The diver light is a light source carried by underwater divers to illuminate the underwater environment. Scuba divers generally carry stand-alone lights, but diver supplied on the surface can carry lights that are supported by the supply of cables.
Light diving is routinely used during night dives and cave dives, when there is little or no natural light, but also has useful functions during the day, as water absorbs longer (red) first wavelengths then yellow and green with increasing depth. By using artificial light, it is possible to see objects in full color at greater depths.
Video Dive light
Need
Water is responsible for the attenuation of light due to absorption so that the use of diving light will enhance the vision of underwater divers. As the depth increases, more light is absorbed by water. The absorption of color depends on the purity of the water - the purest water is most transparent to the blue frequency, but the impurities can reduce this significantly. Color vision is also affected by larger turbidity and particles.
Maps Dive light
History
Initial underwater lights are either permanent flood lights or portable lights with dry batteries for use by divers in standard wetsuits. Siebe Gorman & amp; Company Ltd develops a portable light model with a parabolic lens and attaches to the corselet divers through the ball and socket together allowing the diver to use both hands while working.
In 1906, tungsten filaments were introduced and used to produce 200 to 3,000 candle submarines. Siebe Gorman & amp; The company introduced 250-watt mercury vapor hand lights in 1919 that could produce as many as 18,000 candles. To dive in turbid water, a 45 watt sodium hand lamp becomes the preferred choice. Initial lights should be turned on under water to avoid cracking of heated glass when entering cold water.
The first lantern available to the US Navy has 150 candlepower. Initial testing indicates the need to increase cable length in the US Navy Standard Lantern from 125 feet to 250 feet in 1915 to enable greater operational reach. The United States Navy Experimental Diving Unit continues to evaluate dive lights for wet and dry lighting output, battery duration, watertight integrity, and maximum operating depth.
modern sources
Filament incandescent, Halogen, HID, LED.
Modern diving lights usually have an output of at least about 100 lumens. The bright diving lights have a value of about 2500 lumens. Halogen lamps provide this light at a power consumption of more than 50W. High intensity discharge lamps (HID) and Light-emitting diodes (LEDs) can provide similar output for less power.
Configuration
Hand held (Integral)
Light source and power supply are placed in the same water and pressure resistant housing. The lights are switched on and off by a mechanism built into the housing
Light Canister
The tube light comes from when the size of the battery needed for sufficient burning time from the high output light is too large to carry comfortably at the hands of the diver. This work uses light heads with light sources, which are small and light enough to carry easily on hand or overhead, and power through the cables of waterproof battery tubes, which carry harness diver.
Head mount
Head mount lamps are used by divers who need to use both hands for other purposes. This could be underwater work by commercial divers, or through strict restrictions for a cave diver or a wreck. With heads riding, there is a greater risk of dazzling other divers around it, because the lights move with the diver's head, and this arrangement is more appropriate for the diver working or exploring on their own. General mounted helmets for commercial work are often monitored by closed-circuit helmet video cameras.
Both one-piece lights are meant for hand-held, and headlights powered from the tube or cable provided by the surface are used for headlights. There are also some one-piece headlights specially made for head mounting, and full face masks made by Ocean Reef that have integrated lighting.
Head lamps caving can sometimes be used as head mount lights for shallow cave dives, as they are waterproof, but are generally not designed for use under much pressure.
Surface is provided
If the diver is equipped with respiratory gas from the surface, it will be easier to supply electricity to the lamp from the surface through the same umbilical. Additional cables are generally used for this purpose. The head lamp is functionally the same as the light of the tube, and is usually mounted on the helmet.
Construction
Housing
Some materials are used for housing. Printed plastic injection is most popular for low end and some stronger bulbs are produced in large quantities. Low volume products and home-made lamps are generally manufactured from high-grade aluminum or engineering plastics such as acetal (Delrin), or occasionally stainless steels, brass or bronze. Lenses (ports) are usually high grade transparent plastic or hardened glass. The o-ring seal is a standard for sealing joints and connections and for sealing penetration through impermeable housing for control of the switch.
Power supply
Alkaline batteries, zinc-carbon batteries, Nickel-metal hydride (NiMH) batteries, lithium-ion batteries, lead-acid batteries, and surface supplies with cables are commonly used as power supplies.
