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Highly reflective mirrors for reverse vending machines
Optical coatings in sensor technology
The better light components are filtered, the faster the conveyor belt runs
There are numerous automated processes in packaging logistics, from measuring objects such as parcels on conveyor belts to checking security and labeling stickers, reading barcodes or capturing data matrix codes (DMC). Sensors whose optical function is crucial for the respective application are used for all of these tasks.
Anti-reflective coatings minimize interfering reflections
In order to avoid disturbing light reflections or unwanted reflections, the optical components of the sensors, such as lenses, cover glasses, deflection mirrors or filter glasses, are provided with an anti-reflective coating, i.e. “anti-reflective”. This suppresses interfering light reflections, increases the image contrast and thus increases the efficiency of the system. In this way, the detection systems with the sensors can reliably detect and record objects or codes, even with faster moving belts.
Optical filters increase efficiency
Special filters are used to filter out the visual light spectrum, i.e. sunlight and other ambient light, e.g. in a production hall, is blocked, while infrared radiation, for example, is transmitted. This is possible, for example, with daylight filters, also known as daylight blockers. These filters are also important for hyperspectral camera solutions or multispectral detection systems, in which the images from a VIS camera and a camera system with an IR filter are superimposed. This ensures better readout results. Hyperspectral cameras simultaneously record images and spectra (wavelengths) of a target object. Spectral bands of the target are continuously recorded using imaging spectroscopy. The cameras combine spatial, radiometric and spectral information for better and more detailed imaging, which is facilitated by filters that can be set to the IR, NIR or SWIR spectrum, for example.
Application example: Bandpass filter in a packing station
In a packing station, an optical bandpass filter can increase the reliability and accuracy of optical detection by only allowing the desired light signal to pass through and suppressing interfering signals. This improves the performance of both camera systems and laser scanners during parcel detection. An optical bandpass filter only allows light of a certain wavelength (or a narrow wavelength range) to pass through and blocks all other wavelengths.
In a packing station, the bandpass filter is typically used for:
- Interfering light suppression: In storage or packing stations, there are often different light sources (e.g. neon tubes, daylight, sunlight, LEDs). A bandpass filter can suppress this interfering light, which is not part of the actual detection.
- Contrast enhancement for laser detection or LED illumination: If a laser scanner or LED with a specific wavelength is used for object detection, the filter only allows the reflected light from this source to pass through. This makes the detection signal stronger and more precise because only relevant information reaches the detector (e.g. a camera).
- Better recognition of barcodes, labels or markings: Many packing stations use cameras to capture barcodes, QR codes or labels. A bandpass filter can help to allow only the light spectrum with the best contrast between the background and the code.
- Reduction of reflections and interference: Especially with glossy or reflective surfaces (e.g. packet films), a filter can help to minimize reflections that could impair detection.
![[Translate to English:] Optische Sensoren in einer Packstation](/fileadmin/bte/Inhaltsbilder/News/AdobeStock_365725810_Web_Scanner_Logistic.jpg "[Translate to English:] Case Study Packstation")
Application example: bandpass filter for volume measurement
Optical measurement technology is also often used for volume measurement in packing stations, for example with 3D cameras, laser scanners or time-of-flight sensors. Optical bandpass filters help to increase measurement accuracy and interference immunity in these systems. Here, too, unwanted ambient light can be blocked and only light in the desired wavelength range can pass through, typically the light from a measuring source (e.g. laser, infrared LED). The advantage here is a higher signal-to-noise ratio, which contributes to more precise volume measurement. In addition, corresponding optical filters can emphasize the measuring radiation of volume measuring systems. These often work with laser beams or structured light, usually in the visible or near-infrared range (e.g. wavelengths of 850 nm or 940 nm). The bandpass filter is precisely matched to this wavelength so that only the measuring light reflected by the object reaches the camera or sensor. The bandpass filters also help to suppress irrelevant light components (e.g. due to stray light), which reduces measurement errors caused by overexposure or misinterpretation. Optical filters also contribute to increased accuracy in 3D imaging and better volume calculation. In systems with stereo cameras, time-of-flight or structured light projection, they ensure that only specific, relevant light patterns such as gratings or dot patterns are used for evaluation.
Customized solutions for almost all sorting tasks
At Bte Born, we offer tailor-made optical coating solutions with numerous different coatings, from anti-reflective coatings to mirrors and optical filters, which can be precisely adapted to the requirements of individual applications: “Customized” is our standard!
