Diameter 100 Collimated Light Source - 90-Degree Turn

I. Most common industrial vision measurement errors are caused by the lens Engineers working on machine-vision projects often encounter frustrating problems: the measured size of the same part changes when its placement height varies slightly; circular holes near the image edge appear elliptical; and pin or small-hole measurements drift despite repeated software calibration. Often, the issue is incorrect lens selection rather than an inadequate algorithm, and a telecentric lens should be considered. II. The core difference between telecentric and ordinary industrial lenses The main difference is optical-path design. Ordinary lenses use diverging and converging rays and exhibit obvious perspective parallax: nearby objects appear larger and distant objects smaller. Even height variations of a few tenths of a millimeter on a fixture can cause measurement errors. A telecentric lens uses a special structure so that incoming chief rays are parallel to the optical axis. Within the depth of field, slight vertical workpiece movement produces essentially no change in magnification, eliminating the underlying near-large/far-small parallax problem. III. Three mainstream industrial telecentric lens types Common types are object-space telecentric, image-space telecentric, and bi-telecentric. Object-space telecentric lenses are most widely used for routine production-line measurement, offering good cost performance for most planar dimensional inspections. Bi-telecentric lenses maintain parallel rays on both object and image sides, offer higher achievable accuracy and very low distortion, and suit applications with exceptionally high measurement-stability requirements, at substantially greater cost. Image-space telecentric lenses serve more specialized applications, primarily advanced research and microscopic imaging, and are rarely used on ordinary industrial lines. IV. When telecentric lenses are essential and when they are unnecessary Not every vision project needs a telecentric lens. Ordinary industrial lenses are sufficient for presence/absence inspection, simple positioning and recognition, or coarse defect screening, avoiding unnecessary equipment cost. Telecentric lenses become essential for precision dimensional measurement, inspection of thick parts, hole position and diameter measurement, or stepped-part inspection where placement height varies and imaging affects results. They are key to maintaining inspection accuracy. V. Main industrial applications Applications are extensive. In 3C electronics, lenses inspect connector pin spacing, glass-cover dimensions, and precision-button contours. Semiconductor applications include wafer, chip-pin, and miniature-component contours and spacing. Automotive applications measure pin, gear, and battery-component hole diameters and outlines. Pharmaceutical packaging, precision hardware, and optical-component inspection also rely on them. Production lines experiencing fluctuating measurements or inaccurate yield decisions often see immediate improvements in data consistency and inspection stability after installing a suitable telecentric lens. VI. Common selection and commissioning pitfalls Experience from project sites provides several practical lessons. First, do not pursue high magnification indiscriminately. Excessive magnification reduces the field of view, so slight part displacement can move it out of frame. Determine the field from both workpiece size and camera sensor dimensions, preferably retaining a 10%-20% margin for fixture vibration and placement variation. Second, telecentric lenses have a fixed nominal working distance; large departures substantially reduce telecentric performance and resolution and directly impair measurement accuracy. Third, match the lens and illumination. Telecentric lenses are better suited to parallel illumination; ordinary diverging ring lights can darken image edges and cause blur, reducing overall system performance. VII. Precision control and routine maintenance Although telecentric-lens distortion is already low, it cannot be ignored. Software calibration cannot be expected to compensate for intrinsic lens defects. Evaluate distortion during selection and prioritize well-controlled products. Routine maintenance is also essential: dust, grease, and scratches interfere with edge imaging and cause measurement errors. Regular cleaning and inspection prevent equipment deterioration from reducing accuracy. VIII. Assessing advantages and limitations objectively Compared with ordinary lenses, telecentric lenses are larger, heavier, and considerably more expensive. Large-field-of-view models cost substantially more. They require installation space and mechanical stability and may not fit compact equipment well. Selection must balance accuracy, installation conditions, and budget rather than simply pursuing the highest configuration. Choosing to actual requirements is the best solution. IX. The optical foundation of precision measurement Telecentric lenses are core hardware in precision machine-vision measurement. They are not universal solutions, but address parallax and magnification drift that ordinary lenses struggle to overcome. Stable, reliable measurement requires algorithm optimization and commissioning, suitable illumination, and a lens matched to operating conditions. Projects with unstable dimensions, thickness-induced imaging errors, or poor measurement repeatability should evaluate a suitable telecentric lens against their actual conditions.

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