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Abstrak :
ABSTRAK Tujuan dari eksperimen yang dilakukan adalah untuk menyelidiki hal-hal yang berkaitan dengan pembentukan plasma, yakni zat yang tersusun dari muatan-muatan listrik bebas berupa ion-ion positif dan elektron elektron negatif yang jumlahnya nyaris sama. Plasma yang digunakan dalam eksperimen terbentuk dari udara laboratorium yang di iradiasi dengan berkas laser energi tinggi ( IJ - 2J ) dalam sebuah chamber yang dilengkapi dengan suatu rangkaian listrik DC. Dengan memberikan beda tegangan tertentu antara dua elektrode yang berada dalam chamber, maka elektron-elektron dari plasma yang berada diantara kedua elektrode tersebut akan ditarik oleh elektrode positif dan menimbulkan arus listrik pada resistor yang ada dalam rangkaian. Besar arus listrik yang mengalir ini dapat ditentukan harganya dengan cara mengukur besar tegangan pada resistor menggunakan cathode ray oscilloscope. Chamber yang merupakan kotak tertutup berisi plasma yang diamati, dilengkapi dengan pengukur tekanan, dan di hubungkan ke sebuah pompa vakum. Dengan memvariasi besar tekanan udara dalam chamber, jarak antar elektrode, beda tegangan antara elektrode, maupun besar energi laser, dapat diperoleh harga besaran-besaran fisis yang diselidiki, juga korelasi-korelasi antara suatu besaran fists, dengan besaran fists lainnya.

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ABSTRACT An investigation has been conducted on the formation of plasma generated by focusing an intense Laser radiation. A high voltage from DC source is used to trigger electrical breakdown between two electrodes which an air of laboratory will be investigated. The electrical breakdown caused by laser radiation observed by measuring the voltage of pick up resistor in the electrical circuit. The value of electric current flows in resistor can be calculated from the value of voltage, it expresses the amount of electrons flow from plasma. By variating air pressure in the chamber, distance between two electrodes, potential difference between two electrodes, and laser energy, we can find correlations between: air pressure versus breakdown probability, air pressure versus electron number density, Laser energy versus electron number density, electric field per pressure versus electron drift velocity, etc.

Abstrak :
ABSTRACT
As transmission medium in optical communication system, optical fiber is also characterized by elastic properties beside of transmission properties of optical fiber. The Young Modulus of Elasticity of optical fiber could be measured by considering a bare optical fiber as cantilever which resonant with an acoustical vibration. To detect the cantilever vibration, a HeNe laser light is launched into the cantilever of optical fiber through its free end and the output laser light is detected by a PMT and observed by the channel 2 of an oscilloscope. Channel 1 of the oscilloscope observes the signal of the acoustical vibration.

Regulating both the frequency and amplitude of the vibration or the position of the pinhole of the PMT, the resonance frequency of the cantilever could be detected accurately. Using the data of the resonance frequencies of various length of the cantilever has been calculated.

Abstrak :
ABSTRACT
Data acquisition system using diode array for a spectrometer has been designed and constructed. The light detection is performed by a photodiode array consisting of 512 photodiodes. The superior quantum efficiency of the detector and the direct increase of optical flux with photodiode electrons make it works as a very fast detector. This detector is supplemented with a charge-coupled device working as a shift register for the array, and as a result each light spectrum can be scanned in less than one minute.

The detecting subsystem is followed by a 12 bit analog to digital conversion module which operates at the speed of 26 uses. This data acquisition system is also equipped with an Z BO CPU controlled interface module for its data transfer to an IBM PC, to allow further processing and analysis of the data as well as its final display. In addition to each individual subsystem testing, the whole integrated system has also been tested with a known spectrum and the result is satisfactory.

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ABSTRAK
An N2 laser system that consists of transversely excited atmospheric (TEA) oscillator and transversely excited (TE) amplifier has been designed and constructed. The laser system employs single common spark gap for both oscillator and amplifier. The optimum operating voltage is 15 kV at 2 Hz repetition rate. The measured energy of the output oscillator-amplifier system has maximum value of 55 pJ and beam divergence of 2 mrad horizontally and 1 mrad vertically.

