Early high-speed visualisations of electrical voltages were made with an electro-mechanical oscillograph,. These gave valuable insights into high speed voltage changes, but had a very low frequency response, and were superseded by the oscilloscope which used a cathode ray tube (CRT) as its display element.The Braun tube, forerunner of the Cathode Ray Tube was known in 1897, and in 1899 Jonathan Zenneck equipped it with beam-forming plates and a magnetic field for deflecting the trace, and this formed the basis of the CRT. Early cathode ray tubes had been applied experimentally to laboratory measurements as early as the 1920s, but suffered from poor stability of the vacuum and the cathode emitters. V. K. Zworykin described a permanently sealed, high-vacuum cathode ray tube with a thermionic emitter in 1931. This stable and reproducible component allowed General Radio to manufacture an oscilloscope that was usable outside a laboratory setting.After World War II surplus electronic parts became the basis for the revival of Heathkit Corporation, and a $50 oscilloscope kit made from such parts proved its premiere market success.
An analog oscilloscope is typically divided into four sections: the display, vertical controls, horizontal controls and trigger controls. The display is usually a CRT with horizontal and vertical reference lines called the graticule. CRT displays also have controls for focus, intensity, and beam finder.
The horizontal section controls the time base or "sweep" of the instrument. The primary control is the Seconds-per-Division (Sec/Div) selector switch. Also included is a horizontal input for plotting dual X-Y axis signals. The horizontal beam position knob is generally located in this section.
This control may instead be called "shape" or "spot shape". It adjusts the voltage on the last CRT anode (immediately next to the Y deflection plates). For a circular spot, the final anode must be at the same potential as both of the Y-plates (for a centred spot the Y-plate voltages must be the same). If the anode is made more positive, the spot becomes elliptical in the X-plane as the more negative Y-plates will repel the beam. If the anode is made more negative, the spot becomes elliptical in the Y-plane as the more positive Y-plates will attract the beam. This control may be absent from simpler oscilloscope designs or may even be an internal control. It is not necessary with flat panel displays.
Modern oscilloscopes have direct-coupled deflection amplifiers, which means the trace could be deflected off-screen. They also might have their beam blanked without the operator knowing it. To help in restoring a visible display, the beam finder circuit overrides any blanking and limits the beam deflection to the visible portion of the screen. Beam-finder circuits often distort the trace while activated.
A switch selects the trigger source. It can be an external input, one of the vertical channels of a dual or multiple-trace oscilloscope, or the AC line (mains) frequency. Another switch enables or disables auto trigger mode, or selects single sweep, if provided in the oscilloscope. Either a spring-return switch position or a pushbutton arms single sweeps.
They have a few (widely spaced) frequency ranges, and relatively wide-range continuous frequency control within a given range. In use, the sweep frequency is set to slightly lower than some submultiple of the input frequency, to display typically at least two cycles of the input signal (so all details are visible). A very simple control feeds an adjustable amount of the vertical signal (or possibly, a related external signal) to the sweep oscillator. The signal triggers beam blanking and a sweep retrace sooner than it would occur free-running, and the display becomes stable.
Oscilloscopes with two vertical inputs, referred to as dual-trace oscilloscopes, are extremely useful and commonplace.Using a single-beam CRT, they multiplex the inputs, usually switching between them fast enough to display two traces apparently at once. Less common are oscilloscopes with more traces; four inputs are common among these, but a few (Kikusui, for one) offered a display of the sweep trigger signal if desired. Some multi-trace oscilloscopes use the external trigger input as an optional vertical input, and some have third and fourth channels with only minimal controls. In all cases, the inputs, when independently displayed, are time-multiplexed, but dual-trace oscilloscopes often can add their inputs to display a real-time analog sum. Inverting one channel while adding them together results in a display of the differences between them, provided neither channel is overloaded. This difference mode can provide a moderate-performance differential input.)
Switching channels can be asynchronous, i.e. free-running, with respect to the sweep frequency; or it can be done after each horizontal sweep is complete. Asynchronous switching is usually designated "Chopped", while sweep-synchronized is designated "Alt[ernate]". A given channel is alternately connected and disconnected, leading to the term "chopped". Multi-trace oscilloscopes also switch channels either in chopped or alternate modes.
True dual-beam CRT oscilloscopes did exist, but were not common. One type (Cossor, U.K.) had a beam-splitter plate in its CRT, and single-ended deflection following the splitter. Others had two complete electron guns, requiring tight control of axial (rotational) mechanical alignment in manufacturing the CRT. Beam-splitter types had horizontal deflection common to both vertical channels, but dual-gun oscilloscopes could have separate time bases, or use one time base for both channels. Multiple-gun CRTs (up to ten guns) were made in past decades. With ten guns, the envelope (bulb) was cylindrical throughout its length. (Also see "CRT Invention" in Oscilloscope history.)
