Author Archives: Matt Pinter

Advances in LED lighting

Lighting based on the use of Light Emitting Diodes (LEDs) has reached a point at which the brightness and efficiency they now provide an attractive alternative to tungsten incandescent bulbs and halogen-based illumination systems. With a reliability measured in thousands of hours, LEDs provide cost-effective lighting solutions in both commercial lighting and machine vision applications.

Due to the demands of the commercial marketplace, many LED manufacturers have focused their efforts on developing LED products that produce warm, neutral and cool white lights with color temperatures that range from 2700K to 8300K. In industrial applications, cool white lights may be adequate. However, it is often necessary for system integrators to use illumination products outside the visible range in the IR and UV spectrum.

Alternative wavelengths

The deployment of Short-wave infrared (SWIR) LED lighting, for example, can enable objects whose colors are almost identical using visible light to be differentiated. Near Infra Red (NIR) LED lighting, on the other hand, will illuminate samples with light that can penetrate into and through materials such as paper and plastic. Illuminating a product with UVA, UVB or UVC LED light, on the other hand, can cause material under inspection to be excited and fluoresce, emitting light at a specific wavelength in the visible spectrum.

By packing hundreds of LEDs together in an Integrated Array, LED vendors offer lighting developers a source of high intensity light in a single unit. A variety of such integrated arrays that contain up to 100 LEDs on a single housing are on offer from LED vendors.

Arrays with a small light emitting surface up to 14mm, for example, can be employed that challenge applications where incandescent, halogen and CFL lighting were previously used, since they can deliver between 500-6500 lumen. Larger integrated arrays with light emitting surfaces greater than 14mm, on the other hand, can be used to create lighting for systems where ceramic and pulse-start metal halide illumination had been employed, since they can deliver light between 3000-18,000 lumen.

Just as the total quantity of visible light emitted by LED integrated arrays has increased dramatically over the past decade, so too has the speed at which such devices can be strobed. Multi-die LED arrays can now operate at over 100,000 strobes per second, producing up to 10 times the light output that would be achieved otherwise in constant operation. However, since such LEDs arrays do not include any controllers, lighting vendors often develop their integrated constant current drivers with built-in strobe inputs, obviating the need for their customers to develop external drivers to control the light.

In certain specialized embedded imaging applications, it may be important for a system developer to illuminate a product with light in a number of spectral bands. This is particularly important in microscopy, where a user may need to choose the wavelength of light that will enable the best image of an object to be imaged. To do so, custom ring based lighting systems can meet these needs (Figure 1).

Figure 1: In certain specialized embedded imaging applications, it may be important for a system developer to illuminate a product with light in a number of spectral bands. This is particularly important in microscopy, where a user may need to choose the wavelength of light that will enable the best image of an object to be imaged. To do so, Smart Vision Lights offers custom ring based lighting systems that can meet these needs.

Shaping light

Like their incandescent rivals, LED arrays emit light in all directions. To shape the output from the LED, designers of industrial lighting systems take the bare LED die and mount their own custom designed primary optics onto the die. While these optics have traditionally been manufactured from glass, injection molded silicon optics can provide a more cost-effective solution. However, the light from such primary optics may still be too broad for certain applications. Hence, secondary optics, such as lenses and reflectors can be mounted on the device to collect the light from the primary optic to direct it to a target.

As cost-effective as LED lighting solutions have become, the diode laser may challenge LED technology in both commercial and industrial lighting applications. While LEDs lose efficiency when driven by high electrical currents, the efficiency of diode lasers increases, providing more light than LEDs. Today, however, diode lasers are more expensive to fabricate than LEDs. However, as time progresses, their cost are likely to decrease, providing another source of inexpensive illumination for machine vision systems designers.

Figure 2: To shape the output of the light from a bare LED die, designers of industrial lighting systems often mount their own custom designed primary optics onto the die. While these traditionally were manufactured from glass, today, injection molded silicon provide a more cost-effective solution.

