Before you proceed with the blog I want to make sure that its exactly not the serial to parallel port converter so that you can connect your parallel port printer or device to serial port through it and it will work. It is more or less useful for certain simple Input/Output application with computer. During one of my robotics project I wanted to control stepper motor through the computer. The idea was that I will wright a program which will run and will send that data to the stepper motor driver through parallel port. Well its very simple you just need a driver IC which will take TLL input from the parallel port and will drive stepper motor. But wait I have laptop with no parallel port and the I was using MATLAB for programming. So I searched USB-to-Parallel port converter and I got it. I bought it for just Rs.200 and was very happy. I came to my room and attached it to my computer and here comes the role of vista which has no support to the old win98 driver shift with the device. I searched lot in internet and somehow managed to install the driver properly. I started matlab hoping that matlab will recognized it as parallel port but later I found out that matlab has no support to add-on parallel ports so the idea totally failed. Infact MATLAB no more support parallel port. I switched to serial port, again I bought USB-to-parallel port converter and it worked fine with MATLAB.
After Installing it I found out the in order to interface it I need a microcontroller which has USART like atmega16 and you need to program your micro-controller so that in can communicate it with computer. Well now I know how to program micro-controller and code has to be written in the computer side. But I gave a second thought and realize that there is another and simple way also for this you don't need any micro-controller at all. Most of the part is done at the coding side and I have written function that you can directly use. So here we go
Check List-
1) Serial Port or USB-to-serial Port converter.
2) Matlab installed
4)
<>
Monday, December 14, 2009
Saturday, May 23, 2009
Mystery of empty Space
Newton's Age-
The concept of empty space comes from the age of Newton. In his Hypothesis of Light of 1675, Newton posited the existence of the ether to transmit forces between particles. So according to Newton all the empty space was filled with ether. People tried for many years to find the existance of ether. One of the experiments to find the existence of the ether is to find the speed of light in the direction of rotation of the earth and in the direction opposite to it. Now if the ether exist it will be affected by the rotation of the earth since Newton assumed that it has some inertia and hence will be in motion due to rotation of the earth. The light traveling through this rotating ether will have two different velocity depending upon light is moving in the direction of the ether or opposite to it. People tried to detect the speed of light in two different direction and they found that light has same speed in both direction so the concept of the ether was assumed to be wrong. Also Newton assumed that light is made up of particles called corpuscular "Newton's corpuscular theory of light " which moves in ether and hence in order to light to come from sun to earth it need some medium and which Newton assumed as ether. After the "Double slit experiment" it was found out that the light is electromagnetic wave and it don't need the medium to travel, the concept of ether was completely disproved and for many years it was believed that vacuum is empty ie no matter no field nothing ....
Higgs Field-
In the year of 1960 a Peter Higgs introduced the new concept of Higgs filed. In order to understand this let us discuss little bit of Particle Physics. Suppose we take a piece of ice and smash it very hard, what we will get is water molecule. Smash the water molecules very hard and we will get oxygen and hydrogen atom. For many years it was assumed that atoms are the building block of matter but later experiments on J. J. Thomson on discharged tube proved that even atoms are made up of small particles called electron , proton and neutrons ( Thomson atomic model, Rutherford atomic model etc ). In order to study these particles Particles accelerators are used, where this particles are accelerated to very large speed and then allowed to collide with each other. After smashing this particles very hard in such particle accelerator physicist figured out that even this particles are made up small particles called quarks, leptons etc. In order to explain formation of all electrons , neutrons protons and all matter. A theory was developed called " Standard model " which makes thousands of prediction which are even experimentally verified but there is one problem with this theory it says that all the fundamental particles in Standard model is mass less this is exactly opposite to what we observe in day to day life. Every particle which has no mass should travel through speed of light ( like photon ) but we see that each of matter like my hand when I am typing this is moving with some finite speed also Every matter around us has some mass, electron, proton etc everything has some mass. In order to solve this problem Peter Higgs proposed a theory that says that all space is filled with a smooth filed called " Higgs Field " and it interact with all particles and slow them down ( or prevent these particle to move with the speed of light ) . So the question is can we feel this field? well the answer is yes we can feel this field the fact that my electrons and proton in my hands are not moving with the speed of light is because of Higgs filed. Now the question is can the Higgs field be turned of light electromagnetic filed ( turn of the source of em waves ), the answer is now because it is a vacuum field. It is proved mathematically though that after some picoseconds of the Big-Bang the this Higgs field was actually turned of and for some picoseconds of this time all the particles was moving with the speed of light and then after some picoseconds this Higgs field was turned on and all the fundamental particles come together to form electron, proton, neutron then atom then molecule then stars then galaxy etc. ( See my post on Creation of Universe ).
