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公开(公告)号：GB1347760A
公开(公告)日：1974-02-27
申请号：GB2893471
申请日：1971-06-21
Applicant: CARY INSTRUMENTS
Abstract: 1347760 Measuring optical dichroism CARY INSTRUMENTS 21 June 1971 [22 June 1970] 28934/71 Heading G1A The variation of linear or circular dichroism of a sample with wavelength is measured by Fourier spectroscopy. Light from a broadband source of light 10 is collimated at 11 and polarized linearly (28) by device 26. The light is then passed through a Mach-Zehnder interferometer comprising beam splitter 30 and two mirror systems 38, 35, the first of which is movable with respect to the second. The intention is to produce in the recombined beam two components 43, 49 whose polarization directions are orthogonal and which do not fluctuate in intensity. The effect of motion of mirror system 38 is progressively to retard in phase the component 49 with respect to the other and produce an alteration in the effective polarization of the combined beam through the repeated cycle from left circularly polarized (LCP) 101 through right circularly polarized (RCP) 105 and back to 101, Fig.4. This provides for cyclically and alternately LCP and RCP light to be presented to a sample 14 for the measurement of circular dichroism and right plane and left plane polarized light for the measurement of linear dichroism. To measure spectral variations in these quantities, advantage is taken of the fact that the frequency at which the phase retardation of component 49 takes place varies with the wavelength of the light. Thus, by an analysis of the frequency components in the signal produced by photo-detector 15, a dichroism spectrum may be produced. The detector circuitry includes amplifier 19, connected to analog to digital converter 20 to allow analysis by computer 23 of the detector output. The computer also receives information in the form of a demodulation cosine (for linear) or sine (for circular dichrosim) function in order to derive the dichroism spectra, from detectors 83, 88 which form part of separate optical systems monitoring the distance of movement of the mirror system 38 and thus accurately noting the phase retardation. One system, using broad band source 80 and polarizer 98, provides a beam passing through the interferometer offset in relation to the main beam 29, and is for identification of the zero phase position of the demodulation function. The second system using a laser source 86 provides with detector 88 a fringe counting system to measure deviations from the zero. Both systems are provided with polarizers e.g. the same dichroic element, at 75, 76. The interferometer mirror systems shown may be modified but there should be an even number in one and an odd number in the other, system. The polarization directions produced thereby may differ from that shown, but should always provide two orthogonal components for the recombined beam. The motion of the moveable mirror system may be continuous or stepwise. The system is particularly useful for measurements in the infrared region of the spectrum.
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公开(公告)号：GB1263324A
公开(公告)日：1972-02-09
申请号：GB1811769
申请日：1969-04-09
Applicant: CARY INSTRUMENTS
IPC: G01N21/19
Abstract: 1,263,324. Measurement of circular dichroism. CARY INSTRUMENTS. April 9, 1969 [April 22, 1968], No. 18117/69. Heading G1A. Circular dichroism measurement apparatus utilizes detector circuitry arranged to provide a logarithmic output. In the arrangement of Fig. 1, radiation from a source of ultraviolet, visible or infrared radiation, is passed through a monochromator which is scanned through a particular range of narrow wavelength bands. Radiation then passes through a polarizer 15, either the ordinary or extraordinary beam from which only being used and passed to polarisation modulator 17 which produces an output ranging alternately between left- and right-circularly polarized radiation. The modulation may be sinusoidal or square-wave. After passage through sample 19 the radiation is detected by photo-tube 21. This is followed by a preamplifier 24. The signal is then acted on by a logarithmic inverter 26. This may be an operational amplifier (29) Fig. 2 (not shown) with a diode or transister in its feedback loop, in which case preamplifier 24 is an inverter, or may be a feedback control to the voltages applied to the dynodes of a photo-multiplier when this is used as the detector 21, Fig.2a (not shown). The signal from 26 is an A.C. signal (sinusoidal or square wave) of amplitude depending on the logarithms of the transmitted right and left circularly polarized components of the radiation beam. The signal may be applied directly to indicator device 41, in which case the device 41 performs isolation of the A. C, portion of the signal and may comprise a capacitor, or an inductor (e. g. forming part of a transformer) but is preferably first of all shaped into a true square wave form (in synchronism with the modulations of device 17) and filtered by a long or short time constant circuit in filter circuit 40, detailed in Fig. 3 (not shown). The signal arriving at indicator 41, which is a potentiometer bridge arrangement, detailed in Fig. 4 (not shown), is compared with a square -wave reference source, the potentiometer slider being connected to the pen of the recording chart 60, which is moved in synchronism with the monochromator scan, so that a record of circular dichroism versus wavelength is obtained. The order of devices 26 and 40 (when present) may be reversed, in an alternative system. In another alternative set-up, the sample is mounted between the monochromator and polariser, Fig. 7 (not shown). The filter 40 may be replaced by a synchronous rectifier driven in synchronism with the polarisation modulator. The resulting D. C. signal is compared with a D.C. reference signal at 41.
