Advanced illumination

It is necessary to obtain completely different results for (1) and (2), which can be achieved by adjusting the “irradiation solid angle”

(Example 1)If white light is shined on a red apple, it will appear red because it absorbs blue and green light and reflects only red.f green light is shined on a red apple, it absorbs green and reflects no color, making it appear black.

If you want to image a small workpiece at high resolution, it is necessary to carefully select the wavelength of the lighting and the numerical aperture of the lens.

There is a cylindrical container with a picture of a bird printed on it.Let’s capture an image of this with a combination of lens + camera +lighting.What is the difference between a good image and a bad image?

SmartvisionLights

The irradiation solid angle is the angle of incident light to a point on an object, and the size of the irradiation solid angle controls the appearance of unevenness.

AS manufacturing technology has advanced in recent years, various products can be mass-produced in a short period of time. As a result, “product inspections” are no longer able to keep up with visual inspections by humans due to the demand for higher accuracy, inspection speed, and difficulty in training new employees. Replacement of visual inspection is underway with machine vision (image processing equipment), which inspects products for defects based on image data captured by industrial cameras and lenses.Machine vision has many advantages, such as 24-hour operation, programmable operation, and reduced variation in inspection results. However, machine vision is not simply a matter of installing cameras. In fact, the human eye excels in its ability to constantly focus on a product depending on its distance and viewing angle, and it is able to recognize both bright and dark areas in a single glance. It can flexibly respond to any given situation. In contrast, machine vision often requires a single image of the product being delivered by a fixed camera, lens, and lighting, and unless the defective part is clearly visible in the image, it is impossible to correctly determine whether the product passed or failed.

Flat Dome Lights

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The three most basic colors are Red, Green, and Blue and are represented by the acronym RGB.Mixing the three colors of light in equal proportions produces white light.Indoor lighting such as fluorescent lamps and sunlight appear white because the various colors of light are mixed in proportion to each other.In addition, almost any color can be produced by controlling the balance of RGB.

As described above, the color, type, size, and installation method of lighting can change the way an object is seen. The selection of the lighting is essential together with the camera and lens.VS Technology offers verification with actual objects, so please contact us for more information.

Adjust the brightness of the lighting and the shutter speed of the camera to clearly define the areas you want to emphasize and those you prefer not to.

There is no difference under natural and visible light, but as we move to longer wavelengths, the water appears blacker and the difference becomes clearer.

Exposure of certain objects, including phosphors, to ultraviolet light causes a fluorescence phenomenon (excitation) that absorbs the ultraviolet light and emits light with a longer wavelength.This allows the position of objects that are difficult to recognize with visible light to be captured more easily.

Tplvision

Using this property, we can control whether an object is “brightened” or “darkened” by using monochromatic lighting on a colored object.“In fact, using a monochrome camera and lighting a red (R) green (G) and blue (B) object with each color of red (R), green (G), and blue (B) will produce the following image.

In addition to highlighting defects, the same concept of lighting selection can be used to eliminate excess background or unnecessary objects.

A rough, low-reflective workpiece such as paper or untreated wood will appear equally bright no matter where the light is projected.On the other hand, a workpiece that is shiny and highly reflective, such as a mirror, polished metal or glass, is captured in a completely different image depending on where the light is projected from.

(1) When you want to make the unevenness stand out as a defect.(2) When you do not want the unevenness to stand for defects, but want to detect other stains, etc.

It can transmit through specific objects. This allows detection of substances within the object that are not visible with visible light.It can also darken and detect areas that contain more moisture than their surroundings, due to the absorption properties of moisture in a specific wavelength range of infrared light.

The lighting is uneven on both sides and top and bottom, and the lighting is partly reflected in the image making it too bright.

Machine VisionBar light

As shown above, when the light source color that includes the color of the object is irradiated, the object can be imaged brightly (white).Conversely, if the object is illuminated by a light source color that does not include the object’s color, the object can be imaged dark (black).

(Example 2)When white light is shined on a yellow banana, it absorbs blue light and retlects a mixture of red and green light, making it appear yellowish.“If you shine blue light on a yellow banana, it absorbs blue and appears blackish because it absorbs blue.

Wenglor Bar Light

“Light” is a class of waves called electromagnetic waves.The range of this light that the human eye can perceive is called “visible light” and extends from about 380 nm to 780 nm (nanometers).The wavelength range used in imaging is even wider than visible light, ranging from ultraviolet to infrared.

Among wavelengths invisible to the human eye, wavelengths shorter than visible light are called “ultraviolet light” and longer wavelengths are called “infrared light”.(See the figure on the previous page.)

The basic idea is to focus on the object by adjusting the depth of field with the aperture and brightness of the lighting.(In some cases, the image may be intentionally blurred.)

(Example 3)When detecting blue stains on a red object, red lighting can be used to capture the object brighter and the stain darker, resulting in a high-contrast image.

The color of an object is determined by the color of the light that reaches the object from a light source, such as the sun, and is reflected without being absorbed by the object.

Resolution is expressed by the above formula, but if the same lens (same NA) is used, the longer the wavelength, the greater the spatial resolution=less finely resolved.