Answer: microdot

AnswerCrossword Clue
MICRODOT1mm pic
MICRODOTSpy's device
MICRODOTUltrasmall photo
MICRODOTSpy pic, maybe
MICRODOTPinhead-size spy photo
MICRODOTMiniature photograph
microdotA tiny tablet or capsule (of LSD)
microdota copy of printed matter reduced to the size of a dot
microdotA microphotograph, esp. of a printed or written document, that is only about 0.04 inch (1 mm) across
microdotDenoting a pattern of very small dots