Choose the appropriate industrial camera lens to consider what are the problems
Industrial camera lens selection process, is the industrial camera lens gradually explicit process parameters.
As imaging devices, industrial camera lens and light source, camera usually together constitute a complete image acquisition system, so the industrial camera lens choices are restricted by the system requirements.
Generally can analysis according to the following several aspects to consider.
One, wavelength, zoom whether or not industrial camera work wavelength need zoom is relatively easy to determine down, need to change the magnification of the application in the process of imaging, the zoom lens, otherwise the prime lens is ok.
About the industrial camera work wavelength, common is visible, there are other band applications.
Do you need another filter measures?
Monochromatic light or polychromatic light?
Can effectively avoid the influence of stray light?
Consider the problem of this a few clear, comprehensive measure wavelength to determine the lens again after work.
Second, the special request priority combining with the actual application, there may be special requirements, should be more clear.
If there's any measurement functions, for example, whether to need to use industrial camera lens, imaging depth of field is very big, and so on.
The depth of field is often ignored, but it is any imaging system must be considered.
Three, working distance, the focal length the working distance and focal length is often combined with consideration.
Generally, can use the train of thought: the resolution of the first clear system, combined with CCD pixel size can know magnification, coupled with spatial structure constraint can know about the image distance, further estimate the focal length of the camera lens.
So the industry is the focal length of the camera lens and industrial camera working distance, system resolution (
And the CCD pixel size)
Four, and the size of the image plane and the image selected industrial camera image plane size to be compatible with digital sensor surface size, follow the principle of 'big compatible with little' -
Digital sensor surface can't exceed lens labeled as dimensions -
Otherwise the image quality is not confirmed at the edge of the field.
As qualitative requirements mainly focus on two of MTF and distortion.
In measuring application, especially should attach importance to distortion.
Five, the aperture and interface industrial camera lens aperture main effect like the brightness.
But now the machine vision, the final image brightness is decided by many factors: camera aperture, gain, integral time, light, etc.
So, in order to obtain the necessary image brightness have more link for adjustments.
Industrial camera interface refers to its connection with the camera interface, they both need to match, can't match directly transfer should be considered.
Six, cost and technical maturity if after the above factors have a number of solutions can meet the requirements, can consider to cost and technical maturity, to weigh the meritocratic selection.
For example, to coin detection matching industrial camera lens imaging system, constraint conditions: camera CCD 2/3 inch, pixel size 4.
65 mu m, C.
Working distance is greater than 200 mm, the system resolution of 0.
Light source USES white LED light source.
Fundamental analysis is as follows: 1.
Used with white LED light source, lens should be visible.
No zoom, choose prime lens.
For industrial detection, among them with a measuring function, so the selected small lens distortion requirements.
Working distance and focal length of imaging magnification M = 4.
65 / (
093 focal length f = '* M/L (
= 200 * 0.
093 = 17 mm distance requirement is larger than 200 mm, the choice of lens for the focal length should be greater than the 17 mm.
Select camera image plane should not be less than the CCD size, or at least two-thirds of inches.
Interfaces is C mouth of the lens can be used with the camera.
No request aperture.
From the above aspects can preliminarily concluded that the lens of the analysis and calculation of the 'outline' : the focal length is more than 17 mm lens, optical wavelengths, C, at least with 2/3 inch CCD can be used, and imaging distortion is smaller.
According to these requirements, can be further selection, if many lenses can meet these requirements, you can choose according to qualification.