David L. Hecht

Laser Printing With The Linear TIR Spatial Light Modulator

A linear spatial light modulator has been developed for laser printing. It provides capability for parallel modulation of several thousand points across a line of illumination, which is then imaged onto a photosensitive medium. The spatial light modulator, which has been described previously, utilizes a VLSI silicon chip containing addressing electronics, drive transistors, and a series of metal lines. This chip is pressed against a single crystal piece of lithium niobate, so that flinging fields created by voltage differences between metal lines are proximity coupled into the crystal and generate locally controllable changes in the index of refraction. The device is read out in total internal reflection off the proximity coupling interface, with schlieren readout imaging optics used to convert the phase modulation of the wavefront to a modulated line image. This paper will review the basic device concept, describe some of the device design and operating parameters, discuss printer application considerations, and show results from a breadboard level printer.

Advanced optical information processing with total internal reflection electro-optic spatial-light modulators

This paper presents an overview of advanced optical information processing with Total Internal Reflection Electro-optic Spatial Light Modulators which have been developed to realize high performance image bars for optical recording applications such as xerographic printing. The examples emphasize special techniques enabled by modeling the electro-optic interaction in grazing incidence geometry; these include methods to control the size, position, uniformity, and efficiency of pixels by adjusting illumination conditions, electrode geometry, and spatial frequency filters.

Acoustooptic And Electrooptic Diffraction Light Modulators

This paper presents an overview of the operating principles and characteristics of acoustooptic and electrooptic diffraction light modulators. Functionally, these may be categorized into temporal light modulators, spatial light modulators, and tuneable color filters. Physically, they may be categorized by driving mechanism and by optical geometry. Acoustooptic modulators may employ traveling wave or standing wave ultrasonic fields to induce photoelastic modulation of the optical indices of refraction. Electrooptic modulators may use electrostatic fields or traveling electromagnetic waves. The three principal classifications based on optical geometry are bulk-wave, total internal reflection, and guided optical wave devices. In bulk optical devices, the optical beam interaction occurs within the active medium, largely unaffected by material interfaces. In total internal reflection devices, the optical beam can interact with a perturbation confined near surface of the active material, but otherwise maintains bulk propagation characteristics. In guided wave optical devices, the light is confined to a dielectric waveguiding structure whose optical index characteristics are further perturbed by the active modulation. For most diffraction modulators, the controlling physical principle is the conservation of momentum, which may be elaborated as wavevector matching or phase matching conditions. Spatial light modulators involve control of the wavevector components transverse to the optical propagation direction. Color filters affect the wavevector component along the optical propagation direction. Temporal modulators affect the amplitude or frequency of a light source considered as a whole: they may utilize transverse or longitudinal modulation; frequency shifts are fixed by the conservation on energy.

VLSI-based image bar for laser beam recording

There are many image bar technologies which make use of a full width light modulator which projects one-to-one onto the photoconductor. An alternative to these full width image bars makes use of a micro image bar, in which all of the drive electronics are integrated on a single monolithic VLSI circuit. The TIR linear spatial light modulator is such a device which is built using an integrated circuit in conjunction with an electro-optic crystal to achieve light modulation.There are many image bar technologies which make use of a full width light modulator which projects one-to-one onto the photoconductor. An alternative to these full width image bars makes use of a micro image bar, in which all of the drive electronics are integrated on a single monolithic VLSI circuit. The TIR linear spatial light modulator is such a device which is built using an integrated circuit in conjunction with an electro-optic crystal to achieve light modulation.

Alultibeam Acoustooptic And Electrooptic Modulators

Multibeam acoustooptic and electrooptic modulators enable ideband laser recording and optical data processing with reduced speed mechanical scanning. This paper presents an overview of the characteristics of several types of multibeam modulators based on optical diffraction including multifrequency AO, multiport AO, and E0 modulator arrays. First, the functions of multibeam modulators in page and disc recording formats are reviewed. The characteristics of acoustooptic traveling wave modulators are discussed with particular emphasis on the modulation capabilities of multifrequency multibeam modulators in parallel and sequential operation. The alternative imaging operation mode of acoustooptic modulators is described including pulse imaging and snapshot imaging. The characteristics of multiport AO modulators with multiple rf channels are compared with those of multifrequency modulators. Finally, full line simultaneous recording techniques are considered with some comparison of recently developed electrooptic spatial light modulators and acoustooptic methods.