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In this project we show that how we design a laser follower robot to move on any track. In this project we use two slow speed motor for running the platform of the small robot. In this project we use 89c2051 microcontroller as a main processor. We use this processor to run the vehicle. This controller is basically a  20 pin ic. In this project we use two sensor also. These sensor are connected to the port p3.4 and port p3.5


Pin no 20 is connected to the positive supply. In this project we provide a 5 volt dc power supply. This power supply is truly regulated power supply. Pin no 10 is connected to the negative supply. Here we supply a negative voltage on this pin. Crystal is connected to the pin no 4 and 5 of the microcontroller. Crystal provide a clock signal to run the vehicle and process all the internal requirement of the  circuit. We use two sensor and these two sensor are connected to the p3.4 and p3.5 of the microcontroller.For the regulated power supply we use ic 7805 as a regulator to provide a fix 5 volt power supply.

When we move the robot on surface then infra red light is not reflected from the surface. When Laser light is not fallingfrom the surface then sensor is not getting a signal. We program the robot like this  when sense the light  then it means  position of sensor is on the surface. If the sensor1 gets signal from laser then one motor change its direction and due to that robot change its path and when sensor2 gets signal then only vehicle move backwatd. We use three sensor for two motorís. if the one sensor gets signal from laser then vehicle move backward , if one sensor1 and sensor3 gets signal then vehicle change its direction. Microcontroller provide a signal to the motor circuit. Motor is not directly connected with the microcontroller. For the safety of the main processor we interface the motor with optocoupler circuit. Here we use pc 817 ( 4 pin opto coupler) to interface the micro controller with  the motor circuit. We use H bridge circuit with the motor. H bridge basically control the movement of the motor. With the help of this H bridge we change the direction of the motor. We use four transistor circuit with each motor. We are using four transistor circuit. Out of these four transistor  two transistor is NPN and two transistor and PNP transistor.  One NPN and One PNP provide a one direction voltage and motor moves on one direction. Second NPN and second PNP transistor again change the direction of the motor automatically. In this project we will also make it autopath. We will connect Two infrared sensors with ir transmitter  on left and right for moving right and left. Others will work for antifalling function.

How laser works


The word "laser" stands for "light amplification by stimulated emission of radiation." Lasers are possible because of the way light interacts with electrons. Electrons exist at specific energy levels or states characteristic of that particular atom or molecule. The energy levels can be imagined as rings or orbits around a nucleus. Electrons in outer rings are at higher energy levels than those in inner rings. Electrons can be bumped up to higher energy levels by the injection of energy-for example, by a flash of light. When an electron drops from an outer to an inner level, "excess" energy is given off as light. The wavelength or color of the emitted light is precisely related to the amount of energy released. Depending on the particular lasing material being used, specific wavelengths of light are absorbed (to energize or excite the electrons) and specific wavelengths are emitted (when the electrons fall back to their initial level).

The ruby laser was the first laser invented in 1960. Ruby is an aluminum oxide crystal in which some of the aluminum atoms have been replaced with chromium atoms. Chromium gives ruby its characteristic red color and is responsible for the lasing behavior of the crystal. Chromium atoms absorb green and blue light and emit or reflect only red light.

For a ruby laser, a crystal of ruby is formed into a cylinder. A fully reflecting mirror is placed on one end and a partially reflecting mirror on the other. A high-intensity lamp is spiraled around the ruby cylinder to provide a flash of white light that triggers the laser action. The green and blue wavelengths in the flash excite electrons in the chromium atoms to a higher energy level. Upon returning to their normal state, the electrons emit their characteristic ruby-red light. The mirrors reflect some of this light back and forth inside the ruby crystal, stimulating other excited chromium atoms to produce more red light, until the light pulse builds up to high power and drains the energy stored in the crystal.

The laser flash that escapes through the partially reflecting mirror lasts for only about 300 millionths of a second-but very intense. Early lasers could produce peak powers of some ten thousand watts. Modern lasers can produce pulses that are billions of times more powerful.

Another characteristic of laser light is that it is coherent. That is, the emitted light waves are in phase with one another and are so nearly parallel that they can travel for long distances without spreading. (In contrast, incoherent light from a light bulb diffuses in all directions.) Coherence means that laser light can be focused with great precision.

Many different materials can be used as lasers. Some, like the ruby laser, emit short pulses of laser light. Others, like helium-neon gas lasers or liquid dye lasers emit a continuous beam of light. Our ICF lasers, like the ruby laser, are solid-state, pulsed lasers.

How the First Ruby Laser Works


In contrast to an ordinary light source, a laser produces a narrow beam of very bright light. Laser light is "coherent," which means that all of a laser's light rays have the same wavelength and are in sync.

