Use of Ultraviolet Nano light emitting diodes In Forensic Science

Use of Ultraviolet Nano light emitting diodes In Forensic Science

In this proposal I review the progress in developing AlGaN-based deep UV LEDs. Starting from first LEDs which is of red color from visible spectrum produced by Nick Holon yak Jr., the world reached to the LEDs that are extremely bright for the purpose to us I fiber optics which are used in telecommunication. Now a days UV LEDs are in use. UV LEDs have many advantages over mercury lamps sources including lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching. Light-emitting diodes (LEDs) can be manufactured to emit light in the ultraviolet range. Ultra violet can also be used for many purposes. This range of spectrum is brought too many useful purposes. Ultraviolet is also responsible for the formation of bone-strengthening vitamin D in most land vertebrates, including humans. Ultra violet Light emitting diodes are now used for many purposes. Although practical LED arrays are very limited below 365 nm. LED efficiency at 365 nm is about 5–8%, whereas efficiency at 395 nm is closer to 20%, and power outputs at these longer UV wavelengths are also better. These LEDs can be used for the purification and sterilization. Also these can be used for the purpose of disinfection of air. In this proposal it is claimed that UV LEDs can also be used for the purpose of investigation in crime investigation, especially in forensic testing Labs. The fingerprints, blood stains bite marks or other injury marks can be made to shown more clearly near UV LEDs. This will because of the highly absorbed property UV lights in th material to which finger prints or other marks will be tested. As for theses have the shorter wavelength as old forensic lights using in today’s forensics.

INTRODUCTION:

LED are semiconductor p-n junctions that under forward bias conditions can emit radiation by electroluminescence in the UV, visible or infrared regions of the electromagnetic spectrum. The quanta of light energy released is approximately proportional to the band gap of the semiconductor.

Explanation:

A light-emitting diode (LED) is a two-lead semiconductor light source. It is a basic p-n junction diode, which emits light when activated. OR we can say that A light emitting diode (LED) is essentially a PN junction opto-semiconductor that emits a monochromatic (single color) light when operated in a forward biased direction.




LEDs convert electrical energy into light energy.When a fitting voltage is applied to the leads, electrons are able to recombine with electron holes within the device, releasing energy in the form of photons. This effect is called electroluminescence, and the color of the light (corresponding to the energy of the photon) is determined by the energy band gap of the semiconductor.


Nitride-based semiconductors, such as GaN, InGaN and AlGaN, are materials that are used in ubiquitous white, blue and green LEDs, and laser diodes (for Blu-ray players) which is a huge industry with a multi-billion dollar market. The technologies of these semiconductors have progressed and matured enormously over the last two decades and has resulted in very low cost production for these devices.


Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light but longer than X-rays. Though usually invisible, under some conditions children and young adults can see ultraviolet down to wavelengths of about 310 nm,[1][2] and people with aphasia (missing lens) can also see some UV wavelengths. Near-UV is visible to a number of insects and birds.


The Nano LED range is a novel and economical light source system that utilizes laser diode and LED technology to generate short optical pulses over a wide range of repetition rates and wavelengths. Optical pulses as short as 70ps can be generated at repetition rates up to 1MHz.


The Nano LED package consists of a Nano LED controller and a range of interchangeable Nano LED sources, each designed to be used over a specific wavelength range. LED based sources generate nanosecond pulses, while laser diode based sources generate picosecond pulses.


Each Nano LED source contains adjustable collection optics and a bayonet mounting flange to make incorporation into any optical system easy. Dedicated drive electronics in each Nano LED source means that plug-n-play operation is possible across the Nano LED range. A synchronization output allows straightforward triggering of your existing data acquisition electronics.


The GaN-AlN material system is well suited for UV optoelectronic devices (emitters, detectors and optical modulators) because its energy gap can be tuned by changing its alloy composition to cover all three regions of the UV electromagnetic spectrum {UV-A (340-400 nm), UV-B (290-340 nm) and UV-C (200-290 nm).

Applications of UV Light:

There are many applications that utilize the UV region of the electromagnetic spectrum such as water sterilization, air purification, surface disinfection, free-space non-line-of-sight covert communication, epoxy curing, counterfeit detection, light therapy and fluorescence identification of biological/chemical agents. AlGaN is a good candidate as it has a large band gap that corresponds to the UV range and also the maturity of LED technology.


