CN102508145B - Method for measuring CCD (Charge Coupled Device) chip dark current and double temperature constant - Google Patents
Method for measuring CCD (Charge Coupled Device) chip dark current and double temperature constant Download PDFInfo
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- CN102508145B CN102508145B CN201110330695.6A CN201110330695A CN102508145B CN 102508145 B CN102508145 B CN 102508145B CN 201110330695 A CN201110330695 A CN 201110330695A CN 102508145 B CN102508145 B CN 102508145B
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- ccd chip
- temperature
- dark current
- ccd
- integral time
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Abstract
The invention discloses a method for measuring the CCD (Charge Coupled Device) chip dark current and double temperature constant. The method is realized by the following steps of: arranging a CCD chip in a dewar flask temperature control room, and configuring a reference temperature such that the CCD chip works at the reference temperature, wherein the temperature control room is sealed and light-proof; controlling the CCD chip to shoot an image through a control circuit, and uploading the information of the image to a computer; calculating an average gray value of the obtained image; drawing a fitting curve by utilizing the average gray value of the image and corresponding integration time to obtain a dark current; and finally calculating the double temperature constant by measuring the dark current at a plurality of different temperatures. The method disclosed by the invention has the advantages of high parameter measurement precision and good stability, and is suitable for precise measurement of the dark current and the double temperature constant of the CCD chip.
Description
The invention belongs to field of measuring technique, be specifically related to the measurement to CCD chip dark current and double thermal constant, for development, assessment and the screening of CCD chip.
Background technology
In the middle of the development and application of CCD chip, restriction due to processing and measuring technique, the measured value that causes the actual dark current of CCD chip, double thermal constant and manufacturer to provide has certain difference, and in some crucial applications, need quantitatively to understand the actual performance parameter of CCD chip, thereby to collecting to such an extent that data are reasonably proofreaied and correct, obtain data more accurately.Therefore, be necessary to propose dark current and the double thermal constant that a kind of method is effectively measured CCD chip, by these two performance parameters, CCD output data processed to the data that obtain more gearing to actual circumstances.
The system of traditional measurement CCD chip parameter is owing to there is no temperature control device, cause measuring dark current and the double thermal constant of CCD chip, thereby cannot assess the noise of CCD chip and the degree of correlation of temperature, user is not had on cDNA microarray can be not for reference with the parameter of temperature correlation, is unfavorable for the use of user to CCD chip simultaneously yet.
Summary of the invention
The object of the invention is to for the problems referred to above, a kind of method of measuring CCD chip dark current and double thermal constant is proposed, by using Dewar flask temperature controlled compartment to regulate the working temperature of CCD chip, the measurement of realization to CCD chip dark current and double thermal constant, for user provides detailed and performance parameter temperature correlation, thereby guides user is to the screening of CCD chip and use.
For achieving the above object, the present invention includes following technical scheme:
1) CCD chip to be measured is placed in the middle of Dewar flask temperature controlled compartment, the sealing of Dewar flask temperature controlled compartment is light tight, makes, in the environment of CCD chip in a unglazed photograph, CCD chip to be connected with control circuit corresponding interface, and this control circuit is used for controlling the imaging of CCD chip;
2) electronic shutter carrying by CCD chip is adjusted the integral time of CCD chip, controls the exposure of CCD chip and carries out image taking;
3) choose temperature parameter and regulate Dewar flask temperature controlled compartment, make CCD chip be in a 80K and work to the steady temperature of normal temperature, establishing temperature is T
ref;
4) choose at least 50 (t integral time that are spacedly distributed
1, t
2, t
3..., t
x), wherein X is actual number integral time of choosing, and uses the exposure that regulates CCD chip these integral time, to each integral time, takes and is no less than 5 images;
5) for each of the t choosing integral time
i, i ∈ 1,2,3 ..., X, extracts 1 image in photographic images sequence centre position, asks the average gray value μ of image
i;
6) to X coordinate (t
i, μ
i/ K), carry out linear fit, obtain straight line, obtain the slope of this straight line, be dark current μ
i, wherein K is system-gain, i ∈ 1,2,3 ..., X;
7) choose Y the CCD chip operation temperature (T being spacedly distributed
1, T
2, T
3..., T
y), the working temperature of CCD chip is set respectively, for each work temperature with these integral time
i, i ∈ 1,2,3 ..., Y, measures its corresponding dark current μ
ii, Y is the number of selected CCD chip operation temperature;
8) by each work temperature
ia corresponding dark current μ
ii, construct Y coordinate points (log
2μ
ii, T
i-T
ref), and this Y is carried out to linear fit to punctuate obtain straight line, try to achieve this straight slope a, calculate double thermal constant
y is the number of selected CCD chip operation temperature, T
reffor reference temperature.
