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In

NRL Memorandum Report 5702

VIM

A Gated Microchannel Plate Image IntensifierPackaged in a Reflex Camera Back

S. HAUVER, R. E. PECHACEK, J. R. GREIG,D. P. MURPHY AND M. RALEIGH

Experimental Plasma Physics BranchPlasma Physics Division

December 19, 1985

"V.•

This research was supported by the Defense Advanced Research Projects Agency and monitored bythe Naval Surface Weapons Center under Contract #N60921-85-WR-W0240.

1,1.I41 OF4 4

al-

NAVAL RESEARCH LABORATORYWashington, D.C.

Approved fo. public relfase. distribution unlimited.

-.- .... . " •- • . . .. I 1..2 n1sa S S. - . . ---

~TrCT177AMSICATION OF 'rIST~ PAGE 0~ i6 c tREPORT DOCUMENTATION PAGE

Ia. REPORT SECURITY CLASSIFICATION 1b. RESIRICTIVF -MARKINGS

UNCLASSIFIED ______________________

2a. SECURITY CLASSiF)CArION AUTH~ORITY 3 DISTRIBUTION/AI/AILABILITY OF AEPO~r

2b. DECL4SSIFICATIOP'/,DOWNGRADING ýCHEC'ULE Appro-red for public release; distribution unlimited.%~-.

4. PEiRFORMING ORGANIZATION REPORT NUMBER(S) 5. MONITORING ORGo'NIZATION REPORT NIUMBER(S)

NRL.NMemorandum Report 5702

6a. NAME OF PERFORMIN4', ORGANIZATIOlv 6b OFFICE SYMBOL 7a. NAME OF MONITORING ORGANIZATION(if applicable) NNaval Research LAboratory Code 4760 1aval Surface Weapons Center

6C. ADDRESS (City, State, and ZIP Co&e) 7b. ADDRESS (City, State, an ZIP Code)

Washington, DC 20375-500C Whi~te Oak, Silver Spring, MD 20910

aa. NAME OF FUNDINGISPONSORiNG 8b. OFFICE SYMBOL 9 PROCUREMENT INSTRUMENT IDENTIFICATION NUMBER* "WMIIZTION(if applicable)

DARPA______ ________________ __

lBc. ADDRESS (City, State, and ZIP Code) 10. SOURCE OF FUNDING NU.MBERSPROGRAM IPROJECT ITASK( WORK UNIT

Ar-'' A 229ELEMENT NO. NO. NO. ACCESSION NO.* ~'[ 62707E I DN180-127

11 TITLE (include Security Classification)

A Gated Microchannel Plate Image Intensifier Packaged in a Reflex Camera Back

12. PERSONAL AUTHOR(S)Hauver, S., Pechacek, R.E.. Greig, J.R.. Murhy. D.P. and Ptalelah. M.

13a. TYPE OF REPORT 13b. TIME COVERED 14 DATE OF REPORT (Year Month,f Da) S AECUNTinterim IROM To 1I8 December 19

16. SUPPLEMENTARY NOTATION This research was supported by the Defen6e Advanced Research Projects Ageracy andmonitored by the Naval Surface Weapons Center under Con~ract N60921-85-WR-WO240.

17 COIS4TI CODE 18. SUBJECT TERMS ýConvrsueon reverse ii' necessary and identify by' block number)

FELD GROUP sue GR~OUP -Framing camera) .Image intensifier II

1 9 A8STRAC7 (ContinLe omn reverse it neces~sary and identify~ byakck number)

We describe a fas~t (exposures down to -610 ns) electrically triggered camera back/shutter designed for use with theHa~sselblad 500C still camera. This camera back contains a microchannei plate image intensifier which can be gated

* and provides a gain of approximately X 1000. It reads out on to Polaroid film through a fiber optic face plate. Thegated camera back is interchangeable with the regu~lar Polaroid back (or any other) for the Hasselblad 500C andmaintains the athrough the lens* focu,7ing.

