Chiopt Classroom | How to do the industrial lens selection?

Industrial lens selection is a very important and key link, because industrial lens selection is related to the imaging quality of machine vision. Let's learn about the basic parameters, formula and examples of lens selection.

1. basic parameters of lens selection

Field of view (FOV)

Working distance (WD)

Sensor size

Pixel size

Interface (Mount)

2. model selection formula

focal length f=WD × CCD Chip size ( H or V) / FOV( H or V)

3-1. Example of industrial lens selection - area array lens

Disc screw Identification & tooth burrs

Known conditions:

Lens type: FA;

Camera model: 1/2.5 "500W Basler;

Chip diagonal 6.4mm;

Fov:150*150mm, diagonal 210mm;

calculation:

Optical magnification =6.4/210=0.03x;

The working distance is not required, but the closer it is, the better; WD is better between 2-4 times of the field of vision, so 2x is selected here; Focal length ≈ optical magnification *wd ≈ 0.03 × 420 ≈12mm； The final model selection is fa1201c.

3-2. Example of industrial lens selection telecentric lens

Known conditions:

1 "chip;

Field of vision 40mm*35mm;

Telecentric lens.

calculation:

Magnification = chip / field of view =12.8/40=0.32x;

Find an image plane equal to or greater than 1 "; The magnification is slightly less than 0.32x; According to the lens specification, tc0527a meets the requirements.

When to use telecentric lens?

① High precision measurement

② Very small vision or close working distance

3-3. Example of industrial lens selection - line scan lens

Known conditions:

8k7 μ Chip;

Visual field 600mm;

The shorter the working distance, the better.

calculation:

Chip size length =8k*7 μ= 56mm；

Magnification = image size/object size=56/600=0.093 X;

So find an image plane equal to or greater than Φ 56, the magnification can support 0.093x; When 0.16x, WD is 256mm; When calculating 0.093x, WD ≈ 256 × (0.16/0.093)=440mm； According to the lens specification, ls4005a meets the requirements.

LS6016A也满足需求：

When 0167x, WD is 404mm; When calculating 0.093x, WD ≈ 404 × (0.167/0.093)=725mm。 For similar parameters, the shorter the working distance, the more expensive the lens is, and the choice shall be weighed according to the actual demand.

4. selection process of line scan lens

Chip: determine camera chip size and resolution

Determine the flange distance and interface of the camera

Magnification: calculated lens magnification = chip length / field length

Find lenses with similar magnification in the product manual

Connecting ring: confirm whether the lens o/i distance and working distance meet the requirements

Matching ring

Through the above cases, we can roughly solve some problems encountered in the selection of industrial lens. If you have any questions, you are welcome to leave a message for consultation. Xiaobian will make every effort to answer them for you!