Understanding Illumination and Light Measurement

Fundamental knowledge of illumination and light measurement is key when specifying LED lighting for industrial automation

When choosing an LED light, designers of machine vision systems must fully understand the nature of the part that needs to be illuminated. To allow the system’s camera to capture an image with the highest contrast, developers can choose from a number of different lighting products. These range from line lights, ring-lights, spotlights and backlights – all of which may be used in on- or off-axis configurations and/or multiple wavelengths ranging from UV, visible to IR/wavelengths.

One of the most important considerations in choosing any type of lighting, however, is the amount of light required for any given application. Backlighting a part, for example, to perform dimensional measurements, may not require an extremely bright backlight. Alternatively, for high-speed line-scan applications where parts are moving at high-speed and camera exposure times are fast, an extremely bright light may be required.

Measuring light

For system integrators tasked with comparing lights from different manufacturers, discerning the amount of light emitted from LED lights that may at first seem comparable may be a difficult task since light output can be specified in a number of different ways.

When a part is illuminated by an LED light, luminance provides a measure of the amount of light reflected from a surface and indicates the brightness of light emitted or reflected from a surface. This can be measured in candelas/square meter (cds/m2) or foot-lamberts (fLs).

Illuminance, on the other hand, describes the measurement of the amount of light illuminating the surface area and is measured in lux or foot-candles and correlates with how humans perceive the brightness of illuminated areas.

While photometric measurements such as luminance and illuminance provide a measurement of light in terms of its perceived brightness to the human eye, radiometric measurements provides information amount the amount of light power (or energy) at all wavelengths. Photometric measurements are often used to determine the power from UV or IR lights and are not commonly used in machine vision applications. Such photometric measurements include irradiance and radiance.

While, irradiance provides a measure of the radiant power received by a surface per unit area and is measured in Watts per square meter (W/m2), radiance is the radiant power emitted by a surface, per unit solid angle per unit projected area which is measured in Watts/steradian/m2.

For the machine vision system designer working in the visible spectrum, the most useful of these measurements is illuminance. Illuminance meters can be used to perform this measurement with lights used in constant operation and those that are strobed.

Measuring the illuminance of a light in constant operation is relatively easy. However, strobed light illuminance can also be calculated using a light meter. If, for example, the if the light is strobed for 10ms and the LED turned off for 100ms before the next strobe is activated, then the actual intensity is approximately  1/10 of what it would be if the light was on constantly.

Inverse square law

Often, a systems integrator will choose a light – for example, a spotlight – and place it a specific distance from the part to be illuminated. If more light is required, one of the most useful rules of thumb in determining how this can be achieved is the inverse square law (Figure 1). Since the intensity of the light decreases as the inverse square of the distance, the amount of light drops as 1/(distance from the part)2. Thus, a light placed 2ft from a part will have ¼ of the visible light placed 1ft away. Obviously then, placing a light closer to the object to be illuminated an increase the amount of light considerably.

inverse square law

Figure 1: The inverse square law can be used to determine the amount of light and any given distance since the intensity of the light decreases as the inverse square of the distance. Thus, the amount of light drops as 1/(distance from the part)2.

Placing a light closer to a part can increase the illuminance level but in cases where this cannot be accomplished, developers should also consider how the amount light used to illuminate the object can be maximized. In the case of a spotlight used to illuminate an object, for example, properly focusing the light over a given field of view and distance can increase the amount of illumination.  For example, a 100mm diameter spotlight at a distance of 1m requires a 5.8o lens on the LED to maximize the illumination level at that distance (Figure 2).

Figure 2: Focusing the light over a given field of view and distance can increase the amount of illumination. For example, a 100mm diameter spotlight at a distance of 1m requires a 5.8o lens on the LED to maximize the illumination level at that distance.

To date, it is difficult to compare lighting products. Because of this, the AIA (www.a3automate.org), the EMVA (www.emva.org) and JIIA (www.jiia.org) are developing a standard to allow machine vision systems developers to compare different lights from different manufacturers from a practical rather than a theoretical standpoint. It is hoped that this standard approach will allow effective lighting performance comparisons across manufacturers and within manufacturers’ product lines based primarily on factors as the light intensity at a specified working distance, light pattern uniformity, size/shape (FOV) and the projected light beam spread.

