Polarized light creates a very faint pattern near the center of the visual field, called Haidinger's brush.

* Polarized light-related phenomena such as double refraction, or Haidinger's brush

* Haidinger's brush

Simulated appearance of Haidinger's brush for vertically polarized light.

Haidinger's brush is an entoptic phenomenon first described by Austrian

Haidinger's brush is caused by the blue cones, which contain one of the four visual pigments used by human vision, xanthophylls ( also known as lutein ).

Haidinger's brush is usually attributed to the dichroism of the pigment of the macula.

Simulated appearance of a computer screen viewed through a polarizer, showing typical size and intensity of Haidinger's brush

Many people find it difficult to see Haidinger's brush initially.

To see Haidinger's brush, start by using a polarizer, such as a lens from a pair of polarizing sunglasses.

This is followed shortly by Haidinger's brush.

The fact that the sensation of Haidinger's brush corresponds with the visual field correlate of the macula means that it can be utilised in training people to look at objects with their macula.

Wearing blue spectacles ( to enhance the Haidinger's brush image ) and an occluder over the other eye, the user will hopefully notice the Haidinger's brush where their macula correlates with their visual field.

The goal of the training is for the user to learn to look at the test object in such a way that the Haidinger's brush overlaps the test object ( and the viewer is thus now looking at it with their fovea ).

He was the first to observe the slight polarization dependence of the human eye, observed via the phenomenon now known as Haidinger's brush.

* Haidinger's brush is a very subtle bowtie or hourglass shaped pattern that is seen when viewing a field with a component of blue light that is plane or circularly polarized and rotating with respect to the observer's eye.

* Haidinger's brush

* Bill Reid, “ Haidinger's brush ,” Physics Teacher, Vol.

* Haidinger's brush

Some shrubs may be of good landscaping value, other areas of brush may need to be cleared.

Natural hazards include a hot, dry, dusty harmattan haze that may reduce visibility during the dry season and brush fires.

: Hot, dry, dusty harmattan haze may reduce visibility during dry season ; brush fires

Primer pockets may need to be cleaned with a primer pocket brush to remove deposits that prevent the primer from being properly seated.

The removal of prairie dogs " causes undesirable spread of brush ", the costs of which to livestock range may outweigh the benefits of removal.

Owners may patch tears and rips, and brush off surface dirt, but old leather and bark clothing always look old.

It may be seen as a yellowish horizontal bar or bow-tie shape ( with " fuzzy " ends, hence the name " brush ") visible in the center of the visual field against the blue sky viewed while facing away from the sun, or on any bright background when looking through polarized sunglasses.

The principal tools for a calligrapher are the pen, which may be flat-balled or round-nibbed, and the brush ( Reaves and Schulte 2006 ; Child 1985 ; Lamb 1956 ).

* A simple jig ( a tool ) that the smith might only use a few times in the shop may get the minimum of finishing: a rap on the anvil to break off scale and a brushing with a wire brush.

In heavily forested areas, a specialist brush truck may be used.

Caltrops are known to have been in use since Roman times and may have been used earlier: the concept was familiar to the 4th century BC Greeks, who used rocks, brush, nets and trees placed in the path of enemy conveyances on land or ensnarement devices hidden under water to achieve the same result: stop the enemy or suspected hostile in his tracks for examination or to prevent or limit incursions.

Usually designed to be waterproof, the product may come with an applicator brush or be applied with a finger.

It affords him not only a country holiday, in itself a remarkable event which he enjoys immensely, however ignorant of the countryside he may be, but also a brush with a society girl, riding on pneumatics and wearing some kind of Rational Dress.

Typically, a pictorial photograph appears to lack a sharp focus ( some more so than others ), is printed in one or more colors other than black-and-white ( ranging from warm brown to deep blue ) and may have visible brush strokes or other manipulation of the surface.

The disadvantage is that it also increases the associated odor and may require the use of a brush to remove bits of feces that may have " skid-marked " on the shelf.

It is typically found in thick brush, near open-canopied glades where it may graze and feed on grasses.

Giant anteaters typically rest in dense brush but may use tall grass on cooler days.

Some of the " comb " or " brush " symbols, which collectively compose as much as a sixth of all the symbols so far discovered, may represent numbers.

For small delicate figures, a pen or a fine brush may be used for laying on the ether solution.

The malabsorption may be due to a loss of brush border enzymes, erosion and flattening of the villi, and inflammation of the lamina propria.

The non-bristled end of the brush may end in a loop or a ball.

These types are used on rough ground, where the blades may frequently be fouled by other objects, or on tougher vegetation than grass, such as brush ( scrub ).