For newcomers to the field of optics, it is necessary to understand the differences between the object-square telecentric lens and the image-square telecentric lens. Telecentric lenses can be categorized into two main types according to the optical path design: object-square telecentric lenses and image-square telecentric lenses.

1. Object Telecentric Lens：By controlling the main light ray of the object side parallel to the optical axis, the effect of changes in object distance on imaging is eliminated. In practice, when the distance between the object to be measured and the lens changes, the size of the image captured with the Objective Telecentric Lens does not change significantly and the imaging magnification remains stable. This feature makes it a great choice for industrial inspection, for example, when measuring the dimensions of a part, even if the position of the part on the conveyor belt fluctuates slightly, to ensure the accuracy of the measurement results.

2. Like a square telecentric lens：Problems caused by sensor position errors and uneven illumination are minimized by making the main image-square ray parallel to the optical axis. In the imaging process, the image-square telecentric lens can effectively avoid the image distortion caused by the inaccurate sensor installation position, and at the same time, it can also reduce the image brightness difference caused by uneven illumination, so as to obtain high-quality and high-precision images. Therefore, it is often used in fields that require extremely high image quality, such as high-precision medical image analysis and semiconductor chip inspection.

Bilateral telecentric lenses (double telecentric lenses) combine the advantages of both and are mostly used in ultra-high precision measurement systems (e.g. semiconductor inspection). In actual projects, like the square telecentric is used less frequently, industrial scenarios are more inclined to choose the object-square or double telecentric solution.