AmazonTrack Lighting

Most high magnification dark-field condensers require oil immersion fluid between the condenser and microscope slide because the angle of incidence of light leaving the top of condenser is greater than the critical angle for glass to air;  thus no light emerges from the condenser until it has the immersion oil applied to the condenser surface (Bagnell 2012). High magnification objectives designed for dark-field microscopy also have a built in iris diaphragm that permits the NA of the objective to be reduced.

Dark-field can be added to almost any light microscope for less than many other techniques. A simple method uses spider-stops (shown above) to create a cone of light by placing the spider-stops in a filter tray below the condenser or on top of the light source below the condenser. These metal filters can be purchased for a few dollars.  Early on I used small coins like a penny, dime, nickel or quarter and placed them in the center of a light blue filter or on the light source under the condenser to achieve dark-field lighting. You will need different sized coins for different objectives and moving the condenser up or down also varies the light cone size. Spider-stops and coins generally only work with low power objectives but are easy to try though results will vary. Another method to add dark-field requires a desk lamp or fiber optic lamp and lighting the specimen from above and removing the condenser (R. Vossen, 2004). I have used this “top-lighting” method successfully with larger aquatic arthropods and low magnification objectives 2.5X and 5X. Some phase condensers have a dark-field option that can be used with low power objectives (10 to 40X) and if there isn’t a dark-field option sometimes you can achieve good dark-field by using the wrong phase ring with some objectives.

Track rails are constructed of extruded aluminum. The live circuit and neutral conductors are made of heavy gauge copper and encased in extruded PVC insulators to prevent contact with aluminum extrusion. Tracks can be cut to custom length. They can also be joined together to form simple linear runs or complex configurations. Various connector options, including straight, “L”, “T”, “X” and adjustable push-in connectors, are available to mechanically and electrically join track sections together and provide design continuity throughout a space. A track system must be fully polarized and grounded throughout to ensure safe operation. Grounding is accomplished with a dedicated bus bar or through a grounding channel in the track. A current limiter is attached to a track system for limiting the amount of electrical load that can be placed on the circuit. Tracks can be surface mounted, recessed into the ceiling with special housing or clips, or pendant mounted from the ceiling using suspension stems.

The BA310 is designed for the daily routine work in universities, clinics, laboratories, and life sciences or medical applications.

LEDTrack lighting

Lamp-based LED luminaires, however, are not effective use of LED technology. The retrofit LED lamps incorporated in these fixtures must conform to the form factor and physical dimension of legacy light sources, which leads to compromise in thermal, electrical and optical design for LED systems. While lamp-based LED luminaires are still a common choice of design in entry-level track lighting systems, a solution that fulfils the requirement of high efficiency, high reliability, highly controllable, and high quality lighting calls for integrated design of LED lighting systems.

Syphilis is a sexually transmitted disease caused by Treponema pallidum, a bacterium classified under the Spirochaetes phylum. Schaudinn and Hoffmann discovered the bacteria Treponema pallidum in tissue of patients with syphilis in 1905.  In 1906, Landsteiner (he also discovered different AB0 blood types) introduced the use of dark-field microscopy for the detection of the spirochete causing syphilis which in turn increased the popularity of dark-field microscopy (Tampa et al. 2014).

An integrated LED track head combines LEDs, optics, and thermal management system into a single housing. The LED driver is either co-located with other components or housed in a dedicated gear box. The luminaire comes with a die cast aluminum housing that serves double duty as the heat sink in some designs.

Today’s LEDs deliver an exceptionally high efficacy. But even with LEDs, the tradeoff between color and efficacy still come into play. If luminous efficacy is an emphasis, light sources with a color rendering index (CRI) in the low to mid 80s are very likely to be used. However, the high source efficacy of LEDs affords us an opportunity to enjoy high color rendering lighting in virtually all applications. Task and accent lighting typically demands the use of light sources with a minimum CRI of 90, which means the spectral power distribution (SPD) of the light sources is balanced in exact proportions.

The amount of energy emitted as various wavelengths of the visible light spectrum also determines the apparent color (correlated color temperature, or CCT) of the light being produced by a source, which in turn affects the pleasantness of a space and subjective interpretation of brightness. LEDs can be specified in a nominal CCT of 2700K, 3000K, 3500K, 4000K, or 5000K. In LED lighting, the chromaticity consistency within the beam of light, and from luminaire to luminaire matters a lot to architectural and accent lighting. A higher level of color control on a particular group of LED must be exercised to keep variations of light color within defined acceptance criteria.

