses in the DCTM range covers fields of view from 16.6 to 300 mm, meaning that a lens can be chosen to match the particular application, minimising the cost of these large lenses. The DTCM series also supports the highest pixel resolution among area scan cameras.
A choice of C-mount or F-mount lenses means that a wide range of applications can be accommodated. These include metrology, inspection and extremely accurate measurement of large items such as engine parts, glass or metal sheets, PCBs and electronic components, LCDs, etc. Key features of the DTCM series are:
Although the different lens families are designed for use for a variety of sensor sizes, some of them are optimised for specific sensors:
Depth of field and optical accuracy can be further improved using the DTCL series of telecentric backlight LED illumination sources.