Information

Why is flash light harmful to what aquatic life forms?

Why is flash light harmful to what aquatic life forms?


We are searching data for your request:

Forums and discussions:
Manuals and reference books:
Data from registers:
Wait the end of the search in all databases.
Upon completion, a link will appear to access the found materials.

When visiting an aquarium, it's often not allowed to take photographs with a flashlight on. It is said that the flash light with very high intensity is harmful to the displayed life forms.

I respect that and try to capture images without flash.

I'd still like to know how flash light interacts with the animals (or even the plants) in an undesirable way? Is it harmful because they are not used to it?

The light emitted from the arc of a welder for example is so intense, that it destroys the human eye. Laser is another example. Technology is so advanced that we can produce harmful light sources that not even the winking reflex can protect us against. Maybe a flashlight used for photography is the welding arc for aquatic life?

Additional light can increase growth of algae, which would in turn influence the (very little) ecosystem in an aquarium. On the other hand, I don't think the short bursts of light from photographic flashes introduce enough light to have an impact. Or do they?

The motivation for this question is not to be knowledgeable about what creatures are not harmed by flash in order to fry them in light. Advancements in camera technology make it unnecessary to add more light to the scene in the form of flash light. What made me curious about it is that except for the industrial light sources mentioned above, we rarely consider single bursts of light to be dangerous for us humans. We are much more concerned about the continuous sunlight.


I am sure the main reason is that flash lights, certainly in a dark aquarium, are very frightening and might cause temporary blindness for the animals. If someone flashes in your eyes, you can't see for a few seconds as well. That will cause distress for the animals and distressed animals live considerably shorter.

The total amount of light is indeed much to small to cause algal growth and real blindness is not likely from camera flashes.

EDIT: I've found this article that will certainly be of interest to your question.


Harmful Effects on Toxin Dinoflagellates in Shrimp Culture Ponds

Phytoplankton are the key food item in both aquaculture and mariculture. Both systems are utilizing phytoplankton as food for the animals being farmed. In aquaculture, phytoplankton must be obtained and developed artificially through various adapted procedures, writes Mr. Prakash Chandra Behera, Technical Manager (Aquaculture Division) PVS Group, India.

The plankton population in form of desirable bloom undertaken throughout the culture period as part of best pond management practice. Phytoplankton is used as a food stock for the production of zooplankton which are in turn used to feed cultured organisms.

Living dinoflagellates are one of the most important components in phytoplankton. Many dinoflagellates are primary producers of food in the aquatic food webs. Dinoflagellates are an integral part of the first link in the aquatic food chain: the initial transfer of light energy to chemical energy (photosynthesis).

The dinoflagellates along with other phytoplankton enter in to the aquaculture pond through water intake from adjacent tide water. Due to applied nutrients and water conditions, immediately the dinoflagellates proliferate its bloom in desire level or sometimes in heavy blooms which is harmful to pond condition. These blooms appear in red-brown or red -green water coloration.

Dinoflagellates

  • Eukaryotic single-celled algae
  • Many have two flagella, which allow the cells to have limited mobility
  • Cells are covered by a theca (sheath) that can be smooth or ornamented
  • Some species are able to migrate vertically through the water column, seeking nutrients, prey, or protection from harmful UV rays.
  • Nearly half of known species are capable of photosynthesis and contain light-harvesting pigments (autotrophs)
  • Some species survive by other nutritional modes, and may absorb organic matter or engulf prey (heterotrophs)
  • Many species employ a combination of autotrophic and heterotrophic behaviors

Of the 2000 known species, about 60 are able to produce complex toxins. Dinoflagellates are a very successful group, at times to the detriment of the ecosystem. When conditions are favorable, a population explosion or bloom may occur, sometimes resulting in contamination of fish and shellfish and posing a threat to human and animal health.

The growth of dinoflagellates are regulated by several factors including water, temperature, solar irradiation, turbidity, and nutrient concentrations. Acidic pond water is typically treated with calcium-based compounds aiming to raise the pH and promotes the growth of phytoplankton. Nutrients are supplied by the use of fertilizers and artificial feeds in which aquaculture ponds usually meet the ideal conditions for phytoplankton growth.

