Method and system for high speed signal processing
AssigneeFEI Company
InventorsHenricus Gerardus ROEVEN, Rob BRAAN, Bart Jozef JANSSEN, Jeroen KEIZER
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Abstract
A method and system for acquiring data from a pixelated image sensor for detecting charged particles. The method includes reading a pixel voltage of one or more of the multiple pixels multiple times without resetting the image sensor and digitizing the pixel into a first number of bits. The camera outputs a digitized compressed pixel voltage in a second, less, number of bits. The maximum range of the digitized compressed pixel voltage is less than a maximum range of the pixel voltage.
Claims20
A method for acquiring data from a camera including a pixelated image sensor for detecting charged particles, comprising:
- obtaining multiple pixel voltages of a pixel of the image sensor by reading one or more pixels of the image sensor multiple times without resetting the image sensor;
- digitizing each of the multiple pixel voltages into a first number of bits;
- and
- compressing each of the digitized multiple pixel voltages into a digitized compressed pixel voltage in a second, lower, number of bits, wherein a maximum range of the digitized compressed pixel voltage is less than a maximum range of the pixel voltage, and wherein the digitized compressed pixel voltage is generated by removing at least a most significant bit (MSB) of the digitized pixel voltage.
A method for acquiring data from a camera including a pixelated image sensor for detecting charged particles, comprising:
- repetitively reading the image sensor without resetting the image sensor to obtain multiple pixel voltages of a pixel of the image sensor;
- compressing each of the multiple pixel voltages into a compressed pixel voltage, wherein the compressed pixel voltage is a difference between the pixel voltage and a first threshold voltage responsive to an amplitude of the pixel voltage not less than an amplitude the first threshold voltage and less than an amplitude of a second threshold voltage, and wherein a range of the compressed pixel voltage is not greater than the amplitude of the first threshold voltage, and the range of the compressed pixel voltage is lower than a range of the pixel voltage;
- digitizing the compressed pixel voltage;
- and
- outputting the digitized compressed pixel voltage.
A system for acquiring data from a sample, comprising:
- a charged particle source for irradiating charged particles towards the sample;
- a camera for detecting charged particles emitted from the sample responsive to the irradiation, the camera includes an image sensor with multiple pixels and one or more analog-to-digital converters (ADCs), wherein the camera is configured to:
- convert charged particles impinging a pixel of the multiple pixels into a pixel voltage;
- compress the pixel voltage into a compressed pixel voltage, wherein the compressed pixel voltage is a difference between the pixel voltage and a first threshold voltage if an amplitude of the pixel voltage is not less than an amplitude of the first threshold voltage and less than an amplitude of a second threshold voltage, and wherein a range of the compressed pixel voltage is not greater than the amplitude of the first threshold voltage, and the range of the compressed pixel voltage is lower than a range of the pixel voltage;
- digitize the compressed pixel voltage;
- and
- output the digitized compressed pixel voltage;
- an image processor for receiving the digitized compressed pixel voltage from the camera and generating a differential pixel voltage based on the digitized compressed pixel voltage;
- and
- a controller for forming an image of the sample based on the differential pixel voltage.
Dependencies are inferred from the claim text.