Photometer and method for compensating for ambient temperature changes in a photometer
AssigneeSpectro Scientific, Inc.
InventorsDavid B. Chamberlin, Michael Edward Glowinski, Donald Stanton Lavery
Life of this patent
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Abstract
A photometer and associated method includes a source of radiation to be directed through a sample and a detector stage configured to measure radiation after passing through the sample. A voltage follower circuit is connected to the detector and is configured to provide an output signal which varies as a function of the detector output voltage and which varies as a function of the ambient temperature. A processing subsystem is configured to determine a temperature compensation factor from the voltage follower circuit output signal.
Claims29
A photometer comprising:
- a source of radiation to be directed through a sample;
- a detector stage configured to measure radiation after passing through the sample, the detector stage including:
- at least one detector outputting a voltage in response to radiation incident on the detector, and
- a voltage follower circuit connected to the detector and configured to provide an output signal which varies as a function of the detector output voltage and which varies as a function of the ambient temperature;
- and
- a processing subsystem configured to determine a temperature compensation factor from the voltage follower circuit output signal.
A method of compensating for ambient temperature changes for a photometer, the method comprising:
- pulsing a source of radiation at a frequency;
- detecting radiation passing through a sample using a voltage follower circuit connected to a detector;
- and
- determining a temperature compensation factor from the voltage follower circuit output signal by:
- filtering an offset voltage from the voltage follower circuit output signal,
- determining the amplitude of the filtered voltage follower circuit output signal, and
- determining the offset voltage level.
A method of compensating for ambient temperature changes for a photometer, the method comprising:
- connecting a detector to the gate of a transistor and configuring the transistor source to provide an output signal including an AC detector signal and an offset voltage;
- using the offset voltage to determine temperature changes of the transistor resulting in transconductance changes of the transistor;
- and
- using said determined temperature change to calculate a temperature compensation factor to be applied to said AC detector signal.
Dependencies are inferred from the claim text.