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公开(公告)号：DE1589648B1
公开(公告)日：1970-07-30
申请号：DE1589648
申请日：1967-11-07
Applicant: CARY INSTRUMENTS
Inventor： BISHOP HOOPER PAIGE
IPC: G02F1/01
Abstract: 1,182,190. Light modulators. GARY INSTRUMENTS. 27 July, 1967 [13 April, 1967], No. 34563/67. Heading H4F. The subject matter of this Specification is substantially the same as that described in Specification 1,182,189 but the apparatus for modulating the ellipticity of polarization of a monochromatic light beam whose wavelength varies, so that the ellipticity varies cyclically and so that the amplitude of the cyclical variation of the ellipticity is maintained at an optimum level, which includes a modulator operable on a linearly polarized light beam to produce at least one emergent beam having cyclically varying ellipticity, and means operable upon one such emergent beam for deriving a modified beam whose intensity varies cyclically as a function of the cyclically varying ellipticity, is such that the modulator is only controlled by the modified light beam to maintain the amplitude of the cyclical variation of the ellipticity at the predetermined optimum level i.e. the modulator does not include a piezoelectric sensor and thus does not oscillate in a selfresonant manner.
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Patent Agency Ranking
公开(公告)号：GB1182189A
公开(公告)日：1970-02-25
申请号：GB3456267
申请日：1967-07-27
Applicant: CARY INSTRUMENTS
IPC: G02F1/01
Abstract: 1,182,189. Light modulators. CARY INSTRUMENTS. 27 July, 1967 [7 April, 19671, No. 34562/67. Heading H4F. [Also in Division G1] Apparatus for modulating the ellipticity of polarization of a monochromatic light beam whose wavelength varies, so that the ellipticity varies cyclically and so that the amplitude of the cyclical variation of the ellipticity is maintained at an optimum level, comprises a modulator operable on a linearly polarized light beam to produce at least one emergent beam having cyclically varying ellipticity, and means operable upon one such emergent beam for deriving a modified beam whose intensity varies cyclically as a function of the cyclically varying ellipticity which is utilized to control the modulator to maintain the amplitude of the cyclical variation of the ellipticity at the predetermined optimum level. In the embodiment described the modulator comprises a strainbirefringence modulator although it may comprise an electro-optic modulator, and the modulated light beam is used to measure the circular dichroism of a sample for different wavelengths although it may be used to determine the optical rotation produced by specimens. Also, the modulated and modified beams comprise the ordinary and extraordinary beams of the input light beam, whereas they may comprise the same beam a beam splitting device being used. The strain birefringence modulator, Fig. 2, comprises a fused silica plate 10 which is cyclically stressed along its X axis by means of piezoelectric elements 13, which receive a sinusoidal drive signal from amplifier-oscillator 21 and cause the plate to vibrate longitudinally at its fundamental resonant frequency. The plane polarized light beam 11 having electric vector E is incident over small cross-section 11a and the amplitude of the electrical oscillations from amplifier oscillator 21 is such as to maintain the peak retardation i.e. peak birefringence magnitude, at 11a constant. Plate 10 is arranged to oscillate in a self-resonant manner by means of a piezoelectric sensor 15 attached to the plate. The amplitude of oscillation of the plate is controlled by a control signal 22, which causes the amplification of the amplifier to vary so as to maintain the peak strain of each cycle of vibration of the plate at such a magnitude as is