2019-09-02 Bloomberg Businessweek

ByE.TammyKim

PhotographbyDanielShea

Night Vision Binoculars

Nightvisiontechnologyhasbecomereliableandwidespread,

usedbyeveryonefromsoldierstobirders.Althougha digital

approachis becomingpopular,lightintensificationremainsthe

industrystandard.Asmoonlightreflectedoffanobjectenters

thesebattery-poweredbinoculars,itpassesthroughthelensinto

animage-intensifyingtube.A photocathodethenconvertsthelight

intoelectronsthatareamplifiedbya photomultiplieranddirected

towarda phosphorescentscreentoproducea visibleimage.

Whenlight,in theformof

photons,hitsthehigh-

voltageintensifiertube,it

interactswitha negatively

chargedphotocathode

normallymadeofalkali

metals(sodium,potassium,

andcesium)ormetalloids

suchasantimony.

Maycontain

or require

PRODUCT COURTESY NIGHT OWL OPTICS, FIRST TEXAS PRODUCTS LLC

Themetalstransferenergy

fromthelightparticlesto

electronsthat,withthehelpof

thebattery,areaimedatthe

screen.Weseetheresulting

imagein green,whichhasa

wavelengthof 532 nanometers.

Theglasslens(silicon

dioxide)is chemically

treatedtoabsorband

channelasmanylight

particlesaspossible.

6

C

Carbon

7

N

Nitrogen

8

O

Oxygen

1

H

Hydrogen

3

Li

Lithium

11

Na

Sodium

14

Si

Silicon

15

P

Phosphorus

19

K

Potassium

51

Sb

Antimony

55

Cs

Cesium

PROP STYLIST: ANNA SURBATOVICH

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