Higgs Bosons-
Higgs field is quantum mechanical field like electromagnetic filed. Now if we produce the ripple in the electromagnetic filed it is quantized and which is called a photon. In the same way if we can produce a ripple in the Higgs filed we can actually get what we call "Higgs Boson". In order to produce a ripple in Higgs field we need large amount. Physist at CERN and Fermi lab are trying to find out the presence of this Higgs Bosons. The particles will be accelerated to very large velocity and the will be allowed to collide this large amount of energy will produce the ripple in the Higgs field and which will be detected as Higgs Boson.
General Relativity and Higgs Field-
According to general relativity the universe should expand or contract. It has been found experimentally that the universe is actually expanding (red shift in spectrum of light coming from distance galaxy ) . The rate at which universe is expanding depends upon the matter inside the universe also after certain limit of expansion due to gravity the rate of the expansion should slow down. Now Higgs field has some energy which is of order of 1 trillion per cc , if we put this amount of energy in equations of relativity we will find that the universe will expand in just few picoseconds. In order to take care of this another field is assumed which has negative energy and which cancel out the energy due to Higgs field. In our day to day life everything should have positive energy but infect in quantum mechanics we can have negative energy.
If we assume that Higgs field do exist and so we will have the vacuum energy. Now as the universe will expand we will have more of vacuum and so more amount of energy and since the rate of expansion depends upon the energy of the universe it will also increase with the expansion of the universe.
Astrophysicist study the light coming from distance galaxy and so if a galaxy is billion light year from earth the light we are getting now is basically come from that galaxy billion year ago so what we are measuring is how the galaxy was billion year ago , this allow as to go back in time. Astrophysicist at using the giant telescope at Hawai has found out that the galaxy far away from as where expanding slower then the rate at which near by galaxy is expanding that means the expansion rate is speeding up. So according to general relativity the vacuum energy is contributing in the expansion rate. Physicist has found the exact amount of energy is required after canceling the Higgs field energy.
The concept of empty space comes from the age of Newton. In his Hypothesis of Light of 1675, Newton posited the existence of the ether to transmit forces between particles. So according to Newton all the empty space was filled with ether. People tried for many years to find the existance of ether. One of the experiments to find the existence of the ether is to find the speed of light in the direction of rotation of the earth and in the direction opposite to it. Now if the ether exist it will be affected by the rotation of the earth since Newton assumed that it has some inertia and hence will be in motion due to rotation of the earth. The light traveling through this rotating ether will have two different velocity depending upon light is moving in the direction of the ether or opposite to it. People tried to detect the speed of light in two different direction and they found that light has same speed in both direction so the concept of the ether was assumed to be wrong. Also Newton assumed that light is made up of particles called corpuscular "Newton's corpuscular theory of light " which moves in ether and hence in order to light to come from sun to earth it need some medium and which Newton assumed as ether. After the "Double slit experiment" it was found out that the light is electromagnetic wave and it don't need the medium to travel, the concept of ether was completely disproved and for many years it was believed that vacuum is empty ie no matter no field nothing ....
Higgs Field-
In the year of 1960 a Peter Higgs introduced the new concept of Higgs filed. In order to understand this let us discuss little bit of Particle Physics. Suppose we take a piece of ice and smash it very hard, what we will get is water molecule. Smash the water molecules very hard and we will get oxygen and hydrogen atom. For many years it was assumed that atoms are the building block of matter but later experiments on J. J. Thomson on discharged tube proved that even atoms are made up of small particles called electron , proton and neutrons ( Thomson atomic model, Rutherford atomic model etc ). In order to study these particles Particles accelerators are used, where this particles are accelerated to very large speed and then allowed to collide with each other. After smashing this particles very hard in such particle accelerator physicist figured out that even this particles are made up small particles called quarks, leptons etc. In order to explain formation of all electrons , neutrons protons and all matter. A theory was developed called " Standard model " which makes thousands of prediction which are even experimentally verified but there is one problem with this theory it says that all the fundamental particles in Standard model is mass less this is exactly opposite to what we observe in day to day life. Every particle which has no mass should travel through speed of light ( like photon ) but we see that each of matter like my hand when I am typing this is moving with some finite speed also Every matter around us has some mass, electron, proton etc everything has some mass. In order to solve this problem Peter Higgs proposed a theory that says that all space is filled with a smooth filed called " Higgs Field " and it interact with all particles and slow them down ( or prevent these particle to move with the speed of light ) . So the question is can we feel this field? well the answer is yes we can feel this field the fact that my electrons and proton in my hands are not moving with the speed of light is because of Higgs filed. Now the question is can the Higgs field be turned of light electromagnetic filed ( turn of the source of em waves ), the answer is now because it is a vacuum field. It is proved mathematically though that after some picoseconds of the Big-Bang the this Higgs field was actually turned of and for some picoseconds of this time all the particles was moving with the speed of light and then after some picoseconds this Higgs field was turned on and all the fundamental particles come together to form electron, proton, neutron then atom then molecule then stars then galaxy etc. ( See my post on Creation of Universe ).
