Exaktera Lighting, A Comprehensive Review

Lighting is the part of a machine vision system that most often decides whether it works. Get it right and a simple camera and a basic algorithm will sail through the job. Get it wrong and no amount of resolution or clever software will rescue the image. So the companies that make the light matter far more than most buyers give them credit for.

The lighting landscape has just changed in a way worth knowing about. Three of the names we rate most highly, Advanced Illumination, ProPhotonix and LUMIMAX, are now part of the same group, Exaktera. What used to be three separate suppliers is now one portfolio with over 150 years of combined heritage behind it. We work with and offer all three. This is a straight review of them, what each is genuinely best at, when to use the main lighting techniques and how the group stacks up against the alternatives.

The three brands and what each does best

The three lighting companies in Exaktera are not three versions of the same thing. That is the point of them. Each grew up solving a different part of the lighting problem. Between them they cover almost anything a vision system needs. Here is what each is for.

Advanced Illumination. The broad generalist of the three, the one we supply most. Based in Vermont, Advanced Illumination makes close to the full span of machine vision lighting. Bar lights, bright field and dark field ring lights, dome lights, backlights, coaxial and spot lights, high-intensity line lights and pattern-projecting spots. Its MicroBrite range packs real intensity into a small housing. Its UltraSeal washdown lights are sealed to IP69K with a crevice-free body for food, beverage and pharmaceutical lines. Advanced Illumination also wrote the reference most of the industry learned from, A Practical Guide to Machine Vision Lighting. If you want one brand that can light almost any job, this is it.

ProPhotonix. The specialist, the one to reach for when the job is unusual. Based in Cork, ProPhotonix builds its lights around chip-on-board LED arrays, which pack a lot of light into a small, uniform source. Its COBRA line lights are a mainstay of line scan and web inspection. It also covers wavelengths most brands do not, from UV through visible to SWIR, which matters for materials that only show their defects outside the visible range. ProPhotonix makes structured-light lasers too, the 3D PRO family, for laser triangulation and 3D profiling. When your application needs a specific wavelength, a long line light or a laser rather than an LED, this is the brand that tends to have it.

LUMIMAX. The high-power specialist, engineered in Germany by iiM. LUMIMAX is built for the jobs that need serious intensity and precise timing. High-power LED spot lights, area lights and flat domes, dome lights, bar lights and dedicated strobe lighting, much of it with the overdrive and controller technology that lets a light fire far brighter for a very short pulse. That matters on fast lines, where you need to freeze motion with a bright, short flash rather than a continuous glow. LUMIMAX is the newest of the three to many buyers outside Germany. It is the one to look at when raw power and strobe control are the priority.

When to use diffuse, dark field or structured light

The hardest part of lighting is rarely the brand. It is the technique. The same part can look perfect under one kind of light and invisible under another. Choosing the geometry is where most of the skill sits. These are the main techniques and when each earns its place.

Direct or bright field. Light aimed straight at the part from a ring or a bar. It is the general-purpose starting point and gives strong, even illumination on matte surfaces. It struggles on shiny parts, where it bounces straight back as glare.

Diffuse. Soft, even light from every angle, usually from a dome or a diffuse ring. This is the answer for shiny, curved or reflective surfaces, the ones that glare under direct light. A dome gives a cloudy-day evenness that cancels reflections, which is why it is the standard for reading codes and print on cans, foil and glossy packaging.

Dark field. Light that grazes the surface at a low angle instead of hitting it square on. Flat areas stay dark and anything standing proud of the surface, a scratch, an engraving, an embossed character, lights up brightly. Dark field is the technique for surface defects and for reading marks pressed or etched into a part.

Backlight. Light from behind the part that puts a crisp silhouette in front of the camera. Nothing beats it for measurement, for checking shape and for finding holes or gaps, because the edge it produces is clean and repeatable.

Coaxial or on-axis. Light fed down the same axis as the camera through a beam splitter. It is made for flat, specular surfaces such as wafers, screens and polished metal, where it reveals fine detail that angled light would hide.

Structured light. A pattern projected onto the part rather than flat illumination. A projected grid or line adds texture to a featureless surface. A laser line read at an angle is the basis of 3D profiling and height measurement. Advanced Illumination makes pattern-projecting spots for this. ProPhotonix makes the 3D PRO laser family. When you need shape or height rather than a flat image, this is where lighting and 3D meet.

Colour and wavelength. The colour of the light is a lever in its own right. A matched colour can lift one feature and drop another. Infrared can cut through some materials and suppress ambient light. Ultraviolet brings out fluorescence. This is where ProPhotonix earns its keep, with LEDs from UV to SWIR for jobs a standard white light cannot touch.

Where this range goes to work

Between the three brands, the group covers the full spread of lighting jobs. A few of the common ones.

•        Surface defect detection on metal, plastic and glass, using dark field and the right wavelength

•        Reading codes and print on shiny or curved packaging, using diffuse dome light

•        Measurement and gauging against a clean backlit silhouette

•        Line scan and web inspection with long, high-intensity line lights

•        Washdown inspection on food, beverage and pharmaceutical lines with IP69K sealed lights

•        Freezing fast motion with high-power strobe lighting

•        3D and height measurement with structured-light lasers

•        Outdoor and ANPR work where high intensity has to beat sunlight

In almost every one of these, the light is doing the heavy lifting. A well-chosen illuminator turns a hard inspection into an easy one. A poor one leaves you fighting the image in software for the life of the system.

How the group compares with the alternatives

Exaktera is not the only strong name in lighting. The main alternatives are worth knowing. CCS is the large Japanese maker with a very broad catalogue and a strong following in precision work. Effilux, from France, is well regarded for large-area and custom lighting. Smart Vision Lights, from the United States, is known for high-intensity and outdoor-capable units with built-in drivers. Each is a capable supplier in its own right.

What the Exaktera group offers that a single maker cannot is the combination. One supplier relationship now reaches the broad everyday range of Advanced Illumination, the wavelength and laser specialism of ProPhotonix and the high-power strobe engineering of LUMIMAX. For a buyer that is simpler to deal with. For a difficult application it means the odds of the right light existing somewhere in the group are high.

Our own position is straightforward. We work with and offer all three brands because they are excellent, not because we are tied to them. If the best answer for your job sits with another maker, we will tell you. The point of talking to us is to get the right light, not a particular badge.

How to choose the right light

If all of this makes lighting sound complicated, that is because it can be. The good news is that the choice follows a logical path from the part and the feature you need to see. We built our illumination selector to walk that path with you. It asks a handful of questions about your inspection and points you to a geometry, a colour and the lights that suit. For anything it cannot settle, our team is here.

Not sure which light you need? Try our illumination selector tool and find the right one in under a minute.

Get in touch at info@clearview-imaging.com or call +44 (0)1844 217270

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