Tool of the present invention has the following advantages:
1) the present invention, owing to adopting Dewar flask to carry out temperature control, has realized the measurement with temperature correlation dark current and two parameters of double thermal constant.
2) the present invention adopts the mode of linear fit to calculate for double thermal constant and dark current parameter, can get rid of the stochastic error that single measurement causes.
3) data acquisition that the present invention chooses, with taking multiple, is chosen the method for intermediate image, has well got rid of the error of imaging system, has improved the precision of measurement parameter.
Accompanying drawing explanation
Fig. 1 is the present invention's hardware acquisition system used block diagram;
Fig. 2 is that the present invention measures CCD chip dark current μ
iwith double thermal constant T
dprocess flow diagram.
Embodiment
CCD chip is a kind of widely used image device, be widely used in many fields such as uranology, Aero-Space, biology and medical research, molecular dynamics, spectroscopy, underwater photography, X ray detection, it is vital for this performance parameter to CCD chip, assessing.At present, CCD chip is assessed mainly and is comprised:
The photoelectron number that quantum efficiency η: CCD produces under wavelength X is irradiated and the ratio of incident light subnumber, this parameter characterization CCD chip to the monochromatic responding ability of specific wavelength.
Responsiveness parameters R: CCD under setted wavelength monochromation illumination, the ratio of signal voltage and exposure.This parameter has been described CCD quantum efficiency and system-gain on the whole.
Saturation degree μ
p.sat: the photon number that can receive when CCD reaches capacity.
System-gain K: the electron number that system pixel produces and the ratio of gray-scale value.
Dark noise
the noise summation relevant to CCD chip sensing circuit.
Signal to noise ratio snr: the signal that photon produces and the ratio between noise signal.
Absolute sensitivity threshold value μ
p.min: signal to noise ratio (S/N ratio) equals 1 o'clock required average photon number.
Dynamic range DR: saturation degree is in the ratio of absolute sensitivity threshold value.
The error of departs from linear relation between the output signal of Linearity error LE:CCD chip and incident optical signal.
Dark signal heterogeneity DSNU:CCD chip is the standard deviation of each pixel output gray level value and the ratio of its average under unglazed photograph.
Photo response heterogeneity PRNU:CCD chip under 50% saturated conditions of exposure, the standard deviation of each pixel output gray level value and the ratio of average.
Dark current μ
i: CCD chip is big or small without obtaining output current under light conditions.
Double thermal constant T
d: without under light conditions, corresponding temperature when dark current is increased to reference temperature and goes out a times of dark current value.
The present invention is mainly to the parameter dark current μ in above-mentioned
iwith double thermal constant T
dmeasure.
Below with reference to accompanying drawing, the present invention is described clearly and completely to parameter dark current μ
iwith double thermal constant T
dperfect measurement flow process.
With reference to Fig. 1, the present invention's whole system used comprises Dewar flask temperature controlled compartment, CCD chip, control circuit and computing machine.CCD chip mount is in the Dewar flask temperature controlled compartment of sealing, its working temperature can be controlled by Dewar flask temperature controlled compartment, CCD chip is driven into picture by control circuit, and the output information of CCD chip is uploaded on computing machine, and computing machine calculates the performance parameter of CCD chip to be measured according to image information.For different measurement parameters, by regulating the working temperature of Dewar flask temperature controlled compartment, gather corresponding image information, then according to calculating measurement parameter with the specific step of parameter correlation.