Luminescence Effect of Dinoflagellate

These are tiny plants in plank tonic form live in sea water and obtain source of energy from sunlight during day. In darkness the dinoflagagellates emit bright blue light( luminescence) in response to movement within water. This mechanism is regulated by activity of enzymes (luciferases) upon luminescent (luciferins) and requires oxygen. The dinoflagellates are making flash light during dark time and light became brightest after several hours of darkness. The glowing activities is reduced in early morning and there is no longer to luminescence upon shaking.

Harmful Toxin Effects of Dinoflagellate

Dinoflagellate 'blooms' (cell population explosions) can cause discoloration of the water (known as red tides) which can have harmful effects on the surrounding sea life and aquaculture. When toxic species are in bloom conditions ,the toxins can be quickly carried up the food chain and indirectly passed into other consumers via fish and shellfish consumption, sometimes resulting in gastrointestinal disorders, permanent neurological damage, or even death. Some dinoflagellates species produce toxins that can kill both finfish and shrimp and indirectly to other consumers.

There are different types of harmful dinoflagellate blooms

  • Gonyaulax polygramma - Cause oxygen depletion
  • Dinophysis acuta sps - Diarrhetic Shellfish Poisoning (DSP)
  • Gambierdiscus toxicus, Ostreopsis mascarenensis - Ciguatera Fish Poisoning
  • Alexandrium acatenella sps - Paralytic Shellfish Poisoning (PSP)
  • Karenina breve sps - Neurotoxin Shellfish Poisoning (NSP)
  • Gymnodinium mikimotoi.- Harmful to fish ,shrimp and marine invertebrates .The cells may cause damage or clog the gills of these animals.

Harmful Effects of Dinoflagellate to Shrimp Health

  • Dinoflagellate 'blooms' can cause critically damages to cultured shrimps by toxin effects and sudden fluctuation of water parameters of culture pond.
  • Shrimps deaths occur because of large numbers algal cells become trapped in the creatures' gills, causing respiratory failure, hemorrhaging, or bacterial infection . Species of the diatom genus Chaetoceros, for example, become lodged in the gills, where their spiny filaments destroy the hosts' tissue.
  • Depletion of dissolved oxygen level increases of ammonia content and toxic gasses in pond water.
  • Instability of pH and promote to inhabitant of pathogenic organisms in pond.
  • Increase the chance of diseases and microbial load in pond.
  • Appearance of gill diseases, annetena rot etc, less appetite, poor growth, bad molt, soft shell, low survival rate and chance of mass mortality of shrimps.

Control Measures

  • Avoid the water intake to shrimp farms during red bloom phase (red tide) from near water sources.
  • Follow the best management practice to prevent the entry of bloom water in shrimp pond.
  • Do not exchange pond water if blooming phase occur near water sources.
  • If no bloom observed in adjacent intake water , exchange maximum water in possible period.
  • In severity condition, operate aerators for more period and stop the periodical nutrients to pond water.
  • Strictly follow the feed management practice.

Treatments

  • Treat the pond water with required doses of chlorine etc to during the pond preparation.
  • For best result use quality algaecide or de- dinoflgellate product to pond water during culture period.
  • In critical conditions, use oxygen developer and ammonia adsorbent products immediately followed by application of zeolite product.
  • Apply best soil & water probiotics products to pond for better results in 2-3 weeks intervals.
  • Also, application of soluble aluminum iron compound have greater effectiveness for removing phosphorus from pond nutrition concentration and controlling dinoflagellate growth.
  • Use of required doses of Ferric chloride or ferrous sulfate has the potential to reduce phosphorus concentration for lowering bloom density.

Proper pond and water quality management is essential to successful and quality shrimp production. Maintaining a good culture environment through use of proper management practices will reduce the risk of disease and increase production, shrimp quality, and marketability.


