GB2328015A - Diffraction spectrometer comprising an attenuator - Google Patents
Diffraction spectrometer comprising an attenuator Download PDFInfo
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- GB2328015A GB2328015A GB9816699A GB9816699A GB2328015A GB 2328015 A GB2328015 A GB 2328015A GB 9816699 A GB9816699 A GB 9816699A GB 9816699 A GB9816699 A GB 9816699A GB 2328015 A GB2328015 A GB 2328015A
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- Prior art keywords
- attenuator
- sample
- radiation
- detector
- directing
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- 230000005855 radiation Effects 0.000 claims abstract description 87
- 230000004907 flux Effects 0.000 claims description 18
- 238000000034 method Methods 0.000 claims description 17
- 238000002798 spectrophotometry method Methods 0.000 claims description 6
- 238000005286 illumination Methods 0.000 claims 2
- 238000001228 spectrum Methods 0.000 abstract description 7
- 230000003595 spectral effect Effects 0.000 description 4
- 239000004973 liquid crystal related substance Substances 0.000 description 3
- 238000002835 absorbance Methods 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 238000012569 chemometric method Methods 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- 239000003814 drug Substances 0.000 description 2
- 229940079593 drug Drugs 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000003278 mimic effect Effects 0.000 description 2
- 230000007935 neutral effect Effects 0.000 description 2
- 238000004566 IR spectroscopy Methods 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000002596 correlated effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 238000010238 partial least squares regression Methods 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/12—Generating the spectrum; Monochromators
- G01J3/18—Generating the spectrum; Monochromators using diffraction elements, e.g. grating
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- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- General Physics & Mathematics (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
- Spectrometry And Color Measurement (AREA)
Abstract
This invention is concerned with a spectrophotometer including means for illuminating a sample 32 and for directing and diffracting radiation from the sample to be spectrally analyzed, which comprises a radiation source, slits, grating 12, an attenuator 34 and a detector 36. The instrument can be configured pre-dispersive (radiation dispersed before it reaches the sample) or post-dispersive (radiation dispersed after it reaches the sample). The attenuator comprises a plurality of alternating elements whose attenuation may be adjusted. Each element attenuates a different part of the diffracted spectrum.
Description
TITLE OF THE INVENTION
NOVEL SPECT-ROPHOTOMETER
BACKGROUND OF THE INVENTION
This invention relates to a novel spectrophotometer method and apparatus. Spectrophotometers are devices for measuring intensity of radiation in relation to various portions of the electromagnetic spectrum.
The spectral range includes near-, mid-, and far-Infrared, ultraviolet and visible radiation.
There is a desire for relatively inexpensive (process) spectrophotometers. Spectrophotometers are known which contain moving gratings to direct radiation of selected wavelengths on the sample to be analyzed. See U.S. Pat. No. 4,540,282. Spectrophotometers which are filter based or which utilize a holographic filter with the calibratidn equation permanently etched into it are also known. See U.S. Pat. Nos.
5,526,121, 3,867,639, 4,487,476 4,848,904, 4,809,340 and 3,905,919.
However, these instruments either have moving parts which makes them very sensitive to the environment in which they are used, or require such devices as photomultiplier tubes which must be individually read, holographic filters which are very expensive and difficult to make, logarithmic converters which require the correlation between the sample and parameter of interest to be logarithmic, or rotating filter instruments which limits the number of wavelengths that can be used.
It is an object of the present invention to develop a novel spectrophotometer.
SUMMARY OF THE INVENTION
This invention is concerned with a spectrophotometer including means for illuminating a sample and for directing and diffracting radiation from the sample to be spectrally analyzed, which comprises a radiation source, slits, grating, an attenuator and a detector.
The instrument can be configured pre-dispersive (radiation dispersed prior to illuminating the sample) or post-dispersive (radiation dispersed after reflecting from the sample). In the pre-dispersive mode, the source illuminates a fixed grating whose output is directed through or towards a sample. An attenuator comprising a series of attenuator elements is positioned between the sample and the detector in such a manner that each attenuator element attenuates a different wavelength (or wavelength range). The radiation from the sample is then focused onto the detector using a lens assembly.
