Difference between telecentric lens and ordinary lens

Today, Dehong Technology takes you to analyze the difference between telecentric lens and ordinary lens. Telecentric industrial lens is mainly a lens specially designed to correct the parallax of traditional industrial lens. It can reach The image magnification does not change with the change of the object distance, which is a very important application for the case where the measured objects are not on the same object surface.

    The closer the ordinary industrial lens target object is to the lens (the shorter the working distance), the larger the image will be. When using ordinary lenses for dimensional measurement, the following problems exist:

(1) Because the measured objects are not in the same measurement plane, the magnification is different;

(2) Large lens distortion

(3) Parallax, that is, when the object distance becomes larger, the magnification of the object also changes;

(4) the resolution of the lens is not high;

(5) The uncertainty of the edge position of the image due to the geometric characteristics of the visual light source.

    The telecentric lens can effectively solve the above problems existing in ordinary lenses, and there is no judgment error of this nature, so it can be used in high-precision measurement, metrology and so on. A telecentric lens is a high-end industrial lens that usually has superior image quality and is particularly suitable for sizing applications.

    No matter where, at a certain working distance, the same magnification will be obtained after refocusing, because the maximum field of view of a telecentric lens is directly related to the closeness of the light bar of the lens. The larger the lens size, the more the scene required Big. Telecentric measuring lenses provide superior image quality with less distortion than traditional fixed-focus lenses. This optical design makes the image plane more symmetrical and can be used for precise measurements with software.

Common lens advantages: low cost, practical, and versatile.

Disadvantages of ordinary lenses: there will be changes in magnification and parallax.

General lens application: imaging of large objects.

Advantages of telecentric lenses: constant magnification, does not change with depth of field, no parallax.

Disadvantages of telecentric lenses: high cost, large size and heavy weight.

Applications of Telecentric Lenses: Measurements, CCD-based Measurements, Microcrystallography