Differential spectrophotometer

Claim 2

A differential spectrophotometer comprising means for radiating a beam of light to be passed through a sample; photoelectric conversion means for detecting the light beam passed through the sample; means including a dispersing means for dispersing the light beam disposed at a first position in the path of the light beam from said light source toward said photoelectric conversion means through the sample so that a monochromatic light beam can be separated from said light beam to be detected by said photoelectric conversion means; means for selectively positioning a transparent plate at a second position in the path of the light beam from said light source toward said photoelectric conversion means through the sample so that said transparent plate can be disposed at an angle with respect to the light beam passing through said second position thereby producing a slight difference between the wavelength of the monochromatic light detected by said photoelectric conversion means when said transparent plate is disposed at said second position and the wavelength of the monochromatic light detected by said photoelectric conversion means when said transparent plate is not disposed at said second position; means for driving said dispersing means so that said dispersing means can scan the wavelength of said monochromatic light thereby alternately deriving from said photoelectric conversion means a first electrical signal representative of the absorption of the light by the sample when said transparent plate is in said second position and a second electrical signal representative of the absorption of the light by the sample when said transparent plate is not in said second position; and means for generating a third electrical signal representative of the difference or ratio between said first and second electrical signals.

Claim 3

A differential spectrophotometer as claimed in claim 1, in which means are provided for varying the angle of incidence of the light beam passing through said second position with respect to said transparent plate.

Claim 4

A differential spectrophotometer as claimed in claim 1, in which said means for selectively positioning said transparent plate at an angle with respect to the light beam passing through said second position includes means for causing movement of said transparent plate so that it cuts periodically across the light beam passing tHrough said second position.

Claim 5

A differential spectrophotometer as claimed in claim 1, in which means are provided for varying the angle of incidence of the light beam passing through said second position with respect to said transparent plate, and said means for selectively positioning said transparent plate at an angle with respect to the light beam passing thorough said second position includes means for causing movement of said transparent plate so that it cuts periodically across the light beam passing through said second position.

Claim 6

A differential spectrophotometer comprising means for radiating a beam of light; means for dispersing the light beam thereby obtaining a monochromatic light beam; means for dividing the monochromatic light beam into a first and a second light beam so that the first and second light beams pass through a sample to be examined disposed in the path of the first light beam and a reference sample disposed in the path of the second light beam respectively; a first and a second detector for detecting the light beams passed through the respective samples; means for periodically bringing a transparent plate in the path of the light beam from said light source toward said light beam dividing means at an angle with respect to the light beam passing along the path thereby producing a slight difference between the wavelength of the light beam detected by said detectors when said transparent plate is in the path of the light beam and the wavelength of the light beam detected by said detectors when said transparent plate is out of the path of the light beam; means for driving said dispersing means so that said dispersing means can scan the wavelength of the light beam to be detected by said detectors thereby alternately deriving from each of said detectors a first electrical signal representative of the absorption of the light by the associated sample when said transparent plate is in the path of the light beam and a second electrical signal representative of the absorption of the light by the associated sample when said transparent plate is out of the path of the light beam; means for generating a third electrical signal representative of the difference or ratio between said first and second electrical signals appearing from one of said detectors; means for generating a fourth electrical signal representative of the difference or ratio between said first and second electrical signals appearing from the other said detector; and means for comparing said third electrical signal with said fourth electrical signal.

Claim 7

A differential spectrophotometer comprising means for radiating a beam of light; means for dispersing the light beam thereby obtaining a monochromatic light beam; means for dividing the monochromatic light beam into a first and a second light beam so that the first and second light beams pass through a sample to be examined disposed in the path of the first light beam and a reference sample disposed in the path of the second light beam respectively; a first and a second detector for detecting the light beams passed through the respective samples; means for periodically bringing a transparent plate in the path of the light beam from said light source toward said light beam dividing means at an angle with respect to the light beam passing along the path thereby producing a slight difference between the wavelength of the light beam detected by said detectors when said transparent plate is in the path of the light beam and the wavelength of the light beam detected by said detectors when said transparent plate is out of the path of the light beam; means for driving said dispersing means so that said dispersing means can scan the wavelength of the light beam to be detected by said detectors thereby alternately deriving from each of said detectors a first electrical signal representative of the absorption of the light by the associated sample when said transparent plate is in the path of the light beam and a second electrical signal representative of the absorption of the light by the associated sample when said transparent plate is out of the path of the light beam; means for generating a third electrical signal representative of the difference or ratio between said first and second electrical signals appearing from one of said detectors; means for generating a fourth electrical signal representative of the difference or ratio between said first and second electrical signals appearing from the other said detector; and means for comparing said third electrical signal with said fourth electrical signal.