Because the proposed spectrophotometer allows the calibration equation to be adjusted over time in an inexpensive manner by adjusting the attenuation element(s) prior to operating the device and because it uses a single detector, not a detector array or CCD(Charge
Coupled Device), it will be inexpensive to manufacture while being compact and rugged allowing use in a manufacturing and process environment. Additionally, because the output signal is directly proportional to concentration, no computer unit would be necessary; the signal can be fed directly into a Distributed Control System (DCS) or equivalent.
Thus it is an object of the present invention to provide such a process spectrophotometer. Other aspects of the invention will become evident upon review of the disclosure as a whole.
DETAILED DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of the spectrophotometer embodying the present invention in the pre-dispersive mode.
FIG. 2 is a plan view of the spectrophotometer embodying the present invention in the post-dispersive mode.
FIG. 3 is an example of regression coefficients which would be used with the sample attenuator.
FIG. 4 is a synthesized detector voltage output as it correlates to concentration of water in a powder.
DETAILED DESCRIPTION OF THE INVENTION
The novel spectrophotometer comprises a means for illuminating a sample which is to be spectrally analyzed; a detector; and a first radiation directing and diffracting means for directing radiation to and diffracting radiation from said sample onto said detector, said first radiation directing and diffracting means including, a fixed grating; a sample attenuator containing one or more attenuating elements and a focusing lens assembly. The means for illuminating the sample being a radiation source output such as a light source; said radiation source being directed onto or through the sample, then to the detector. The spectrophotometer can optionally contain slits, which, if positioned directly after the source, can be used to emulate a point source or, if positioned after the grating, can be used as wavelength selective elements.
In one embodiment of this invention, the novel spectrophotometer can be configured to operate so that the output from the radiation source (11) is dispersed before it impinges on sample (predispersive mode). As such, spectrophotometer (10) is constructed so that the radiation source (11) is directed at and illuminates the fixed grating (12). The output from the fixed grating (12) is then directed at or through the attenuator (13). The output from the attenuator (13) is then directed at or through a sample (14). The radiation output passed through the sample is then focused, using a lens assembly (15), on to the detector (16). The attenuator elements are positioned such that each attenuator element attenuates a different wavelength or wavelength range. The variability of attenuation can be achieved, for example, by coating a transmitting substrate (e.g. quartz for the visible or near-infrared) with variable quantities of a coating material (e.g. a metal oxide such as silicone oxide). Spectrophotometer (10) cari optionally contain slits (18) or (40) which are positioned either between the radiation source and the grating or after the grating, or a combination thereof, depending on its application.
In another embodiment of this invention, the novel spectrophotometer can be configured to operate so that the radiation source is dispersed after it gets to the sample (post-dispersive mode). See
Fig. 2. As such, spectrophotometer (30) is constructed so that the output from the radiation source (31) is directed at or through a sample (32) and then at or through the fixed grating (33). The radiation output from the fixed grating (33) is then directed at or through the attenuator (34). The radiation output-from the attenuator (34) is then focused, using a lens assembly (35), on to the detector (36). Spectrophotometer (30) can optionally contain slits which are positioned either between the radiation source and the grating or after the grating, or a combination thereof, depending on its application.
In still another embodiment, the invention can be configured to operate so that a certain amount of radiation from the radiation source (11) or (31) is directed at a reference detector (23) or (38) to provide a background signal which can be used to compensate for source fluctuations over time. As such, the spectrophotometer (10) or (30) is constructed so that some of the radiation output (11) or (31) is directed to the reference detector (23) or (38) by the use of a beam splitter (20) or (37) which is located just after the fixed grating in spectrophotometer (10) and positioned between the radiation source and the sample in spectrophotometer (30). The radiation from the source after being split can then be sent directly to the reference detector (see Fig. 2) or a second directing and diffraction means (21) and/or a focusing lens assembly (22) is optionally employed to direct radiation towards the reference detector (see Fig. 1). The diffraction means can be a mirror reflector means or the like, which is a mechanically tooled or holographic grating. The second radiation directing and diffraction means is located after the beam splitter and before the reference detector. The amount of radiation that reaches the reference detector should be enough so that it is above the detector noise level. Optimally, the amount of radiation that reaches the reference detector is approximately 50% of the source output.