Light Damage to Vision in Marine Species

As most of you likely know, marine animals in the depths of the ocean receive significantly less sunlight than we humans do here on terra firma. Over the course of millions of years of evolution and natural selection, their eyes have adapted to this reality. Most fish species have rod cells and cone cells, similar to humans, and some can also see in color&mdashor even light in the ultraviolet spectrum. However, fish have developed different eye structures (e.g., more or less concavity, protrusion) to account for their need to see in darker waters. For example, some fish are able to see blue light wavelengths, even though they have never seen sunlight, and may lack the photoreceptors to even detect other forms of light.

Close up of a fish eye (Photo Credit : Kletr/Shutterstock)

In the furthest depths of the ocean, where light rarely reaches, primitive eyespots may be the only source of vision for some creatures, while others are already completely blind. When a bright light, e.g., from a submersible or a photography flash, strikes these marine animals in their eyes, it can be incredibly intense and traumatic. Imagine going years without seeing any light, and then suddenly having your world flooded by it. Humans have trouble adjusting to sunlight when they leave a dark movie theatre, and that&rsquos only two hours of darkness, not an entire lifetime!

When such intense light exposure occurs, a number of things can occur, including retinal bleaching, stunning/dazing, or permanent vision damage. We will explain these different impacts briefly below.

Retinal Bleaching

When a deep-sea fish eye is exposed to a bright light or flash, it can cause some of the cells of the retina to become &ldquobleached&rdquo. Depending on the species, and the intensity of the exposure, this bleaching may be temporary, lasting only 10-15 minutes, before the rod and cone cells are once more able to absorb light properly. However, some research has shown that the bleaching and temporary blindness can last for days, making these organisms easy prey and significantly disrupting and harassing their natural life cycle.

Stunning/Dazing

This is a reaction that we as humans can certainly understand. When we have a flashlight shone in our eyes, we are oddly stunned by it, as it fills our vision in an unpleasant way, often freezing us in place for a moment as we adjust. The same thing is seen in animals who run across the road in the middle of the night the headlights will often freeze them in place, rather than encourage them to flee and avoid harm.

In the deep waters of Earth&rsquos oceans, many divers and researchers have reported this type of stunned behavior when marine creatures had lights shone on them. If you have ever gone on a night dive, you have likely seen how fish will often stop directly in the beam of the light, rather than escaping back into the darkness. In situations like this, the eyes of fish so close to the surface are likely adapted to sunlight, and won&rsquot suffer any permanent damage, but putting a spotlight on them is still a form of harassment. Not only that, highlighting the location of these animals makes them an easy target for predators, which becomes a real problem if you are shining and stunning a protected or threatened creature. There have even been reports of predatory fish following groups of night divers, knowing that they will benefit from the stunning effects of their bright lights.

Permanent Vision Damage

Numerous research studies have found that the use of white lights at great depths can permanently blind creatures exposed to such illumination. Studies on shrimp near geothermal vents shows that exposure to light left them permanently without the ability to see, and various crab species can be blinded by exposure to even small amounts of artificial light. For this reason, experts, academics and researchers take special care to avoid using bright white lights or flash photography at great depths. Unfortunately, there is no way to control the behavior of underwater photographers, amateur divers and the general population from using lights underwater in an irresponsible way.


Step 2: Preparing the Power Cells

The power cell is your flashlight's main source of energy. Basically there are two strips of metal, one for the anode and one for the cathode. The "Copper Strip" will provide the positive energy while the "Zinc Strip" for the negative.

Procedures: Assembling The Power Cell:
1st.) Roll tissue paper around your "Copper Strip" until you reach the 3rd sheet.
2nd.) After reaching the third sheet, roll the "Zinc Strip" until you reach your final sheet, which is the 5th sheet.
3rd.) Now tie some copper wire around the PowerCell, this prevents your tissue from tearing once it gets wet.
4th.) I recycled a pulley since it fits snugly on the PVC Coupling, puncture 2 slits for the metal strips to fit in.
5th.) Insert both metal strips through the pully's hole and seal/ waterproof it using epoxy/ superglue/ hotglue.


Fundamentals of light

To understand the effects of light on the human physiology, it is important to understand light. Briefly, light is radiation in a specific range of the electromagnetic spectrum. It is best and most completely described by its spectral distribution, which quantifies the amount of energy (or the number of photons) as aਏunction of wavelength (with visible light in the wavelength range between 380 and 780 nm).

