CN106199370A - For detecting the test device of CCD charge conversion factor - Google Patents

Abstract

The invention discloses a kind of test device for detecting CCD charge conversion factor, described test device is made up of light source, ammeter, drive circuit board and processing module；The method have the benefit that: provide a kind of test device for detecting CCD charge conversion factor, this test apparatus structure is simple, easy and simple to handle, and only the drive circuit board in device need to be made trickle change just adapts to the testing requirement of various CCD.

Description

For detecting the test device of CCD charge conversion factor

Technical field

The present invention relates to a kind of CCD charge conversion factor detection technique, particularly relate to a kind of for detecting the conversion of CCD electric charge The test device of the factor.

Background technology

In numerous performance parameters of CCD, charge conversion factor (CVF) is to weigh an important finger of CCD device performance Mark, it can characterize CCD and the electric charge collected is converted to the ability of voltage, with the saturation voltage of CCD, responsiveness, dark current The performance parameters such as density are closely related.

Gordon R.Hopkinson et al. introduced the method for a series of measurement charge conversion factor in its works (A Guide to the Use and Calibration of Detector Array Equipment, Gordon R.Hopkinson, Teresa M.Goodman, Stuart R.Prince, SPIE Press, 2004), these methods are domestic The documents and materials such as outer paper are quoted, including: 1. reset Leakage Method: according to the definition of charge conversion factor, by measuring CCD's Reset leakage current, amplitude output signal, the time of integration and effectively pixel number calculate；2. x-ray method: pass through at a certain temperature The x-ray bombardment CCD device of external radiation source, produces a number of freedom-hole-electron pair, then to working in integrating state Under output node voltage measure, obtain CVF value；3. Mean-Variance method: by the statistics of output signal institute band noise Rule calculates.There are problems in preceding method in practical operation: 2. method all exists with method test result 3. Bigger error；2. method needs the test device of complexity and harsher test environment；Method 3. process is loaded down with trivial details, test job amount Greatly；And maximum of which deficiency is that three kinds of methods the most do not possess versatility: 1. such as method requires that CCD is operated in normal imaging State, must determine according to the sequential during normal imaging time of integration therein, but the work schedule of every kind of CCD the most not phase With, when different types of CCD is tested, must be every kind of the most individually designed drive circuit of CCD, workload is big, time-consumingly consumes Power, and poor universality；The physical characteristic parameter of method 2. and the most then heavy dependence CCD self, the most not only adds workload, Also add the test period of device parameters simultaneously, consume substantial amounts of manpower and materials.

Summary of the invention

For the problem in background technology, the present invention proposes a kind of test dress for detecting CCD charge conversion factor Putting, its innovation is: described test device is made up of light source, ammeter, drive circuit board and processing module；The light of described light source Can regulate according to intensity；Multiple drive socket and output socket it is provided with, the driving pin grafting of CCD on described drive circuit board In drive socket, the output pin of CCD is plugged in output socket；

Described light source is arranged on the top of drive circuit board, and region drive circuit board being used for arrange CCD is positioned at light source Range of exposures in, the sensitive surface of CCD is relative with light source；Described ammeter is connected with output socket and processing module respectively；Place Reason module is connected with output socket；

Described drive circuit board can make the light integrated area of CCD be continuously maintained in light integrating state by drive socket (will The pin of the upper corresponding anti-blooming grid of CCD is persistently placed in low level state, and with this understanding, if CCD is by illumination, light integrated area will Continuously produce electric charge), meanwhile, drive circuit board can make light integrated area and the vertical transitions district of CCD by drive socket Between charge pathway be continuously maintained in conducting state and (will persistently be placed in height by the pin of corresponding first transfer control gate on CCD Level state, the first transfer control gate is transferred to vertical turning for controlling electric charge from the light integrated area of CCD defined in the present invention Moving district, this allows for the internal sustainable existence of CCD can store the potential well of electric charge, and these potential wells are interconnected, thus Define the steady electric field within through CCD, light integration the electric charge produced can be evenly distributed in the inside of CCD, as long as Illumination condition does not changes, and CCD output within the unit interval will keep stable), meanwhile, drive circuit board can be by driving Dynamic socket makes the charge pathway between the vertical transitions district of CCD and horizontal transfer district be continuously maintained in conducting state (will be on CCD The pin of corresponding second transfer control gate is persistently placed in high level state, and the second transfer control gate defined herein is used for controlling Electric charge is transferred to horizontal transfer district from the vertical transitions district of CCD, and in this case, electric charge just can turn from vertical continuously Move district and be transferred to horizontal transfer district), meanwhile, drive circuit board can pass through the drive socket output control gate to CCD and resetting gate Periodically apply to control pulse (output control gate and resetting gate are used for controlling electric charge and outwards export from horizontal transfer district), make CCD periodically outside output signal, meanwhile, described drive circuit board can be by output socket by outside for the output signal of CCD Output；The CCD that this paragragh is illustrated each funtion part state in which internal, is hereinafter abbreviated as state to be measured；

