【Telecentric Lens】Contrast between macro lens and telecentric lens

In: Lens Wiki On: Monday, April 20, 2020 Hit: 2363

In industrial applications, telecentric lenses are well known for their higher resolution, higher contrast and higher cost than conventional lenses. But this article is not about it, but macro lens, why macro lens can challenge the excellent performance of the telecentric lens, it is worth special attention? I believe you will have an answer after reading this article.



As a rising star, macro lens has many advantages that telecentric lens does not have. Of course, due to the different structure, there will be some shortcomings in some aspects. It is important to choose the right lens in different situations to achieve a balance between effect and cost. In this paper, two products of DZO dongzheng optics, namely telecentric lens TC031150E and macro lens MC2535A, are compared.

Compared with the telecentric lens, the macro lens has a variable working distance (multiplier), a larger field of view than the lens diameter, distortion comparable to the telecentric lens, a larger aperture, smaller volume, and lower cost. The resolution of the telecentric lens can generally reach the diffraction limit of the designed aperture value, while the aperture of the macro lens is larger than the telecentric lens, so it is difficult to achieve the diffraction limit. Correspondingly, the amount of light into the macro lens is far greater than that of the telecentric lens, as shown in FIG. 1.




                                                                      2.Resolution card comparison table

In terms of resolution, the maximum identifiable area of the two images is concentrated in the fifth group from the first element to the second element, which is about 32-36lp/mm, and the resolution of the converted image is about 110lp/mm. From FIG. 3, the two lenses satisfy the theoretical value, while the contrast of the telecentric lens seems to be higher.

     3.TC031150E MTF


In terms of distortion, the distortion of telecentric lens is generally less than 0.1%, and the telecentric lens of DZO is generally less than 0.05%. As shown in FIG. 3a and b, the DZO macro lens can control the optical distortion below 0.1%, which is difficult for the non-telecentric lens. Therefore, the macro lens can completely replace the expensive telecentres in terms of accurate 2D contour measurement and detection of minor defects.



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