During the day, light intensities outside can reach illuminances up to 100,000 lx in direct sunlight and 25,000 lx in full daylight. Light intensities in closed rooms are considerably lower and standard office lighting is only

500 lx, often lower [37, 81]. The spectrum of daylight, which is light from the sun filtered by the atmosphere is relatively broadband in its distribution (Fig.  2 a). The availability of daylight depends on geographical location and season. In the timeframe of human evolution, it is a rather recent development that light can be available during all times of day through artificial light. Artificial light allows for illuminating indoor and outdoor spaces. It comes in many forms, e.g. incandescent, fluorescent, or light-emitting diode (LED) lighting. While light generated by these technologies may all appear “white”, the underlying spectra are rather different (Fig.  2 b). The reason why many different types of spectra might have the same appearance lies in the retina. Critically, different spectra, even if they create the same visual impression, may vary in their chronobiological effects on the circadian clock.

Spectral power distributions of common light sources in our environment. a Spectral power distributions of daylights at different correlated colour temperatures (CCT 4000 K 6500 K 10,000 K). Spectra are normalised to 555 nm. b Spectral power distributions of a white LED (top), aਏluorescent source at 3000 K (middle), and an incandescent source (tungsten-filament 2856 K, bottom). All three artificial sources have the same luminous flux (normalised to 100 lm), and approximately the same colour temperature (2700� K), but the spectra are very different in shape and scale (see y axis)

It is important to keep in mind that there are multiple ways how light is quantified and reported in the literature in particular when focussing on its repercussions on human physiology. For example, while the absolute spectral distribution of a light is the most complete description, many investigators report the illuminance (in lux [lx]), or the correlated colour temperature, which is the temperature of a hypothetical black-body radiator with the same colour as the light source in question. Unfortunately, until recently, there have been no standard quantities that experimenters were asked to report, and therefore, summarising the chronobiological and somnological literature on the effects of light remains a਌hallenge. Recently, the Commission International de l�lairage (CIE), the international standard body for quantities related to light, issued a new standard containing a reference framework for quantifying the effects of light on non-visual functions [31]. In practice, experimenters employing light as an intervention should report, at a minimum, the spectral power distribution of the light, as seen from the participant’s point of view. Detailed minimum guidelines are given in [83].


Conductivity (Electrical Conductance) and Water

Water and electricity don't mix, right? Well actually, pure water is an excellent insulator and does not conduct electricity. The thing is, you won't find any pure water in nature, so don't mix electricity and water. Our Water Science School page will give you all the details.

Conductivity (Electrical Conductance) and Water

Multi-parameter monitor used to record water-quality measurements.

You're never too old to learn something new. All my life I've heard that water and electricity make a dangerous pair together. And pretty much all of the time that is true—mixing water and electricity, be it from a lightning bolt or electrical socket in the house, is a very dangerous thing to do. But what I learned from researching this topic was that pure water is actually an excellent insulator and does not conduct electricity. Water that would be considered "pure" would be distilled water (water condensed from steam) and deionized water (used in laboratories), although even water of this purity can contain ions.

But in our real lives, we normally do not come across any pure water. If you read our article about water being the "universal solvent" you know that water can dissolve more things than just about any other liquid. Water is a most excellent solvent. It doesn't matter if the water comes out of your kitchen faucet, is in a swimming pool or dog dish, comes out of the ground or falls from the sky, the water will contain significant amounts of dissolved substances, minerals, and chemicals. These things are the solutes dissolved in water. Don't worry, though—if you swallow a snowflake, it won't hurt you it may even contain some nice minerals your body needs to stay healthy.

Free ions in water conduct electricity

USGS employees electrofishing in the Frio River, Texas.

Water stops being an excellent insulator once it starts dissolving substances around it. Salts, such as common table salt (sodium chloride (NaCl)) is the one we know best. In chemical terms, salts are ionic compounds composed of cations (positively charged ions) and anions (negatively charged ions). In solution, these ions essentially cancel each other out so that the solution is electrically neutral (without a net charge). Even a small amount of ions in a water solution makes it able to conduct electricity (so definitely don't add salt to your "lightning-storm" bathwater). When water contains these ions it will conduct electricity, such as from a lightning bolt or a wire from the wall socket, as the electricity from the source will seek out oppositely-charged ions in the water. Too bad if there is a human body in the way.

