LIT Sales Dictionary
Solid State Light
A. Photon: An elementary particle, the quantum of the electromagnetic interaction and the basic unit of light and all other forms of electromagnetic radiation. It is also the force carrier for the electromagnetic force. The effects of this force are easily observable at both the microscopic and macroscopic level, because the photon has no rest mass; this allows for interactions at long distances. Like all elementary particles, photons are currently best explained by quantum mechanics and will exhibit wave–particle duality, exhibiting properties of both waves and particles. For example, a single photon may be refracted by a lens or exhibit wave interference with itself, but also act as a particle giving a definite result when quantitative momentum (quantized angular momentum) is measured.
B. Wave theory VS. particle theory (Wave-Particle Duality): Postulates that all particles exhibit both wave and particle properties. A central concept of quantum mechanics, this duality addresses the inability of classical concepts like “particle” and “wave” to fully describe the behavior of quantum-scale objects. Standard interpretations of quantum mechanics explain this paradox as a fundamental property of the Universe, while alternative interpretations explain the duality as an emergent, second-order consequence of various limitations of the observer. This treatment focuses on explaining the behavior from the perspective of the widely used Copenhagen interpretation, in which wave–particle duality is one aspect of the concept of complementarity, that a phenomenon can be viewed in one way or in another, but not both simultaneously.
The idea of duality originated in a debate over the nature of light and matter that dates back to the 17th century, when competing theories of light were proposed by Christiaan Huygens and Isaac Newton: light was thought either to consist of waves (Huygens) or of corpuscles particles (Newton). Through the work of Max Planck, Albert Einstein, Louis de Broglie, Arthur Compton, Niels Bohr, and many others, current scientific theory holds that all particles also have a wave nature (and vice versa). This phenomenon has been verified not only for elementary particles, but also for compound particles like atoms and even molecules. In fact, according to traditional formulations of non-relativistic quantum mechanics, wave–particle duality applies to all objects, even macroscopic ones; but because of their small wavelengths, the wave properties of macroscopic objects cannot be detected.
In 1901, Max Planck published an analysis that succeeded in reproducing the observed spectrum of light emitted by a glowing object. To accomplish this, Planck had to make an ad hoc mathematical assumption of quantized energy of the oscillators (atoms of the black body) that emit radiation. It was Einstein who later proposed that it is the electromagnetic radiation itself that is quantized, and not the energy of radiating atoms.
When Einstein received his Nobel Prize in 1921, it was not for his more difficult and mathematically laborious special and general relativity, but for the simple, yet totally revolutionary, suggestion of quantized light. Einstein’s “light quanta” would not be called photons until 1925, but even in 1905 they represented the quintessential example of wave–particle duality. Electromagnetic radiation propagates following linear wave equations, but can only be emitted or absorbed as discrete elements, thus acting as a wave and a particle simultaneously.
C. Solid State Point Sources or Arrays: Not LEDS!
A. Relative spectral emission: The amount of light that gets out is an optical phenomenon that happens when a ray of light strikes a medium boundary at an angle larger than a particular critical angle with respect to the normal to the surface. If the refractive index is lower on the other side of the boundary, no light can pass through and all of the light is reflected. The critical angle is the angle of incidence above which the total internal reflection occurs.
When light crosses a boundary between materials with different refractive indices, the light beam will be partially refracted at the boundary surface, and partially reflected. However, if the angle of incidence is greater (i.e. the ray is closer to being parallel to the boundary) than the critical angle – the angle of incidence at which light is refracted such that it travels along the boundary – then the light will stop crossing the boundary altogether and instead be totally reflected back internally. This can only occur where light travels from a medium with a higher [n1=higher refractive index] to one with a lower refractive index [n2=lower refractive index]. For example, it will occur when passing from glass to air, but not when passing from air to glass.
B. Etendue: Etendue or étendue is a property of pencils of rays in an optical system, which characterizes how “spread out” light is in area and angle. It may also be seen as a volume in phase space.
From the source point of view, it is the area of the source times the solid angle the system’s entrance pupil subtends as seen from the source. From the system point of view, the etendue is the area of the entrance pupil times the solid angle the source subtends as seen from the pupil. These definitions must be applied for infinitesimally small “elements” of area and solid angle, which must then be summed over both the source and the diaphragm as shown below.
