Active solid-state devices (e.g. – transistors – solid-state diode – Field effect device – Charge transfer device
Reexamination Certificate
1999-10-26
2001-01-16
Ng{circumflex over (o)}, Ng{circumflex over (a)}n V. (Department: 2814)
Active solid-state devices (e.g., transistors, solid-state diode
Field effect device
Charge transfer device
C257S231000
Reexamination Certificate
active
06175126
ABSTRACT:
TECHNICAL FIELD
This invention relates to charge coupled devices, and more specifically, to an improved use of a charge coupled device including an asymmetrical split and for use primarily in spectroscopy applications. The inventive method and apparatus is useful in both kinetic spectroscopy and multiline spectroscopy.
BACKGROUND OF THE INVENTION
Charged coupled devices (CCDs) have been in use for decades and are well known in the field of spectroscopy. Spectroscopy typically involves illuminating one or more rows of a CCD with the spectrum of a signal and then analyzing the captured spectrum represented by the varying magnitudes of charge which accumulate on the various elements of the CCD. For example, if one row of the CCD is used to capture the spectrum, the varying magnitudes of charge along the row represent the varying amplitudes of different wavelengths which comprise the spectrum.
The use of CCDs in spectroscopy may be divided into at least two well known types: multiline spectroscopy and kinetic spectroscopy. Commercially available CCDs are usually extremely application specific, and typically are manufactured for use in either multiline spectroscopy, kinetic spectroscopy, or some other application. Conventional CCDs include little or no ability to adapt to different applications.
Kinetic spectroscopy involves obtaining multiple spectra, one at a time, at a relatively high rate, and then reading them from the CCD.
FIG. 1
shows a conceptual diagram of a CCD for use in kinetic spectroscopy. The first row of elements
101
is utilized to capture a spectrum by focusing the desired spectrum only on row
101
. After the spectrum is captured at row
101
, it is shifted down to row
102
immediately below row
101
and the next spectrum is captured at row
101
. In one commercially available CCD, all rows except the top row
101
are masked. Thus, once the spectrum is captured and shifted down into row
102
, it is no longer subject to distortion from unwanted light signals and the masked rows operate effectively as a memory. Utilizing, for example, an off the shelf 1024×256 CCD
100
of the type described, approximately 65,000 spectra per second may be collected for subsequent read-out through horizontal register
103
and amplifier
104
.
Although the arrangement shown in
FIG. 1
has been widely accepted in the prior art for performing kinetic spectroscopy, there are drawbacks to such an arrangement. First, since only one row of CCD elements is typically utilized to capture the spectrum, the device is not very sensitive. If the spectrum is focused on plural rows of CCD elements, the device will be more sensitive, however, the read out time will increase dramatically since a spectrum occupying N rows of elements will require N times the read out time when compared with a spectrum occupying one row. The slower read out time is unacceptable in certain applications.
Another problem with the arrangement described is that it is relatively inflexible. Specifically, the CCD with all of its rows except one masked is not suitable for multiline spectroscopy, described below. More particularly, multiline spectroscopy requires several spectra to be captured simultaneously. The availability of only one row of unmasked elements in the arrangement of
FIG. 1
is unsuitable. Thus, if the specific application changes, a whole new design is required.
In view of the above, it can be appreciated that there exists a need in the art for a more sensitive CCD based device which is able to capture and read out spectra at a fast rate for use in kinetic spectroscopy, and which is flexible enough to be adapted for different uses.
Multiline spectroscopy is another branch of spectroscopy which is often implemented using CCD devices.
FIG. 2
shows a conceptual diagram of a CCD being utilized to effectuate multiline spectroscopy.
In multiline spectroscopy, several separate and distinct spectra are captured by a CCD and read out separately for analysis through horizontal shift register
210
. The plural spectra are usually captured simultaneously, and then later shifted out of the CCD sequentially for storage and analysis. The arrangement in
FIG. 2
includes such a charge coupled device
200
, a plurality of exemplary spectra represented by
201
through
204
, and a horizontal register
210
for reading out the spectra. Additionally, the regions
205
through
208
represent separation bands in order to prevent energy from each distinct spectrum from contaminating the energy in the regions storing the other spectra.
In operation, the spectra are first captured on the CCD
200
, perhaps with the use of a mechanical shutter. Next, the spectra are read by placing them into horizontal register
210
and then shifting each spectrum from register
210
for later storage, analysis or any other required processing.
A problem with the use of arrangements such as that of
FIG. 2
to accomplish multiline spectroscopy is that the dark bands
205
through
208
must be independently read into horizontal register
210
and shifted out. Accordingly, the overall operation of the device is much slower than desirable.
Another problem with the arrangement of
FIG. 2
for multiline spectroscopy is that if it is desired to utilize the same chip for kinetic spectroscopy, a large waste in space and time results. Specifically,
FIG. 6
shows a conventional CCD device
601
and includes a representation
602
of a single spectrum stored in one row of the device. In operation, the spectrum
602
is transferred into horizontal register
603
for shifting out. The dark charge from region
603
must then also be shifted out. This results in wasted time and thus, slower throughout.
Alternatively, when a device is being utilized to capture single spectrum using the technique described, an arrangement such as that shown in
FIG. 7
may be used. The arrangement of
FIG. 7
includes a relatively small CCD for capturing a single spectrum and a horizontal register
702
for the read out of such spectrum. However, if it is later desired to do multiline spectroscopy utilizing a larger CCD device, the entire chip would have to be replaced.
In view of the above there exists a need in the art for an improved CCD arrangement for performing multiline and kinetic spectroscopy. Additionally, such device should be adaptable easily for either of the foregoing types of spectroscopy and should be efficient when operated in either mode. Finally, there exists a need for improved speed when performing either type of spectroscopy utilizing CCD devices.
SUMMARY OF THE INVENTION
The above and other problems of the prior art are overcome and a technical advance is achieved in accordance with the present invention which relates to an improved charge coupled device (CCD) which includes an asymmetrical split, independent control over the regions on each side of the asymmetrical split, and two horizontal registers for reading information from the CCD. The horizontal registers, one on each side of the CCD, are also independently controllable like the shifting on each side of the asymmetrical split.
In operation, the device may be used for kinetic spectroscopy or for multiline spectroscopy. In either case, a spectrometer, for example, is preferably utilized to capture light, split it into its spectrum, and convey the spectrum to the CCD.
When utilized for kinetic spectroscopy, a single spectrum may occupy multiple rows of elements, thereby increasing sensitivity over prior art single row spectroscopy devices. Unlike the prior art however, unacceptable additional read out time is not required because the spectra may be binned at the asymmetrical split, a technique only possible due to the independent control of the regions of the CCD on opposite sides of the split.
The inventive device is also capable of rapidly transferring sequentially acquired spectra to a horizontal register for read out while independently transferring dark charge, in the opposite direction, to a different horizontal register. Accordingly, when operating in the kinetic spectroscopy m
Ng{circumflex over (o)} Ng{circumflex over (a)}n V.
Ohlandt Greeley Ruggiero & Perle L.L.P.
Roper Scientific, Inc.
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