final prototype with adaptor

we were working on compatibility of our prototype.

finally we reached by using converter and adapter.

following picture is the finished prototype of radiation detector

finishing the detector

we are trying to finish our detector with built in dc/dc converter and a adaptor for portability,
we are still working on fiber optics, there may be a possibility to interact this detector with fiber and radiation in turn.

RADIATION DETECTOR

In order to detect the light intensity, we started our task in investigating photo-diodes. after we received enough data and components,fabricated the circuit which is shown below.

fiber optics

- Optical fiber (or "fiber optic") refers to the medium and the technology associated with the transmission of information as light pulses along a glass or plastic strand or fiber. Optical fiber carries much more information than conventional copper wire and is in general not subject to electromagnetic interference and the need to retransmit signals. Most telephone company long-distance lines are now made of optical fiber. Transmission over an optical fiber cable requires repeaters at distance intervals. The glass fiber requires more protection within an outer cable than copper. For these reasons and because the installation of any new cabling is labor-intensive, few communities have installed optical fiber cables from the phone company's branch office to local customers (known as local loops). A type of fiber known as single mode fiber is used for longer distances; multimode fiber is used for shorter distances [1].



What are Fiber Optics?

Fiber optics (optical fibers) are long, thin strands of very pure glass about the diameter of a human hair. They are arranged in bundles called optical cables and used to transmit light signals over long distances.

If you look closely at a single optical fiber, you will see that it has the following parts:

* Core - Thin glass center of the fiber where the light travels
* Cladding - Outer optical material surrounding the core that reflects the light back into the core
* Buffer coating - Plastic coating that protects the fiber from damage and moisture

Hundreds or thousands of these optical fibers are arranged in bundles in optical cables. The bundles are protected by the cable's outer covering, called a jacket.

Optical fibers come in two types:

* Single-mode fibers
* Multi-mode fibers

See Tpub.com: Mode Theory for a good explanation.

Single-mode fibers have small cores (about 3.5 x 10-4 inches or 9 microns in diameter) and transmit infrared laser light (wavelength = 1,300 to 1,550 nanometers). Multi-mode fibers have larger cores (about 2.5 x 10-3 inches or 62.5 microns in diameter) and transmit infrared light (wavelength = 850 to 1,300 nm) from light-emitting diodes (LEDs).

Some optical fibers can be made from plastic. These fibers have a large core (0.04 inches or 1 mm diameter) and transmit visible red light (wavelength = 650 nm) from LEDs[2].


references:
[1]http://searchtelecom.techtarget.com/sDefinition/0,,sid103_gci212716,00.html
[2]http://electronics.howstuffworks.com/fiber-optic1.htm

spectrometer

A spectrometer is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum. The variable measured is most often the light's intensity but could also, for instance, be the polarization state. The independent variable is usually the wavelength of the light. A spectrometer is used in spectroscopy for producing spectral lines and measuring their wavelengths and intensities.In general, any particular instrument will operate over a small portion of this total range because of the different techniques used to measure different portions of the spectrum. Below optical frequencies (that is, at microwave and radio frequencies), the spectrum analyzer is a closely related electronic device[1].

References
1.http://en.wikipedia.org/wiki/Spectrometer

filters and monochromator

Optical filters: generally, belong to one of two categories.
the absorptive filter,
the interference or dichroic filters.
Optical filters selectively transmits light having certain properties (often, a particular range of wavelengths, that is, range of colours of light), while blocking the remainder.In astronomy, optical filters can be used to eliminate light from the Sun or from a star much brighter than the target object[1].


In our project we use filters in order to select the radiation with particular wavelength that is used by solar cell from the available spectrum of light source which is equal to that of sun's spectrum.


A monochromator is an optical device that transmits a mechanically selectable narrow band of wavelengths of light or other radiation chosen from a wider range of wavelengths available at the input[2].
Selecting Wavelengths is to isolate a wavelength of choice—and get it out of the monochromator—is to adjust the position of “the rainbow” so that a desired wavelength passes through the slit and the undesired wavelengths hit the edges of the slit and the inside wall of the monochromator around the slit and are blocked. This
is the reason why many monochromators are painted black inside so that light that strikes the walls of the monochromator is absorbed instead of reflecting around inside and possibly escaping through the exit slit. This fine adjustment, of which wavelengths fall where in the exit plane, is accomplished by slightly—very slightly—adjusting the position of the grating. In modern instruments, this is controlled by a servomotor controlled by a computer. The monochromator can be calibrated by
using a lamp with a well defined spectral line and adjusting the grating position until that line comes out of the exit slit. The grating’s position is then set to “display” that known wavelength. In some instruments this is done
automatically[3].


references:
1.http://en.wikipedia.org/wiki/Filter_(optics)
2.http://en.wikipedia.org/wiki/Monochromator
3.http://www.shsu.edu/~chm_tgc/primers/pdf/mono.pdf

light matter interaction

Interaction of light takes in many ways like:
absorption and emission of photons
Rayleigh scattering
refraction
fluorescence
resonance fluorescence etc
these are all appear to be different but closely related[1].
Atomic excitation and de-excitation is seen in the presence of photon as shown below[2].


(2) Light Scattering
An isolated atom scatters light because the electric field of the incident light wave forces the electrons in the atom to oscillate back and forth about their equilibrium position. By the laws of electromagnetism, when a charge changes its velocity, it emits radiation. Light is emitted uniformly in all directions in the plane ⊥ to oscillation, but decreases in amplitude as the viewing angle shifts away from that plane[3]

Measaurement of brightness of light is possible by caluclating the heat like power per unit area or by measuring the increased heat in black body which is exposed to light, one can meaasure the brightness of light[4].
(The light energy is being converted to heat energy, and the amount of heat energy absorbed in a given amount of time can be related to the power absorbed, using the known heat capacity of the object. More practical devices for measuring light intensity, such as the light meters built into some cameras, are based on the conversion of light into electrical energy, but these meters have to be calibrated somehow against heat measurements. )

references:
1.http://elchem.kaist.ac.kr/vt/chem-ed/light/light-ma.htm
2.http://csep10.phys.utk.edu/astr162/lect/light/molecular.html
3.www.its.caltech.edu/~ch24/lecture2324_2004.pdf
4.http://www.vias.org/physics/bk5_01_03.html