Also referred to as strobe, pulsed and blinking light, flashing light is the rapid, repeated change in brightness of light over time.
Some pulsed light sources are designed to have a fixed frequency and duration. While others are controlled by programmable power supplies that can change not only the frequency and duration but also the amplitude. To select a system for the measurement of pulsed light it is often necessary to know the parameters of the sources output. Frequency of a pulse of light is most often stated in hertz. Hertz (Hz) is the SI base unit used to define cycles per second. Pulse duration is the interval between the time, during the first transition (rise), that the amplitude of the pulse reaches a specified level of amplitude, and the time the pulse amplitude drops (fall), on the last transition, to the same level. The amplitude is the maximum or peak output during a pulse which can be stated in optical units such as lux, W/cm2, Watts, candela etc.
Pulsed light is used in many applications because it draws attention for safety/hazard warning, has the ability to penetrate surfaces in UV curing and phototherapy applications, and can minimize damage to materials while eradicating microbes in germicidal and other applications.
Pulsed UV lamps are designed to provide high intensity bursts of UV light. In certain curing applications using pulsed light is more advantageous to the product than continuous light. Pulsed light delivers more energy faster, and at lower temperatures. In applications where heat and prolonged exposure to UV light could be damaging to the product, pulsed light is the ideal solution. Additionally pulsed light has the ability to deliver light at high peak power for deeper penetration. Any application where process control is required to ensure the quality of the end product, users must verify their system is in spec. Using a light meter/radiometer to measure and validate that their process is working properly is essential.
Aircraft Anti-Collision Lighting
FAA regulations require most aircraft to incorporate exterior lighting that enable other aircraft to see them. These include red and green positioning lights on the wings, red beacon lights on the top and bottom of the fuselage, and flashing white anti-collision strobe lights. The FAA has regulations around the intensity minimum intensity of these lights (minimum light they must produce in candela) in addition to the flash rate. Airlines, MROs, and manufacturers of anti-collision lights must verify that the intensity and flash rate are within spec of the regulation. Using a meter specially designed to measure light from flashing sources is critical in the validation and maintenance process.
In addition to airplane anti-collision lighting, the FAA has regulations regarding anti-collision lighting on structures that rise 200 feet above ground level. These structures include buildings, bridges, antennas, wind turbines, towers, and equipment to enable aircraft flying overhead to see there is an obstruction. The FAA lists requirements for the color of the light, intensity, beam pattern and sequence for these obstruction lights. Non-compliance of structure lighting can result in hefty fines, as well as creating a safety hazard for aircraft.
Safety Hazard Lighting
Pulsed lighting often adds great benefits compared to CW light sources in applications where gaining attention is critical. Temporal modulation (blinking, flashing) is a powerful tool for drawing attention. The human eye is five times more sensitive to pulsed/flashing light when the proper frequency and duration is applied. For this reason pulsed lights are widely used in many signaling applications for aviation, marine navigation, land transportation, and safety hazard warning. Depending on the application, regulations may dictate the intensity and flash rate of hazard lights. Inspectors may need to verify compliance for new installations, and state and federal regulators may require periodic checking of these lights as directed by the NPFA 72 strobe testing requirement.
Intense Pulsed Light for Medical Applications
Intense pulsed light (IPL) is commonly used for medical treatments of skin conditions including brown spots, redness, age spots, broken blood vessels, and rosacea, and for other cosmetic treatments including hair removal. The pulsed light allows for deep penetration into the skin where a chromophore absorbs the light and kills the unwanted cells. IPL instruments typically use light sources with a broad-spectrum output, since different wavelengths of light address different cosmetic conditions. Shorter wavelengths found in the UV region are used to treat conditions on the surface of the skin, while longer wavelengths in the infrared spectrum penetrate deep into tissue, all without damaging the other layers of skin. Professional-grade devices that use intense pulsed light should be checked periodically that their operation and output are within spec.
Pulsed Light for Disinfection and Sterilization
Pulsed UV is often used for disinfection /sterilization as well as for curing. It is often noted as being more effected for curing thicker materials due to the ability to offer deeper penetration. Most light measurement systems are design to measure CW (continuous wave) light sources. Capturing the light output of a source that is not continuous can add significant difficulty to the measurement as the light meter must respond to changes in intensity at greater speeds, often over many ranges of intensity.
Audience scanning lasers are special effects lighting used to increase audience stimulation, add a feeling of inclusion and gain a higher level of audience attention and satisfaction. Like fireworks, burst colorful light add to the ambiance in dance clubs, and concerts. Pulsed UV lamps are designed to provide high intensity bursts of UV that if left on continuously could cause unnecessary heating, shortening of lamp life, and greater costs to run.
Selecting a Pulsed Light / Flash Measurement System
ILT has designed our measurement systems to measure as fast as 500 samples/sec, with the front end storing a charge that allows even faster integrated light measurements. Units can provide readouts including, graphically profiling the rise of the pulse, W (joules), W/cm2 (J/cm2), Lux (lux*sec), candela, effective candela, flash count, integral, peak intensity, frequency and more. We offer a range of systems, from bench-top to hand-held, to meet a broad set of environments and applications. The table below is designed to help you select a system based on your light source, light measurement, and environmental needs. Our specialists are also on hand to answer any questions and help guide you in determining which system is best for you. Additionally, many of our systems and detectors can be customized to meet unique requirements. Please use the contact form at the bottom of this page for further assistance.