Light-emitting diodes (LEDs) can be manufactured to emit light in the ultraviolet range, although practical LED arrays are very limited below 365 nm. LED efficiency at 365 nm is about 5–8%, whereas efficiency at 395 nm is closer to 20%, and power outputs at these longer UV wavelengths are also better. Such LED arrays are beginning to be used for UV curing applications, and are already successful in digital print applications and inert UV curing environments. Power densities approaching 3 W/cm2 (30 kW/m2) are now possible, and this, coupled with recent developments by photo initiator and resin formulators, makes the expansion of LED-cured UV materials likely.


Literature Review:


In 1907 British scientist H. J. Round of Marconi Labs discovered that some inorganic Substances glow if an electric voltage is impress on them. Henry J. Round discovered the physical effect of electroluminescence, an optical and electrical phenomenon in which a material emits light in response to an electric current passed through it or to a strong electric field. In 1927 The Russian Oleg Vladimirovich Losev independently reported on the creation of an LED, but no practical use was made of the discovery. In 1961 Bob Biardand and Gary Pittman (Texas Instruments) find out that gallium arsenide (GaAs) give off infrared radiation when electric current is applied. They receive a patent for this diode the light produced was very dim and not bright enough to stimulate further research.

I. Father Of LED:

In 1962 the first visible spectrum LED light was produced by Nick Holon yak Jr., a consulting engineer for General Electric Company and it was red in color. This coined his nickname, 'Father of the Light Emitting Diode'.
He also holds 41 patents and his other inventions include the laser diode and the first light dimmer. (Another interesting fact about Holon yack was that he was once the student of John Bardeen, the co-inventor of the transistor.)






The red LED's were not bright enough to be seen in daylight so the first LED applications were mainly used as indicator lights for military use. In 1972, electrical engineer, M George Crawford a student of Holon yak, invented the first yellow colored LED for the Monsanto Company using gallium arsenide phosphide in the diode. Crawford also invented a red LED that was 10 times brighter than Holon yak’s.


II. First Visible LEDs:


It should be noted that the Monsanto Company was the first to produce visible LEDs. In 1968, Monsanto produced red LEDs used as indicators. But it was not until the 1970s that LEDs became popular, as technology progressed in the 1970's additional colors were created and as new colors became available, new uses for LED lights were in demand. LED's were used in applications such as calculators, digital watches and test devices.
When Fairchild Optoelectronics began producing low-cost LED devices (less than five cents each) for manufacturers. LEDs became popular.

III. LEDs in telecommunication:

In 1976, Thomas P. Pearsall invented a high-efficiency and extremely bright LED for use in fiber optics and fiber telecommunications. Pearsall invented new semiconductor materials optimized for optical fiber transmission wavelengths. The first super bright LED's were developed in the 1980's and were brighter, more stable and cost efficient which saw the demand for LED's rise dramatically.
From 1990 the use of LED's became standard in various industrial applications from switch cabinets to measuring instruments, in consumer products such as Hi-Fi equipment, telephones or personal computers and in traffic signal installations for road and railway or in indoor and outdoor automotive lighting.
Gallium Nitride LEDs:


In 1994, Shuji Nakamura invented the first blue LED using gallium nitride. For two decades LED lights have been replacing incandescent globes in homes and businesses, offering a cheaper, more efficient service in a wide variety of contexts. Ultraviolet light-emitting diodes (UV-LEDs) have started replacing UV lamps. The power per LED of high-power LED products has reached 12 W (14 A), which is 100 times the values Observed ten years ago. In addition, the cost of these high-power LEDs has been decreasing.


Zheludev, N. (2007). "The life and times of the LED: a 100-year history"






IV. UV nano LEDs


Here we started the development of the world's first ultraviolet light-emitting diodes (UV-LEDs) in collaboration with the University of Tokushima in April 2000, and have been supplying related products ever since. In recent years, as people are becoming more concerned about protecting the environment the role of UV-LEDs is becoming more important.