Interestingly, if the water contains very large amounts of solutes and ions, then the water becomes such an efficient conductor of electricity that an electrical current may essentially ignore a human body in the water and stick to the better pathway to conduct itself—the masses of ions in the water. That is why the danger of electrocution in sea water is less than it would be in bathwater.

Lucky for hydrologists here at the USGS, water flowing in streams contains extensive amounts of dissolved salts. Otherwise, these two USGS hydrologists might be out of a job. Many water studies include investigating the fish that live in streams, and one way to collect fish for scientific study is to shoot an electrical current through the water to shock the fish ("zap 'em and bag 'em").


When are children taught about light?

In Year 1 children explore materials and may use the terms opaque (non see-through) and transparent (see-through) to describe different materials.

In Year 3 children begin to fully explore &lsquolight&rsquo. The new National Curriculum, introduced in 2014, requires children in Year 3 to understand that they need light to see and that light is reflected from surfaces. They will explore shadows and learn how shadows are formed when a light source is blocked by an opaque item. Children will consider the dangers of looking directly at light sources (mainly the sun) and how they can protect their eyes.

In Year 6 children consolidate their knowledge of light gained in Y3. They extend this understanding by learning about how light travels in straight lines. They will learn how we see, by understanding light travels from the light source to an object and then reflects to our eyes. Children consider why shadows have the same shape as the object that made them. Children may also explore rainbows, colours in bubbles and light appearing to bend in water.


While plants need light to grow, not all light or plants are the same. If someone asks, “What kind of light do plants need” they may be referring to the light spectrum. Plants are affected by light that falls into the “blue” spectrum of the light scale. Daylight, fluorescent light and grow lights all have “blue” tones in them and will help provide the light your plant needs. Incandescent and halogen lights are more “red” and will not help your plant grow.

The question, “What kind of light do plants need” may also refer to time needed in light. Normally they are referred to as low/shade, medium/part sun or high/full sun plants. Low or shade plants may need only a few hours of light a day while high or full sun plants need eight or more hours of light a day.


Are they needed for safety?

Lights that are needed for safety or security should not be turned off, as this may cause a safety hazard. Instead, they should be modified so that they meet the Golden Rules. This can be accomplished in several ways including switching the bulb to an amber, orange, or red LED, adding shielding, and/or re-positioning the light to face downward and away from the beach. Motion sensors can also be helpful. If the fixture can’t be sufficiently modified, it can be replaced with a Wildlife Lighting Certified fixture.

Are they balcony lights?

Shields can be installed over certain balcony lights to restrict the light to the balcony itself and limit illumination and visibility from the adjacent beach – remember that these should have a long-wavelength bulb installed in them. Find Balcony lights that are Wildlife Lighting Certified.

Are they utility pole lights?

Lights on utility poles can be turned off by the power company at your request if they are on your property. If you feel light is still needed for safety, additional shielding can be added to many pole fixtures (i.e. house side shields) that can make the direct light source less visible from the beach.

What about parking lots?

Pole lights in parking lots can be replaced with full cut off fixtures, angled so the light is aimed away from the beach, covered by shields, and fitted with a long-wavelength light source.

What about pool lights?

Pool lights can cause cumulative glow onto other surfaces due to the light reflecting off the water. To address this issue, pool lights can be locked on an amber or red color during the marine turtle nesting season. Additionally, you can plant or improve vegetation buffers to block the pool lights and cumulative glow from the beach.

Can you turn them off?

Decorative lights, such as uplights, string lights, or lights in trees, serve no purpose for human safety. These can be quickly and effectively turned off immediately and should not be turned on until after sea turtle nesting season ends, October 31. Remember, only turn off lights that are NOT needed for safety or security.

What about interior lights?

White lights inside the building can be visible from the beach and are often much brighter than the exterior lights. Interior lights can quickly turn a turtle friendly building into one that causes disorientations. There are several quick, inexpensive, and effective ways to prevent interior lights from being visible from the beach.