Silicone Optics Set to Revolutionize LED Lights

Silicone Optics: Optimal Control, Low Cost 

When LED light manufacturer Smart Vision Lights (Muskegon, Michigan, USA) joined forces with optical engineers at LumenFlow (Wyoming, Michigan, USA) to create prototypes for a 5-million-lux LED linear light, they expected great results. What they didn’t count on was being able to manufacture them for a fraction of the normal tooling cost of $100,000 per mold. They did it by using silicone, the malleable compound that produces a host of benefits for applications that require cameras with premium optics.

Enter Silicone Optics: The Perfect Match for LEDs

LEDs offer a trifecta of benefits prized in the machine vision industry: greater spectral control, low cost and maintenance, and high efficiency. However, these solid-state emitters are similar to their incandescent predecessors in that they emit light in all directions. In the machine vision industry, where controlling light is critical to success, the lamp needs to collect all available light and direct it to its target.

Silicone optics overcome this and many other challenges when compared to acrylic, for example, primarily because they allow end users to control light with the precision previously only available with complex, cost-prohibitive glass optics.

What Sets Silicone Apart?

The benefits of the new optical-grade silicone are many. It offers high transmission across a broad spectrum, with 95 percent transmission or better from 365 nm (UV) to 2000 nm (IR). It is also robust, maintaining optical function over its lifetime. During the manufacturing process, optical-grade silicone holds fine structure patterns and possesses reverse curves in a single molding tool. And silicone’s ability to form complex optical elements using multiple shots in a single injection mold allows for a lower total cost solution for complex, multipart optics.

What it doesn’t do is age or yellow over time, like polycarb, vinyl, or acrylic, or react to UV light or harsh chemicals. Crazing due to heat is a nonissue in temperature ranges from from –115°C to 200°C.

The Beauty of the Silicon Molecule

The advantages of silicone optics are rooted in the unique properties of the silicone molecule. Its long, spaghetti-like structure results in a liquid that slowly cures into a flexible solid with a low index of refraction. This characteristic lowers light losses at the interface between optic and air or multipart optics.

Despite retaining a flexible semi-rigid shape, silicone’s liquid origin means it can be formed into very fine structures below 10 nm to create diffractive, holographic, Fresnel, and other optical structures with minimal loss. And because the silicone maintains this flexibility for up to a year or more, injection-molded optics easily can be blown out of the mold without sacrificing fine structures.

Discovering the Benefits of Silicone Optics

Matt Pinter, Smart Vision Lights’ head of engineering, had looked at extruded acrylic rods to focus the light from the water-cooled LEDs, but they would need to be upward of 5 cm in diameter. Poor surface quality compromised the integrity of the light line, and the material was vulnerable to high temperatures.

The engineering team then designed a 40-mm-diameter silicone complex optic that could handle the 5 million lux and associated heat while maintaining the focus of the light line. The silicone optic comprised two 40-mm molded large-aperture silicone lenses placed back-to-back.

Each cylinder included a complex conic structure that reduced induced aberrations common to rod optics. Since silicone remains a “living material,” the lenses could be made in 6-inch (15.4 cm) segments and butted together. Due to the material’s fluidity, the molecules flowed back together. This allowed manufacture of the light at lengths up to 9 feet (2.74 m).

A larger object distance also was possible, which meant less heat stress on the optics and the LEDs. Finally, the back-to-back placement allowed the inclusion of a wire polarizer, which was unheard of in LED lights of that intensity.

Smart Vision Lights’ 5-million-lux linear light is a promising development in molded optical materials and technology. By showcasing the unique chemical properties inherent in optical-grade silicone, Smart Vision Lights has opened the door for LED manufacturers to explore the development of new, low-cost applications.