UV-LEDs are LEDs that emit UV rays with a wavelength of approximately 400nm or shorter. They are divided into near-ultraviolet light-emitting diodes (NUV-LEDs), whose emission wavelength is approximately 300 to 400nm, and deep-ultraviolet LEDs (DUV-LEDs), whose emission wavelength is approximately 200 to 300nm. UV-LEDs are promising candidates for various applications: replacing UV lamps; fluorescence light sources for





lighting and displays; high-resolution light sources for microscopes and exposure machines; light sources for chemical excitation as used for resin curing, medicine, and biotechnology; excitation light sources for spectroscopy as used for banknote identification, DNA chips, and environmental monitoring; sanitary light sources for disinfection and sterilization (figure?1)


UV-LEDs that emit light at a power of a few mill watts have already replaced UV lamps for banknote identification in automated teller machines. Prototype light sources for resin curing and exposure machines (which require a large cumulative light intensity) have been made, and commercial products are being released accordingly. The external quantum efficiency of NUV-LED, in particular, has greatly improved because of developments in crystal growth, chip processing, and packaging technologies, reaching 30% at a wavelength of 365nm, 50% at 385nm, and 60% at 405nm. The power per LED of high-power products at a wavelength of 365nm has reached 12W, which is 100times the values from ten years ago, 118 mW. The cost of these high-power LEDs has decreased as a result of mass production, making them available for various applications.
The researchers, Yu-Jung Lu, et al., from National Tsing-Hua University in Hsinchu, Taiwan, have published their study on the nano-LEDs in a recent issue of Applied Physics Letters.





UV LED Exposure Box


The new nano-LEDs have a unique structure that consists of 40-nm-thick nano disks sandwiched between two layers of nano rods, resulting in a nano disk-in-nano rod geometry. The nano disks are made of indium gallium nitride (InGaN), a semiconducting material that is widely used in LEDs and solar cells, while the nano rods are made of gallium nitride (GaN). However, InGaN LEDs capable of emitting light of the entire visible spectrum have not been achieved until now.


Poensgen, Tobias (January 22, 2013) InfiniLED MicroLEDs achieve Ultra-High Light Intensity


The InGaN/GaN nano disk/nano rod structure is similar to a well-known quantum well structure, but in a reduced dimensionality (reduction in lateral sizes),” coauthor Shangjr Gwo, a physics professor at National Tsing-Hua University, told PhysOrg.com. “The InGaN nano disks sandwiched between the p- and n-GaN regions act as the full-color visible-light emitters when electrons and holes are injected across the p-n junction at a forward bias voltage. The electroluminescent light comes from the electron-hole recombination within the InGaN nanodisks.”


As the researchers explained, the key to achieving full-color LEDs was overcoming large lattice strains, which degrade long-wavelength emissions. The InGaN/GaN nano rod system resolves this issue due to the strain relaxation in the nanostructured geometry.


The researchers hope that these full-color nano-LEDs can be used in high-resolution imaging techniques that can resolve ultra-small sub wavelength features of objects. To do this, these techniques must overcome the diffraction limit, which is a fundamental limit on imaging resolution caused by the spreading out of waves.


http://phys.org/news/2011-06-nano-leds-emit-full-visible-spectrum.html#jCp

Expected Results:

As at a crime scene, fast and accurate detection of possible traces is of vital importance. Many biological fluids are fluorescent in nature, when such traces are illuminated with light of the right wavelength, they fluoresce and are detectable to the investigator. Crime scene determines choice of filter the degree to which various substances become visible when using different filters depends on the state of the substance (trace) and the surface on which the substance exists. Therefore it can be predicted that UV LEDs will e more efficient for these purposes in future for many forensic purposes such as collecting only blood stains excluding other unnecessary stains on clothes or different body parts in case of any murder or any other crime investigation. The conditions of the crime scene often will determine which sort of light (i.e.. wavelength) will be most effective. These UV LEDs if used for these purposes instead of old fluorescent lights then it will have many advantages which he old has not including lower power consumption, long life time, high versatility regarding the size of illuminated area.So this will be a great invention in that kind of crime investigation.