In still another embodiment, the invention can be configured to operate so that a certain amount of radiation from the radiation source (11) or (31) is directed at a reference detector (23) or (38) through a reference attenuator (17) or (39) to provide a background signal which can be used to compensate for source fluctuations over time. As such, spectrophotometer (10) or (30) is constructed so that some of radiation output (11) or (31) is directed to the reference detector (23) or (38) by the use of a beam splitter (20) or (37) which is located just after the fixed grating in spectrophotometer (10) and positioned between the radiation source-and the sample in spectrophotometer (30). The radiation from the source after being split can then be sent at-or through a reference attenuator (39), which is positioned between the radiation source (31) and the reference detector (38), and then directly to the reference detector (38) (see Fig. 2). Alternatively, the radiation can be sent optionally to or through a second directing and diffraction means (21), and then to or through a reference attenuator (17). A focusing lens assembly (22) is optionally employed to direct radiation towards the reference detector (see Fig. 1). The reference attenuator (17) can be positioned anywhere between the beam splitter (20) and the reference detector (23). The above described embodiment of the reference attenuator allows negative coefficients to be used in the calibration. Those attenuator elements in the sample path with an attenuation greater than the reference attenuator will be analogous to multiplying by a negative coefficient at that attenuator elements wavelength. In a like manner, those attenuator elements with attenuation less than the reference attenuator will result in a positive multiplication.
Still in another embodiment, the invention can be said to comprise a method of spectrophotometry comprising forming a radiation flux along a path from a radiation source (11), sending the flux to or through fixed grating (12), sending the flux at or through attenuator (13), to or through a sample (14), then through focusing lens assembly (15), on to the detector (16).
Still in another embodiment, the invention can be said to comprise a method of spectrophotometry comprising forming a radiation flux along a path from the source (31), sending the flux to or through sample (32) then sending the flux to fixed grating (33), sending the flux at or through attenuator (34), to or through a sample (32), then through focusing lens assembly (35), on to the detector (36).
In still another embodiment, the invention can be said to comprise a method of spectrophotometry comprising directing a certain amount of radiation from the radiation source (11) or (31) to a reference detector (23) or (38) to provide a background signal which can be used to compensate for source fluctuations overtime. The radiation output (11) or (31) is directed to the reference detector (23) or (38) by the use of a beam splitter (20) or (37) and optionally a directing and diffraction means (21) and focusing lens assembly (22) to direct radiation towards the reference detector (23) or (38).
In still another embodiment, the invention can be said to comprise a method of spectrophotometry comprising directing a certain amount of radiation from the radiation source (11) or (31) to a reference attenuator (17) or (39) then to a reference detector (23) or (38) to provide a background signal which can be used to compensate for source fluctuations overtime. The radiation output (11) or (31) is directed to or through the reference attenuator then to the reference detector (23) or (38) by the use of a beam splitter (20) or (37) and a directing and diffraction means (21) and focusing lens assembly (22) to direct radiation towards the reference detector (23) or (38) is optionally employed.
The grating is a fixed (no movement) dispersive element which deconvolutes the white radiation from the radiation source into spatially separated components. The desired wavelengths are selectable at various angles off of the normal of the grating.
The attenuator comprises a series of (neutral density) filters or controlled liquid crystal elements, which are positioned in such a manner that each filter or element attenuates a different wavelength or wavelength range. Radiation passing through the image plane from the grating will experience variable attenuation based on the density of the attenuator element at that point. In the case of a mechanical attenuator, the attenuation can be adjusted by unlocking the elements and adjusting the position in the image plane. The attenuation of each element is selected based on the desired regression coefficient at that particular wavelength and each element is positioned prior to operation of the spectrophotometer. When using a liquid crystal or equivalent, the attenuation can be controlled electronically. The wavelength coverage of the unit will be dependent upon the number and width of the individual elements.