SVL is Proud to be a Sponsor of M.A.R.S

Smart Vision Lights is proud once again to be able to sponsor the Muskegon Area Robotics Students (M.A.R.S).  The goal of M.A.R.S. is to provide area students with hands-on experience building and programming robots for competitive events. We do want to wish the team great success in their upcoming events.

Muskegon M.A.R.S Muskegon Area Robotics Students

LED Bulbs Offer Greater Value and Performance

Which type of light bulbs offer the best value for your business? If your answer is LED (light-emitting diode) bulbs, you’re correct.

TSLOT

LED lights, such as Smart Vision Lights’ new T-SLOT light, offer dramatic efficiencies and cost savings over incandescent bulbs and compact fluorescent (CFL) bulbs.

• LEDs last longer, with a 50,000-hour average lifespan, versus 8,000 hours for CFLs and 1,200 hours for incandescent bulbs.
• LEDs use less energy — between 6-8 watts per unit of light (or lumen) generated. Incandescent bulbs use 60 watts per lumen, and CFLs use between 13-15 watts.
• LED bulbs also generate less heat, are more durable, and have less sensitivity to cold and humidity.

That means more light output for less money: A company running 30 LED bulbs for a year will typically spend less than half of what it costs to run a similar number of CFL bulbs, and 10 percent of what it costs to run incandescent bulbs.

In a report about solid-state lighting technology, the U.S. Department of Energy wrote that at peak performance levels, “LEDs far surpass the efficacy of current linear fluorescent, compact fluorescent, high intensity discharge, and incandescent sources.” Among the most commonly used light source technologies, the department wrote, “only LED is expected to make substantial increases in efficacy in the near future.”

When you’re looking for a cost-efficient, energy-saving, and environmentally conscious option for your lighting needs, consider LED options such as Smart Vision Lights’ T-SLOT lights.

sources:
http://www.designrecycleinc.com/led%20comp%20chart.html
http://apps1.eere.energy.gov/buildings/publications/pdfs/ssl/led_energy_efficiency.pdf
http://energy.gov/eere/ssl/led-basics

 

Smart Vision Lights’ Custom Light Adds Flexibility to Multi-Product Pharmaceutical Packaging Line

Specializing in multiple package configurations on a variety of blister packaging lines, contract pharmaceutical packager PCI needed the right light architecture to optimize its machine vision inspection. Smart Vision Lights met the challenge by developing the TL305, a custom on-off axis LED light that provides extremely intense and diffused multidimensional light for highly reflective surfaces.

Read more at Healthcare Packaging to learn how SVL’s solution delivers better images and more robust inspections or PCI by reducing “hot spots” and glare and increasing the camera’s color response.

M.A.R.S. robot (sponsored by SVL)

M.A.R.S. robot (sponsored by Smart Vision Lights) finished the preliminary round at districts in Howell in 4 place out of a field of 40 robots.  Team did a great job but lost in the quarter finals when the robot failed with a communication problem.

IMG_0176 IMG_0182

New Projects Highlight SVL’s Custom Light Design Capabilities

Matt Pinter, head engineer of Smart Vision Lights, loves it when a customer throws down the gauntlet, asking for a custom light design that they can’t find anywhere else. Here are a few designs that recently came out of SVL’s laboratory:

Custom Designed IR Ring Light by SVL

Custom Designed IR Ring Light by SVL

  • We worked with Chris B. Boehnen, Ph.D., Team Lead Secure Computer Vision Team, from a multi-program science and technology laboratory, who needed an IR Ring light that had a very low divergence of light, almost collimated ring light. A SWIR “Cannon” light was provided for this application, which required a uniform (homogenous) light with a range of 3 feet to 15 feet coverage.
  • A logistics customer needed a light for reading barcodes from a distance of up to 2 meters. We started with our OverDrive ODDM light module, and adjusted the light focus to match the camera’s field of view. The OverDrive high output helped the system to capture high quality images during the extremely short exposure times and high frame rates used in many logistics applications.
  • Another recent customer required a high-output light with linear polarization. This light was designed specifically to handle the extra heat generated by the light rejected by the polarizing filter.
  • A large pharmaceutical customer recently needed lights for an inspection line for blister packages containing capsules, tablets, and clear gel caps on various backgrounds. The solution – the TL305 Diffuse On- and Off-Axis Light  – provided a solution that reduced “hot spots” and glare.