Higgs Bosons-
Higgs field is quantum mechanical field like electromagnetic filed. Now if we produce the ripple in the electromagnetic filed it is quantized and which is called a photon. In the same way if we can produce a ripple in the Higgs filed we can actually get what we call "Higgs Boson". In order to produce a ripple in Higgs field we need large amount. Physist at CERN and Fermi lab are trying to find out the presence of this Higgs Bosons. The particles will be accelerated to very large velocity and the will be allowed to collide this large amount of energy will produce the ripple in the Higgs field and which will be detected as Higgs Boson.
General Relativity and Higgs Field-
According to general relativity the universe should expand or contract. It has been found experimentally that the universe is actually expanding (red shift in spectrum of light coming from distance galaxy ) . The rate at which universe is expanding depends upon the matter inside the universe also after certain limit of expansion due to gravity the rate of the expansion should slow down. Now Higgs field has some energy which is of order of 1 trillion per cc , if we put this amount of energy in equations of relativity we will find that the universe will expand in just few picoseconds. In order to take care of this another field is assumed which has negative energy and which cancel out the energy due to Higgs field. In our day to day life everything should have positive energy but infect in quantum mechanics we can have negative energy.
If we assume that Higgs field do exist and so we will have the vacuum energy. Now as the universe will expand we will have more of vacuum and so more amount of energy and since the rate of expansion depends upon the energy of the universe it will also increase with the expansion of the universe.
Astrophysicist study the light coming from distance galaxy and so if a galaxy is billion light year from earth the light we are getting now is basically come from that galaxy billion year ago so what we are measuring is how the galaxy was billion year ago , this allow as to go back in time. Astrophysicist at using the giant telescope at Hawai has found out that the galaxy far away from as where expanding slower then the rate at which near by galaxy is expanding that means the expansion rate is speeding up. So according to general relativity the vacuum energy is contributing in the expansion rate. Physicist has found the exact amount of energy is required after canceling the Higgs field energy.
Wednesday, May 13, 2009
Interfacing Experimental Instruments with computer
Once you have decided what experiments you are going to do, the next thing to decide is the measuring instruments you will be needing for building you experimental setup. Most common instruments in the field of condense matter physics experiments are picoammeters, voltage source, cryostat, magnets, LCR meter , oscilloscope , signal generator etc. Now in order to get good results and reducing experiments time you need to interface this instruments with computer in order to completely automize your experiments. The reasons behind doing this is -
1)Manual control of instruments and experiments often lead to human error.
2)It take lot of time and men power when your experiments is human control.
3)Results you get using manual control are often not of good quality.
So in order to overcome this problems you need to make a completely autonomous experimental setup and hence you need to interface these instruments with computer.
The instruments I have in my labs are-
Before starting that let us discuss the protocols used to interface instruments and the software we can use to interface these instruments.
The basic communication method with the computer are-
http://www.icselect.com/gpib_intfcbds_ds.html
some comes with serial port interface. The serial port is given in many old computer but now in latest computer and Laptops you can't have the serial port for such situation you can use USB-SERIAL PORT CONVERTER.
some instruments comes with USB port and almost all computer has USB port so you don't need to install some other hardware.