 1. High-voltage electricity causes the quartz flash tube to emit an intense burst of light, exciting some of the atoms in the ruby crystal to higher energy levels.


 2. At a specific energy level, some atoms emit particles of light called photons. At first the photons are emitted in all directions. Photons from one atom stimulate emission of photons from other atoms and the light intensity is rapidly amplified.


 3. Mirrors at each end reflect the photons back and forth, continuing this process of stimulated emission and amplification.


 4. The photons leave through the partially silvered mirror at one end. This is laser light.


There are many types of lasers, including solid-state, gas, semiconductor, or liquid. The ruby laser is a solid-state laser. Solid-state lasers provide the highest output power of all laser types. The National Ignition Facility laser will also be a solid-state laser, but will use a special glass (rather than crystals of ruby) to amplify the initial laser pulses to very high energy levels. The NIF laser will be the most powerful laser in the world.




How a Laser Works:

The Basics of an Atom

Everything we see within the universe is made up of an infinitesimally large number of combinations of the 100 different kinds of atoms. The arrangement and bonding of these atoms determines what material/object they constitute.

Atoms are constantly in motion. They continuously vibrate and move. Although all atoms are vibrating to a degree, atoms can be in a different state of excitation (i.e. they can have different levels of energy). If a large degree of energy is applied to an atom then it can leave what is referred to as ground-state energy level and go to an excited level. The level of excitation is proportional to the amount of energy applied.

A simple atom as shown in Figure 1 consists of a nucleus, which consists of protons and neutrons and what is often referred to as an electron cloud. For a simplistic interpretation of the atom model it is easy to think of the electrons within the electron cloud following discrete paths or orbits within the cloud. This analogy suits our purpose as we can then consider these orbits to be the different energy levels that make up the atom. If we add some form of energy to the atom we can assume that electrons from the lower-energy orbitals will transfer to the higher-energy orbitals at a greater distance from the nucleus, resulting in a higher level of excitation.


When atoms reach a higher-energy orbital the eventually seek to return to the ground-state energy level. Upon returning to ground-state energy level the excess energy is released in the form of a photon - a particle of light.


The Connection Between Atoms and Lasers

Laser is an abbreviation for Light Amplification by Stimulated Emission of Radiation.

A laser is a device that controls the way in which energised atoms release protons. There are many different types of laser available; all the different types of laser rely on the same basic elements. In all types of laser there is a lasing medium, which is pumped to get the electrons within the atoms to a higher-energy orbital i.e. to get the atoms excited. Typically, very intense flashes of light or an electrical discharge pump the lasing medium and create a large number of excited-state atoms. This creates a high degree of population inversion (the number of excited state atoms versus the number of atoms at ground-state energy level). At any stage the excited state atoms can release some of the energy and return to a lower-energy orbital. The energy released, which comes in the form of photons, has a very specific wavelength that is dependant on the level of energy or excitation of the electron when the photon is released. Two identical atoms with electrons in identical states will release photons with identical wavelengths. This forms the basis for laser light.

Laser light has the following properties:

∑ Laser light is monochromatic. It contains one specific wavelength of light, which as described earlier is determined by the amount of energy released when the electron drops to a lower-energy orbital.
∑ Laser light is coherent. Each proton moves in step with the other (i.e. all protons have wave fronts that move in unison).
∑ Laser light is highly directional (i.e. a laser beam is very tight and concentrated

To ensure the aforementioned properties are apparent within the laser light the process briefly mentioned earlier, 'stimulated emission' must occur.

Any photon that has been released by an atom, (which therefore has a wavelength, phase and energy level dependant on the difference between the excited atom state and the ground-state energy level) should encounter another atom that has another electron in the same excited state, stimulated emission can occur. The first photon can stimulate or induce atomic emission so that the emitted photon vibrates with the same frequency and direction.

To produce laser light it is necessary to have a pair of mirrors at either end of the lasing medium. These mirrors are often known as an optical oscillator due to the process of oscillating photons between the two mirrored surfaces. The mirror positioned at one end of the optical oscillator is half-silvered, therefore it reflects some light and lets some light through. The light that is allowed to pass through is the light that is emitted from the laser. During this process photons are constantly stimulating other electrons to make the downward energy jump, hence causing the emission of more and more photons and an avalanche effect, leading to a large number of photons being emitted of the same wavelength and phase.

Below is a graphical illustration of what has been detailed above. The graphics illustrate how laser light is created using a ruby laser, the first fully functioning laser. Theodore Maiman invented the ruby laser on May 16th 1960 at the Hughes Research Laboratories (for more information on dates relating to laser invention see a Brief History of Lasers).


of Laser

Components required:







Crystal 12Mz






Ic base



Transformer 0-12v 500mA









Tr 548



Tr 558



Resistances 10k