References:

1. Theodore D. Moustakas, Yitao Liao, Chen-kai Kao, Christos Thomidis, Anirban Bhattacharyya, Dipesh Bhattarai and Adam Moldawer. Deep UV-LEDs with high IQE based on AlGaN alloys with strong band structure potential fluctuations


2. http://phys.org/news/2011-06-nano-leds-emit-full-visible-spectrum.html#jCp


3. S. Nikishin,B.Borisov,G.Kipshidze,V.Kuryatkov,M.Holtz, and H.Temkin,.UV LEDs


4. Yoshihiko Muramoto, Masahiro Kimura and Suguru Nouda future of ultraviolet light-emitting diodes: UV-LED will replace the UV lamp(2014)


5. Zheludev, N. (2007). "The life and times of the LED: a 100-year history"


6. Poensgen, Tobias (January 22, 2013) InfiniLED MicroLEDs achieve Ultra-High Light Intensity

A Complete Report On Parallel Universe

A Complete Report On Parallel Universe

1.     Title:

Parallel Universe

2.     Objective:

To explain concept of parallel universe by quantum physics

3.     Abstract:

Parallel universe is the theory which states that our universe is not the only universe, but there exists many universes parallel to each other. And this concept is proposed by MWT theory which is based on idea that there is a possibility that all possible events, no matters how silly or fantastic, might occur.

4.     Background:

The parallel universe is a whole universe just like ours but there can be no interaction between us as the term parallel suggests never meet. It is basically a part of universe which is defined as if there exists everything. The universe we live in may not be the only one out there. Our universe is only a small part of an infinite number of universes around us making a multiverse concept. There are many physicists who tried to explain the concept of multiverse three of the theories are given below.

4.1.Infinite Universe:

  

     This theory suggests that there are infinite universes around us .If we look far enough then it means you would encounter infinite versions of you i.e. space time goes on forever and starts repeating at some time.

4.2.Bubble Universe:

The theory proposed by Tuft University cosmologist Alexander Vilenkin suggests if infinite space time extension creates infinite universes then other universes could be created from the theory of eternal inflation.This means universe expanded rapidly after Big Bang in result inflating like a balloon. In this case some part is inflating, some stops inflating thus giving rise to many isolated bubbles.

5.     Parallel Universe:

Basically the idea of parallel universes arises from string theory proposed by Paul Steinhardt and Neil Turok. According to this theory if you are trying to explain something to somebody in this universe then there might be somebody else in another universe trying to explain the same thing to somebody else.

5.1.Concepts of Parallel Universe:

According to MIT cosmologist Max Tegmark, there are four levels of parallel universes:

1.      An infinite universe that according to the laws of probability must contain another copy of earth somewhere

2.      Other distant regions of space with different physical parameters but follows same basic laws.

3.      Other universes where each possibility that can exist does exist described by the many worlds interpretation of quantum physics

4.      Entirely distinct universes that may not even be connected to occur in any meaningful way and very likely have entirely different fundamental laws.

6.     Description:

To the average person, quantum mechanics is the convoluted, science fiction branch of physics. A radical new theory plays into that, proposing that parallel universes exist and interact with each other-and that scientists may be able to test for them. However, we don’t see these universes because our cosmic vision is limited by the speed of light. Light started travelling at moment of Big Bang, 14 billion light years (since space is expanding).This volume of space is Hubble volume and represents an observable universe.

6.1.Many World Theory

In 1957, a young Princeton University doctoral candidate named Hugh Everett came up with a radical idea that there exist parallel universes, exactly like our universe. These universes are all related to our indeed, they branch off from ours, and our universe is branched off of others. Within these universes, our wars have had different outcomes that the ones we know. Species that are extinct in our universe have evolved and adopted in others. In other universes, we humans may have become extinct.

According to Griffith, main points of many world theory are,

·         The universe we live in just one of an unknown “gigantic” number of worlds, some of which are almost identical to ours, but most are “very different”.

·         All the worlds are equally real, existing continuously through time with precisely defined properties.

Dr Michael Hall from Griffith's Centre for Quantum Dynamics says the 'Many-Interacting Worlds' theory may even create the extraordinary possibility of testing for the existence of other worlds

According to many world theory, when quark measurement is processed, there are two possibilities, the weapon can either fire or not, at this moment, the theory claims that, the universe splits into two different universes account for two different endings. The weapon will discharge in one reality, but not discharge in other.