Now this was the hardware part now lets switch to software part. Every instruments use a mode for communicating with the computer and our next task is to discuss this mode or protocol for interfacing with the instruments. This protocols are-
The better way is to use some software which can make our life lot easier. In the range of scientific measurement software most important are LabView and Matlab. I am also going to post Matlab and LabView tutorials in my blogs but for now we will only consider intefcing using this Matlab. Installing matlab is easy like other software , you just need to follow instruction given in the screen don' forget to install "TEST AND MEASURMENT TOOL BOX". Once you have installed matlab just run it go to the command window and type
>tmtool
after this test and measurement tool box will open click the refresh sign to refresh any hardware connected to you computer. At the left side you will find list of all interface like GPIB , Serial , TCPIP etc if your instrument is connected to GPIB board just go to GPIB tree and then click connect button in the right side of the window , it will show the status to be connected if instrument is connected with the computer. Now you can send SCIP commands from the text box above the send and query button.In order to check if everything is going fine just type
*IDN?
and press inquiry button
the response of this command will be a text string which will be having the information about the connected instrument.
Whenever you send some SCIP commands such that the response of the instrument is to send some text string either you can use inquiry or use send and then read command in sequence.
Once you are done with programing your instrument you can go to log session tab where you will find all the codes for what you have done manually you can use this code to make an m-file.
In instrument control tool box you will also find -
Enjoy!
1)Manual control of instruments and experiments often lead to human error.
2)It take lot of time and men power when your experiments is human control.
3)Results you get using manual control are often not of good quality.
So in order to overcome this problems you need to make a completely autonomous experimental setup and hence you need to interface these instruments with computer.
The instruments I have in my labs are-
- Tektronix TDS1012B oscilloscope.
- Tektronix AFG3101 Singal generator.
- LCR meter.
- Kaithly Picoammeter cum voltage source.
- Kaithly nanovoltemeter.
- Cryostat.
Before starting that let us discuss the protocols used to interface instruments and the software we can use to interface these instruments.
The basic communication method with the computer are-
- Serial Port communication.
- GPIB (General Purpose Interface Bord).
- USB
http://www.icselect.com/gpib_intfcbds_ds.html
some comes with serial port interface. The serial port is given in many old computer but now in latest computer and Laptops you can't have the serial port for such situation you can use USB-SERIAL PORT CONVERTER.
some instruments comes with USB port and almost all computer has USB port so you don't need to install some other hardware.
Now this was the hardware part now lets switch to software part. Every instruments use a mode for communicating with the computer and our next task is to discuss this mode or protocol for interfacing with the instruments. This protocols are-
- SCIP commands.
- VISA
- IVI
The better way is to use some software which can make our life lot easier. In the range of scientific measurement software most important are LabView and Matlab. I am also going to post Matlab and LabView tutorials in my blogs but for now we will only consider intefcing using this Matlab. Installing matlab is easy like other software , you just need to follow instruction given in the screen don' forget to install "TEST AND MEASURMENT TOOL BOX". Once you have installed matlab just run it go to the command window and type
>tmtool
after this test and measurement tool box will open click the refresh sign to refresh any hardware connected to you computer. At the left side you will find list of all interface like GPIB , Serial , TCPIP etc if your instrument is connected to GPIB board just go to GPIB tree and then click connect button in the right side of the window , it will show the status to be connected if instrument is connected with the computer. Now you can send SCIP commands from the text box above the send and query button.In order to check if everything is going fine just type
*IDN?
and press inquiry button
the response of this command will be a text string which will be having the information about the connected instrument.
Whenever you send some SCIP commands such that the response of the instrument is to send some text string either you can use inquiry or use send and then read command in sequence.
Once you are done with programing your instrument you can go to log session tab where you will find all the codes for what you have done manually you can use this code to make an m-file.
In instrument control tool box you will also find -
- Instrument Objects
- Instrument driver.
Enjoy!
Magnetic Semiconductors
In order to get deep understanding of this topic we need to first understand what is semiconductor and what are magnetic materials. So lets start the discussion about magnetic materials.
MAGNETIC MATERIALS
All the elements discovered by us are described in periodic table and the way each of this elements are distinguished in periodic table is dependent upon electronic structure of this elements. Electronic structure is the way total no of electron is distributed in the shell. For example Hydrogen as 1 electron in its shell. Now consider the example of Al which has atomic mass 13 and its electronic configuration is 2,8,3 here nucleus and first two completely filled shell are bind up together and they are called core because they have no significant contribution since they are completely filled orbitals. The outermost shell has three electrons and hence contribute to magnetic moment. An electron contribute to magnetic moment in two way
1)orbital motion - An orbiting electron can be considered as current carrying loop which contribute to magnetic moments.