Claim 8

A differential spectrophotometer as claimed in claim 5, in which means are provided for varying the angle of incidence of the light beam passing along said path with respect to said transparent plate.

Claim 9

A differential spectrophotometer as claimed in claim 5, in which said means for periodically bringing said transparent plate in the path of the light beam at an angle with respect to the light beam passing along said path includes means for causing movement of said transparent plate so that it cuts periodically across the light beam passing along said path.

Claim 10

A differential spectrophotometer as claimed in claim 5, in which means are provided for varying the angle of incidence of the light beam passing along said path with respect to said transparent plate, and said means for periodically bringing said transparent plate in the path of the light beam at an angle with respect to the light beam passing along said path includes means for causing movement of said transparent plate so that it cuts periodically across the light beam passing along said path.

Claim 11

A differential spectrophotometer comprising: first means for radiating a beam of light to be passed through a sample; second means, responsive to the light beam passing through said sample, for detecting the light impinging thereon and generating a signal representative of the light detected; third means, disposed at a first position in the path of the ligHt beam irradiated by said first means, for dispersing said light beam toward said second means through said sample, so that a monochromatic beam can be separated from said light beam to be detected by said second means; fourth means, disposed at a second position, in the path of the light beam from said first means toward said second means, for separating the light beam impinging thereon into first and second light beam components, having first and second respective wavelengths, the difference between which is constant, comprising means for selectively positioning a transparent plate at said second position in the path of the light beam at an angle with respect to the direction of the light beam passing through said second position, thereby producing a constant difference between the wavelength of the monochromatic light detected by said second means when said transparent plate is disposed at said second position and the wavelength of the monochromatic light detected by said second means, when said transparent plate is not disposed at said second position; fifth means, coupled to said third means, for driving said third means, so that said third means can scan the wavelength of said monochromatic light, thereby alternately deriving from said second means, a first electrical signal representative of the absorption of the light by the sample, when said transparent plate is at said second position and a second electrical signal, representative of the absorption of the light by the sample, when said transparent plate is not in said second position; and sixth means, coupled to said second means, for generating a third electrical signal representative of the difference or ratio between said first and second electrical signals.

Claim 12

A differential spectrophotometer comprising: first means for radiating a beam of light to be passed through a sample; second means, responsive to the light beam passing through said sample, for detecting the light impinging thereon and generating a signal representative of the light detected; third means, disposed at a first position in the path of the ligHt beam irradiated by said first means, for dispersing said light beam toward said second means through said sample, so that a monochromatic beam can be separated from said light beam to be detected by said second means; fourth means, disposed at a second position, in the path of the light beam from said first means toward said second means, for separating the light beam impinging thereon into first and second light beam components, having first and second respective wavelengths, the difference between which is constant, comprising means for selectively positioning a transparent plate at said second position in the path of the light beam at an angle with respect to the direction of the light beam passing through said second position, thereby producing a constant difference between the wavelength of the monochromatic light detected by said second means when said transparent plate is disposed at said second position and the wavelength of the monochromatic light detected by said second means, when said transparent plate is not disposed at said second position; fifth means, coupled to said third means, for driving said third means, so that said third means can scan the wavelength of said monochromatic light, thereby alternately deriving from said second means, a first electrical signal representative of the absorption of the light by the sample, when said transparent plate is at said second position and a second electrical signal, representative of the absorption of the light by the sample, when said transparent plate is not in said second position; and sixth means, coupled to said second means, for generating a third electrical signal representative of the difference or ratio between said first and second electrical signals.

Claim 13

A differential spectrophotometer according to claim 9, wherein said fourth means comprises means for rotating said transparent plate about an axis perpendicular to the surface of the plate upon which light is incident, whereby said angle is maintained constant during the rotation of said plate.