These are just some examples of custom lighting applications that we have designed with our customer’s specific needs in mind. Have a lighting challenge? Contact us – because at Smart Vision Lights we never stop innovating!

Smart LED Driver… Innovation Is as Innovation Does, Sir!

Integrated LED Driver powerpoint slide

Why Doesn’t Everyone Have an Internal LED Driver? The answer to that question tells you a lot about the industrial LED suppliers.  First, let’s look at the undeniable facts:

Internal drivers mean you have one less thing to buy, one less thing to install, and fewer headaches overall. So why are all the other LED manufacturers just now starting to put internal drivers in their new products?

It’s not cost. Smart Vision Lights has always put our SMART driver inside every light, and we don’t cost more than the competition. So, external drivers aren’t cheaper.

It’s not performance. Our SMART internal LED drivers do everything you need: current control; continuous or strobe operation; NPN/PNP strobe input triggers; intensity adjustments, etc.

It’s not about LED lifetime. Competitors will say it’s because it allows the customer to replace a driver if it fails, but how often to LED drivers fail? Ours don’t, which is why we have the best warranty in the LED lighting business – 10 years of guaranteed protection. So why doesn’t everyone offer internal LED drivers? The real answer is that it’s cheaper for the manufacturer to produce an external driver though it makes more work for the customer. Ask yourself: If external drivers are better than internal drivers, then why are most new LED lights coming with internal drivers?   Smart Vision Lights has led the LED lighting industry by putting every driver in the light housing, and testing every light against the latest standards including new safety standards like IEC 62471. It’s easy to claim innovation, but it’s better to lead by example, don’t you think? It’s just SMART business.

Just the Facts Ma’am:  Some of you are nodding right now, but like me, you like proof, otherwise it is just marketing sping. So, let’s look at the competition and what they offer:

Company A –  No internal driver, they offer an “in-line” driver in the power cable.

Company B –  Mainly external drivers

Company C – Traditionally external drivers but new lights have internal drivers. Internal drivers are “constant” operation.

Company D – Internal drivers that are “constant” operation

Company E – Mainly external drivers except some newer lights have an internal driver (less than 5% of models). The internal driver does over drive the LED’s in strobe or flash mode.

Company F – Internal on new lights and external driver on older lights, but internal drivers are “constant” operation only.

Company G –  All external drivers Many of the lights listed above will use a third party driver.

But if something goes wrong, whom do you turn to for solutions: the light OEM or the driver manufacturer?  If you’re a customer that needs stringent light controls for your industrial application, and you don’t buy from Smart Vision Lights, you’ll likely have to spend several hundred dollars on an external driver, but that’s just the beginning of your pocketbook woes.  You’ll have to pay for wiring up an additional controller, programming the drivers with the right parameters for that light (do it wrong and you’ll damage the light), and add panel space to mount the external drivers.

Shift Into OverDrive with SMART Drivers In addition to avoiding the extra labor, wiring, and space requirements that come with an external driver, Smart Vision Lights’ SMART Drivers also come with OverDrive capability for strobe and flash operations. SMART benefits include:  Ease of use – light and controller, 1 wiring.

  • No Programming – Light voltage and current are set. Timing is set to follow the camera AND lights are monitored for protection so the light cannot be damaged.
  • Power – OverDrive lights store energy in the light. Depending on the strobe time the light will store the energy/current needed. This allows high output light to be directly connected to a smart camera with the need of an additional power supply. The light will steadily draw current and store the energy for the strobe/flash.
  • Cost – Our lights usually cost less our competitors with the additional controller…Add in an external strobe driver and you’re paying a lot more for a lot less light.