2)Spin moments - An electron is associated with a intrinsic property ( like mass ) which is called spin magnetic moment.
Now each orbit in a shell can accommodate two electron of opposite spin. So if there is equal no of up spin and down spin electron the net magnetic moment is zero and hence the element will not show any magnetic behaviors which is not the case of Aluminum. Here outermost shell has 3 electrons and so it should have some magnetic moment. But as we observe Al is not magnetic. The reason is atomic Al is indeed magnetic but the solid Al is non-magnetic because in solid Al all outermost electron get detached from the core and now free to move throughout the crystal, thats why its metallic in nature as well as non-magnetic.
Silicon-
Now consider the case of Si it has atomic no of 14 and it has 4 electron in outermost shell but in this case the bonding is covalent bond and the electrons are not free to move around the crystal which makes it non-metallic and 4 electrons make it non-magnetic. Now if we dope Si with little bit of Al say 1:15000, Al will fit exactly at the same place of Si but one electron less. This vacancy of electron is called hole and it is free to move around the crystal and hence can contribute to current contribution similarly if it is doped with Br there will be extra electron which will be now free to move around and can contribute to current conduction. This kind of materials are called semiconductors.
Iron-
Iron has atomic no 26 and its electronic configuration is 2,8,14,2. The outermost 4th shell electrons are free to move around making it metal but the 3rd unfilled orbital electrons are bound to the core and hence can't move since it is partially filled it contribute to magnetic moment.
Gedollinium (Gd)-
It has electronic configuration of 2,8,18,25,9,2 the outermost electron are free to move around and hence make it metal second most outer shell is half filled and give net magnetic moments.
Now we have enough of knowledge about magnetic and semiconductor materials and we will try to come up with a material which is both magnetic as well as semiconductor.
Magnetic Semiconductors-
If we dope semiconductor with the atoms having magnetic behavior we can get magnetic semiconductor. If we consider doping Si with Gd the problem is that Gd has a very big core and can not fit in the crystalline structure of Si. Now from here the research starts. One way is to make the Si amorphous by some means and then dope it with Gd. During this research you need to meke various sample with different doping techniques and different doping concentration then take there characteristics etc in order to come up with a material which has good magnetic as well as semicondutor property.
If we can come up with this type of material it can have remarkable technological applications. One application is Giant Magneto Resistance. Consider the case of Doping some X atom which has magnetic property with Y semiconductor now this X atom will take some definite position in the Y crystalline structure with random spin polarization. Now if by some means ( actually applying electric filed across the material and at the semiconductor metal junction applying magnetic field at metal side to make all spin polarized to same direction ) we can inject same spin electron into this material due to randomly oriented X atoms spin this elections will not be so comfortable in flowing across the material and hence will show some resistance. Now if we apply the magnetic filed across this material all the doped atom X will now become polarized to same direction as of polarization of the incoming electron and hence the elections can now move more easily across the material giving us less resistance. This phenomenon is actually called magneto resistance.
One of the application of this kind of material is in hard disk we have in our computer. We know that the data is stored in this disk in form of magnetic poles. Now when this kind of material will be allowed to pass over this stored data disk surface, depending upon the magnetic field at a particular site the resistance of the material will change and hence the current in the circuit will change which can be detected to read the data stored.
This kind of thiking bring us to whole new idea of electronics which is called "SPINTRONCS".
where we use spin of the electron to store data as well us to transfer information. How spin can be used in making next generation memory devices and memories will be the topic of my other post. That is it for now.
Enjoy!
MAGNETIC MATERIALS
All the elements discovered by us are described in periodic table and the way each of this elements are distinguished in periodic table is dependent upon electronic structure of this elements. Electronic structure is the way total no of electron is distributed in the shell. For example Hydrogen as 1 electron in its shell. Now consider the example of Al which has atomic mass 13 and its electronic configuration is 2,8,3 here nucleus and first two completely filled shell are bind up together and they are called core because they have no significant contribution since they are completely filled orbitals. The outermost shell has three electrons and hence contribute to magnetic moment. An electron contribute to magnetic moment in two way
1)orbital motion - An orbiting electron can be considered as current carrying loop which contribute to magnetic moments.
2)Spin moments - An electron is associated with a intrinsic property ( like mass ) which is called spin magnetic moment.