Etendue is important because it never decreases in any optical system. A perfect optical system produces an image with the same etendue as the source. The etendue is related to the Lagrange invariant and the optical invariant, which share the property of being constant in an ideal optical system. The radiance of an optical system is equal to the derivative of the radiant flux with respect to the etendue.
The term étendue comes from the French word for extent or spread. The French word for the optical property is étendue géométrique, meaning “geometrical extent”.
Other names for this property are acceptance, throughput, light-grasp, collecting power, and the A? product. Throughput and A? product are especially used in radiometry and radiative transfer where it is related to the view factor (or shape factor). It is a central concept in nonimaging optics.[2
How this relates to our product is the light allows the LED source to escape the entendue limit by defying the limit and channeling outer rays back into the LED light source thus creating an infinite source of light in a “superior perfect retroflective efficiency situation.”
C. T.I.R.: Total Internal Reflection (Our device is a TIR System)
D. Photonic lattice – PhLat Light: Acts as a nanometer scale lens and collimates the light before it leaves the package.
E. Plasma waveguide: Flexible, highly efficient vehicle for the transmission of light.
F. Radiation pattern: The graphic representation of the strength and direction of electromagnetic radiation in the vicinity of a transmitting aerial. The dispersion or radiation pattern of the light is determined by the LED lamp’s mechanical construction. A narrow radiation pattern (Figure 5) will appear very bright when viewed on-axis, but with a narrower viewing angle. The same LED die could be mounted to give a wider viewing angle, but with its on-axis intensity reduced – a tradeoff inherent in all LED indicators. High brightness LEDs with a 15° to 30° viewing angle are ideal for information panels directly in front of the subject but an automotive dashboard may require an angle of 120° or more.
G. Geometric optics: Refers to the physical laws giving an explanation for the path of a light beam in materials. Basic concepts in geometrical optics are, e.g., reflection, refraction, transmission, absorption and diffusion.
H. C.L.T.: Combined Lighting Technology
I. O.N.E.: Optical Navigation Engine
J. LIT: Luminance Integrated Technologies
A. Electromagnetic Spectrum: The range of all possible frequencies of electromagnetic radiation. The “electromagnetic spectrum” of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object.
The electromagnetic spectrum extends from low frequencies used for modern radio to gamma radiation at the short-wavelength end, covering wavelengths from thousands of kilometers down to a fraction of the size of an atom. The long wavelength limit is the size of the universe itself, while it is thought that the short wavelength limit is in the vicinity of the Planck length, although in principle the spectrum is infinite and continuous.
B. Visible Spectrum: The visible spectrum is the portion of the electromagnetic spectrum that is visible to (can be detected by) the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 390 to 750 nm. In terms of frequency, this corresponds to a band in the vicinity of 400–790 THz.
C. Color Rendering Index (CRI): The measure of a light source’s ability to render the color of objects “correctly,” as compared with a reference source with comparable color measurement; the scale peaks at 100.”
D. Volumetric scattering: (internal scattering) takes place inside media containing microparticles. Light entered into the medium containing microparticles is scattered by microparticles and propagates in various directions.
E. Infared (IR): Electromagnetic radiation with wavelengths longer than visible light but shorter than radio waves.
F. Ultraviolet (UV): Radiation lying in the ultraviolet range; wave lengths shorter than light but longer than x-rays.”
G. Tristimulus colorimetry: States that all colors can be seen as mixtures of the three primary colors blue, green and red (often called RGB). There are different so called color charts giving us each color tone as a function of components. The most used of the chromacity charts is the CIE 1931 Yxy chart.
H. CRI: Color Rendering Index (is a quantitative measure of the ability of a light source to reproduce the colors of various objects faithfully in comparison with an ideal or natural light source. For instance, cars under street lights often appear gray rather than their true color. This is an example of poor CRI.) CRI@100 is a perfect sunny day.
I. C.I.E. Color Space: The CIE system characterizes colors by a luminance parameter Y and two color coordinates x and y which specify the point on the chromaticity diagram. This system offers more precision in color measurement than do the Munsell and Ostwald systems because the parameters are based on the spectral power distribution (SPD) of the light emitted from a colored object and are factored by sensitivity curves which have been measured for the human eye.
