Photometric analyzer

Claim 2

A pHotometric analyzer comprising: a light tight housing; a member movable relative to said housing inside thereof, said member having at least first and second light filters fixed relative thereto at first and second different positions thereon, respectively; first means fixed relative to said housing to shine light through a mixture of gases, and subsequently thereto, to shine light through said first and second filters in succession as said member is moved; second means mounted on said housing to move said member, said first filter having a passband effectively at a first wavelength where a first predetermined gas has no substantial absorption, said second filter having a passband effectively at a second wavelength where said first predetermined gas does have substantial absorption; a photomultiplier having a logarithmic output fixed relative to said housing inside thereof in a position to receive light from said first means which has passed through said gas mixture and through said filters, said photomultiplier having an output lead and being adapted to impress an output signal on the said output lead thereof; first and second circuit means connected from said photomultiplier to sample and hold the photomultiplier output signal during first and second times that said photomultiplier is illuminated by the passage of light through said first and second filters, respectively; and third means output from all of said circuit means to indicate a first difference in the magnitudes of the output signal of said photomultiplier at said first and second times, said first difference being directly proportional to the concentration of said first gas.

Claim 3

The invention as defined in claim 1, wherein a probe is provided that is adapted to be fixed relative to a stack inside thereof, said probe having a perforate wall, said first means including a device fixed relative to and at the inner probe end to direct light toward said photomultiplier, one of said circuit means including an inverter amplifier connected from said photomultiplier to said third means, and fourth means connected to said probe to purge the interior of said probe with air, said amplifier having an adjustable input to set the output of said third means equal to zero while said probe is purged as aforesaid.

Claim 4

The device as defined in claim 1, wherein said member has a third light filter at a position thereon different from those positions of said first and second light filters, said first means being adapted to shine light through said gas mixture and subsequently thereto through each of said light filters in succession as said member is moved, said third light filter having a passband effectively at said second wavelength, a first neutral density filter fixed relative to said member in the optical path through said third light filter, third circuit means connected from said photomultiplier to sample and hold the output signal thereof during the time that said photomultiplier is illuminated by the passage of light through said third light filter and said first neutral density filter, and a single-pole, double-throw switch having a pole connected to said third means and a contact connected from the outputs of said second and third circuit means, respectively, said third means including an amplifier with an adjustable gain to calibrate for full scale when said switch connects said third means to said amplifier.

Claim 5

The invention as defined in claim 3, wherein said third means includes a D.C. voltmeter connected from the utput of said amplifier and calibrated in concentration.

Claim 6

The invention as defined in claim 1, including a third light filter fixed relative to said member at a position thereon different from the positions of said first and second light filters, said first means also being adapted to shine light through said gas mixture and subsequently thereto through each of said filters in succession, said third filter having a passband effectively at a third wavelength different from said first and second wavelengThs where a second predetermined gas has substantial absorption, said second gas having no substantial absorption at said first wavelength, third circuit means connected from said photomultiplier to sample and hold the output signal thereof during the time that said photomultiplier is illuminated by the passage of light through said third filter, said third means also being connected from said third circuit means and being adapted to indicate a second difference in the magnitudes of the output signal of said photomultiplier at first and third times that said first and third filters are respectively located in front thereof, said second difference being directly proportional to the concentration of said second gas.

Claim 7

The invention as defined in claim 5, wherein a probe is provided that is adapted to be fixed relative to a stack inside thereof, said probe having a perforate wall, said first means including a device fixed relative to and at the inner probe end to direct light toward said photomultiplier, said second and third circuit means respectively including second and third amplifiers connected from the output of said photomultiplier to said third means, and fourth means connected to said probe to purge the interior of said probe with air, said second and third amplifiers having variable inputs to set the output of said third means equal to zero while said probe is purged as aforesaid, said third means having an adjustable gain amplifier.