required to maintain constant peak retardation independent of wavelength. To measure the circular dichroism of a sample 25, Fig. 3, and its variation with wavelength, a scan drive 28 is coupled to a monochromotor 27 to cause it sequentially to select different narrow wavelength bands from a light source 26 for transmission at 29. The light beam is linearly polarized 30 and transmitted at 31 and 60 as the ordinary and extraordinary beams respectively. The cyclically varying elliptically polarized light leaving modulator 10 at 33 is incident upon sample 25 which absorbs unequally the circularly polarized components of opposite sense i.e. circular dichroism, and phototube 34 detects the resulting fluctuating light flux components and the D.C. component. The D.C. component I 2 corresponds in magnitude to the sum of the intensities of the two circular components transmitted by the sample, and the fluctuating components I 1 are approximately sinusoidal A.C., one component of frequency equal to the fundamental frequency of the modulator plate and the other components having frequencies which are odd multiples of the fundamental and corresponding in magnitude to the difference between the transmission levels for the circularly polarized components of opposite sense. The phototube output is fed to read-out circuitry 37 together with a synchronizing input signal from amplifier 21 and the ratio I 1 to I 2 is derived which is very nearly proportional to the value of circular dichroism and is recorded on " circular dichroism versus wavelength " chart paper 43. If the D.C. component is held constant by means of an A.G.C. arrangement then the A.C. component itself is a measure of the circular dichroism. To provide automatic control of peak retardation at the modulator the extraordinary beam 60 is passed twice through the modulator by means of mirror 62 and via a quarter-wave plate 64 and an analyser 66 to produce the modified beam 108 whose intensity varies cyclically and contains the fundamental frequency of the phase delay fluctuations of the modulator multiplied by the Bessel function at twice the differential phase delay. Thus when the fluctuating phase delay reaches about 110 degrees the fundamental component of the modified light beam intensity fluctuation is reduced to zero and with further increase beyond 110 degrees of peak optical phase delay fluctuation the fundamental in intensity fluctuation reappears with reversed sign providing a null in the fundamental component of intensity at about 110 degrees peak optical phase delay. The output of photomultiplier 67 which receives modified beam 108 drives amplifier 71 containing a synchronous rectifier, the timing for which is derived from oscillator amplifier 21 on lead 72. The output 75 is compared at 73 with a reference standard input voltage 74 and the comparator produces a difference output at 22 to control oscillator amplifier 21 so that the system reaches an equilibrium condition with a peak optical phase delay of approximately 110 degrees.
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公开(公告)号：DE1920143A1
公开(公告)日：1969-11-06
申请号：DE1920143
申请日：1969-04-21
Applicant: CARY INSTRUMENTS
Inventor： EUGENE HOOPER GERALD
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公开(公告)号：FR1540784A
公开(公告)日：1968-09-27
申请号：FR124340
申请日：1967-10-13
Applicant: CARY INSTRUMENTS
IPC: G02F1/01
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公开(公告)号：CH515516A
公开(公告)日：1971-11-15
申请号：CH1373070
申请日：1970-09-16
Applicant: CARY INSTRUMENTS
Inventor： PAIGE BISHOP HOOPER
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公开(公告)号：DE1572622A1
公开(公告)日：1970-03-26
申请号：DE1572622
申请日：1967-11-07
Applicant: CARY INSTRUMENTS
Inventor： HOWARD CARY HENRY
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