Synchronization between the oscillator and amplifier was achieved by varying the gas pressure in amplifier tube, inductance between oscillator and spark gap as well as the optical path between the oscillator and amplifier. The result of its characterization showed that this system is capable to producing BOO % amplification in a single pass.

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ABSTRAK
A compact, simple and low-cost transversely excited atmospheric (TEA) pressure ultraviolet nitrogen laser {337 nm) has been designed and constructed employing the conventional Blumlein circuit. The measured energy of the output pulse of 337 nm is around 80 -J at 25 kV of charging voltage and l atm operating gas pressure. The beam divergence is found to be 7.7 mrad horizontally and 1.5 mrad vertically. The energy output decreases slightly with increasing gas pressure and gas flow rate, while the beam divergence is relatively stable with respect to the same operating parameters.

Abstrak :
Computer simulation program has been developed on the basis of Liapunov approach for the study of MRAC technique applied to pressure control for a vacuum system. Both proportional and integral feedback as well as disturbance feedforward is considered in the closed-loop system. The simulation result obtained with a personal computer demonstrates that this MRAC technique is feasible and provides effective and satisfactory control despite its poor initial control policies and wide range of choice for the adaptive gains. For a series of step disturbance, MRAC resulted in continually improved control with very good agreement obtained between process and reference model responses after the second disturbance.

Abstrak :
A fluorescence spectrometer, with gating PMT (Photo Multiplier Tube) has been designed and constructed for the observation of Time Resolved Spectroscopy. Employed as a source far the fluorescence spectrometer a pulsed N2 lasers with about 5-nanosecond pulse width and 400-kilowatt power. Gating PMT carries out the sampling. In this method some of the dynodes of the PMT are being biased at voltages below normal operating voltage, while the other dynodes are held at their normal voltages. Sampling pulses generated by avalanche transistor are fed into the dynodes of the lower voltage to operate the PMT. A variable delay circuit of the order of nanosecond with respect to the N2 lasers pulse delays the sampling pulses. The output of the PMT is read on an oscilloscope and the lifetime of the fluorescence can be obtained by plotting the output of the PMT vs. the delay time.

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ABSTRACT
A vacuum chamber has been designed and constructed for the observation the primary plasma and secondary plasma which is generated by the bombardments of brass by N2 Laser beam with about 5 ns pulse width and 1 1W power.

The Radius and spectral emission of the resulting secondary plasma of the brass sample at the surrounding gas pressure range 2 and 8 torr in N2, is presented.

This study can be developed to generated plasma and it can used for the analysis the composition the sample irradiated by N2 laser beam.

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ABSTRAK
The design and construction of eight-bit tune delay autocorrelator is discussed, suitable for use in photon correlation experiments. The sampling time of the correlator can be varied from 1 usec to 100/usec, devide into a number ( typically 256 ) channels (time interval). The instruments records the number of pulses occuring in each sampling time and is stored in location memory in a RAM-BANK. The data is stored in binary form, the data can be converted to analog form by digital to analog converter and is displayed on an oscilloscope.

Abstrak :
ABSTRACT
The principles of frequency stabilization is to keep constant the optical path length in laser cavity by controlling the laser- tube length. In this system used temperature servo control to control the laser tube length.

As reference to an error derived by a sensitive frequency discriminator. Basically the operation of this sensitive frequency discrimantor utilized the longitudinal Zeeman Laser, which splits atomic gain profile.

When a longitudinal magnetic field is applied to an internal mirror of single mode He-Ne Laser, the active medium acquires a negative circular dichroism. There fore the intensity of the left cicular polarization (LCP) output of the, laser will be different from the intensity of the right circular polarization (RCP) output and only when the two are simmetrically disposed about the center line will their intensities be equal. This intensity difference as feedback can be detected by passing the output beam throught Wallaston prism and the two orthogonally polarized beams are received by two identical photodiodes. The difference between the output of photodiode as amplified and the resulting signal is passed throught a system controller (PID) before it is fed back as heating or cooling current of peltier elements. This current controls the resonator length thermally and lock the laser frequencies of the two polarized beam symmetrically on either side of the profile.