The regression coefficient, which must be determined before operating the instrument, is determined using conventional chemometric methods. In the simplest case of one channel (wavelength) being solely responsive to the parameter of interest, this parameter is calculated by using equation 1.
C kx X (1) where C is parameter of interest, k is the coefficient, and A is the absorbance. To calculate k, equation 2 is used after measuring the absorbance, A, with a standard of known parameter value.
> C / X (2)
In a situation where there exist spectral overlap and noise in the spectra, equations 1 and 2 are extended to a multivariate mode. A discussion of least squares fitting is found in P. Geladi et al., Anal. Chem.
Acta, 185:1-17 (1986); H. Kalivas et al., Mathematical Analysis of
Spectral Orthoganlity, Marcel dekker, inc. New York, NY, 1994;
G. Jreskog et al., Systems Under Indirect Observations, Causality/Structure/Prediction, , Vols. I and II, North-Holland, Amsterdam, 1983; Martens et al., Multivariate Calibration, John Wiley and Sons, New York and Hskuldsson, J. Chemometrics, 2: 211 228(1988). These references also provide a description of Partial Least
Squares and other chemometric methods to determine the coefficients. In the more general case the concentration is calculated using equation 3:
Mathematically, the (neutral density) filter array or liquid crystal elements act as a cross multiplier, the ki of equation 3, of the spectrum, the Ai of equation 3. The resolution of the instrument is dependent on the width of the attenuator elements because the diffracted radiation is a continuum whereas the attenuator elements are discrete units. The lens assembly acts as a summation device. Therefore, the signal impinging on the detector is directly proportional to the parameter of interest. The elements can be adjusted at any time to account for a shift in the calibration by adjusting the attenuation of each element to match the new regression equation. To achieve the equivalent of a single wavelength instrument, the wavelengths that are not of interest can be 100% attenuated.
The beam splitter is used only to monitor the source fluctuations or, in case a reference attenuator is used, to allow for negative correlation coefficients, and is not involved in deconvoluting the spectrum.
EXAMPLE
A particular example is that of moisture concentration in a drug active.
Near infra-red (IR) data are collected on various drug active samples using a scanning spectrophotometer. This Near IR data is then correlated to the moisture concentration of the samples which is determined using a primary analytical method (for example a titration method). The initial coefficients are calculated using a standard regression method, in this example Partial Least Squares (Figure A). The spectral range is limited to appropriate wavelengths, in this example 1400 to 1500 nm. The regression coefficients are then scaled to fall within the appropriate range that can be covered by the sample attenuator.
Figure3: Partial Least Squares Regression Coefficients
Wavelength Cbannel Number
Figure 4: Synthesized data output
Laboratory Values Next, the sample attenuator elements are appropriately positioned and the sample is loaded into position. The light passes through or reflects from the sample, passes through the attenuator and is focused onto the detector.
In this example, the scaled regression coefficients are multiplied with the intensity spectra obtained on the standard scanning near-infrared instrument to mimic the convolution between sample and sample attenuator. The multiplied intensity spectra are summed to mimic the response after focusing onto the detector. Figure B displays the synthetic detector response as it correlates to moisture concentration.
Claims (22)
1. A spectrophotometer including: a means for illuminating a sample to be spectrally analyzed; a detector; and a first radiation directing and diffracting means for directing radiation to and diffracting radiation from said sample onto said detector said first radiation directing and diffracting means including a fixed grating; a sample attenuator containing one or more attenuating elements; and a focusing lens assembly; said fix grating located after the illumination means but before the sample attenuator, said sample positioned after the sample attenuator but before the focusing lens assembly and detector.
