GB942874A - Tracking accuracy control for analysers - Google Patents
Tracking accuracy control for analysersInfo
- Publication number
- GB942874A GB942874A GB976661A GB976661A GB942874A GB 942874 A GB942874 A GB 942874A GB 976661 A GB976661 A GB 976661A GB 976661 A GB976661 A GB 976661A GB 942874 A GB942874 A GB 942874A
- Authority
- GB
- United Kingdom
- Prior art keywords
- attenuator
- output
- thermocouple
- photo
- monochromator
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 230000005855 radiation Effects 0.000 abstract 1
- 239000000126 substance Substances 0.000 abstract 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
- G01J3/28—Investigating the spectrum
- G01J3/42—Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry
Landscapes
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- General Physics & Mathematics (AREA)
- Spectrometry And Color Measurement (AREA)
Abstract
942,874. Photo-electric spectrometers. BECKMAN INSTRUMENTS Inc. March 17,1961 [March 21,1960], No. 9766/61. Heading G1A. The invention relates to double beam spectrometers of the type in which light is alternately passed through the substance to be investigated and through an adjustable attenuator. The two beams are recombined and directed through a variable monochromator to a thermocouple or like detector whose output is fed back to adjust the attenuator. In such a spectrometer it is possible to use an integrator to smooth the signal controlling the attenuator in order to eliminate the spurious high-frequency noise signals. This arrangement, however, results in an error in instantaneous reading which becomes more serious the greater the rate of variation of the detector signal. According to the invention this error is minimized by either reducing the time constant of the integrating circuit or reducing the rate of change of frequency in the monochromator (or both) when large changes in the detector output occur. As shown rotating frames 14,15 containing half mirrors direct radiation alternately through cell 22 containing the test example and through comb attenuator 23. The recombined beam passes through monochromator 12, swept through a range of frequencies by motor 29, and on to thermocouple 13. The output of the couple is amplified and fed demodulator 34 and control circuit 40. The demodulator output is fed to filter-type integrator 35 whose output controls attenuator 23 in a manner reducing the alternating signal from the thermocouple. The control circuit, as shown in more detail in Fig. 2, includes an amplifier tuned to the switching frequency, and a rectifier and filter stage driving a lamp 45. The intensity of the light from the lamp is sensed by photo-diode 46 and serves, according to the position of switch 42, to reduce the time constant of integrating circuit 35 or to reduce the speed of motor 29. In another arrangement (Fig. 3, not shown) two photo-diodes view lamp 45, one controlling the integrator and the other the motor speed. It may be arranged that one of these controls only becomes effective when the range of adjustment of the other is exhausted.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US1651560A | 1960-03-21 | 1960-03-21 |
Publications (1)
Publication Number | Publication Date |
---|---|
GB942874A true GB942874A (en) | 1963-11-27 |
Family
ID=21777522
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB976661A Expired GB942874A (en) | 1960-03-21 | 1961-03-17 | Tracking accuracy control for analysers |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB942874A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20140313511A1 (en) * | 2011-08-17 | 2014-10-23 | Korea Research Institute Of Standards And Science | Rotating-element ellipsometer and method for measuring properties of the sample using the same |
-
1961
- 1961-03-17 GB GB976661A patent/GB942874A/en not_active Expired
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20140313511A1 (en) * | 2011-08-17 | 2014-10-23 | Korea Research Institute Of Standards And Science | Rotating-element ellipsometer and method for measuring properties of the sample using the same |
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