Contents

Fluorescent Edit

Fluorescent black light tubes are typically made in the same fashion as normal fluorescent tubes except that a phosphor that emits UVA light instead of visible white light is used. The type most commonly used for black lights, designated blacklight blue or "BLB" by the industry, has a dark blue filter coating on the tube, which filters out most visible light, so that fluorescence effects can be observed. [9] These tubes have a dim violet glow when operating. They should not be confused with "blacklight" or "BL" tubes, which have no filter coating, and have a brighter blue color. [10] [9] These are made for use in "bug zapper" insect traps where the emission of visible light does not interfere with the performance of the product. The phosphor typically used for a near 368 to 371 nanometer emission peak is either europium-doped strontium fluoroborate ( SrB
4 O
7 F : Eu 2+
) or europium-doped strontium borate ( SrB
4 O
7 : Eu 2+
) while the phosphor used to produce a peak around 350 to 353 nanometres is lead-doped barium silicate ( BaSi
2 O
5 : Pb +
). "Blacklight blue" lamps peak at 365 nm. [11]

Manufacturers use different numbering systems for black light tubes. Philips uses one system which is becoming outdated (2010), while the (German) Osram system is becoming dominant outside North America. The following table lists the tubes generating blue, UVA and UVB, in order of decreasing wavelength of the most intense peak. [a] Approximate phosphor compositions, major manufacturer's type numbers and some uses are given as an overview of the types available. "Peak" position is approximated to the nearest 10 nm. "Width" is the measure between points on the shoulders of the peak that represent 50% intensity.

Various phosphor compositions used in blacklight [a]
Phosphor
Mixture
Peak
(nm)
Width
(nm)
Philips
suffix
Osram
suffix
U.S. Type Typical use
450 50 /71 hyperbilirubinaemia, polymerization
SrP
2 O
7 :Eu
420 30 /03 /72 photochemical polymerization
SrB
4 O
7 :Eu
370 20 /08 /73 ("BLB") [b] forensics, lapidary, night clubs
SrB
4 O
7 :Eu
370 20 /78 ("BY") [c] insect attraction, polymerization, psoriasis, tanning beds
BaSi
2 O
5 :Pb
350 40 /09 /79 "BL" [c] insect attraction, tanning beds
BaSi
2 O
5 :Pb
350 40 /08 "BLB" [b] dermatology, lapidary, forensics, night clubs
SrAl
11 O
18 :Ce
340 30 photochemistry
MgSrAl
10 O
17 :Ce
310 40 medical applications, polymerization

"Bug zapper" tubes Edit

Another class of UV fluorescent bulb is designed for use in "bug zapper" flying insect traps. Insects are attracted to the UV light, which they are able to see, and are then electrocuted by the device. These bulbs use the same UV-A emitting phosphor blend as the filtered blacklight, but since they do not need to suppress visible light output, they do not use a purple filter material in the bulb. Plain glass blocks out less of the visible mercury emission spectrum, making them appear light blue-violet to the naked eye. These lamps are referred to by the designation "blacklight" or "BL" in some North American lighting catalogs. These types are not suitable for applications which require the low visible light output of "BLB" tubes [13] lamps.

Incandescent Edit

A black light may also be formed by simply using a UV filter coating such as Wood's glass on the envelope of a common incandescent bulb. This was the method that was used to create the very first black light sources. Although incandescent black light bulbs are a cheaper alternative to fluorescent tubes, they are exceptionally inefficient at producing UV light since most of the light emitted by the filament is visible light which must be blocked. Due to its black body spectrum, an incandescent light radiates less than 0.1% of its energy as UV light. Incandescent UV bulbs, due to the necessary absorption of the visible light, become very hot during use. This heat is, in fact, encouraged in such bulbs, since a hotter filament increases the proportion of UVA in the black-body radiation emitted. This high running-temperature drastically reduces the life of the lamp, however, from a typical 1,000 hours to around 100 hours.