With reference to Fig. 2, the present invention measures CCD chip dark current μ
iwith double thermal constant T
dmethod, comprise the steps:
Step 1, CCD chip to be measured is placed in the middle of Dewar flask temperature controlled compartment, the sealing of Dewar flask temperature controlled compartment is light tight, make in the environment of CCD chip in a unglazed photograph, CCD chip is connected with driving circuit corresponding interface, this driving circuit is for controlling the working temperature of the imaging of CCD chip and adjusting Dewar flask temperature controlled compartment, and the temperature of Dewar flask temperature controlled compartment is the working temperature of CCD chip.
Step 2, the electronic shutter carrying by CCD chip are adjusted the integral time of CCD chip, control the exposure of CCD chip, during photographic images, first the electronic shutter of controlling CCD chip by control circuit is opened, control circuit starts timing simultaneously, when timing arrives the integral time of appointment, control circuit controls the electronic shutter of CCD chip and cuts out, and last control circuit is read image information and is uploaded in the middle of computing machine from CCD chip.
Step 3, choose temperature parameter and regulate Dewar flask temperature control system, make CCD chip be in a 80K and work to the steady temperature of normal temperature, establishing temperature is T
ref.
Step 4, choose at least 50 (t integral time that are spacedly distributed
1, t
2, t
3..., t
x), wherein X is actual number integral time of choosing, and uses the exposure that regulates CCD chip these integral time, to each integral time, takes and to be no less than 5 images, the image of all shootings is all uploaded in the middle of computing machine by control circuit.
Step 5, for each of the t choosing integral time
i, i ∈ 1,2,3 ..., X, extracts 1 image in photographic images sequence centre position, asks the average gray value μ of image
i.
Step 6, to X coordinate (t
i, μ
i), i ∈ 1,2,3,, X, carries out linear fit, obtains straight line, obtains the slope of this straight line, is dark current μ
i.
Step 7, choose the CCD chip operation temperature (T that Y is spacedly distributed
1, T
2, T
3..., T
y), the working temperature of CCD chip is set respectively, for each work temperature with these integral time
i, i ∈ 1,2,3 ..., Y, measures its corresponding dark current μ
ii, Y is the number of selected CCD chip operation temperature.
Step 8, by each work temperature
ia corresponding dark current μ
ii, construct Y coordinate points (log
2μ
ii, T
i-T
ref), and this Y is carried out to linear fit to punctuate obtain straight line, try to achieve this straight slope a, calculate double thermal constant
y is the number of selected CCD chip operation temperature, T
reffor reference temperature.
More than describing is only example of the present invention; do not form any limitation of the invention; obviously for those skilled in the art; after having understood content of the present invention and principle; all may be in the situation that not deviating from the principle of the invention, structure; carry out various corrections and change in form and details, but these corrections based on inventive concept and changing still within claim protection domain of the present invention.
Claims (2)
1. a method of measuring CCD chip dark current and double thermal constant, comprises the steps:
1) to be tested is placed in the Dewar bottled CCD chip which room temperature, room temperature dewar sealed opaque, the CCD chip is a no-light environments, the CCD chip is connected to the corresponding interface of the control circuit, which a control circuit for controlling the CCD imaging chip;
2) electronic shutter carrying by CCD chip is adjusted the integral time of CCD chip, controls the exposure of CCD chip and carries out image taking;
3) choose temperature parameter and regulate Dewar flask temperature controlled compartment, make CCD chip be in a 80K and work to the steady temperature of normal temperature, establishing temperature is T
ref;
4) choose at least 50 (t integral time that are spacedly distributed
1, t
2, t
3, t
x), wherein X is actual number integral time of choosing, and uses the exposure that regulates CCD chip these integral time, to each integral time, takes and is no less than 5 images;
5) for each of the t choosing integral time
i, i ∈ 1,2,3 ..., X, extracts 1 image in photographic images sequence centre position, asks the average gray value μ of image
i;
6) to X coordinate (t
i, μ
i/ K), carry out linear fit, obtain straight line, obtain the slope of this straight line, be dark current μ
i, wherein K is system-gain, i ∈ 1,2,3 ..., X;
7) choose Y the CCD chip operation temperature (T being spacedly distributed
1, T
2, T
3, T
y), the working temperature of CCD chip is set respectively, for each work temperature with these integral time
i, i ∈ 1,2,3 ..., Y, measures its corresponding dark current μ
i, Y is the number of selected CCD chip operation temperature;
8) by each work temperature
ia corresponding dark current μ
i, construct Y coordinate points (log
2μ
i, T
i-T
ref), and this Y coordinate points is carried out to linear fit obtain straight line, try to achieve this straight slope a, calculate double thermal constant
y is the number of selected CCD chip operation temperature, T
reffor reference temperature.
