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Set up Koehler illumination on the microscope. If using a manual microscope, remove the condenser stop before setting up Koehler illumination and replace it once Koehler illumination has been set up.

What isbouncelighting

There are no additional optics in the above sample collection path, making oblique contrast ideal for two-photon and confocal microscopy, as no intensity is lost. It is also used to introduce contrast in patch-clamp experiments.

After passing through the specimen, the light rays enter the microscope objective and converge at the rear focal plane before they are observed through eye pieces or on a camera. As the light in oblique contrast hits the sample at an angle, only the diffracted sidebands of light on one half of the direct beam will be collected by the objective, as shown in figure 2b. This means that there is constructive and destructive interference between the direct light beams and collected sidebands.

Similarly to Differential Interference Contrast (DIC), images produced using oblique contrast have shadowed regions, giving a pseudo three-dimensional effect. The light strikes the specimen at an oblique angle, rather than an axial angle, which introduces phase changes to reveal features with a much greater contrast than brightfield illumination.

Obliqueillumination microscopy

The IR861T is an Omni-directional taxiway and apron edge fitting suitable for CAT III all weather operation airfield ground lighting (AGL) systems.

The IR852ML is an omnidirectional Fully Flush LED inset light fixture that is used to guide aircraft on to the parking stand.

Taxiway edge lighting fixtures, blue in color, can be utilised on all taxiways where centreline lighting is not provided.

Where taxiway edge lighting is to be used the criteria for the spacing between each installed fixtures is dependent on whether they are to be located on a straight section of taxiway or on a curve. Full details on how to calculate the spacing requirements can be found in ICAO Annex 14.

Oblique lighting ishelpful forwhattypes of evidence

Oblique contrast utilises an oblique condenser containing a sector stop with a small off-centre slit which makes the light go through the sample at an angle, so the specimen is illuminated from one direction only, shown in figure 2a. The sector stop is located beneath the lens and aperture diaphragm of the condenser. Light from the source passes through the slit which causes it to pass through the condenser lens at an oblique, off-axis angle. The specimen is then illuminated an angle.

Edge lighting can also be installed to denote the limits of aprons, parking areas, hard standings, servicing areas and other designated paved areas. Generally, this type of lighting would be elevated, but where manoeuvring is difficult it is likely to be inset.

atg airports offer a range of airfield lighting solutions including apron and taxiway edge lighting, compliant to all the latest standards.  Click on an image below for more information about specific types and models of airfield taxiway lighting.

To make a brightfield microscope capable of oblique contrast, the only additional components needed are an oblique condenser and an infrared or visible light source. The condenser is placed in the condenser housing above the light source. The oblique contrast mechanism (sector stop) of the condenser is located below the condenser lens and aperture diaphragm.

Oblique lightingexample

Your microscope is now set up for oblique contrast. Please contact Scientifica if you have any questions or require any further guidance.

Movement around the taxiways and aprons can be achieved more safely due to the many different lighting applications that are available to the airport.

With a standard condenser used in brightfield microscopy, the specimen is axially illuminated; light passes through the centre of the specimen, diffracting at different angles as it hits the specimen before recombining at the back of the image plane. As the light diffracts at different angles and therefore travels a longer distance before reaching the image plane, the phase of the light is affected. However, when light of equal amplitude and wavelength and inverse phase combines it cancels out so there is no overall change in phase. This is called destructive interference. Therefore, there is no overall change in the image.

Oblique lightingeye exam

Oblique contrast is suitable for imaging thin, transparent or nearly transparent samples such as cell cultures or thin brain slices. It can be used for visualising specimens that can’t be stained, such as living cells, tissues or organisms.

Then, adjust the direction of the sector stop by turning the diaphragm control knob. Close down or open the stop to adjust the amount of oblique illumination until the desired image is achieved. The amount of oblique illumination needed depends on the specimen and the amount of detail required. The oblique condenser enables the angles of illumination to be altered through 360 degrees without moving the specimen.

The IR852T is an Omni-directional taxiway and apron edge fixture suitable for CAT III all weather operation airfield ground lighting (AGL) systems.

The fixture used on a taxiway edge lighting circuit or an apron lighting circuit are the same in type. Both provide a blue light indicating the edge of the taxiway or the edge of the hard standing of an apron.

As oblique contrast doesn’t use polarised light, it is suitable for imaging vertebrate axons. Vertebrate axons are myelinated by a birefringent material and, unlike polarised light, the unpolarised light doesn’t affect the refractive index of the myelin. As petri dishes are also birefringent, oblique contrast is ideal for imaging samples within these, for example cultures of bacteria.

What is oblique lightingin Forensic Science

Oblique contrast is a microscopy technique used to increase the contrast of images of thin, transparent, unstained samples, the details of which can be difficult to visualise using brightfield microscopy. Two main advantages of oblique contrast are that it is a cheap and easy way of improving the contrast of your images.

Oblique lightingphotography

By drawing on our world-wide experience in high-profile AGL lighting projects, atg airports can help you to overcome complex challenges and achieve programme targets.

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Firstly, pull out the oblique slider and open the oblique iris so the condenser is adjusted for brightfield illumination.

Apron edge lights provide a blue light around the edge of the apron to indicate the end of the hard standing. The comply to the same standards in ICAO as would the taxiway edge light.

When making adjustments, check that the sector stop is still positioned correctly and that the slider is not too far in or out.