Claim 8

The invention as defined in claim 6, wherein said member has fourth and fifth light filters at different positions thereon which are also different from the positions of said first, second and third light filters, said first means being adapted to shine light through said gas mixture, and subsequently thereto, through each of said light filters in succession as said member is moved, said fourth and fifth light filters having passbands effectively at said second and third wavelengths, respectively, a first neutral density filter fixed relative to said member in the optical path through each of said fourth and fifth light filters, fourth and fifth circuit means connected from said photomultiplier to sample and hold the output thereof during the time that said photomultiplier is illuminated by the passage of light through said fourth and fifth light filters, respectively, and first and second single-pole, double-throw switches each having a pole connected to said third means and a pair of contacts connected from the outputs of said second and fourth, and third and fifth circuit means, respectively, said third means including a first auxiliary amplifier with an adjustable gain to calibrate for full scale when said switches connect said fourth or fifth circuit means to said first auxiliary amplifier.

Claim 9

The invention as defined in claim 7, wherein said member includes a rotatable wheel, said filters being angularly spaced therearound, said second means including a substantially constant speed motor, and pulse generating means responsive to the position of said wheel and having an output connected to said circuit means to cause the same to sample the output signal of said photomultiplier synchronously when a corresponding filter passes through the field of view of said photomultiplier.

Claim 10

The invention as defined in claim 8, wherein a counter and first, second, third, fourth and fifth gates are connected from said pulse generating means respectively to said first, second, third, fourth and fifth circuit means to cause said first, second, third, fourth and fifth circuit means to sample over mutually exclusive periods of time.

Claim 11

The invention as defined in claim 9, wherein said pulse generating means includes a reset pickup to reset said counter once for each revolution of said wheel.

Claim 12

The invention as defined in claim 10, wherein said third means includes a D.C. voltmeter for each said difference, said first auxiliary amplifier being connected to one of said voltmeters, and a second auxiliary, adjustable gain amplifier connEcted to the other of said voltmeters.

Claim 13

The invention as defined in claim 5, wherein said member has fourth and fifth light filters at different positions thereon which are also different from the positions of said first, second and third light filters, said first means being adapted to shine light through said gas mixture and subsequently thereto through each of said light filters in succession as said member is moved, said fourth and fifth light filters having passbands effectively at said second and third wavelengths, respectively, a first neutral density filter fixed relative to said member in the optical path through each of said fourth and fifth light filters, fourth and fifth circuit means connected from said photomultiplier to sample and hold the output signal thereof during the time that said photomultiplier is illuminated by the passage of light through said fourth and fifth light filters, respectively, and first and second single-pole, double-throw switches each having a pole connected to said third means and a pair of contacts connected from the outputs of said second and fourth, and third and fifth circuit means, respectively, said third means including an amplifier with an adjustable gain to calibrate for full scale when said switches connect said fourth or fifth circuit means to said amplifier.

Claim 14

The invention as defined in claim 1, wherein said member includes a rotatable wheel, said filters being angularly spaced therearound, said second means including a substantially constant speed motor, and pulse generating means responsive to the position of said wheel and having an output connected to said circuit means to cause the same to sample sychronously when a corresponding filter passes through the field of view of said photomultiplier.

Claim 15

The invention as defined in claim 13, wherein a counter and first, second, third, fourth and fifth gates are connected from said pulse generating means respectively to said first, second, third, fourth and fifth circuit means to cause said first, second, third, fourth and fifth circuit means to sample over mutually exclusive periods of time.

Claim 16

The invention as defined in claim 14, wherein said pulse generating means includes a reset pickup to reset said counter once for each revolution of said wheel.