Now each orbit in a shell can accommodate two electron of opposite spin. So if there is equal no of up spin and down spin electron the net magnetic moment is zero and hence the element will not show any magnetic behaviors which is not the case of Aluminum. Here outermost shell has 3 electrons and so it should have some magnetic moment. But as we observe Al is not magnetic. The reason is atomic Al is indeed magnetic but the solid Al is non-magnetic because in solid Al all outermost electron get detached from the core and now free to move throughout the crystal, thats why its metallic in nature as well as non-magnetic.
Silicon-
Now consider the case of Si it has atomic no of 14 and it has 4 electron in outermost shell but in this case the bonding is covalent bond and the electrons are not free to move around the crystal which makes it non-metallic and 4 electrons make it non-magnetic. Now if we dope Si with little bit of Al say 1:15000, Al will fit exactly at the same place of Si but one electron less. This vacancy of electron is called hole and it is free to move around the crystal and hence can contribute to current contribution similarly if it is doped with Br there will be extra electron which will be now free to move around and can contribute to current conduction. This kind of materials are called semiconductors.
Iron-
Iron has atomic no 26 and its electronic configuration is 2,8,14,2. The outermost 4th shell electrons are free to move around making it metal but the 3rd unfilled orbital electrons are bound to the core and hence can't move since it is partially filled it contribute to magnetic moment.
Gedollinium (Gd)-
It has electronic configuration of 2,8,18,25,9,2 the outermost electron are free to move around and hence make it metal second most outer shell is half filled and give net magnetic moments.
Now we have enough of knowledge about magnetic and semiconductor materials and we will try to come up with a material which is both magnetic as well as semiconductor.
Magnetic Semiconductors-
If we dope semiconductor with the atoms having magnetic behavior we can get magnetic semiconductor. If we consider doping Si with Gd the problem is that Gd has a very big core and can not fit in the crystalline structure of Si. Now from here the research starts. One way is to make the Si amorphous by some means and then dope it with Gd. During this research you need to meke various sample with different doping techniques and different doping concentration then take there characteristics etc in order to come up with a material which has good magnetic as well as semicondutor property.
If we can come up with this type of material it can have remarkable technological applications. One application is Giant Magneto Resistance. Consider the case of Doping some X atom which has magnetic property with Y semiconductor now this X atom will take some definite position in the Y crystalline structure with random spin polarization. Now if by some means ( actually applying electric filed across the material and at the semiconductor metal junction applying magnetic field at metal side to make all spin polarized to same direction ) we can inject same spin electron into this material due to randomly oriented X atoms spin this elections will not be so comfortable in flowing across the material and hence will show some resistance. Now if we apply the magnetic filed across this material all the doped atom X will now become polarized to same direction as of polarization of the incoming electron and hence the elections can now move more easily across the material giving us less resistance. This phenomenon is actually called magneto resistance.
One of the application of this kind of material is in hard disk we have in our computer. We know that the data is stored in this disk in form of magnetic poles. Now when this kind of material will be allowed to pass over this stored data disk surface, depending upon the magnetic field at a particular site the resistance of the material will change and hence the current in the circuit will change which can be detected to read the data stored.
This kind of thiking bring us to whole new idea of electronics which is called "SPINTRONCS".
where we use spin of the electron to store data as well us to transfer information. How spin can be used in making next generation memory devices and memories will be the topic of my other post. That is it for now.
Enjoy!
Saturday, May 9, 2009
My Lab
To organize my blogs more efficiently I have decided to introduce the concept of "My Lab". This will be sort of my online lab where I will discuss experiments I have done. Well I am not rich enough to buy expensive equipments like Tektronix signal generator, Agilent picoammeter, capacitance meter etc. Whenever I need to perform experiments I borrow this instruments from some of Prof. of my department or other, get my work done and then return it back so you can call it sort of my virtual lab.
Introduction to my lab-
In my lab I have manly experimental setup dealing with condens matter physics experiments. But depeneding upon my interest you can also find experiments related to other brach of physics. At now I have experimental setup for measuring IV characteristics, temperature depenedent measurment, magnetic field dependent measurments, time depenedent experiments , capacitance measurments and soon I will also introduce some fabrication related facilitites in my lab like making ohmic and schottky contacts in GaN. n and p type doping of GaN, Chemical Vapor deposition technique etc.