Voltage depends on the need of a particular light source and typically ranges from 1.2V for a single NiMH cell, up to 12V for a lead-acid accumulator. Surface-powered helmet lights can use 24 or 36V power supplies. High voltage is generally not used except in the final stages of the HID circuit, for safety reasons.
Switch
Lights that must be switched on or off require switches that are unaffected by pressure and water resistance.
- Magnetic switches have the advantage of working through housing without the need for penetration, but can affect a reliable compass for navigation. The magnet is held in an external slider or bezel, and may rust if exposed to water.
- Switch the switch with a rubber mold that actually passes the switch lever and the seal to the house has been used for production and special lights.
- The external lever operating the internal switch via a rotating shaft sealed with O-rings is also used.
- The pushbutton can be used but it must be enough spring to compensate for external pressure. This is usually done by using a small diameter pushrod with an O-ring seal, and a medium strength spring. Outside the head mushrooms are widely used for comfort.
- The screw cap cover is common. This is almost always a removable cover to replace the battery, so it should be removable and sealed properly. The end of this lamp is further screwed into the body to make contact between the battery and the contacts. O-ring seal seals are used to prevent leaks while allowing the cover to move axially to close the contacts. Double O-ring is more reliable as if the first leaked second is the backup. This type of switch is best operated as little as possible under water and is often uncomfortable to use, relatively stiff, sometimes requiring both hands to operate.
Accessories
Technical divers often use Goodman type handles to carry light on the back of the hand, so the hand can be used without dropping the light. This type of grip is initially stiff, and is used to carry lightweight tube heads, but is now also used for small one piece pieces. Derivatives use bungee to hold the light in place
Block angle
Narrow beam (beam) vs. wide beam (spotlight), focus vs. (with adjustable lens or reflector):
The angle of the blade is selected to match the conditions and activities of the planned dives. Cave divers often choose narrow spotlights when diving in good visibility because it provides good lighting at a relatively long distance, which is useful when navigating to unfamiliar spaces where it is actually possible to see a considerable distance ahead. Some people feel that in poor visibility, or at short distances, narrow rays are not widely used, and wider light spreading light into more useful areas. Others feel that in a low visibility setting the wide-angle rays are disturbing because they tend to reflect back to much light from the back-scatter particulate. Video lighting usually requires a wider spotlight because the video camera's point of view should be accommodated for good results. In the case of very wide angle videos, such as GoPro and the like, a very wide angle of light is required.
The beam angle may be as tight as 8 to 10 degrees in extreme cases, or as wide as 140 Â ° with a plain flat glass port. Even a wider angle is possible (over 180 °) with a vaulted port on light, or a "test tube" lamp without a reflector. LED lights typically use internal "lenses" to produce focused light. It actually focuses the rays by internal reflections on the parabolic surface. Some lens options may be available for different angles of emission for a given LED, but most models of light use are only selected by the manufacturer.
Some underwater lights have a focusing facility where the angle of jets can be adjusted. There are two ways you can do, depending on the basic emission patterns of the light source. HID lamps, which generally produce non-directional light, are usually centered by reflectors, which can glide longitudinally over the light. They produce blocks with central bright areas and general lighting that spread around them. This is great for illuminating the combination of near and far areas at the same time, but not great for wide-angle video, since hot-spots will confuse auto exposure software and the results are generally over-exposed in hot spots and less ambient lighting..
Other lights use a lens system on the front of the light, which may be focused by the axial movement of the lens, which may be on the screw thread for good control.
Function
Primary, backup, video light
Primary
Usually a strong light is suitable for the planned activities of diving, with sufficient strength and appropriate angle of light. The angle of light emitting and output required depends on the purpose of the dive.
Back Up
The backup lamp is taken if the main light fails during the dive. This is especially important in diving cave and crash penetration, where light is required to facilitate navigation out of enclosed spaces. The cave diver was trained to carry three submarine lights as a result of an accident analysis by Sheck Exley published in 1977.
Video light
Video light is a special application. They are generally unimportant for the safety of dives, but are necessary for video cameras to obtain acceptable image quality, whether for video recording, or for surface teams to monitor the work performed by divers. Modern underwater video light is now relatively small, has run time 45-60 minutes and produce 600-8000 lumens. The LED light is powered by a Lithium-ion battery and usually has a 5600K color temperature (daylight).
Temporary gallery (temporary)
See also
References
External links
- Blackbeard's Glowing Shipwreck, P3 Magazine
Source of the article : Wikipedia
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