Automated vision inspection equipment light source debugging and application

Automated machine vision technology to detect the detection of network equipment for the detection of the principle of work to carry out simple that we are able to use the traditional industrial camera simulation research artificial naked eye detection, in addition to the most important camera, the light source is also a very critical, because the detection of the object's requirements of the enterprise different users to use the social environment on the brightness of the light requirements are also understood to be different, and therefore in the choice of vision system companies light source and the application of the program debugging are a Very delicate, in this Sputnik technology for everyone to organize the introduction of machine vision information system light source type and role and machine vision management system light source selection points. Today, China is mainly for you to organize the introduction of machine vision inspection equipment light source in the selection of some of the more common problems

1. Direct light: the light that directly illuminates the object. Direct light is characterized by shadows behind the illuminated object. Direct sunlight on a sunny day.

2. Diffuse light: Light that is a mixture of light from different angles. Diffuse light does not produce shadows when it illuminates an illuminated object. For example, shadowless light is diffuse light, and sunlight reflected by clouds on a cloudy day is also diffuse light.

3. Parallel light: light that shines in the same direction and is parallel.

4. Polarized light: all light amplitude plane is the same plane, called polarized light.

5. Direct reflection (specular reflection).

6. Diffuse reflection:

Bright field of view: Reflects light directly into the lens. It does not mean that the object in the field of view is a bright field of view. The brightness of an object is relative, and the brightness of the light source will make the dark field in physics brighter.

Dark field of view: scatters light into the lens.

Light Penetration and Reflectance:Light with long wavelengths (infrared light) penetrates well; short wavelengths have good reflectance. Infrared light is preferred for penetrating plastic film to inspect objects; ultraviolet light is preferred for observing dust scratches on glass.

Diffuse ratio:Reflective ability. Light with high diffusivity has poor penetration.

People cannot see infrared and ultraviolet light, but cameras can detect infrared and ultraviolet light; cameras also have limited sensitivity to infrared and ultraviolet light, refer to the sensitivity characteristic curve of the camera. Some objects fluoresce under UV light.

Commonly used illumination: Bright field of view, dark field of view, backlight illumination.

Usually the camera is mounted directly above the test object, so when using coaxial light, it is a bright field of view; when using low-angle light, it is a dark field of view.

The size of the outline of the test object, choose a variety of backlighting illumination.

The choice of light source color:

1. The light penetration or diffusion characteristics.

2, the object under test is colored: what different colors of the object for the reflection of what affects the color of the light, the camera by observing the problem is bright (white); absorption as well as a variety of other colors of light, the camera can observe the ability is dark (black). Wavelength close, less absorption; wavelength difference is large, more absorption.

3. Even the same color object, due to the different materials, the characteristics of the reflected light will be different. When short wavelength light irradiates different materials, the difference in reflectivity is large, while when long wavelength light irradiates, the difference in reflectivity is relatively small.

Polarizing plates and polarizing filters:

Function:1. Eliminate reflection interference;

Principle: In specular reflection (physical), the incident light is polarized and the reflected light is polarized. In diffuse reflection, the incident light is polarized and the reflected light is unpolarized.

An example:Take a toy and image it in a glass window, there will be an image of the light source reflected from the glass in the field of view, which will interfere. The light source is equipped with a polarizing plate and the lens is equipped with a polarizing filter. Polarized light reflected by the glass is still polarized light, filtering this polarized light with a polarizing filter can eliminate the image interference of the light source; there is diffuse reflection on the toy, automated inspection systemand there is always some diffuse light entering the lens that can be imaged.

Disadvantage: the brightness will be cut.

2, identify the material: the same beam of polarized light after analyzing the refraction of different product materials, amplitude surface angle by changing the size of the enterprise as well as different. This then goes through the polarizing plate filtering technology to get the image brightness is different (embodied in the camera is a color selection is different), you can distinguish between the study of different materials. Application: detection of the main components of bottled liquid.

Hands-on:

1. According to the field of view (field of view is slightly larger than the object under test), the focal length of the lens, the size of the CCD can be estimated working distance.

2. Study of the object under test, the indoor light as a light source, the eye as a lens, you can estimate the imaging effect with bright field lighting or dark field lighting. If you can choose a low angle ring light, the cost will be cheaper than coaxial light. Select the color of the light source according to the color difference between the object under test and the background; determine the size of the object under test according to the size of the object under test; select the type of light source according to the characteristics of the object under test.

3. Pay attention to the details in the operation to prevent the lens from falling off, adjust the bracket with one hand and hold the bracket with the other hand.

4. When debugging, the lower the brightness of the light source, the larger the camera aperture, the smaller the depth of field, it is easier to get the clearest and sharpest image. (With a large depth of field, the image quality is barely clear, but not the sharpest.)

Concepts

Direct light: Light that strikes an object directly. Direct light is characterized by creating shadows behind the object being illuminated. Direct sunlight on a sunny day.

2. Diffuse light: Light that is a mixture of light from different angles. Diffuse light does not produce shadows when it illuminates an illuminated object. For example,automatic visual inspection system shadowless light is diffuse light, and sunlight reflected by clouds on a cloudy day is also diffuse light.

3. Parallel light: light that shines in the same direction and is parallel.

4. Polarized light: all light amplitude plane is the same plane, called polarized light.

5. Direct reflection (specular reflection).

6. Diffuse reflection:

Bright field of view: Reflects light directly into the lens. It does not mean that the object in the field of view is a bright field of view. The brightness of an object is relative, and the brightness of the light source will make the dark field in physics brighter.

Dark field of view: scatters light into the lens.

Light Penetration and Reflectance:Light with long wavelengths (infrared light) penetrates well; short wavelengths have good reflectance. Infrared light is preferred for penetrating plastic film to inspect objects; ultraviolet light is preferred for observing dust scratches on glass.

Diffuse ratio:Reflective ability. Light with high diffusivity has poor penetration.

People cannot see infrared and ultraviolet light, but cameras can detect infrared and ultraviolet light; cameras also have limited sensitivity to infrared and ultraviolet light, refer to the sensitivity characteristic curve of the camera. Some objects fluoresce under UV light.

Commonly used illumination: Bright field of view, dark field of view, backlight illumination.

Usually the camera is mounted directly above the test object, so when using coaxial light, it is a bright field of view; when using low-angle light, it is a dark field of view.

The size of the outline of the test object, choose a variety of backlighting illumination.