2. A spectrophotometer according to claim 1 wherein the radiation source output includes a radiation source such as light and the attenuating elements are positioned, prior to operation, such that each attenuator element attenuates a different wavelength or wavelength range.
3. A spectrophotometer according to claim 1 which optionally contains a beam splitter and a reference detector; said beam splitter directing some of the radiation source output to the reference detector which monitors source fluctuations; said beam splitter located just after the fixed grating and before the reference detector.
4. A spectrophotometer according to claim 3 which optionally contains slits and a reference attenuator; said reference attenuator acting in concert with the sample attenuator to allow for negative coefficients, said reference attenuator located between the beam splitter and the reference detector, said slits located either directly after the radiation source or the grating, or a combination thereof, depending on its application.
5. A spectrophotometer according to claim 4 which optionally contains a second directing and diffracting means to direct the radiation source output toward the reference detector and a focusing lens assembly to focus the radiation source output into the reference detector, said second directing and diffracting means located after the beam splitter and before the reference attenuator.
6. A spectrophotometer according to claim 1 wherein the diffraction means is a mirror.
7. A spectrophotometer according to claim 1 which optionally contains slits.
8. A spectrophotometer including: means for illuminating a sample to be spectrally analyzed; a detector; a first radiation directing and diffracting means for directing radiation to and diffracting radiation from said sample onto said detector said first radiation directing and diffracting means including a fixed grating; a sample attenuator containing one or more attenuating elements; and a focusing lens assembly; said sample positioned after the illumination means but before the fix grating, said fix grating located before the sample attenuator, and said sample attenuator positioned before the focus lens and the detector.
9. A spectrophotometer according to claim 8 wherein the radiation source such as light and the attenuating elements are positioned, prior to operation, such that each attenuator element attenuates a different wavelength or wavelength range.
10. A spectrophotometer according to claim 8 which optionally contains a beam splitter and a reference detector; said beam splitter directing some of the radiation source output to the reference detector which monitors source fluctuations; said beam splitter located just after the fixed grating and before the reference detector.
11. A spectrophotometer according to claim 8 which optionally contains slits and a reference attenuator; said reference attenuator acting in concert with the sample attenuator to allow for negative coefficients, said reference attenuator located between the beam splitter and the reference detector, said slits located either directly after the radiation source or the grating, or a combination thereof, depending on its application.
12. A spectrophotometer according to claim 11 which optionally contains a second directing and diffracting means to direct the radiation source output toward the reference detector and a focusing lens assembly to focus the radiation source output into the reference detector, said second directing and diffracting means located after the beam splitter and before the reference attenuator.
13. A spectrophotometer according to claim 8 wherein the diffraction means is a mirror.
14. A spectrophotometer according to claim 8 which optionally contains slits.
15. A method of spectrophotometry comprising forming a radiation flux along a path from a radiation source, sending the flux to or through a fixed grating, sending the flux at or through a sample attenuator, then to or through a sample, then through focusing lens assembly and on to a detector.
16. A method according to claim 15 which optionally employs a beam splitter to direct some of the radiation flux from the radiation source to a reference detector to provide a background signal which can be used to compensate for source fluctuations over time, the beam splitter being located after the fixed grating but before the reference detector.
17. A method according to claim 16 which optionally contains a reference attenuator, said reference attenuator acting in concert with the sample attenuator to allow for negative coefficients, said reference attenuator located between the beam splitter and the reference detector.
18. A method according to claim 17 which optionally contains a second directing- and diffracting means arrd focusing lens assembly to direct the radiation flux towards the reference detector, the second directing and diffracting means being located after the beam splitter but before reference detector and the focus lens assembly being located after the second directing and diffracting means before the reference detector.
19. A method of spectrophotometry comprising forming a radiation flux along a path from the source, sending the flux to or through a sample then sending the flux to a fixed grating, sending the flux at or through an attenuator, then to or through a sample, then through focusing lens assembly and on to a detector.
20. A method according to claim 19 which optionally employs a beam splitter to direct some of the radiation flux from the radiation source to a reference detector to provide a background signal which can be used to compensate for source fluctuations over time, the beam splitter being located after the fixed grating but before the reference detector.
