Illumination Methods Using Flat Lights
Flat lights are most commonly used in one of these illumination methods.
Back Lights
By using flat lights as a common back light illumination, it is possible to create sharp silhouettes in applications such as pick-and-place. Additionally, this illumination method can be used for the inspection through clear parts.
Brightfield
Flat lights are used as direct lighting for the examination of high-gloss surfaces. In the captured image, the surface appears as a mirror. By positioning a surface illumination in the reflected field of vision, faulty areas and markings in the area to be examined can be detected.
LBB & ZVZF Flat Lights
Flat lights for Machine Vision lighting applications are available in three different back light sources: white light, red light and infrared light. These flat lamps create a homogeneous and diffuse light area in several different sizes – from small area LED flat lights to large area LED flat lights. This machinevision backlight solution creates high intensity illumination in any industry using image processing!
The depth of field depends on the lens aperture. The smaller the lens aperture, the larger the depth of field.
1) With more lighting power, …
2) … the aperture of the camera can be closed …
3) … which creates a bigger depth of field (DoF)!
2) … the aperture of the camera can be closed …
3) … which creates a bigger depth of field (DoF)!
In order to find the right size of the flat light, the relative position of the camera has to be taken into consideration. This position requires the vision light to be much larger than the size of the measured field of view.
1) Inspected field of view (FoV)
2) Required field of illumination
2) Required field of illumination
What Is the Parallax Effect?
Parallax is an effect experienced with industrial Machine Vision that relates to height as well as to how a light source is perceived by a camera. It appears when looking across an area from a single viewpoint.
The effects of the objects’ relative position to the camera are very important to understand in order to avoid parallax appearances. Common camera types use integrated calibration tools and telecentric lenses to correct this effect. With lighting, it can be adjusted with over-exposure in some instances.
1) Object 1 as captured with aperture f/8
2) Object 2 as captured with aperture f/8 creating the parallax effect
3) Object 2 as captured with aperture f/4 without the parallax effect
2) Object 2 as captured with aperture f/8 creating the parallax effect
3) Object 2 as captured with aperture f/4 without the parallax effect
Which Effect Has the Inverse Square Law of Light?
The parallax effect as well causes a lack of homogeneity, which cannot be compensated. As light and distance follow the inverse square law of light, the back light for larger field of views require to be even brighter than small flat lights.
1) Objects directly under the camera: 100% brightness
2) Objects seen from a wider angle: less brightness
2) Objects seen from a wider angle: less brightness
Which Working Distance Should Be Chosen?
We recommend to use a working distance (WD) of at least two times the largest diagonal (C) of the field of view (FoV).
WD > 2 × C
By controlling the exposure time and aperture to change the saturation in the image, different results can be achieved.
Left: Aperture f/4
Right: Aperture f/8
Right: Aperture f/8
LBB Flat Lights
LBB flat lights are used to illuminate areas with a luminuous field starting from 200 × 200 mm. Because space is very limited in industrial environments, the LBB flat light comes with 4 mm borders, mounting points around the entire perimeter and a huge range of sizes.
ZVZF Flat Lights
ZVZF flat lights are used to illuminate small areas with a luminuous field starting from 60 × 60 mm. They have a rugged housing with protection class IP67. Due to their extremely thin housing of only 20 mm and small borders of only 4 mm, these vision lights are perfectly suited to fit in hard-to-access industrial environments with limited spaces.
| Light Source | Sizes | Connection | Protection Class | |
|---|---|---|---|---|
| LBB Flat Lights |  White light Red light Infrared light |
200 × 200 mm, 300 × 200 mm, 400 × 200 mm, 300 × 300 mm, 400 × 300 mm, 400 × 400 mm, 500 × 500 mm |
M12 × 1; 5-pin | IP40 |
| ZVZF3 & ZVZF4 Flat Lights | White light Infrared light |
60 × 60 mm, 120 × 120 mm, 180 × 180 mm | M12 × 1; 4/5-pin | IP67 |
| LBB Flat Lights | ||||
|---|---|---|---|---|
|
Light Source
White light
Red light
Infrared light
|
Sizes
200 × 200 mm, 300 × 200 mm, 400 × 200 mm,
300 × 300 mm, 400 × 300 mm, 400 × 400 mm, 500 × 500 mm |
Connection
M12 × 1; 5-pin
|
Protection Class
IP40
|
|
| ZVZF3 & ZVZF4 Flat Lights | ||||
|
Light Source
White light
Infrared light
|
Sizes
60 × 60 mm, 120 × 120 mm, 180 × 180 mm
|
Connection
M12 × 1; 4/5-pin
|
Protection Class
IP67
|
|
