Automated Self Calibration in Optical Detectors
First Claim
1. A method of compensating for drift in a sensor of a device used to measure the temperature of a target, the device having a stable calibration source and a chopper for isolating the sensor when closed, the method comprising:
- collecting a first reading with the chopper closed and the stable calibration source off;
collecting a second reading with the chopper open;
collecting a third reading with the chopper closed and the stable calibration source on;
calculating a source reading using the first, second, and third readings;
calculating a factor using the source reading and a calibration reading; and
compensating for drift using the factor.
1 Assignment
0 Petitions
Accused Products
Abstract
A method and apparatus for automated field calibration of temperature sensors uses a series of readings including a reading of a known source, such as an LED, for use in calculating a factor that is compared to a reference for adjusting the sensor output signal. Calibration readings are taken more frequently after start up to compensate for sensor drift during storage, as opposed to less frequent readings during operation to compensate for slower sensor drift while operational.
15 Citations
20 Claims
-
1. A method of compensating for drift in a sensor of a device used to measure the temperature of a target, the device having a stable calibration source and a chopper for isolating the sensor when closed, the method comprising:
-
collecting a first reading with the chopper closed and the stable calibration source off; collecting a second reading with the chopper open; collecting a third reading with the chopper closed and the stable calibration source on; calculating a source reading using the first, second, and third readings; calculating a factor using the source reading and a calibration reading; and compensating for drift using the factor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 16)
-
-
10. An apparatus for optically measuring temperature adapted for automated self calibration comprising:
-
a sensor responsive to light emission, the sensor susceptible to output drift over time; a chopper for isolating the sensor from a target when closed; a stable calibration source switchably operable for illuminating the sensor and capable of exciting the sensor; a memory for storing reading data and calibration data; a processor coupled to the memory, the stable calibration source, the chopper, and the sensor, operable to collect readings at an interval of time, the readings comprising a first reading with the chopper closed and the stable calibration source off, a second reading with the chopper open, and a third reading with the chopper closed and the stable calibration source on, wherein output drift is compensated by applying a factor calculated from the first, second and third readings. - View Dependent Claims (11, 12, 13, 14, 15, 17)
-
-
18. A method of automated field calibration of a detector comprising a sensor and a chopper and used in optical temperature sensing of a target comprising:
-
determining a reference setting in a controlled environment; storing the reference setting; during detector operation, collecting a first reading with the chopper closed, blocking the sensor from the target; collecting a second reading with chopper open; collecting a third reading with the chopper closed and a calibration source on; and calibrating the detector by compensating for sensor drift using a factor calculated using the reference setting, the first reading, the second reading, and the third reading. - View Dependent Claims (19, 20)
-
Specification