20 DlI,1INUTION/AVAILA~trLITY' OF ABSTRACr 121. ABSTRAC, SECURITY CLASSIFICArION *MJNCLASSIFIED.'UNLIN-4TED 0 SAMC A' LIP'. r7ITIC USERIS UNCLASSIFIED ______

22s3 NAMIE OF RESONSBLE INCIIV.0JAL 22b TELLIEPONE (include Area Code)722c )FFiC. STM aO0* R. E. Pectiarek 0) 767-2 077 Code 4763

* - OD FORM 1473,84 MAR 83 APR edition mvay be used uflt! ena"t~d SEC.URITY C.A!SSI'Ar OjFTlSP GEAll othier editions are obsolitet

CONTENTS

I. IINTRODUCTION............................................1

II. DESCRIPTION OF CAMERA...................................2

a) Mechanical Detail.....................................2b) Electrical Detail........................................3

* -L11. EXAMPLE OF RESULTS......................................4

rv. (IONCLUSIONS............................................. 5

V. ACKNOWLEDGMENT........................................5

VI. REFERENCES............................................. 16

Accession For

NTIS GRA&IDTI(,' TABthmannounced tJustification

2 -Distr~bution/

Availlability CodesjAval an d/cr

Dist Seial

-13

% R', f,

"A GATED MICROCHANNEL PLATE IMAGE INTENSI[FIER"PACiKAGED IN A REFLEX CAMERA BACK

1. INTRODUCTION

One of the missions of our ExDperiinental Plasma Physics group is to study

tne interaction of charged particle beams with reduced density channels in

atmospheric pressure air. Reduced density channels are produced by lasers or

electrical discharges. which emit orders of magnitude more light than is

emitted by a channel-electron beam interaction. In order to photograph the

interaction it is necessary that the camera shutter be closed during the

channel producing discharge and open a few microseconds later for the passage

of the electron beam pulse. It was for this reason that this gated image

intens'fler package was designed.

The proximity focussed microchannel plate intensifier tube (ITT F-4111)

used in thiis package is , continuous operation amplifier of a type used in

night vision devices. .. h.. fi-rst reported use of a channel plate tube as a

-fast shutter was by Albert J. Lieber in 1972, who achieved a shuttering time

of four' nanoseconds. N.P.S. King, et al.,2 reported shuttering times of one

nanosecond for the F-4111. The device described in this present paper uses an

electrical configuration very close to the one described by these later

authors.

The conri~rbution of the present work is one of convenience and

versat:lity. The image intensi.fier package is mounted, interchangeably, on

the bac< of a reflex camera witn its photocathode located at the camera's

-a plcane and a PacK Polaroid f! '!-M OeSLed aga±nis fiber-optic outolft

olate -2'zire 1). A scene to te photographed torough the image intensifier is

focssed -through the rf.lex ort.os of thE camera. No co.ntl.uou_ oe-ation

Manieaipt approved October 9, 1985.

†; . .7.- .

'focus' mode i- necessary for the image intensifier. Further, by replacing

"the image intensifier package with a regular polaroid film back, the scene can

be photographed directly for alignment or reference purposes. Lastly, this

image intensifier system has the advantage of a complete camera system: a

variety of commercially available accessories and a large variety of lenses

-.- each with its own mechanical shutter and iris.

II. DESCRIPTION OF CAMERA

1% a) Mechanical Detail*i The image intensifier package consists of three parts: a metal adapter

plate that mates with a Hasselblad 500/C, an aluminum housing that contains

* the intensifier tube, and a standard plastic Polaroid film pack holder. The

adapter plate and the film pack holder make up a standard 500/C Polaroid

back. in its operating position, the image tube photocathode is located at

the image plane of the camera lens, the output fiber-optic plate is pushing

gently against the Polaroid film, and the film pull-tabs are covered by a

lever. Pulling the lever to expose the pull-tabs also moves the intensifier

tube away from the film, allowing the film to be pulled without wiping on the

fiber-optic plate. The only alterations of standard parts necessary for

assembly of the package are removal of a glass plate from the metal adapter

*l plate and trimming about onE millimeter of the silicone potting comround from

the photocthnote end of the intensifier tube.

Figure 2 is an assembly drawing of the image intensifier housing. Figure

2a is a view of tne siýe that faces the Hasse!blad camera. The cove'olate for

* Tis side is t.e m..al aCapter plate for a Hasselbiad supplied >olaro..o 2-Lrr

"oImera bacý. Al_ of t:he mechan-ca. mat:in mechanisms are thus et,4een.

cHamselrlad parts. n the operating position, the PhotocatnoIe of t.e

1k

,i •...-,- 2i -2 ,i "> .--.- .- , -i-. .< < ., -i -U >"- -> .> -~ .... ..-%.' - 0 -' " -,.: • ., "": . ,,

intensifier tube, including a .135 inch thick silica window, is at the focal

plane of the lens.

Figure 2b is a view of the other side of the housing. This side faces a

pack of Polaroid film and, in the operating position, the fiberoptic faceplate

of the intensifier tube touches the film. The mechanical complexity of the

device is due to the necessity of removing the fiberoptic faceplate from the

Polaroid film when the film is being pulled. The intensifier and holder are

moved away from the film by raising the thumb lever from its normal vertical

osition to a horizontal position. This motion not only moves the intensifier

but it also uncovers the film tabs so that they may be pulled. The thumb

lever is linked to the cam as shown in Figure 2b, and lifting the thunm lever

moves the cam to the right. It is not evident from the assembly drawings, but

the cam can only move left and right, and the intensifier holder can only move

into and out of the plane of the drawing. Two pairs of diagonal slots are

milled into the cam, and as it moves right and left, the cam following rods

* must slide in and out. The range of motion of the intensifier is about 0.030

inches.

b) Electrical Detal!

Figure 3 is an electrical schematic diagram for the ITT F-4111 proximi*ty

focused channel plate :ntensifier tute. The device requires three voltages

plus ground. in the circuit of this system, the inout side of the of the

micrccchannel plate s chosen as ground. A positive dc voltage is applied to

"the ýhotocathote to keep the tube off unless it is pulsed. The outpu t side of

.n e microchanne! -late is tiased to about -C3 Jvolts, Drov v1ng a noT.1ina Zain

of '0,000. The P-20 pnosohor, aluminized anode is biased 5000 volts above the

ii.crochannel plate output side. To turn the tube or, the cathode is pulsed

.w4.:i a negati'ie voltage large enough to overcome the oositive bias and

accelerate photo-electrons into the microchannel plate. The bias voltages are

si..Il.ed' a battery Doerated power supply manuactred by ..- 1 .lectrcni-s, a

cozoanvr that sceciali-es in image ltenoifying tube power supplies. The power

supply is equipped with safety features to prevent the tube from being damaged

by too intense a light input and too ihigh a microchannel plate bias voltage.

The negative gate pulse to the photocathode is a 50 ohm signal between 80

and !20 volts. There are two coaxial connectors leading to the

photocathode. One is used as the input nonnector and the other is to be

terminated. it is useful to use as a termination a line back to an

oscilloscope input, in th~s way, for fast pulse operation, the pulse

-egradation can be monitored.

Appendix I contains manufacturers' data sheets on the Intensifying tube

and the battery operated power supply.

1:l. EX1MPLE OF RESULTS

-ihe net optical gain of the system is about 7000. This number is

"* etermined by comparing film exposure generated directly on the film by an

open shotter photograph of an electrical discharge of known duration through a

set of neutral density flilters, with the film exposure of the same scene

..... he ntensier pulsed fDr se, Žra_ nanoseconds. The same camera and

ei.ns are :;sed 2n both exoosures. A regular polaroti film pack tack is ;;sed

"2 • t:-he first exposure, and the intensifier back for the second. The neutral

!ens, ty .:lters are adjusted to obtain equal exposures and the gain is

2u outed by equating the Productr of lght lain times exposu:re tine for t.e

4

-.;i two equal exposures. This gain is about a factor of ten lower than the quoted

light gain, which is a cw gain.

* Figure 4 is a 100 ns exposure of an interferogram of a reduced density

channel generated by a pulsed CO 2 laser beam ýn one atmosphere of nitrogen

that has been seeded with SF 6 . The interferometer is back lighted by a 0.5 mw

cw HeNe laser. The off-on contrast ratio of the intensifier is such that the

laser :,ay impinge on the ungated cathode for as long as thirty seconds before

tie film is fogged. The two burn spots in the photograph are the result of

•, trying to increase the pulse current capability of the channel plate electron

multiplier and the phosphor anode in an effort to bring the pulse gain up to

the value of the quoted cw gain.

"- IV. CONCLUSIONS

This report describes a single frame, fast (of the order of ten

- nanoseconds exposure time) exposure camera system with a light amplification

factor of 1000. The system uses a commercially available proximity focused

4 micro-channel plate intensifier tube and the Hasselblad 500/C still camera

- svstem. The cost of the single frame system, including a modest lens, came."a

* body, two Polaroid backs, intensifier tube, battery operated power supply, and

machine work is about $13,000.

V. ACKNOWLEDGMENT

The authors are grateful to George Yates of Los Alamos National

Laboratory for discussions and information on the design of fast pulse

gerneraturs.

Thls work was supported by the Defense Advanced Research Project Agency

and monitord by the Naval Surface Weapons Center.

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, .*.

.* . . . . .. . .- .- - , . , . , .. ,, . .

F-41 11, F-411 2, F-4"•13

"NOTE I Other photoathodes availible on special order, inm:ude the S-1.to provide drtectiun and ce'ler~ion of 1.06 A, i.a nd. nd ,T•T. C(Icathode, for special UW" applicutiis.