Electric current at output socket can be detected by described ammeter, and exports testing result to processing module；

The output signal of CCD can be sampled by described processing module, and the signal sampled is converted to digital picture, After obtaining digital picture, the pixel average of digital picture is extracted by processing module, then pixel average is converted to Corresponding ccd signal amplitude.

The principle of the present invention is:

The definition of charge conversion factor is relatively simple, i.e. output voltage and being stored between the electron number at output node Ratio, single from the point of view of definition, if the output voltage of CCD can be got and is stored in the electron number at output node, with regard to energy Calculate the charge conversion factor of this CCD easily；But in practical situation, under prior art conditions, it is impossible to defeated to being stored in Electron number at egress is directly measured, and this results in and cannot directly utilize the definition of charge conversion factor and carry out calculated charge Conversion factor；

The versatility problem of measurement problem and measurement means in order to solve charge conversion factor, inventor is to the most of the same race The CCD of class conducts in-depth research, and in research process, inventor finds, existing CCD, regardless of its kind, Ta Mendou There are following two common ground: 1) workflow of existing CCD the most all follows and " accepts illumination-light integration and produce charge-charge Transfer-output " step, 2) for same CCD, in its response range, under the conditions of different illumination intensity, its output is Different；

For the 2nd) common ground, it will be apparent to those skilled in the art that under normal circumstances, the output of CCD and intensity of illumination There is linear relationship in size, i.e. intensity of illumination is the biggest, and in the unit interval, the electricity of CCD output is the biggest, and electricity can convert Become electron number, then can indirectly reflect that electric charge turns according to the difference of CCD output electricity under the conditions of different illumination intensity completely Changing because of the electron number in sub-definite, and then try to achieve charge conversion factor, along this thinking, inventor has made following derivation:

If the signal amplitude of ccd output signal is V under the conditions of intensity of illumination 1_o1, the corresponding output node quantity of electric charge is Q₁, Under the conditions of intensity of illumination 2, the signal amplitude of ccd output signal is V_o2, the corresponding output node quantity of electric charge is Q₂；Represent single with q The quantity of electric charge (1.6 × 10 of electronics^-19Coulomb), Δ V_o=V_o2-V_o1, Δ Q=Q₂-Q₁, then by the definition of charge conversion factor, its Value can be expressed as:

$CVF=\frac{{\mathrm{\ΔV}}_o}{\mathrm{\Δ}Q/q}$

If the output cycle of single pixel is t, then according to current capacity formula Q/t=I, Δ Q=Δ I_RD× t, Δ I_RD=I_RD1-I_RD2, then above formula can be deformed into following formula:

$CVF=\frac{{\mathrm{\ΔV}}_o}{{\mathrm{\ΔI}}_{RD}\×t/q}$

From existing theory, the inverse in the output cycle of single pixel is exactly the output frequency of pixel, if representing picture with f The output frequency of unit, then have f=1/t, and then above formula is rewritable is:

$CVF=\frac{{\mathrm{\ΔV}}_o}{{\mathrm{\ΔI}}_{RD}}\×q\×f$

After parameters in above formula is analyzed, we it finds that, the numerical value of f depend on control CCD output Time sequential pulse, it is known quantity, as long as being obtained in that Δ V_oWith Δ I_RDWe just can calculate CVF exactly, and is used for calculating ΔV_oWith Δ I_RDParameter all can by existing means carry out quantify detection；