2. measuring method according to claim 1, step 2 wherein) described passing through the integral time that electronic shutter that CCD chip carries is adjusted CCD chip, control the exposure of CCD chip, when taking, first the electronic shutter of controlling CCD chip by control circuit is opened, control circuit starts timing simultaneously, when timing arrives the integral time of appointment, control circuit controls the electronic shutter of CCD chip and cuts out, and last control circuit is read image information and is uploaded in the middle of computing machine from CCD chip.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110330695.6A CN102508145B (en) | 2011-10-26 | 2011-10-26 | Method for measuring CCD (Charge Coupled Device) chip dark current and double temperature constant |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110330695.6A CN102508145B (en) | 2011-10-26 | 2011-10-26 | Method for measuring CCD (Charge Coupled Device) chip dark current and double temperature constant |
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| Publication Number | Publication Date |
|---|---|
| CN102508145A CN102508145A (en) | 2012-06-20 |
| CN102508145B true CN102508145B (en) | 2014-02-12 |
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| CN103852708B (en) * | 2014-03-26 | 2016-06-08 | 中国科学院光电技术研究所 | The electronics gain factor measuring method of a kind of charge coupled device |
| CN103954819B (en) * | 2014-03-28 | 2016-08-17 | 中国科学院半导体研究所 | Nearly zero partially time semiconductor infrared photodetector surfaces dark current measuring method |
| CN104796632A (en) * | 2014-09-11 | 2015-07-22 | 上海鉴谱光电科技有限公司 | Detection device and testing method for embedded linear charge coupled device (CCD) dark noise |
| CN110855915B (en) * | 2019-11-29 | 2020-12-08 | 中国科学院长春光学精密机械与物理研究所 | CCD camera response non-uniformity correction method and device for realizing dark current compensation |
| CN110907033B (en) * | 2019-12-05 | 2022-02-01 | 中国科学院新疆理化技术研究所 | Irradiation test method based on proton displacement effect of ultraviolet detector |
| CN113917217B (en) * | 2021-10-12 | 2024-03-08 | 中国科学院新疆理化技术研究所 | Dark current activation energy testing method for photoelectric imaging device after irradiation |
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| US5608455A (en) * | 1992-07-30 | 1997-03-04 | Fuji Photo Film Co., Ltd | Interline transfer CCD image sensor with reduced dark current |
| US6433326B1 (en) * | 1999-07-14 | 2002-08-13 | Sarnoff Corporation | CMOS/CCD line transfer imager with low dark current |
| CN1183379C (en) * | 2001-11-02 | 2005-01-05 | 中国科学院长春光学精密机械与物理研究所 | Optical pathway extendible CD device photoelectric parameter tester |
| JP2006140935A (en) * | 2004-11-15 | 2006-06-01 | Watec Co Ltd | Small-sized ccd camera, and controller for parameter setting |
| JP2008252851A (en) * | 2007-03-30 | 2008-10-16 | Fujifilm Corp | Ccd type solid-state imaging device, photography device, and picked-up image data correcting method |
| CN101674398B (en) * | 2009-09-25 | 2011-04-27 | 北京空间机电研究所 | Real-time correcting method for dark current of CCD digital image data |
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