21. A method according to claim 20 which optionally contains a reference attenuator, said reference attenuator acting in concert with the sample attenuator to allow for negative coefficients, said reference attenuator located between the beam splitter and the reference detector.
22. A method according to claim 21 which optionally contains a second directing and diffracting means and focusing lens assembly to direct the radiation flux towards the reference detector, the second directing and diffracting means being located after the beam splitter but before reference detector and the focus lens assembly being located after the second directing and diffracting means before the reference detector.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US5478497P | 1997-08-05 | 1997-08-05 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9816699D0 GB9816699D0 (en) | 1998-09-30 |
| GB2328015A true GB2328015A (en) | 1999-02-10 |
Family
ID=21993525
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9816699A Withdrawn GB2328015A (en) | 1997-08-05 | 1998-07-31 | Diffraction spectrometer comprising an attenuator |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2328015A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2346212A (en) * | 1999-01-27 | 2000-08-02 | Ando Electric | Light intensity adjuster for electro-optic sampling probe |
| WO2005047834A1 (en) * | 2003-10-15 | 2005-05-26 | Polychromix Corporation | Light processor providing wavelength control and method for same |
| EP1243902B1 (en) * | 2001-03-23 | 2005-11-02 | C.R.F. Società Consortile per Azioni | Spectrophotometer with electrostatic microshutters |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4571081A (en) * | 1982-09-07 | 1986-02-18 | Coulter Electronics Of New England, Inc. | Light scattering apparatus and method |
| US4615619A (en) * | 1984-03-19 | 1986-10-07 | D.O.M. Associates, Inc. | Stationary, electrically alterable, optical masking device and spectroscopic apparatus employing same |
| US5631735A (en) * | 1993-08-27 | 1997-05-20 | Minolta Co., Ltd. | Spectrometer provided with an optical shutter |
| WO1998023057A1 (en) * | 1996-11-19 | 1998-05-28 | Rdl Commercial Technologies Corporation | High capacity spread spectrum optical communications system |
-
1998
- 1998-07-31 GB GB9816699A patent/GB2328015A/en not_active Withdrawn
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4571081A (en) * | 1982-09-07 | 1986-02-18 | Coulter Electronics Of New England, Inc. | Light scattering apparatus and method |
| US4615619A (en) * | 1984-03-19 | 1986-10-07 | D.O.M. Associates, Inc. | Stationary, electrically alterable, optical masking device and spectroscopic apparatus employing same |
| US5631735A (en) * | 1993-08-27 | 1997-05-20 | Minolta Co., Ltd. | Spectrometer provided with an optical shutter |
| WO1998023057A1 (en) * | 1996-11-19 | 1998-05-28 | Rdl Commercial Technologies Corporation | High capacity spread spectrum optical communications system |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2346212A (en) * | 1999-01-27 | 2000-08-02 | Ando Electric | Light intensity adjuster for electro-optic sampling probe |
| GB2346212B (en) * | 1999-01-27 | 2001-06-20 | Ando Electric | Electro-optic sampling probe having unit for adjusting quantity of light incident on electro-optic sampling optical system module |
| US6297651B1 (en) | 1999-01-27 | 2001-10-02 | Ando Electric Co., Ltd. | Electro-optic sampling probe having unit for adjusting quantity of light incident on electro-optic sampling optical system module |
| EP1243902B1 (en) * | 2001-03-23 | 2005-11-02 | C.R.F. Società Consortile per Azioni | Spectrophotometer with electrostatic microshutters |
| WO2005047834A1 (en) * | 2003-10-15 | 2005-05-26 | Polychromix Corporation | Light processor providing wavelength control and method for same |
| US7196789B2 (en) | 2003-10-15 | 2007-03-27 | Polychromix Corporation | Light processor providing wavelength control and method for same |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9816699D0 (en) | 1998-09-30 |
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| Date | Code | Title | Description |
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| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |