Low cost and high performance bolometer circuity and methods

Patent metadata

Field	Value
Publication number	US-11012647-B2
Application number	US-201916542625-A
Country	US
Kind code	B2
Filing date	Aug 16, 2019
Priority date	Feb 22, 2017
Publication date	May 18, 2021
Grant date	May 18, 2021

Abstract

A bolometer circuit includes a substrate on which a focal plane array (FPA) of active bolometers is provided. Each active bolometer is configured to receive external infrared (IR) radiation and substantially thermally isolated from the substrate. The bolometer circuit also includes one or more blind arrays of blind bolometers shielded from the external IR radiation and substantially thermally isolated from the substrate. Noises in outputs from each column and/or each row of the FPA are corrected, reduced, or suppressed based on a statistical property of outputs from a corresponding column or row of the one or more blind arrays. Noise in each frame of IR image captured by the FPA may also be corrected, reduced, or suppressed using the one or more blind arrays.

First claim

What is claimed is:

1. A bolometer circuit, comprising:
a substrate;
a focal plane array (FPA) of active bolometers arranged in rows and columns, the active bolometers being configured to receive external infrared (IR) radiation and substantially thermally isolated from the substrate,
a first blind array of blind bolometers shielded from the external IR radiation and substantially thermally isolated from the substrate, the first blind array comprising rows corresponding to the rows of the FPA;
a second blind array of blind bolometers shielded from the external IR radiation and substantially thermally isolated from the substrate;
a control circuit configured to select each row of the FPA and a corresponding row of the first blind array according to a timing signal to read out each row of the FPA and the first blind array in a row-by-row fashion, outputs from all rows of the FPA read out in the row-by-row fashion being combined to represent a frame of IR image captured by the FPA; and
a logic device configured to reduce noise in outputs from each row of the FPA based on a statistical property of outputs from the corresponding row of the first blind array and reduce noise in outputs of the blind bolometers of the first blind array based on outputs of the blind bolometers of the second blind array.

2. The bolometer circuit of claim 1 , wherein the first blind array is disposed adjacent to one side of the FPA, and wherein the logic device is further configured to reduce noise in the frame of IR image based on a statistical property of outputs from all rows of the first blind array of blind bolometers.

3. The bolometer circuit of claim 1 , wherein the statistical property determined by the logic device represents noise associated with the reading out of each row of the FPA and the first blind array while removing effects of noise that is common between the active bolometers and blind bolometers of each row.

4. The bolometer circuit of claim 1 , wherein:
the first blind array comprises a same number of rows as the FPA and a plurality of columns; and
the statistical property comprises an average of outputs from the plurality of columns of the first blind array for each row of the first blind array.

5. The bolometer circuit of claim 4 , wherein the average is a sum of outputs from the blind bolometers of the first blind array divided by a number of the blind bolometers of the first blind array.

6. The bolometer circuit of claim 4 , wherein the logic device is configured to reduce noise in the outputs from each row of the FPA at least by subtracting, from an output of each active bolometer in the row of the FPA, the average of the outputs determined from the plurality of columns of the first blind array for the row.

7. The bolometer circuit of claim 1 , wherein the logic device is further configured to detect anomalous blind bolometer(s) among the blind bolometers of the first blind array and exclude output(s) from the anomalous blind bolometer(s) when determining the statistical property.

8. The bolometer circuit of claim 1 , further comprising:
a third blind array of blind bolometers shielded from the external IR radiation and substantially thermally isolated from the substrate, the third blind array comprising a same number of columns as the FPA and a plurality of rows,
wherein the logic device is further configured to reduce noise in outputs from each column of the FPA based on an average of outputs from a corresponding column of the third blind array.

9. The bolometer circuit of claim 8 , wherein the logic device is further configured to reduce noise in the frame of IR image based on an average of outputs from all columns of the third blind array.

10. A bolometer circuit, comprising:
a substrate;
a focal plane array (FPA) of active bolometers arranged in rows and columns, the active bolometers being configured to receive external infrared (IR) radiation and substantially thermally isolated from the substrate,
a first blind array of blind bolometers shielded from the external IR radiation and substantially thermally isolated from the substrate, the first blind array comprising columns associated with the columns of the FPA;
a second blind array of blind bolometers shielded from the external IR radiation and substantially thermally isolated from the substrate;
a plurality of column circuits each associated with a column of the FPA and a corresponding column of the first blind array, the plurality of column circuit being configured to be selectively connected to a row of the FPA or the first blind array according to a timing signal to read out each row of the FPA or the first blind array in a row-by-row fashion, outputs from all rows of the FPA read out in the row-by-row fashion being combined to represent a frame of IR image captured by the FPA; and
a logic device configured to reduce noise in outputs from each column of the FPA based on a statistical property of outputs from the corresponding column of the first blind array and reduce noise in outputs of the blind bolometers of the first blind array based on outputs of the blind bolometers of the second blind array.

11. The bolometer circuit of claim 10 , wherein
the first blind array comprises a same number of columns as the FPA and a plurality of rows;
the column circuits are selectively connected to each row of the first blind array prior to or after being selectively connected to each row of the FPA, such that outputs of the first blind array are read out prior to or after capturing of the frame of IR image; and
the statistical property comprises an average of the outputs from the plurality of rows of the first blind array for each column of the first blind array.

12. A method of generating an output in a bolometer circuit, the method comprising:
receiving external infrared (IR) radiation by a focal plane array (FPA) of active bolometers arranged in rows and columns, the active bolometers being configured to receive the external IR radiation and substantially thermally isolated from a substrate on which the FPA is provided;
compensating outputs of the active bolometers by a first blind array of blind bolometers that are shielded from the external IR radiation and substantially thermally isolated from the substrate, the first blind array comprising rows corresponding to the rows of the FPA;
compensating outputs of the blind bolometers of the first blind array by a second blind array of blind bolometers that are shielded from the external IR radiation and substantially thermally isolated from the substrate; and
selecting each row of the FPA and a corresponding row of the first blind array according to a timing signal to read out each row of the FPA and the first blind array in a row-by-row fashion, outputs from all rows of the FPA read out in the row-by-row fashion being combined to represent a frame of IR image captured by the FPA,
wherein the compensating by the first blind array comprises reducing noise in outputs from each row of the FPA based on a statistical property of outputs from the corresponding row of the first blind array, and
wherein the compensating by the second blind array comprises reducing noise in outputs of the blind bolometers of the first blind array based on outputs of the blind bolometers of the second blind array.

13. The method of claim 12 , wherein the statistical property represents noise associated with the reading out of each row of the FPA and the first blind array while removing effects of noise that is common between the active bolometers and blind bolometers of each row.

14. The method of claim 12 , wherein:
the first blind array co

Assignees

• Flir Systems

Inventors

• Cannata Robert F
• Simolon Brian B
• Aziz Naseem Y

Classifications

• H04N25/677 Primary

  for reducing the column or line fixed pattern noise · CPC title

• H04N25/672

  between adjacent sensors or output registers for reading a single image · CPC title

• H04N25/21

  for transforming thermal infrared radiation into image signals · CPC title

• H04N25/633

  by using optical black pixels · CPC title

• H04N25/76

  Addressed sensors, e.g. MOS or CMOS sensors · CPC title