Claim 17

A photometric analyzer comprising: a light tight housing, a wheel rotatably mounted relative to and inside of said housing; a motor mounted inside said housing, said motor being adapted to rotate an output shaft thereof at a substantially constant angular velocity; a driving connection between said motor drive shaft and said wheel to rotate said wheel at an approximately constant angular velocity about a predetermined axis; first, second, third, fourth and fifth circular light filters having centers lying on a mathematical circular cylinder concentric with the axis of rotation of said wheel, lines joining immediately adjacent filter centers lying in a single plane forming a pentagon, all the sides of said pentagon being equal in length; first means fixed relative to said housing to shine light through a mixture of gases, and subsequently thereto, to shine light through said filters, in succession, as said wheel is rotated at a substantially constant velocity; said first filter having a passband effectively at a first wavelength where a first predetermined gas has no substantial absorption, said second filter having a passband effectively at a second wavelength where said first gas does have substantial absorption, said third filter having a passband effectively at a third wavelength where a second predetermined gas does have substantial absorption, said second gas having no substantial absorption at said first wavelength, said fourth filter being substantially identical to said second filter, said fifth filter being substantially identical to said third filter; a photomultiplier having a logarithmic output fixed relative to said housing inside thereof to receive, in succession, the light passed by each of said filters; a first neutral density filter fixed relative to said wheel coextensive with said fourth filter to attenuate the light which passes through said fourth filter and which is intercepted by said photomultiplier; a second neutral density filter fixed relative to said wheel coextensive with said fifth filter to attenuate the light that passes through said fifth filter and is intercepted by said photomultiplier; count and reset inductive windings fixed relative to said housing inside thereof contiguous to said wheel, said count winding being located contiguous to the peripheral edge of said wheel, said reset winding being spaced from said count winding; a ferromagnetic slug fixed relative to said wheel at said peripheral edge thereof to pass contiguous to said count winding at each of four locations, each of said locations being approximately on a line normal to said wheel axis midway between each corresponding immediately adjacent pair of filters with the exception that a ferromagnetic slug is fixed relative to the wheel in a position to pass contiguous to said reset winding, and that there is no corresponding slug at the wheel periphery where the slug is located which passes contiguous to said reset winding, said reset winding slug being positioned on a line that extends through the center of said first filter and said wheel axis; a digital pulse counter connected from said count winding to count the voltage pulses induced therein, said counter being connected from said reset winding to reset said counter only when a voltage pulse is induced in said reset winding; first, second, third, fourth and fifth AND gates connected from said counter, said counter having five stable states, each of said AND gates being connected in a manner such that the output of each is a voltage pulse having a width equal to one-fifth of the reset period of said counter, all of the output pulses of said AND gates occurring over mutually exclusive periods of time; first, second, third, fourth and fifth sample and hold circuits having first, second, third, fourth and fifth sampling gates, respectively, first, second, third, fourth and fifth storage capacitors, respectively, and first, second, third, fourth and fifth output amplifiers; first, second, third and fourth adjustable input inverter amplifiers connected from said photomultiplier, said first sample and hold circuit being connected from said photomultiplier, said first, second, third, fourth and fifth sampling gates being connected from the outputs of said photomultiplier and said first, second, third and fourth inverter amplifiers, respectively, to the inputs of said first, second, third, fourth and fifth output amplifiers, respectively, the outputs of said first, second, third, fourth and fifth AND gates being respectively connected to said first, second, third, fourth and fifth sampling gates to turn the same on and off, but not necessarily in that order, said first, second, third, fourth and fifth sampling gates being opened when light intecepted by said photomultiplier passes through said first, second, third, fourth and fifth filters, respectively, said first, second, third, fourth and fifth capacitors being connected from the outputs of said first, second, third, fourth and fifth sampling gates, respectively, to a point of reference potential; first and second single-pole, double-throw switches, each of said switches having a pole and first and second contacts, the outputs of said second and fourth output amplifiers being connected to the first and second contacts of said first switch, respectively, the outputs of said third and fifth output amplifiers being connected to the first and second contacts of said second switch, respectively; first and second voltage indicators; and first and second analog adders, said first adder being connected from the output of said first sample and hold circuit and from the pole of said first switch to said first indicator, said second adder being connected from said first sample and hold cIrcuit and from said second switch pole to said second indicator, each of said adders including an adjustable gain amplifier.