The major instruments in my labs are-
1) Agilent Picoammeter- It can measure current in the rang of pico ampere, it also has a voltage source prob so we can use it as voltage source also.
2)Agilen Nanovoltmeter
3)Crystate- It is a device used to set temperature. Using this I can go down to 80K temperature. Liquid nitrogen is used for cooling.
4)Acton Monocromator.
5)White Light source.
6)Tektronix Signal generator AFG3101
7)Tektronix Oscilloscope TDS 1012B
8)Lock in amplifier and chopper.
9)An electromagnet with its power supply. It can produce maximum of 1.5 Tesla of magnetic field.
10)Capacitance-voltage measurments (CV measurments )
Beside this some other things are polarizers, lenses, optical banch, Laser, some chemicals, anneling setup, photodiodes, soldering ions etc.
This was the hareware part in my lab. Now comes the software part. Inorder to completly automize you experimental setup you neet to interface this instruments with compter, detail of this I will discuss in different post. For this you should be very good in C++ programing. You can also use some softwares available to ease your work of interfacing and cotrolling instruments.
The main softwares available in my labs are-
1)MATLAB
2)LabView
3)Origin 8.0
beside this vendors like tektronix also ship softwares to contrlle there instrumetns.
Now what I actually do in my lab is I fabricate different samples and find there electrical charateristics, which include IV charateristics, capacitance measurments etc
Finally this are the list of experiments I can perform in my lab
1)IV characteristics.
2) Temperature dependent IV charateristics
3)Magnetic field depenedent IV characteristics.
4)Time dependent characteristics.
5)Capacitance measurments.
6)DLTS - Deep Level Transient Spectroscopy.
I will discuss each of this in later posts.
enjoy
Prashant Patil
Introduction to my lab-
In my lab I have manly experimental setup dealing with condens matter physics experiments. But depeneding upon my interest you can also find experiments related to other brach of physics. At now I have experimental setup for measuring IV characteristics, temperature depenedent measurment, magnetic field dependent measurments, time depenedent experiments , capacitance measurments and soon I will also introduce some fabrication related facilitites in my lab like making ohmic and schottky contacts in GaN. n and p type doping of GaN, Chemical Vapor deposition technique etc.
The major instruments in my labs are-
1) Agilent Picoammeter- It can measure current in the rang of pico ampere, it also has a voltage source prob so we can use it as voltage source also.
2)Agilen Nanovoltmeter
3)Crystate- It is a device used to set temperature. Using this I can go down to 80K temperature. Liquid nitrogen is used for cooling.
4)Acton Monocromator.
5)White Light source.
6)Tektronix Signal generator AFG3101
7)Tektronix Oscilloscope TDS 1012B
8)Lock in amplifier and chopper.
9)An electromagnet with its power supply. It can produce maximum of 1.5 Tesla of magnetic field.
10)Capacitance-voltage measurments (CV measurments )
Beside this some other things are polarizers, lenses, optical banch, Laser, some chemicals, anneling setup, photodiodes, soldering ions etc.
This was the hareware part in my lab. Now comes the software part. Inorder to completly automize you experimental setup you neet to interface this instruments with compter, detail of this I will discuss in different post. For this you should be very good in C++ programing. You can also use some softwares available to ease your work of interfacing and cotrolling instruments.
The main softwares available in my labs are-
1)MATLAB
2)LabView
3)Origin 8.0
beside this vendors like tektronix also ship softwares to contrlle there instrumetns.
Now what I actually do in my lab is I fabricate different samples and find there electrical charateristics, which include IV charateristics, capacitance measurments etc
Finally this are the list of experiments I can perform in my lab
1)IV characteristics.
2) Temperature dependent IV charateristics
3)Magnetic field depenedent IV characteristics.
4)Time dependent characteristics.
5)Capacitance measurments.
6)DLTS - Deep Level Transient Spectroscopy.
I will discuss each of this in later posts.
enjoy
Prashant Patil
Friday, May 8, 2009
Experimental Physics
A theory is a philosophy unless it is proved experimentally. You might be aware of so called "String theory" , the main problem why peoples can't accept as a theory ( It is still a philosophy to many physicits) is that the strings are so small that we can not prob given the current technology. So Experimental physics is back bone of the modern physics.
First thing to note is that we can not measure any physics quantity accurately, be it the length of the rod. So whenever we report some measured quantity it sould be with proper error involved in it and with proper unit. I will discuss error analysis in different blog. Here we will just introuduce our self to experimental physics.