Track lighting systems provide the most flexible solution for ambient, task, accent lighting and wall washing in offices and hospitality spaces. Variable space layouts, variable room concepts and variable task needs in today’s commercial and hospitality environments call for dynamic, flexible lighting to create appealing, effective spaces. In open-plan offices, meeting rooms, libraries, halls and ballrooms, a lighting solution that adjusts to varying working conditions can boost concentration and motivation. In hotels, restaurants, bars, cafeterias, cafes, nightclubs and discotheques, lighting design must accommodate layout changes and space reconfigurations in order to keep up with the latest trends in hospitality design.

Dark-field is a technique that can be added to almost any light microscope and is economical in cost. Sometimes spider-disks or even coins can be used with low magnification objectives. The use of sliders or multipurpose condensers can produce better results for low power objectives (10, 20 and 40X). High magnification dark-field requires special condensers that have a numerical aperture greater than the high magnification objectives which have an iris diaphragms to reduce the objectives NA below that of the condenser. Dark-field has the ability to detect specimens below the limit of a normal light microscope resolution (200 nm) so that particles and fibers (20-40 nm) can be detected. This makes dark-field useful in the study of nanoparticles and microbes but it can also create beautiful images of aquatic-microorganisms.

Aside from light distribution, glare control is an important consideration in designing track luminaires. Directional luminaires are typically constructed to intentionally regress the position of the LED array. Beam control accessories such as honeycomb louvers, snoots and barn doors may be provided to eliminate high angle glare or soften aperture brightness.

Track Lightingheads

A track light fixture, commonly known as a track head, is detachably engaged to the track via an adapter which communicates electrical current and control signals to the track head. Track rack heads come in forms of lamp-based LED luminaires and integrated LED luminaires. Lamp-based LED luminaires are track light fixtures that use retrofit LED lamps to create the desired beam of light. The retrofit LED lamps are typically directional lamps that use internal reflectors to provide various light distribution patterns ranging from narrow-beam-angle spotlighting to wide-beam-angle floodlighting. Directional lamps include parabolic aluminized reflector (PAR) lamps, bulged reflector (BR) lamps, and multifaceted reflector (MR) lamps. Among these types, PAR and BR lamps are self-ballasted systems that run off a line power, MR LED lamps are low voltage systems and must be powered by transformers that reduce the line voltage to, typically, 12 volts. Lamp-based track heads are commonly gimbal ring fixtures which are the simplest and most cost-effective of all the designs.

Track lightingfor kitchen Ceiling

The ultra-microscope was the first dark-field microscope.  Richard Zsigmondy studied nanoparticles and developed the first ultra-microscope with Siedenkopf.  Zsigmondy received the Nobel Prize in 1925 for his work on nanoparticles. Today there is a renewed interest in nanoparticles and dark-field microscopy has regained importance and popularity.  I use dark-field microscopy to study and photograph mainly aquatic micro-organisms and find that it complements other forms of microscopy.

Oblique illumination was the first step toward dark-field microscopy sometimes referred to as dark-ground microscopy. Dark-field microscopy illuminates specimens with oblique light in the form of a hollow cone. Oblique light from the cone is focused on the specimen but only light that is reflected, refracted or diffracted enters the objective. The specimens are generally highly refractile and must be spaced apart. Dark-field microscopy works primarily by increasing the contrast of the specimen. It does not work well with objects that are crowded or too thick and it can be used to study biological sections if unstained or if covered with silver or gold particles. Other good specimens for dark-field include: cell cultures, microbes, plankton, foods, fibers, crystals, colloids, arthropods, autoradiographs or tissues labelled with metal particles. The subjects appear bright against a black background and can produce striking images. The addition of coloured filters or Rheinberg filters can also be used with the technique though the colours do not provide additional information (R. Berdan 2017). Dark-field microscopy today is also used to examine pathogenic bacteria and in live blood analysis (see article on blood on this web site).

High magnification dark-field microscopy requires special dark-field condensers and the objectives for use with these possess an iris diaphragm which can be used to reduce the numerical aperture of the objective. Numerical aperture (NA) is commonly used in microscopy to describe the light acceptance cone of an objective. Objectives with larger numerical apertures offer more light gathering power and higher resolving power.  The NA of the objective is written on each objective.  More expensive objectives have higher numerical apertures and generally higher magnification objectives have greater NA’s then lower power objectives. For high resolution dark-field the NA of the condenser must be larger than the NA of the objective lens in order to prevent direct light from entering the objective. A 100X objective with NA = 1.25 requires a condenser with NA 1.4.

