Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Reexamination Certificate
2002-08-12
2004-06-08
Le, Que T. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
C398S183000
Reexamination Certificate
active
06747269
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Under 35 U.S.C. § 119 this application claims the benefit of co-pending Japanese Patent Application No. 2001-247199, which was filed Aug. 16, 2001, and is incorporated herein by reference.
BACKGROUND
In many applications, such as optical measurement, optical communications, and optical storage, it often is desirable to measure the transient behaviors of optical signals. As improvements in optical technologies push optical data rates higher, however, there is a corresponding need for optical measurement systems that can accurately measure the resulting high speed optical data signals. Conventionally, the transient pulses of high speed optical signals may be measured by a variety of different optical measurement systems, including sampling optical oscilloscopes.
Referring to
FIG. 1
, in one exemplary implementation, a sampling optical oscilloscope
10
includes a lens
12
for focusing an input light signal, which may be received from, for example, an optical fiber
14
. Sampling optical oscilloscope
10
also includes a sampling streak tube
16
, which includes a photocathode
18
, an acceleration electrode
20
, a sweep electrode system
22
, a slit plate
24
, and a phosphor screen
26
. Photocathode
18
converts incident light received from lens
12
into electrons, which are accelerated toward sweep electrode system
22
by acceleration electrode
20
. Sweep electrode system
22
performs a high speed sweep (i.e., deflection of electrons along a particular direction) across slit plate
24
, transforming time variations of the incident light intensity into spatial electron density variations at different positions on slit plate
24
. Slit plate
24
includes a slit
28
that allows a sample of the swept electrons to reach phosphor screen
26
, where the sampled electrons are converted into light that is detected by a photomultiplier tube
30
.
Referring to
FIG. 2
, U.S. Pat. No. 5,719,623 discloses a multi-channel streak camera
32
that includes an optical lens
34
that converts a subject
36
into a subject image
38
. A converter
40
converts the subject image
38
into a plurality of divided micro-incident electronic images
42
,
44
,
46
consisting of pixels that are separated by a predetermined spacing. The photoelectrons corresponding to the micro-incident electronic images
42
-
46
are passed through openings
48
,
50
,
52
of a focusing electron lens
54
, which focuses each of the micro-incident electronic images
42
-
46
. A sweep electrode system
56
sweeps each of the focused electron beams in a particular direction. The swept electron beams then are focused on an output plane
58
. In this way, variations at different locations in the subject image
38
during the same periods of time may be detected as spatial variations in parallel. In addition, because the subject image is divided into a plurality of smaller micro-incident electronic images, the focusing electron lens
54
may be relatively short in length, reducing space-charge effect blurring.
SUMMARY
In one aspect of the invention, an optical pulse measurement system includes an optical signal divider and an optical signal conversion system. The optical signal divider has an optical input for receiving an input optical signal, multiple optical outputs, and a set of multiple optical channels. The optical channels are coupled between the optical input and respective optical outputs and are operable to delay propagation of optical signals, which are divided from the input optical signal, from the optical input to respective optical outputs by different respective amounts of time. The optical signal conversion system is coupled to the optical signal divider optical outputs and is operable to convert temporal intensity distributions of light that are received from the optical signal divider optical outputs into respective spatial intensity distributions in parallel.
In another aspect, the invention features an optical pulse measurement method. In accordance with this inventive method, optical signals are divided from an input optical signal. Propagation of the divided optical signals is delayed by a first set of different respective amounts of time. Temporal intensity distributions of the delayed optical signals are converted into respective spatial intensity distributions in parallel.
Among the advantages of the invention are the following.
Because the invention converts temporal intensity distributions of light that are received from multiple optical channels into respective spatial intensity distributions in parallel, the invention enables the time waveform of an input optical signal to be measured quickly. In addition, because the divided light signals that are transmitted through the multiple optical channels are delayed by different respective amounts of time, the invention enables the time waveform of high speed input optical signals to be measured with excellent temporal resolution.
Other features and advantages of the invention will become apparent from the following description, including the drawings and the claims.
REFERENCES:
patent: 4053763 (1977-10-01), Harney
patent: 5719623 (1998-02-01), Kinoshita
patent: 2001013336 (2001-01-01), None
patent: 2001044938 (2001-02-01), None
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