Oscilloscope and its applications Taif Aied Faisal M.Sc. Laser and Optoelectronics Engineering

Oscilloscope (scope) is a visual voltmeter with a timer (clock) that shows when a voltage changes. An analog scope uses a cathode ray tube (CRT) similar to a television screen to display voltage patterns. Introduction

Types of Oscilloscope Analogue Oscilloscope Digital Storage Oscilloscope Digital Phosphor Oscilloscope Digital Sampling Oscilloscope

Analogue Scope Digital Storage Scope

Digital Phosphor Scope Digital Sampling Scope

Scope Panel and Probe

Waves types

Analog and digital scope

Scope Division Screen

Scope Integration

Phase Shift Measurements The difference in timing between two otherwise identical periodic signals is to use XY mode to measure the phase shift. This measurement technique involves inputting one signal into the vertical system as usual and then another signal into the horizontal system . It’s called an XY measurement because both the X and Y axis are tracing voltages, the waveform that results from this arrangement is called a Lissajous pattern. From the shape of the Lissajous pattern, you can tell the phase difference between the two signals. You can also tell their frequency ratio.

Lissajous patterns for various frequency ratios and phase shifts

Sweep generator to produce one cycle of a sawtooth waveform when it receives a pulse at its input. PG to produce periodical pulses with a period of T, which is equal to the period of the input signal. X-Y Operation

Measuring light on photocell Scientific data can be gathered by scope A sensor creates electrical signal in response to physical stimuli; such as sound, mechanical stress, pressure, light, or heat. The photocell converts light intensity into electrical signal.

Signal parameters V/div = 2V , T/div = 1ms Vp = 6V , Vp-p = 12 V DC = 2 V, period = 3ms Freq. = 333 hz

CRT Structure and main components of a CRT Face plane of the CRO screen

Electron Gun Electron gun provides a sharply focused electron beam directed toward the fluorescent-coated screen. The thermally heated cathode emits electrons in many directions. The control grid provides an axial direction for the electron beam and controls the number and speed of electrons in the beam.

The Deflection System It consists of two pairs of parallel plates referred to as the vertical and horizontal deflection plates. One of the plates in each set is permanently connected to the ground (0 V), whereas the other plate of each set is connected to input signals or triggering signal of the CRO.

Deflection work A +V is applied to Y I/p e-beam deflect vertically upward A –V is applied to Y I/p e-beam deflect vertically downward. The same is for X I/p.

Applied Voltage Examples =sin(t)