Another common ground of previously described existing CCD is, their workflow the most all follow " accept illumination- Light integration produces charge-charge transfer-output " step, understand based on existing CCD control theory, and " accept illumination-light Integration produces charge-charge transfer " operation that step is relevant all realizes driving by impulse level, and can from aforesaid derivation To find out, in formula, the acquisition of parameters is not required for CCD is normal operating conditions, only requires when CCD can provide unit Between output signal, then the present invention makes CCD be in aforesaid state to be measured, compared to CCD just by drive socket Often duty, aforesaid state to be measured has only to apply fixed level and can be achieved with, when avoiding problems as CCD design driven The problem of sequence, so far, those skilled in the art should be understood that, compared with the CCD driver' s timing complete with design, preceding method is only Need to design the control pulse relevant to CCD output, test job amount and hardware consumption will significantly reduce；

For different types of CCD, the quantity of its control gate possible there are differences, it is also possible to it is special that some CCD possesses some Other additional function, but, no matter which kind of CCD, when they work, the main body principle of institute's foundation is but identical；Applying this Bright time different types of CCD is tested, only will need to be used for controlling the internal electricity of CCD according to the control gate quantity of CCD and function The control gate of lotus transfer is placed in the fixed level state of correspondence, and the control pulse to exporting for controlling CCD electric charge is made small Amendment (as long as the kind of CCD determines, to control pulse modify so that CCD periodically output signal is this area The basic skill that technical staff should possess, and be far smaller than designed for CCD controlling the workload modified of pulse Whole driver' s timing), just can meet the testing requirement of variety classes CCD；Such as, CCD output uses three-phase or four phases Driving, only need to increase the way of output drive signal, and for example CCD has vertical merged grid etc., only need to be set to high electricity Flat；

With the method in background technology 1. compared with, 1. method needs for the most individually designed driver' s timing of different types of CCD, And after using the present invention, it is no longer necessary to carry out complicated loaded down with trivial details design of driving timing sequence work, only need to according to the quantity of control gate or Drive circuit is made some and trickle is adjusted by additional function；With method 2. and 3. compared with, the measurement operation of the present invention need not Understanding the physical parameter of device, test process is the most efficient；

When specifically testing, first pass through drive circuit board by the status adjustment of CCD to state to be measured, then by the illumination of light source Intensity adjustments is to the first light-intensity conditions, now, to the electric current I at output socket_RD1(current equivalence at output socket is that CCD is defeated Electric current at egress) and output signal sample, output signal after treatment, available signal amplitude V_o1, then by light The intensity of illumination in source regulates to the second light-intensity conditions (light intensity of the second light-intensity conditions and the first light-intensity conditions is different), the most right Ccd output signal carries out sampling processing and obtains electric current I_RD2With amplitude V_o2, q and f is, just can calculate according to aforementioned formula The charge conversion factor of this CCD.

For meeting the testing requirement of variety classes CCD, can be by relevant to drive socket and output socket on drive circuit board Circuit structure modularity, when testing object and changing, only need to change corresponding drive socket and output socket, and to controlling arteries and veins Minor modifications is made in punching, then has following preferred version: described drive circuit board is made up of built-up circuit and control module；Described Drive socket and output socket are arranged on built-up circuit, and the output signal of described control module energy drive socket is controlled.

Preferably, described control module uses FPGA to realize.

Preferably, described test device is provided with shell, in light source and drive circuit board are wrapped in by described shell, outward Shell uses light blocking material to make.The shell using light blocking material to make can avoid extraneous light to be irradiated on CCD, prevents survey Test result interferes.

The method have the benefit that: provide a kind of test device for detecting CCD charge conversion factor, should Test apparatus structure is simple, easy and simple to handle, and only the drive circuit board in device need to be made trickle change just adapts to various CCD's Testing requirement.