Addressable track systems are typically accomplished by incorporating data lines. In this case, each track head should be capable of being controlled through a protocol such as 0-10V, DALI or DMX. Addressable lighting control can also be implemented through wireless networking. In this instance, the track luminaire incorporates a wireless communication module, which allows the luminaire to be controlled from a smartphone or handheld device through a wireless protocol such as ZigBee, Z-wave or Bluetooth.

The rate at which heat is removed from the LED module depends on the ability of the heat sink to absorb thermal energy and dissipate it into the surrounding ambient air. The heat sink must be designed with an adequate surface area to ensure the volume of heat flow outpaces the load rate.

Track lightingtypes

Panthera C2 is a new world-class level cased in a revolutionary technical future-orientated solution, now accessible for life sciences.

The downsides of dark-field microscopy are that it is not useful with thick specimens and it is less useful in identifying internal details.  Also dirt, dust and particles in water show up as bright spots. I often need to clean background spots in images using image editing software like Photoshop.

An integrated LED luminaire uses LEDs in conjunction with thermal, electrical and optical components to enable high efficiency, long life system operation and effective delivery of light. A dedicated system allows to incorporate a full sized heat sink for effective transfer of the heat flux from the LED junction to the ambient air. An optical design that extracts and controls light directly from the source provides for highly efficient and precisely controlled optical distributions. Integrated design typically lends adequate spaces to accommodate driver and control circuitry which is significantly more complicated than that of traditional light sources.

Track lightingmodern

Commercial track lighting makes use of a track system created with one or more linear electrified tracks (rails) along which one or more light fixtures may be mounted. Most track systems are line voltage and capable of handling up to 2400 watts on single 20-amp, 120-volt circuit, allowing them to deliver long runs necessary for commercial and architectural applications. The tracks accommodate either one or multiple circuits and come in H-type (Halo compatible), L-type (Lightolier compatible), or J-type (Juno compatible) configurations. The most prevalent multiple-circuit tracks are 2-circuit rails which are designed for use when a higher load capacity is needed or two separately controlled circuits are required on one section of track. Multiple circuits sharing a neutral, however, can generate cross-circuit interferences and neutral harmonics. Some multiple-circuit tracks have independent neutrals, which eliminates harmonics and allows for flicker-free dimming. Tracks may include additional raceways that allow for one or more sets of data lines to run through.

The most classic of all track head design is a cylinder. A cylinder track head typically includes a light engine that is an assembly of the LED module and aluminum heat sink. The LED module is a chip-on-board (COB) LED package or an array of high power LEDs or mid-power SMD LEDs solder mounted on a metal-core printed circuit board (MCPCB). The LED board is fully attached to the heat sink to ensure the heat dissipated by the LEDs can be spread out over a very large area. A thermal interface material (TIM) may be used to minimize thermal contact resistance at the interface.

LED track heads use lenses, reflectors, or a combination of them to regulate luminous flux from the light source. Total internal reflection (TIR) lenses are capable of producing smooth, rotationally symmetric beams with FWHM angular widths between 4 and 60 degrees with intense center beam candlepower (CBCP) for accent lighting or high illuminance uniformity for task or ambient lighting. TIR optics are also available in round or square lens arrays that provide individual optical control for an array of LEDs. The use of compound lens arrays enables miniaturization of optics and compact design of track luminaires. Tight beam control can also be accomplished with facet reflectors which take advantage of a large number of small surfaces (facets) to improve the reflection power and maximize the optical performance. Track lighting systems are also employed to provide uniform illumination and accenting of walls and vertical surfaces. The wall washing beam is usually achieved with asymmetric reflector systems.

The performance and reliability of the LED driver are system design considerations of critical importance. The amount of power delivered to the LED load must be tightly controlled to ensure consistent and predictable light quality. Since most track light fixtures installed in offices and hospitality spaces are intended to deliver task lighting, ripples in the output current provided to the LED load should be smoothed out to ensure flicker-free lighting. The LED load can be dimmed through phase control or constant current reduction (CCR). Selective control of LED luminaires mounted on a single circuit requires the track systems to be addressable.

Dark-field microscopy is ideal for specimens with smooth reflective surfaces. Specimens with a different refractive index or refractive index gradients from their surrounding solution bend the light into the objective.  Some of this is light is also diffracted entering the objective and can undergo interference. Under appropriate conditions dark-field microscopy can detect particles or fibers significantly smaller than the resolution limit of a normal light microscope (0.2 microns or 200 nm). This is possible due to diffraction disks provided the distance between the particles or fibers is greater than the resolving power of the objective.  For this reason a dark-field microscope can detect suspended particles down to 40 nm in size and even bacteria flagella which is approximately 20 nm in width.