Second most important thing is to understand about the measuring instrument. Again no instrument in the world can give you the exact measurment. Since whenever you prob the system of measuring some quantity you are acutally distrubing the system and hence what you are measuring the is the quantity related to this distrubed system, not the original system. The quality and reliability of the instrument depends upon how much less you distrube the system while doing the mesurment. You probably be wondering why I am discussing this because the error in the measurment etc comes with the instruments data sheet but as a experimentalist you should be able to make your own measuring instrument and experimental setup so you should be aware of this things.
The third part comes to analyse the data. You will find in most of the cases the ouput is some voltage or current ( as we use sensors in measurments which give electrical signals as output) so you should be able to intereprate from this signals your actual measurment quantity.
At last what you required to become the best experinetalist is some knowledge about the physics behind the system you are measuring, quantitites you want to measure and there order and error level you expect, some knowledge of electronics and computer Programming ( When you want to design an automated measurment system, which will be the main topic of y discussion ) and lot of patience.
Well if you qualify non of the above qualification, don't get disapointed. The best experimentalist I know , Michal Faraday also failed to satisfy this criterial still he proposed some of the great physics law based upon his experimental observations.
First thing to note is that we can not measure any physics quantity accurately, be it the length of the rod. So whenever we report some measured quantity it sould be with proper error involved in it and with proper unit. I will discuss error analysis in different blog. Here we will just introuduce our self to experimental physics.
Second most important thing is to understand about the measuring instrument. Again no instrument in the world can give you the exact measurment. Since whenever you prob the system of measuring some quantity you are acutally distrubing the system and hence what you are measuring the is the quantity related to this distrubed system, not the original system. The quality and reliability of the instrument depends upon how much less you distrube the system while doing the mesurment. You probably be wondering why I am discussing this because the error in the measurment etc comes with the instruments data sheet but as a experimentalist you should be able to make your own measuring instrument and experimental setup so you should be aware of this things.
The third part comes to analyse the data. You will find in most of the cases the ouput is some voltage or current ( as we use sensors in measurments which give electrical signals as output) so you should be able to intereprate from this signals your actual measurment quantity.
At last what you required to become the best experinetalist is some knowledge about the physics behind the system you are measuring, quantitites you want to measure and there order and error level you expect, some knowledge of electronics and computer Programming ( When you want to design an automated measurment system, which will be the main topic of y discussion ) and lot of patience.
Well if you qualify non of the above qualification, don't get disapointed. The best experimentalist I know , Michal Faraday also failed to satisfy this criterial still he proposed some of the great physics law based upon his experimental observations.
About My Blogs
My interests are in theoretical and experimental physics. Beside this I am also interested in automated robots. In my Blogs I will cover basically experimental Physics Part. Here you can find all about my current and proposed experiments. The idea of sharing this with worlds is that you can use this ides and codes to use it for your self. Theoratical Physics part will be less shared. I will also share my work on robotics. So basically My blogs will be divided in three catagories
1) Theoratical Physics-
Here I will discuss my interested topics on physics, book reviews etc.
2) Experimental Physics-
Here I will discuss about performing experiments and analysing results. All the work by me , I will try to properly document so that you can use it. This experiments will be manly related to Condense Matter Physics.
3) Tech and Robotics-
Here I will share all my robots I have made. AVR microcontroller, Image Processing, using sensors, opamps and some interesting projects.
4)Adventure Sports-
I like to adventure in my life. In this section of my blogs you can find my experiance and some useful information related to some adventure sports like Mountaineering, Paragliding , river rafting , valley crossing etc.
regard,
Prashant Patil
Department of Engineering Physics
IIT Bombay
1) Theoratical Physics-
Here I will discuss my interested topics on physics, book reviews etc.
2) Experimental Physics-
Here I will discuss about performing experiments and analysing results. All the work by me , I will try to properly document so that you can use it. This experiments will be manly related to Condense Matter Physics.
3) Tech and Robotics-
Here I will share all my robots I have made. AVR microcontroller, Image Processing, using sensors, opamps and some interesting projects.
4)Adventure Sports-
I like to adventure in my life. In this section of my blogs you can find my experiance and some useful information related to some adventure sports like Mountaineering, Paragliding , river rafting , valley crossing etc.
regard,
Prashant Patil
Department of Engineering Physics
IIT Bombay
Subscribe to:
Posts (Atom)