7.     Parallel Universes do exist:

There are two possible theories that presents the reasons to believe that parallel universes do exist.

§  Eternal Inflation

§  Ekpyrotic Theory

7.1.Eternal Inflation

Eternal inflation is an inflationary universe model, which is itself an outgrowth or extension of Big Bang theory. In theories of eternal inflation, the inflation phase of the universe’s expansion lasts forever in at least some regions of the universe. The findings of eternal inflation mean that when inflation starts, it produces not just one universe, but an infinite number of universes.

7.2.Ekpyrotic Theory

According to this theory, if the universe is that region that results when two branes collide, then the branes could actually collide in multiple locations. For Example, Sheet flapping on a bed, will touch it at different points. If the sheet were a brane, then each point of collision would create its own universe with its own initial conditions.

8.     Quantum Perspective:

Quantum mechanics is the branch of physics that describes the rules that governs the universe on the microscopic scale. It tries to explain how subatomic particles can behave both as particles and as waves. It also offers an explanation about why particles appear to exist in multiple positions at the same time.

This fuzzy clump of possible positions is described by a wave function, an equation that predicts that many possible spots a given particle can occupy. Though, we talk of universe splitting, this isn’t precisely true. From math view, there is only one wave function and it evolves over time. The superposition of different universes all co-exist simultaneously in same infinite dimensional Hilbert space. These separate co-existing universes interfere with each other yielding quantum behaviour.

Parallel universes is strangest place of all because it would follow different mathematical laws of nature than our universe. In short, any universe that physicists can get to work out on paper would exist, based on the mathematical democracy principle that

Any universe that is mathematically possible has equal possibility of actually existing.

8.1.From where the concept of wave function arises??????

Is it possible for an electron to be at two places at once, or for a cat to be both alive and dead at same time?

According to quantum mechanics, both scenarios are possible and the heart of this concept lies in wave function: The mathematical formula used to describe quantum objects.

8.2.Electron at two places at once

To see how the wave function works, let us consider an electron shooting out of a cathode ray tube. Now the wave function for this electron is just the description of where the electron is. The wave function is an irregular number, the complex number such as an imaginary number. The wave function gives you the prediction of where would electron be in the future. It’s a statement about probability nothing else.

If you consider two electrons with the exact same wave function and look to see where they are you might find that one is at one place (let say A) and the other at another (say B), and once you observed an electron to taking it at point B and not at another point (A). The wave function immediately changes. The physicists say that it collapses. Broad range of possibilities to one specific answer. The active measure the electron is what gives it is its position. And this brings us back to the cat that is both alive and dead at the same time.

9.     Schrodinger’s Cat Paradox:

The quantum mechanical Schrodinger’s cat paradox according to the many-worlds interpretation is:

Every event is a branch point, the cat is both alive and dead, even before the box is opened, but the “alive” and “dead” cats are in different branches of the universe, both of which are equally real, but which do not interact with each other.

As it usually told that a cat and a vial poison are sealed into a box. Then a quantum event happens with the probability of 50% that breaks or does not break the vial of poison and kills or does not kill the cat So is the cat still breathing? The wave function reflects both possibilities.

In the standard interpretation of quantum mechanics, both possibilities are real. The cat is truly both alive and dead until an observer opens up the box. At this point, the kitty collapses into an either alive or dead state.

This is absurd. Cats can’t be both alive and dead at the same time. So how do we get out of this paradox?

One of the two ways: Either the wave function doesn’t really exist, it’s just reflection of our knowledge. Or the cats are both alive and dead but in two Parallel Universes.

Before directly going to main topic that is parallel universes, take into notice some important terms:

10. Collapse Approach:

It states that the measurement of a quantum system invokes a collapse of the quantum wave function, from a super positional state into a state that can be described classically. It suggests that instantaneous action at a distance should simply be accepted in quantum mechanics, as it was with British physicist Issac Newton’s theory of gravitation. Einstein did not like the collapse approach because it suggests that instantaneous action at a distance occurs when the wave function collapses. Einstein along with Boris and Rosen presented what became known as the ERP paper, in 1935 which states that quantum mechanics is incomplete. There must be hidden variables which explain why there is no need for instantaneous travel, which Einstein referred as “spooky actions at a distance”.

