Magnetic stabilization method and system in infrared, visible and ultraviolet spectroscopy

A method for use in a spectroscopic analysis system, which system has:

• a broad-band light source emitting light in the infrared, visible or ultraviolet range,
• a sample cell configured to receive the fluid to be measured,
• a broadband detector arranged to receive emitted light after transmission through the sample call, to detect changes in the emitted radiation after transmission through the sample cell,
• an analyser to analyse the change in transmitted intensity and relate this change to at least one property of a least one measurand in the fluid,
• a rotating optical modulator located in the optical path of the emitted light to act as an optical chopper and/or modulator, and
• an electrically-driven motor arranged to rotate the rotatable optical modulator;
• wherein the optical modulator contains at least some electrically conductive material and the method comprises:
• using the electrically-driven motor to rotate the rotatable optical modulator;
• and
• applying at least one non-contact magnetic field to the rotating optical modulator, to induce electrical currents within the electrically conductive material of the optical modulator which generate a magnetic damping force acting against the rotation of the optical modulator.

A system to improve the noise, stability and response time of a spectroscopic measurement comprising:

• a broad-band light source emitting light in the infrared, visible or ultraviolet range,
• a sample cell designed to receive the fluid to be measured,
• a broadband detector to detect changes in the transmitted radiation after passage through the sample cell,
• optical elements for transmission, refraction or reflection of light throughout the measurement system;
• and
• a microprocessor to analyse the change in transmitted intensity and relate this change to at least one property of a least one measurand in the fluid,
• characterised in that a rotating wheel, disc or cylinder in the optical path is employed to act as an optical chopper and/or modulator containing at least one optical element for spectroscopic measurements for determining at least one property of at least one measurand within a fluid
• wherein at least one non-contact magnet provides a magnetic field to the rotating wheel, disc or cylinder containing at least some electrically conductive, non-ferromagnetic material, and for which an electrically-driven motor rotates the wheel, disc or cylinder and at least one sensor provides feedback of the position and/or motion of the wheel, disc or cylinder, and a controller controls the rotational speed or angular velocity of the wheel, disc or cylinder;
• and wherein
• the magnetic braking induced within the conductive material of the wheel, disc or cylinder is used to damp or brake the rotational motion of the wheel, disc or cylinder;
• whereby the control of the feedback controller for the rotational speed or angular velocity of the wheel, disc or cylinder is enhanced compared to an equivalent motor-driven wheel, disc or cylinder without magnetic braking.