The size of the “seen” spot

About 540 million years ago, organisms evolved eyes, and more than 80% of the objective world information is perceived through the eyes; in the process of development, it has become a rapidly developing branch in the field; we often use machines instead of human eyes to make measurements and judgments, through optical devices and non-contact, automatically receiving and processing images of real objects to obtain the required information or for controlling movement.

The core of machine vision is to use "machine eyes" instead of human eyes to identify, measure and make judgments on objects. Nowadays, they are growing with a precision that exceeds that of human eyes, greatly surpassing the limitations of human eyes themselves or the limitations of the physical environment, and can accurately and finely image micron-level features, such as:

The size of the “seen” spot

Project Background

When producing laser products, in order to maintain a high degree of product consistency, it is necessary to measure the size of the laser spot; during production, it is necessary to accurately measure the center offset of the spot at different distances, the divergence size of the spot, the center angle and other parameters without contact.

Project Difficulties

1. The laser beam cannot be imaged directly, and a filter needs to be installed (there are many types of filters, which are difficult to choose). The brightness of the beam itself is uneven, and the spot imaging is uneven.

2. The sensor is fixed on the guide rail and needs to be measured multiple times at different distances, and the imaging field of view is not easy to control

3. The sensor transmitter is fixed on a linear guide rail that can reciprocate, and the camera lens is fixed. It is necessary to measure the size of the imaging spot of the sensor at different positions from the camera lens, and compare the obtained size data. It is necessary to measure the imaging spot at at least three positions. The measurement error is controlled within 0.01mm

Solution

1. The camera lens and filter positions remain relatively fixed, the sensor moves alone, controls a single variable, and reduces measurement errors

2. Use special filters to reduce the problem of uneven brightness of the light spot caused by the light beam, and make the edge of the imaging light spot sharp and clear, which is convenient for measuring the size.

3. Use mixed positioning to highlight the foreground and be easy to edge

4. Dimension measurement accuracy <0.02mm, angle measurement accuracy <0.05°

Original image imaging effect

Spot imaging effect after processing