Radiant energy – Photocells; circuits and apparatus – Photocell controlled circuit
Reexamination Certificate
1998-05-28
2001-06-12
Le, Que T. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Photocell controlled circuit
C250S2140LA
Reexamination Certificate
active
06246044
ABSTRACT:
DESCRIPTION
1. Technological Field
The invention relates to the field of electrical samplers, particularly those for pulses having short or very short durations.
Pulse metrology permits the description of the temporal development of a signal or an electrical pulse, in particular of its voltage or of its energy, when this signal, or this pulse is unique (non-repetitive), and very short (that is to say it has a duration of the order of a few tens of picoseconds).
Such pulses to be measured generally arise from very fast radiation detectors, which convert into electrical pulses, the energy of a pulse of radiation which they receive, for example an X or gamma or visible or infra-red radiation pulse. Such radiation can be emitted by ultra-fast sources of radiation, such as lasers or sources of synchrotron radiation, or can be the result of a laser-material interaction caused by an ultra-fast laser (that is to say one whose pulse duration is in the picosecond or femtosecond range).
The invention can be applied to any measurement of a very brief and non-repetitive electrical signal, in particular in the physics of events or in the measurement of events, generated by picosecond phenomena.
2. State of the Technology
At the present time, there are sampling oscilloscopes on the market for measuring signals whose spectrum extends as far as 50 Ghz or 70 Ghz. These pieces of equipment permit the measurement of repetitive pulses. The sampling frequency is variable, from 250 kHz to 1 Ghz.
In order to measure single pulses, commercial pieces of equipment do exist on the market: they allow the reconstruction of a spectrum up to 5 Ghz or 7 Ghz.
Among laboratory prototypes, the device described in document U.S. Pat. No. 5,471,162 is known. Such a device relies on the principle of spatial sampling of a pulse. A pulse propagates itself along a propagation line. From this there results a spatial equivalence of the temporal evolution of this pulse which propagates itself along the line with a speed that depends on its physical characteristics. At a particular time t, if the line is of sufficient length, the totality of the pulse is divided up spatially along the line.
If the samplers are arranged along the propagation line, their simultaneous actuation allows a complete sampling of the pulse to be carried out, with a time step equal to the spatial step of the samplers, divided by the speed of propagation.
Also known is an optical sampling device which measures signals of bandwidth up to 35 Ghz. This device is illustrated in FIG.
1
. It comprises a propagation line
2
into which is introduced and along which is propagated a pulse signal
4
to be measured. Sampling ports
6
made of a photo-conductor material (CdTe) are arranged in a regular manner along the line of propagation. These sampling ports are connected to sample taking lines
8
, each of which is itself followed by charge reading means. All of the charge reading means are grouped together in a charge reading device
10
. These charge reading means are connected to a computer
12
programmed to measure the relative charges on each channel and to analyse the pulse
4
. Each sampling port
6
is closed using a triggering light pulse
14
: there must be as many triggering light pulses as there are sampling ports. This device therefore requires a picosecond optical flash of a few tens of nanojoules to trigger the sampling.
These known samplers are therefore photo-conductors, in the case of the optical sampler (
FIG. 1
) and diodes in the case of the compact digitizer.
In these two known structures, samplers sample a part of the signal present at their level on the line. They are positioned in parallel on this propagation line.
These samplers have a limited bandwidth, linked to the bandwidth of the line itself. In addition, the sensitivity of detection (that is to say the quantity of charge sampled in the signal) is also limited. Finally, with regard to the optical sampler, the use of a high power picosecond laser imposes very great experimental financial constraints.
DESCRIPTION OF THE INVENTION
The invention provides a device that allows the problems above to be resolved. The invention employs spatial sampling of a pulse. It is adapted to the measurement of ultra-short electrical pulses, of very broad spectrum, and non-repetitive.
To put it more precisely, the object of the invention is an electrical sampler comprising;
an electrical pulse propagation structure, comprising sections linked in pairs through switches,
means of commanding the open and closed condition of the switches.
The sampler according to the invention therefore uses a propagation line made up of a series of line sections, linked to one another by a switch which can be commanded electrically.
The switches are usually on or closed. The taking of the “samples” can occur on opening these switches, which confines the totality of the charges carried by the pulse in the different sections that make up the line.
Hence an improvement in the sensitivity of the measurement is obtained, while all the charges carried by the pulse to be analysed are utilised.
The invention also relates to an electrical sampler comprising:
an electrical pulse propagation structure, comprising sections isolated from one another and connected in pairs through switches, this propagation structure and that of the switches being produced on two different substrates,
means of commanding the open and closed condition of the switches.
It is therefore possible to separate the manufacture of the propagation structure from that of the switch. One can, for example, produce the sections of the propagation structure, or the line sections using micro-strip technology, on a chosen material substrate of a chosen geometry, and then to use “flip-chip” switches, making use of micro-connection technologies. These switches are chosen and produced on a different support to the sections of propagation structure or line. This possibility opens up a wide choice of technological perspectives, both for the lines and for the switches and allows one to widen the spectrum of the pulses to be measured. The manufacture of the propagation structure and that of the switches on different substrates favours operation at very high frequencies.
The means of commanding the open and closed condition of the switches can comprise a second propagation structure, or propagation line, called a triggering structure or line, to which the switches are connected.
The signal triggering the opening of the switches can then be a voltage step propagating on the triggering structure, or the triggering line. The switches are connected to this triggering structure, or triggering line at desired intervals.
The sampling time step is then defined by the step difference between the signal propagating on the sections of the pulse propagation structure, and a signal propagating on the triggering structure or triggering line, between two successive switches.
Whichever embodiment is being considered, the electrical sampler according to the invention does not require a laser beam to trigger the measurement.
It is possible to produce means of commanding the open and closed condition of the switches that comprise a second and a third propagation structure, both of them called triggering structures, so as to optimise the sampling rate.
One may also employ N triggering structures, with N=3, 4, . . . etc.
According to another embodiment, one incorporates on the sections of the propagation structure, not only the switches that link the different sections, but also a small circuit made up of this switch, and a second switch, which permits the connection of a section to a sample taking line. The advantage is then that, before the opening of the switches, the sample taking lines are not connected to the propagation sections, and they do not hinder the propagation of the signal.
A substrate used to produce the propagation structure is preferably a substrate made of a material having:
a crystalline nature that confers on it good hyperfrequency properties,
a low loss tangent
Burns Doane , Swecker, Mathis LLP
Commissariat A l'Energie Atomique
Le Que T.
LandOfFree
Switched electrical pulse propagation sampler does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Switched electrical pulse propagation sampler, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Switched electrical pulse propagation sampler will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2460776