In dual and multiple-trace oscilloscopes, an internal electronic switch selects the relatively low-level output of one channel's early-stage amplifier and sends it to the following stages of the vertical amplifier.
In free-running ("chopped") mode, the oscillator (which may be simply a different operating mode of the switch driver) blanks the beam before switching, and unblanks it only after the switching transients have settled.
Part way through the amplifier is a feed to the sweep trigger circuits, for internal triggering from the signal. This feed would be from an individual channel's amplifier in a dual or multi-trace oscilloscope, the channel depending upon the setting of the trigger source selector.
Note: The dual beam oscilloscope has two different electron gun which passes through two completely separate vertical channels, whereas dual trace oscilloscope has single electron beam which get split into two and passes through two separate channels.
Dual trace scopes are a single beam / single gun design which either alternate or chop the vertical signal. Alternating draws one trace then the other which works fine at high horizontal rates but not at low. The other method is to Chop between the signals at about 1 MHz which works fine on slow horizontal rates but not at high. In addition horizontal must be common between the two traces. The solution to these limitations is the Dual Beam Oscilloscope which is fundamentally two complete oscilloscopes in a single package sharing the package, power supply, and CRT phosphor. Inside the CRT are two complete gun assemblies.
Our third dual beam oscilloscope is a 7844. It has all the improvements and advantages of the 7000 series line, with the added capability of having two horizontal plug-in slots. These can accept the full range of timebase units available in the series, including delaying, delayed and dual, and can be assigned in any combination to the two beams, providing great versatility. This one is displaying two waveforms with differing horizontal rates.
Our last is the monolithic 5031R dual beam oscilloscope. It has low bandwidth but very high sensitivity and found many applications in the medical field. It has fiber optic readouts similar to the 576 (see Fiber Optic Readout for more information). These readouts allow setup information to be captured in a screen photograph for future reference.
In the experiments, the fibre-coupled microresonator is driven by a 1,550 nm continuous-wave laser via the bus waveguide. It is mounted on a customized sample holder and placed in the object plane of the field-emission TEM (Fig. 1a and Methods). Parallel to the surface, the electron beam passes the waveguide and interacts with the confined optical mode (inset in Fig. 1a). After traversing the structure, the electron kinetic energy distribution is characterized with an imaging electron spectrometer in two different ways. Specifically, high-dispersion electron energy spectra are recorded by positioning a sharply focused electron beam in front of the microresonator. Alternatively, energy-filtered TEM using a collimated beam is used to image the interaction across the entire cavity mode in the near field. Whereas the former yields electron spectra for varying experimental parameters (Fig. 2), the latter enables imaging of individual sideband populations with high spatial resolution (Figs. 3 and 4).
7 1. GENERAL 1.1 Description The ISR 6xx family oscilloscopes are dual-channel oscilloscopes with maximum sensitivity of 1 mv/div, and maximum sweep time of 10 nsec/div. Each of these oscilloscopes employs a 6-inch rectangular type cathode-ray tube with red internal graticule. ISR 658 has a sweep magnification feature with B sweep and provides the read-out function which enables an easy read out for settings and cursor measured values. These oscilloscopes are sturdy, easy to operate and exhibits high operational reliability. 1.2 Features 1) High intensity CRT with high acceleration voltage: The CRT is a high beam transmission, high intensity type with a high acceleration voltage of 2kV for model ISR 622 & 635 and 12kV for the ISR 658. It displays clear readable traces even at high sweep speeds. 2) High stability with less drift: The oscilloscope employs a temperature compensation circuit which is newly developed to reduce the drift of base lines and DC balance disturbance caused by temperature change. 3) A trigger level lock function which makes the triggering adjustment unnecessary: A new trigger level lock circuit is incorporated. This circuit eliminates the procedures of the troublesome triggering adjustment not only for displaying signals but also for that of video signals and large duty-cycle signals. 4) TV sync triggering: The oscilloscope has a sync separator circuit incorporated within the TIME/DIV switch for automatic triggering of TV-V and TV-H signals. 5) Linear focus: Once the beam focus is adjusted to the optimum position, it is automatically maintained regardless to the intensity change. 6) Cursor readout measurement: The unique easy-to-use cursor and numerical readouts make waveform observations and measurement faster and accurate. The on- screen cursors provide seven functions ( V, V%, VdB, T, 1/ T, DUTY, PHASE).(ISR 658 only) 1 2b1af7f3a8