Mercury vapor Edit

High power mercury vapor black light lamps are made in power ratings of 100 to 1,000 watts. These do not use phosphors, but rely on the intensified and slightly broadened 350–375 nm spectral line of mercury from high pressure discharge at between 5 and 10 standard atmospheres (500 and 1,000 kPa), depending upon the specific type. These lamps use envelopes of Wood's glass or similar optical filter coatings to block out all the visible light and also the short wavelength (UVC) lines of mercury at 184.4 and 253.7 nm, which are harmful to the eyes and skin. A few other spectral lines, falling within the pass band of the Wood's glass between 300 and 400 nm, contribute to the output. These lamps are used mainly for theatrical purposes and concert displays. They are more efficient UVA producers per unit of power consumption than fluorescent tubes.

LED Edit

Ultraviolet light can be generated by some light-emitting diodes, but wavelengths shorter than 380 nm are uncommon, and the emission peaks are broad, so only the very lowest energy UV photons are emitted, within predominant not visible light.

A Wood's lamp is a diagnostic tool used in dermatology by which ultraviolet light is shone (at a wavelength of approximately 365 nanometers) onto the skin of the patient a technician then observes any subsequent fluorescence. For example, porphyrins—associated with some skin diseases—will fluoresce pink. Though the technique for producing a source of ultraviolet light was devised by Robert Williams Wood in 1903 using "Wood's glass", it was in 1925 that the technique was used in dermatology by Margarot and Deveze for the detection of fungal infection of hair. It has many uses, both in distinguishing fluorescent conditions from other conditions and in locating the precise boundaries of the condition.

Fungal and bacterial infections Edit

It is also helpful in diagnosing:

    . Some forms of tinea, such as Trichophyton tonsurans, do not fluoresce. [14] infections [15]
    • Corynebacterium minutissimum is coral red
    • Pseudomonas is yellow-green

    Ethylene glycol poisoning Edit

    A Wood's lamp may be used to rapidly assess whether an individual is suffering from ethylene glycol poisoning as a consequence of antifreeze ingestion. Manufacturers of ethylene glycol-containing antifreezes commonly add fluorescein, which causes the patient's urine to fluoresce under Wood's lamp. [17]

    Other Edit

    Wood's lamp is useful in diagnosing conditions such as tuberous sclerosis [18] and erythrasma (caused by Corynebacterium minutissimum, see above). [19] Additionally, detection of porphyria cutanea tarda can sometimes be made when urine turns pink upon illumination with Wood's lamp. [20] Wood's lamps have also been used to differentiate hypopigmentation from depigmentation such as with vitiligo. A vitiligo patient's skin will appear yellow-green or blue under the Wood's lamp. [ citation needed ] Its use in detecting melanoma has been reported. [21]

    See also Edit

    Bili light. A type of phototheraphy that uses blue light with a range of 420–470 nm, used to treat neonatal jaundice.

    Although black lights produce light in the UV range, their spectrum is mostly confined to the longwave UVA region, that is, UV radiation nearest in wavelength to visible light, with low frequency and therefore relatively low energy. While low, there is still some power of a conventional black light in the UVB range. [22] UVA is the safest of the three spectra of UV light, although high exposure to UVA has been linked to the development of skin cancer in humans. The relatively low energy of UVA light does not cause sunburn. UVA is capable of causing damage to collagen fibers, however, so it does have the potential to accelerate skin aging and cause wrinkles. UVA can also destroy vitamin A in the skin.

    UVA light has been shown to cause DNA damage, but not directly, like UVB and UVC. Due to its longer wavelength, it is absorbed less and reaches deeper into skin layers, where it produces reactive chemical intermediates such as hydroxyl and oxygen radicals, which in turn can damage DNA and result in a risk of melanoma. The weak output of black lights, however, is not considered sufficient to cause DNA damage or cellular mutations in the way that direct summer sunlight can, although there are reports that overexposure to the type of UV radiation used for creating artificial suntans on sunbeds can cause DNA damage, photoaging (damage to the skin from prolonged exposure to sunlight), toughening of the skin, suppression of the immune system, cataract formation and skin cancer. [23] [24]

    UV-A can have negative effects on eyes in both the short-term and long-term. [8]

    Ultraviolet radiation is invisible to the human eye, but illuminating certain materials with UV radiation causes the emission of visible light, causing these substances to glow with various colors. This is called fluorescence, and has many practical uses. Black lights are required to observe fluorescence, since other types of ultraviolet lamps emit visible light which drowns out the dim fluorescent glow.

