Essex Corp. and A.G. Edwards will sponsor an investors' briefing, "Emerging Challenges in Defense and Intelligence," by Arthur Money and retired Army Gens. Kenneth Minihan and Claudia Kennedy, August 12 in Boston. Generals Minihan and Kennedy serve on the company's national programs advisory board. Money is on the Essex board of directors. Essex said it plans additional briefings in Washington and San Francisco later in the fall.    . . .    GSI Lumonics Inc. announced that its long-time distributor Optilase has opened India's first laser processing development center in the province of Chennai. The new facility, Laserline Fabrication, is equipped with GSI Lumonics JK series continuous-wave Nd:YAG lasers used with 5-axis motion systems.Optilase said the facility will be a center in which welding, cutting and drilling applications can be tested and developed from proof-of-principle samples through implementation and final process refinement. It said initial emphasis will be on the automotive, heavy electrical and textile markets; the center will also work on joint projects with the Indian Welding Society.    . . .    Ibsen Photonics, a Copenhagen, Denmark-based supplier of holographic phase masks, transmission diffraction gratings and OEM spectrometer modules based on diffraction gratings, announced it has been granted a US patent, "Grating Structures and Methods of Making the Grating Structures," for technology that enables pure fused silica transmission grating designs with beneficial optical properties. Ibsen said design possibilities include polarization and temperature independence combined with highly robust grating surfaces.