The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 23, 1989
Filed:
May. 04, 1987
Emil Kamieniecki, Lexington, MA (US);
William C Goldfarb, Melrose, MA (US);
Optical Diagnostic Systems, Inc., Billerica, MA (US);
Abstract
A method and apparatus are described for the nondestructive readout of a latent electrostatic image formed on a sheet or layer of insulating material. A sheet or layer of semiconductor material is disposed in relatively close proximity to the insulating material. A latent electrostatic image formed on the insulating material (by any known means) causes a surface depletion layer to be produced by induction at the surface of the semiconductor material. The location and distribution of the accumulated charges on the semiconductor material are read out as analog electrical signals corresponding to the AC surface photovoltage induced on the semiconductor material as the semiconductor material is scanned with a low intensity modulated light beam of appropriate wavelength, the magitude of the analog signals depending on the local charge density. The analog electrical signals so obtained are then digitized, processed and stored and/or displayed.