Optical filters have long been critical components in traditional machine vision applications. They maximize contrast, improve color and subject recognition, or otherwise control light reflected from an object under inspection. Typically, filters are used for machine vision tasks that do not vary much from product to product or from one subject to the next. However, recent advances in sensors, artificial intelligence, human-robot interaction and other technologies have led to the use of machine vision in more flexible applications such as sorting, material handling and automated assembly. When choosing a filter for these applications, consider the following.
Midwest Optical Systems has introduced new acrylic longpass filters. Acrylic Longpass Filters are frequently used as enclosure windows, to shield lenses and lighting from damage, or to economically control the wavelength emission in large area, broad spectrum light sources. Because of their durability, they are also commonly used in Food & Drug Administration (FDA) and European Food Safety Authority (EFSA) regulated applications where exposed glass over the inspection area is not permitted. AC370 and AC380 offer anti-abrasion, anti-reflection coatings which can also withstand harsh solvents such as acetone and MEK.
MidOpt President, Barry Warzak is interviewed by new industry publication: MVPro Media – The article features StablEDGE® filters and VISION 2016 highlights.
Some applications that have traditionally relied on single wavelength filters and multiple sensors or multispectral imagers are, with the use of dual band filters employed together with other recent technical advances, now becoming far more affordable. With the resulting reduction in cost barriers, some of these technologies are far more accessible and the potential to benefit a far larger number of individuals and organizations is now greater than ever. Applications include Security/surveillance imaging, 3-D point cloud imaging, gaming, automotive, NDVI imaging and numerous other applications.
Over the past 150 years or more, fossils and other objects from the past have been collected and archived all over the world by museums, colleges and universities, and many private individuals. Usually considerable work has been put into restoring these objects in an attempt to make them appear whole and more aesthetically pleasing. Michael Eklund of the University of Texas and ThinklabZ has coined the term “Progressive Photonics” to describe a series of reproducible steps and techniques that are designed to enhance long term data yield from paleontological and archeological specimens. Progressive Photonics involves the use of specific types of cameras, lighting, optical filtering, staging, shrouding and other tools and equipment for obtaining and recording these images. It relies on fixed, predetermined methods, settings and sequences. It is a recording process designed to be easy to follow, relatively inexpensive, and one that allows for later manipulation of the images/data as may be deemed beneficial by individual researchers, scientists or collectors. Of paramount importance is that the images as seen by the unaided eye and recorded by the camera are known, specific and repeatable by anyone, at anytime, anywhere in the world. For this reason, the use of Photoshopping or other similar manipulation of digital images during the recording process is eschewed. Progressive Photonics is therefore not only an attempt to improve the scientific yield from specimens by adopting standard methodologies, instrumentation and practices for imaging, it ultimately also attempts to restore confidence in the integrity of the resulting data and conclusions drawn from interpretation of those images.
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MidOpt’s BP850 near-IR bandpass optical filter aids in surgical navigation application. During typical sinus and skull base procedures, surgery is performed under low light conditions. Hence it was important to create a system that is unobtrusive to the surgeon. To illuminate the scene, the NaviENT (system developed by ClaroNav) uses an array of 2×96 Near-IR LEDs of 5mm diameter, emitting at 850nm with a 60° field of view. These are mounted inside a tracking box with the Point Grey Bumblebee XB3 camera. Near-IR light projected onto the scene is then captured by the cameras and filtered with MidOpt’s 850nm near-IR band-pass filters (BP850) prior to processing. Since the BP850 ensures out of band blocking, the optical filter removes unwanted ambient light from the scene.
StablEDGE® optical filters are specifically designed to be less susceptible to effects from angular shifting seen when optical filters are used with short focal length (less than 12mm) camera lenses. This feature is becoming increasingly important as today’s trend in machine vision progresses towards more compact inspection layouts, which utilize less space – forcing the camera and lens closer to the subject. As a result, short focal length lenses are now more extensively used than ever before.
In a special anniversary report from IMVE, we get a closer look at MidOpt’s evolution over the past 30 years, along with newly developing applications and emerging markets for precision optical manufacturing.
MidOpt helped showcase the future of machine vision system technology with their SensorSmart Machine Vision and ID Seminar presentation on filters. Optical filters are the simplest and most effective way to gain control over what enters the system and is where image quality begins. Filters are no longer an accessory in machine vision; they’re a necessity.
Red and blue MidOpt Bandpass Filters are used to compare the sensitivity and contrast of plant health in normalized difference vegetation index (NDVI) applications. Each were placed into a camera that had the internal factory infrared filter removed. Raw images were captured, which proved previous findings that red filters perform better than blue when looking at plant health.
MidOpt Filter Kits were showcased at SPIE Photonics West. The FK220 BN Filter Kit is designed with reduced bandwidth for further wavelength separation and is compatible with LED and laser diode light sources. The kit includes blue, green, orange, light red and dark red filters; four near-infrared filters; a linear polarizer; ultra-high contrast polarizing film; and more.
Attempting to capture high-quality images of extremely fast events can be difficult, but it’s required by many analysis applications. In an effort to capture a high-speed bullet, a camera and illumination system was developed, featuring the BP880 MidOpt Bandpass Filter. This filter minimizes background light to effectively illuminate and “freeze” the motion of the projectile.
After automotive manufacturing, sub-assemblies must be inspected to ensure that the molded locking tabs and clips are in place. To determine if machine vision is an option for this application, a cutting-edge vision system incorporating a MidOpt BP635 Bandpass Filter is designed. This detailed inspection plan successfully identifies if the tabs are properly formed.
Machine vision systems are now commonplace in factory automation systems. When building these systems, developers must carefully evaluate the type of product being inspected and how illumination and optics can be used to increase the contrast and resolution of captured images. Here are the most important steps when choosing the best optical filters for your system.
During an automated wheel and tire verification process, a global manufacturer began experiencing unacceptably high levels of false fails. It was determined that by employing a combination dome light and brick light configuration, a MidOpt Bandpass Filter, and multiple smart cameras, the wheels, tires and resulting assemblies could be successfully verified.
Although optical filters are often an afterthought in machine vision systems, they are a critical element for optimizing lighting. Filters can be used to improve contrast, reduce glare, sort colors, remove barcode interference and more. Learn more about the many advantages of optical filters and how to choose the right one for your system, including real-world examples.
Although optical filters are often viewed as an afterthought in machine vision applications, their ability to optimize lighting and the entire vision system makes them so valuable that they should be considered from the initial planning stages of most applications. The value of optical filters arises from their ability to block all unwanted ambient lighting and pass only the output of light needed for inspection while increasing contrast and resolution…