Accompanying drawing explanation

Fig. 1, the structural representation of the present invention；

In figure title corresponding to each labelling be respectively as follows: light source 1, ammeter 2, drive circuit board 3, processing module 4, CCD 5。

Detailed description of the invention

A kind of test device for detecting CCD charge conversion factor, its innovation is: described test device by light source 1, Ammeter 2, drive circuit board 3 and processing module 4 form；The intensity of illumination of described light source 1 can regulate；Described drive circuit board Being provided with multiple drive socket and output socket on 3, the driving pin of CCD is plugged in drive socket, and the output pin of CCD is inserted It is connected in output socket；

Described light source 1 is arranged on the top of drive circuit board 3, and region drive circuit board 3 being used for arrange CCD is positioned at light In the range of exposures in source 1, the sensitive surface of CCD is relative with light source 1；Described ammeter 2 connects with output socket and processing module 4 respectively Connect；Processing module 4 is connected with output socket；

Described drive circuit board 3 can make the light integrated area of CCD be continuously maintained in light integrating state by drive socket；With Time, drive circuit board 3 can make the charge pathway between the light integrated area of CCD and vertical transitions district persistently keep by drive socket In conducting state；Meanwhile, drive circuit board 3 can be made between the vertical transitions district of CCD and horizontal transfer district by drive socket Charge pathway is continuously maintained in conducting state；Meanwhile, drive circuit board 3 can by drive socket to the output control gate of CCD and Resetting gate periodically applies to control pulse, and when CCD is by illumination, CCD just can periodically outside output signal；Meanwhile, The output signal of CCD outwards can be exported by described drive circuit board 3 by output socket；

Electric current at output socket can be detected by described ammeter 2, and exports testing result to processing module 4；

The output signal of CCD can be sampled by described processing module 4, and the signal sampled is converted to digitized map Picture, it is thus achieved that after digital picture, the pixel average in digital picture is extracted by processing module 4, then by pixel average Be converted to corresponding ccd signal amplitude.

Further, described drive circuit board 3 is made up of built-up circuit and control module；Described drive socket and output are inserted Mouth is arranged on built-up circuit, and the output signal of described control module energy drive socket is controlled.

Further, described control module uses FPGA to realize.

Further, described test device being provided with shell, light source 1 and drive circuit board 3 are wrapped in by described shell In, shell uses light blocking material to make.

Claims (4)

1. one kind for detecting the test device of CCD charge conversion factor, it is characterised in that: described test device by light source (1), Ammeter (2), drive circuit board (3) and processing module (4) composition；The intensity of illumination of described light source (1) can regulate；Described drive Being provided with multiple drive socket and output socket on dynamic circuit board (3), the driving pin of CCD is plugged in drive socket, CCD's Output pin is plugged in output socket；

Described light source (1) is arranged on the top of drive circuit board (3), and the upper region for arranging CCD of drive circuit board (3) is positioned at In the range of exposures of light source (1), the sensitive surface of CCD is relative with light source (1)；Described ammeter (2) respectively with output socket and place Reason module (4) connects；Processing module (4) is connected with output socket；

Described drive circuit board (3) can make the light integrated area of CCD be continuously maintained in light integrating state by drive socket；Meanwhile, Drive circuit board (3) can make the charge pathway between the light integrated area of CCD and vertical transitions district persistently keep by drive socket In conducting state；Meanwhile, drive circuit board (3) can be made between the vertical transitions district of CCD and horizontal transfer district by drive socket Charge pathway be continuously maintained in conducting state；Meanwhile, drive circuit board (3) can be controlled to the output of CCD by drive socket Grid and resetting gate periodically apply to control pulse, and when CCD is by illumination, CCD just can periodically outside output signal；With Time, the output signal of CCD outwards can be exported by described drive circuit board (3) by output socket；

Electric current at output socket can be detected by described ammeter (2), and by testing result output to processing module (4)；

The output signal of CCD can be sampled by described processing module (4), and the signal sampled is converted to digital picture, After obtaining digital picture, the pixel average of digital picture is extracted by processing module (4), then pixel average is changed For corresponding ccd signal amplitude.

Test device for detecting CCD charge conversion factor the most according to claim 1, it is characterised in that drive described in: Dynamic circuit board (3) is made up of built-up circuit and control module；Described drive socket and output socket are arranged on built-up circuit, institute The output signal stating control module energy drive socket is controlled.

Test device for detecting CCD charge conversion factor the most according to claim 2, it is characterised in that: described control Molding block uses FPGA to realize.

Test device for detecting CCD charge conversion factor the most according to claim 1, it is characterised in that: described survey Being provided with shell on electricity testing device, in light source (1) and drive circuit board (3) are wrapped in by described shell, shell uses light blocking material Make.