10.1.                    Problems with Collapse Approach

There are a number of problems with the collapse approach:

·         Firstly, it does not adequately define what constitutes a measurement, and therefore it does not adequately define when the collapse of the wave function occurs.

·         Secondly, there are no collapse dynamics within quantum theory itself, and so they need to be added by hand.

·         Thirdly, the collapse approach cannot explain how the quantum world can make contact with the classical world at all, since both systems obey different physical laws.

The third problem is known as the measurement problem.

10.2.                    The Bohm Approach

In 1952, American physicist David Bohm suggested that there is no need for instantaneous action at a distance because the collapse approach is incorrect, and there is no collapse of the wave function.

10.3.                    The Everett’s Many World’s Approach

In 1957, American Physicist Hugh Everett III suggested that Bohm is right, there is no collapse of the wave function, but he interpreted this very differently, devising the many worlds or Everett approach. Any material theory of mind will have to explain why people have subjective experiences. This may be a problem that we will never be able to solve. However, there may already be a theory that explains the subjective nature of consciousness. This is known as the Everett, or many worlds, approach to quantum mechanics.

Collapse approach to quantum mechanics cannot apply their theory to the universe as a whole because an external observer would be required in order to collapse its super positional state. The Everett approach does not face this problem, and so it can describe the entire universe using Schrodinger’s wave equation. This super positional universe is known as the multiverse.

The Everett approach does not face the problem of explaining the appearance of instantaneous action at distance, which is apparent in the collapse approach to quantum mechanics. This is because there is no need to send information between one entangled quantum system and another.

Although Everett only mentioned the word “branches” in his 1957 paper, the realism associated with them soon led to the term Parallel Worlds being used instead. Dewitt was the first to do so when he popularized Everett’s approach in 1970 and by 1977, Everett was defending his theory in these terms.

10.4.                    The preferred Basis Problem

The Everett, or many worlds approach to quantum mechanics solves the measurement problem by stating that

Macroscopic objects also obey the laws of quantum mechanics,

But it then faces a similar problem known as the preferred basis problem. The preferred basis problem asks why the universe is split into the separate worlds, we experience, if it is really part of a multiverse. I am leaving this question answered waiting for another one to solve this problem. However, a clue to this is Decoherence Theory.

11. Islam and Parallel Universes:

God also swears that someday we will travel to one of those extra dimensions.

 I swear by the afterglow of sunset... You will ride one layer from another layer. [Quran 84.16-18]

According to the Quran, we cannot see nor collide with Jinn but they have weight:

 We [Allah] will settle your affair, both you of weight (man and jinn). [Quran 55.31]

The Jinn have weight means that we can detect their gravity and they can detect our gravity. So according to the Quran we cannot see the Jinn nor collide with them but we can detect their gravity. 

Just as the Jinn is of different type that we cannot see nor collide with but we can detect their gravity, there are six other Heavens that we cannot see nor collide with either but we can detect their gravity, superimposed above the visible one:

 So [Allah] decreed them as seven heavens (one above the other) in two days and revealed to each heaven its orders. And We [Allah] adorned the lowest heaven with lights, and protection. Such is the decree of the Exalted; the Knowledgeable. [Quran 41.12]

According to the Quran, only the lowest heaven has visible light. This means that this Dark Matter exists in the six Heavens superimposed above the lowest one. Also according to the Quran, each of these remaining six Heavens is of a different type and each has its own planets like Earth

12. Conclusion:

Many scientists believe that parallel exists but many scientists not. In many view MWT is a pseudo-science. You don’t have any way to prove or disprove this hypothesis. It is an irrefutable. That is, we should have some way to prove or disprove it.But according to Islamic point of view, parallel universe exists.

13. References:

·         http://www.universetoday.com/113900/parallel-universes-and-the-many-worlds-theory/

·         http://www.dailygalaxy.com/my_weblog/2015/06/parallel-universes-are-they-revealed-at-the-quantum-level.html

·         https://www.rt.com/usa/202255-many-interacting-worlds-quantum-mechanics/