NOTE 2 Fiber optim, quartz, 'g"02. or other material, availabe on specialorder. SPECTRAL OUTPUTP-20 PNOSPHORNOTE 3 Other phosphors available on special order. _____P_20 _PHOSPHOR

NOTE 4 Power Supplies can 6e an integr~l part at ,he tube abs•emblv. Gate-able -.nd DC power supplies are a.ailable as separale unitN. Cc

:VOTE 5 Defined as the rmtio of thl total luminou, flux Irom the phosphorscreen to the total luminous flux incident on the phtolocathode from astandard 2.8540 K ru.plen lamp, and measured with a photometer as 40ft-l/ft-c with an input level of IXIO"5 ft-c incident on the pholocathode.The ITT proximity focused channel intensifier tube provideb a variable tube"gain by varying the microchannel plate voltaice. -0

"NOTE 6 There is no degradation of resolution from ,ccnter-to-edge ot screen. 04Re~solution is mea.utd vith 5 X 10-4 footcandle% on the photocathode to 4 45 -,M Gt'"S

determine limiting. or 5 per cent NITF levels %ith a 100 per cent cowr-t* tarEct.

NOTE 7 For coatinuous operation: this value rnay be se.veral orders of m-,gi-p tude hicher for puied oper2tion.

T`YPYCAL 1ATUSAT16f C~ftt"Of PROX0K 177 ,scuSue '7.79CMtAb CW4CARACTMSTfICS ".CAI PfIOuVIa. of

MIC[OCK•i•IL Whflfl TURN of PUICIK 7 1OCUSED ,,FOK OC51O0MI!NOC. ( -- PC YU W, WAFI. ?WON - l

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.4.

TYP' ,AL AB`.OLUTESPECTRAL RESPf'NSE CHIARACTERISTICS

C DA A:

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"Dimensiioial Data I Smir. F411 I 5mni 2 F4112 40mm F-4113 Unit"A Maximum diameter

R Length inominal) 21 21 1 24 mmC Useable Photocathode Aperture IS 25 40 mmi D Useable Screen Aperture is 25 40 mmPotted Weigh t 60 215 grams

ELECTRO-OPTICAL PRODUCTS DIVISION 1173700 E. Pontia~c St. Fort Wayne, Ind. 460

14

ill:--

q . P electrenics.inc 12 _ti ma-32 * mwe73.I*I0

COMPACTr IMAGE INTeNSIFIER TUIBE

GATEABLE" POWER SUIPPLY

MAX

MODEL 2121SP A

Dirre!nslos are in !,:11es

* *Ca-oact Sizevo Ictace Contr-i or P-.c Control ý'V 'S~ec"if when orcer- rg)

*Adjustable ABC shu:z.'wnGrounded ¶?n

SPEC "A ,:p &IAMF77 U.; : "-!' ':C: I' ~ Ax RE.'4A~rS

In1out 701i'age (e,.L S+ +VDC 4.3 5.2 .3 -

Tnout Current lin MAdc - 125 200 -

Cathode Off ~LýL~ +V +WOC 25 30 325 Ref zo MCP-inMCP.Kn A 1 -, VDC - 0 - At B- PotentialMOP-Out 0.4~-- V2 +VDC 700 - 800 Ref to MCP-InAnode YaLLeb wt V3 +VDC 4500 KCOO 5500 Refý to MCP-0utCathode Load CL~ l f - - 100 '18M riruoeMC?-Out Load RL? W2 30 - - -

Anode Load RL3 G, Limited by ABC;,noce! Sense ABC nA d o -

i mperature: Labocra zory Env ironment ~Rco.-i)

1. ABC shuzcc.wn ijustaole with interna bozazi ..ce:er.2. 0 volage tnrol '.ICP models, the '.CP ^uz:zu- voctage is adjuste4 .'i a

Cto +10 '.dc anplie, :. I~.~nr 1 .a ~.a~u~~Pv~aein additicn, trie -Pnaxirnum -ý volitage at - lk' V.dc car be se: via an internal

iax-. '1 ta mz:z

3. On oovl-.Ia nitra

I . A

VI, REFERENCES

1. Albert J. Tileber, Rev. Sol. Instr., Vol, 43, p. 104 (1972).

2. N.P.S. King, G.J. Yates, S.A. Jaramillo, J.W. Ogle, J.L. Detch, Jr., Los

Alamos National Laboratory Report L'AU-81-1126.

I1

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'.4,

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_ _._.. ._ _ ._ _... . . . - . . . . . . . . . . . .a. .