As the machine vision system is widely used in the field of precision testing, general industrial camera is difficult to meet the test requirements, to make up for the shortage of normal lens application, to meet the needs of precise detection, telecentric lens arises at the historic moment.
Relative to ordinary lens, telecentric lens and actually what are the advantages?
Detailed introduction for you.
A: image resolution with quantitative image sensor commonly existing spatial frequency contrast the CTF (
Contrast transfer function)
The measure, the unit for lp/mm (
Per mm line coupling number)
Most of the machine vision integrator is often just brings together a large number of cheap low pixels, low resolution camera, can only be generated after the image of fuzzy.
And USES the telecentric lens, even with small pixel image sensor (
Such as 5.
5 million pixels, two-thirds of & # 39;
, can also generate high resolution images.
Two: the distortion coefficient of the physical size and the size of the image sensor imaging differences in percentage.
Ordinary machine lens distortion is usually higher than 1 ~ 2%, may seriously affect the precision of the measurement level.
Such as: actual 50 mm wide objects, under this kind of lens imaging width could reach 51 mm)
And the distortion of telecentric lens residual is less than 0.
Such as: actual 50 mm wide, width is never greater than 50 when imaging.
5 mm, distortion coefficient, by contrast, is only one over twenty of the normal lens)
, is the advanced technical level, reached the high standard optical testing the limits of the instrument.
3: in metrology applications for precision linear measurement, often need to positive (from the object standard
Don't include side)
In addition, many mechanical parts and can't accurate placement, measuring time is in constant change.
Whereas software engineers need to be able to accurately reflect the real image.
Telecentric lens can perfect solve above confusion: because the entrance pupil at infinity, when imaging will only receive parallel optical axis of the main beam.