    Black light is commonly used to authenticate oil paintings, antiques and banknotes. Black lights can be used to differentiate real currency from counterfeit notes because, in many countries, legal banknotes have fluorescent symbols on them that only show under a black light. In addition, the paper used for printing money does not contain any of the brightening agents which cause commercially available papers to fluoresce under black light. Both of these features make illegal notes easier to detect and more difficult to successfully counterfeit. The same security features can be applied to identification cards such as Passports or Driver's Licenses.

    Other security applications include the use of pens containing a fluorescent ink, generally with a soft tip, that can be used to "invisibly" mark items. If the objects that are so marked are subsequently stolen, a black light can be used to search for these security markings. At some amusement parks, nightclubs and at other, day-long (or night-long) events, a fluorescent mark is rubber stamped onto the wrist of a guest who can then exercise the option of leaving and being able to return again without paying another admission fee.

    In medicine, the Wood's lamp is used to check for the characteristic fluorescence of certain dermatophytic fungi such as species of Microsporum which emit a yellow glow, or Corynebacterium which have a red to orange color when viewed under a Wood's lamp. Such light is also used to detect the presence and extent of disorders that cause a loss of pigmentation, such as vitiligo. It can also be used to diagnose other fungal infections such as ringworm, Microsporum canis, tinea versicolor bacterial infections such erythrasma other skin conditions including acne, scabies, alopecia, porphyria as well as corneal scratches, foreign bodies in the eye, and blocked tear ducts. [25]

    Fluorescent materials are also very widely used in numerous applications in molecular biology, often as "tags" which bind themselves to a substance of interest (for example, DNA), so allowing their visualization. Black light can also be used to see animal excreta such as urine and vomit that is not always visible to the naked eye.

    Black light is used extensively in non-destructive testing. Fluorescing fluids are applied to metal structures and illuminated with a black light which allows cracks and other weaknesses in the material to be easily detected. It is also used to illuminate pictures painted with fluorescent colors, particularly on black velvet, which intensifies the illusion of self-illumination. The use of such materials, often in the form of tiles viewed in a sensory room under UV light, is common in the United Kingdom for the education of students with profound and multiple learning difficulties. [26] Such fluorescence from certain textile fibers, especially those bearing optical brightener residues, can also be used for recreational effect, as seen, for example, in the opening credits of the James Bond film A View to a Kill. Black light puppetry is also performed in a black light theater.

    One of the innovations for night and all-weather flying used by the US, UK, Japan and Germany during World War II was the use of UV interior lighting to illuminate the instrument panel, giving a safer alternative to the radium-painted instrument faces and pointers, and an intensity that could be varied easily and without visible illumination that would give away an aircraft's position. This went so far as to include the printing of charts that were marked in UV-fluorescent inks, and the provision of UV-visible pencils and slide rules such as the E6B.

    Thousands of moth and insect collectors all over the world use various types of black lights to attract moth and insect specimens for photography and collecting. It is one of the preferred light sources for attracting insects and moths at night.

    It may also be used to test for LSD, which fluoresces under black light while common substitutes such as 25I-NBOMe do not. [27]

    In addition, if a leak is suspected in a refrigerator or an air conditioning system, a UV tracer dye can be injected into the system along with the compressor lubricant oil and refrigerant mixture. The system is then run in order to circulate the dye across the piping and components and then the system is examined with a blacklight lamp. Any evidence of fluorescent dye then pinpoints the leaking part which needs replacement.

    The security thread of a US $20 bill glows green under black light as a safeguard against counterfeiting.


    Watch the video: Φως ποδηλάτου (September 2022).


Comments:

  1. Dohosan

    What is it to you to a head has come?

  2. Kajilabar

    Also that we would do without your brilliant phrase

  3. Athdar

    Bravo, the brilliant idea



Write a message