Claim 18

A photometric analyzer comprising: a light tight housing, a wheel rotatably mounted relative to and inside of said housing; a motor mounted inside said housing, said motor being adapted to rotate an output shaft thereof at a substantially constant angular velocity; a driving connection between said motor drive shaft and said wheel to rotate said wheel at an approximately constant angular velocity about a predetermined axis; first, second, third, fourth and fifth circular light filters having centers lying on a mathematical circular cylinder concentric with the axis of rotation of said wheel, lines joining immediately adjacent filter centers lying in a single plane forming a pentagon, all the sides of said pentagon being equal in length; first means fixed relative to said housing to shine light through a mixture of gases, and subsequently thereto, to shine light through said filters, in succession, as said wheel is rotated at a substantially constant velocity; said first filter having a passband effectively at a first wavelength where a first predetermined gas has no substantial absorption, said second filter having a passband effectively at a second wavelength where said first gas does have substantial absorption, said third filter having a passband effectively at a third wavelength where a second predetermined gas does have substantial absorption, said second gas having no substantial absorption at said first wavelength, said fourth filter being substantially identical to said second filter, said fifth filter being substantially identical to said third filter; a photomultiplier having a logarithmic output fixed relative to said housing inside thereof to receive, in succession, the light passed by each of said filters; a first neutral density filter fixed relative to said wheel coextensive with said fourth filter to attenuate the light which passes through said fourth filter and which is intercepted by said photomultiplier; a second neutral density filter fixed relative to said wheel coextensive with said fifth filter to attenuate the light that passes through said fifth filter and is intercepted by said photomultiplier; count and reset inductive windings fixed relative to said housing inside thereof contiguous to said wheel, said count winding being located contiguous to the peripheral edge of said wheel, said reset winding being spaced from said count winding; a ferromagnetic slug fixed relative to said wheel at said peripheral edge thereof to pass contiguous to said count winding at each of four locations, each of said locations being approximately on a line normal to said wheel axis midway between each corresponding immediately adjacent pair of filters with the exception that a ferromagnetic slug is fixed relative to the wheel in a position to pass contiguous to said reset winding, and that there is no corresponding slug at the wheel periphery where the slug is located which passes contiguous to said reset winding, said reset winding slug being positioned on a line that extends through the center of said first filter and said wheel axis; a digital pulse counter connected from said count winding to count the voltage pulses induced therein, said counter being connected from said reset winding to reset said counter only when a voltage pulse is induced in said reset winding; first, second, third, fourth and fifth AND gates connected from said counter, said counter having five stable states, each of said AND gates being connected in a manner such that the output of each is a voltage pulse having a width equal to one-fifth of the reset period of said counter, all of the output pulses of said AND gates occurring over mutually exclusive periods of time; first, second, third, fourth and fifth sample and hold circuits having first, second, third, fourth and fifth sampling gates, respectively, first, second, third, fourth and fifth storage capacitors, respectively, and first, second, third, fourth and fifth output amplifiers; first, second, third and fourth adjustable input inverter amplifiers connected from said photomultiplier, said first sample and hold circuit being connected from said photomultiplier, said first, second, third, fourth and fifth sampling gates being connected from the outputs of said photomultiplier and said first, second, third and fourth inverter amplifiers, respectively, to the inputs of said first, second, third, fourth and fifth output amplifiers, respectively, the outputs of said first, second, third, fourth and fifth AND gates being respectively connected to said first, second, third, fourth and fifth sampling gates to turn the same on and off, but not necessarily in that order, said first, second, third, fourth and fifth sampling gates being opened when light intecepted by said photomultiplier passes through said first, second, third, fourth and fifth filters, respectively, said first, second, third, fourth and fifth capacitors being connected from the outputs of said first, second, third, fourth and fifth sampling gates, respectively, to a point of reference potential; first and second single-pole, double-throw switches, each of said switches having a pole and first and second contacts, the outputs of said second and fourth output amplifiers being connected to the first and second contacts of said first switch, respectively, the outputs of said third and fifth output amplifiers being connected to the first and second contacts of said second switch, respectively; first and second voltage indicators; and first and second analog adders, said first adder being connected from the output of said first sample and hold circuit and from the pole of said first switch to said first indicator, said second adder being connected from said first sample and hold cIrcuit and from said second switch pole to said second indicator, each of said adders including an adjustable gain amplifier.

Claim 19

The invention as defined in claim 16, wherein said first, second, fourth, third and fifth AND gates produce output pulses in succession in that order to gate on their corresponding respective first, second, fourth, third and fifth sampling gates.