Based on the fact that the human eye has three different types of color sensitive cones, the response of the eye is best described in terms of three “tristimulus values”. However, once this is accomplished, it is found that any color can be expressed in terms of the two color coordinates x and y.
The colors which can be matched by combining a given set of three primary colors (such as the blue, green, and red of a color television screen) are represented on the chromaticity diagram by a triangle joining the coordinates for the three colors.
The C.I.E. Chromaticity Diagram
The diagram at left represents the mapping of human color perception in terms of two CIE parameters x and y. The spectral colors are distributed around the edge of the “color space” as shown, and that outline includes all of the perceived hues and provides a framework for investigating color.
The diagram given here is associated with the 1931 CIE standard. Revisions were made in 1960 and 1976, but the 1931 version remains the most widely used version. The diagram at lower left is a rough rendering of the 1931 CIE colors on the chromaticity diagram.
Diagram with annotation
Associate with colors
The 1976 CIE Chromaticity Diagram
A. Lumen: A measurement of light based on how many photos hit a given surface.
B. LUX: a measure of lumens per square meter.
C. Candela: the SI base unit of luminous intensity; that is, power emitted by a light source in a particular direction, weighted by the luminosity function (a standardized model of the sensitivity of the human eye to different wavelengths, also known as the luminous efficiency function). A common candle emits light with a luminous intensity of roughly one candela. If emission in some directions is blocked by an opaque barrier, the emission would still be approximately one candela in the directions that are not obscured.
D. Watt is a derived unit of power in the International System of Units (SI), named after the Scottish engineer James Watt (1736–1819). The unit, defined as one joule per second, measures the rate of energy conversion.
E. Volt: the SI unit of potential difference and electromotive force, formally defined to be the difference of electric potential between two points of a conductor carrying a constant current of one ampere, when the power dissipated between these points is equal to one watt.
F. Milliamp (mAh): This is a rating for batteries. The higher the milliamp rating, the longer the cell can provide power.
G. Brightness: the luminance of a body, apart from its hue or saturation, that an observer uses to determine the comparative luminance of another body. Pure white has the maximum brightness, and pure black the minimum brightness.
H. Smart Batteries: ONE HeadLIT™ uses smart lithium-ion battery technology which means they recharge at the same rate they discharge, e.g., 30 minutes of use – 30 minutes to recharge.
I. Discharge: An electrical device that releases stored energy
J. Power: A source or means of supplying energy.
K. Hot swap: Terms used to describe the functions of replacing computer system components without shutting down the system. More specifically, hot swapping describes replacing components without significant interruption to the system, while hot plugging describes the addition of components that would expand the system without significant interruption to the operation of the system. (A machine may have dual power supplies, each adequate to power the machine)
A. Laminar flow: Smooth and regular fluid flow – the direction of motion at any point remaining constant as if the fluid were moving in a series of layers sliding over one another without mixing.
B. Comfort: A state of physical ease and freedom from pain or constraint.
C. Visual impairment: Impairment of the sense of sight
D. R.O.I.: A performance measure used to evaluate the efficiency of an investment or to compare the efficiency of a number of different investments. To calculate ROI, the benefit (return) of an investment is divided by the cost of the investment; the result is expressed as a percentage or a ratio.
E. Reliability – dependability: the quality of being dependable or reliable.
F. Risk: Risk Management is the identification, assessment, and prioritization of risks (defined in ISO 31000 as the effect of uncertainty on objectives, whether positive or negative) followed by coordinated and economical application of resources to minimize, monitor, and control the probability and/or impact of unfortunate events or to maximize the realization of opportunities.
G. Trip hazard: Something such as a wire that people might catch their feet on and trip over.
H. Aseptic technique: A set of specific practices and procedures performed under carefully controlled conditions with the goal of minimizing contamination by pathogens.
I. O.R. Time: The necessity to increase operating room efficiency is born out of the current medical climate that creates financial and productivity pressures on hospitals, physicians, and staff. This problem is not new but rather has been addressed in a number of different ways over the past decade.
J. Ergonomics: The study of designing equipment and devices that fit the human body, its movements, and its cognitive abilities.
K. JBMA Standards (Japan Business Machine Makers. Association) standards