Laser interrogation of surface agents

A method for laser interrogation of surface agents moving relative to an interrogator, said method comprising the steps of:

• a) providing a laser;
• b) outputting a substantially monochromatic beam from said laser;
• c) focusing said beam with a beam-focusing telescope;
• d) directing said beam at a target substance;
• e) measuring a relative motion between said beam and said target substance;
• f) receiving a distance-to-target signal for a point offset substantially from said target substance;
• g) adjusting a focus of a receiver telescope based on said relative motion and said distance-to-target signal;
• h) receiving inelastically scattered radiation from said target substance at a spectrum of wavelengths characteristic of said target substance with said receiver telescope;
• i) dispersing said spectrum of wavelengths of said inelastically scattered radiation;
• j) imaging said dispersed spectrum onto a focal plane array detector;
• k) comparing said image of said dispersed spectrum of said target substance to an image of a spectrum of inelastically scattered radiation of a known substance;
• and
• l) identifying said target substance if said image of said dispersed spectrum of said target substance matches substantially said image of said inelastically scattered radiation of said known substance.

A system for laser interrogation of surface agents moving relative to the system, said system comprising:

• a laser, said laser outputting an output beam;
• a beam-focusing telescope having an axis of transmission, said beam-focusing telescope receiving and focusing substantially said output beam;
• a first reflector substantially aligned with said axis of transmission for directing said output beam in a first direction, said first direction being substantially perpendicular to the axis of transmission;
• a second reflector substantially aligned with said first direction for directing said output beam in a second direction, said second direction being substantially perpendicular to said first direction;
• a receiver telescope, said receiver telescope having a focal direction substantially opposite to said second direction, said receiver telescope comprising further:
• a primary reflector, said primary reflector disposed to reflect at least some radiation scattered inelastically from a target;
• a focusable secondary reflector disposed to reflect and focus said inelastically scattered radiation toward a first focal point;
• a secondary reflector focusing mechanism to move said focusable secondary reflector along said focal direction;
• a spectrograph, said spectrograph receiving said inelastically scattered radiation from said receiver telescope;
• means for range finding, said range finding means outputting a distance-to-target signal in a third direction;
• wherein said third direction is at a predetermined angle to said second direction in a direction of said relative motion;
• and
• wherein said focusing mechanism moves said secondary reflector based on said distance-to-target signal and a rate of said relative motion to focus substantially said inelastically scattered radiation at said first focal point.

An apparatus for laser interrogation of surface agents moving relative to the apparatus, said apparatus comprising:

• an aluminum honeycomb structure;
• a laser fixedly disposed on said structure, said laser outputting an output beam;
• a beam-focusing telescope fixedly disposed on said structure and having an axis of transmission, said beam-focusing telescope receiving and focusing substantially said output beam;
• a first reflector fixedly disposed on said structure and substantially aligned with said axis of transmission for directing said output beam in a first direction, said first direction being substantially perpendicular to the axis of transmission;
• a second reflector fixedly disposed on said structure and substantially aligned with said first direction for directing said output beam in a second direction, said second direction being substantially perpendicular to said first direction;
• a receiver telescope, said receiver telescope having a focal direction substantially opposite to said second direction, said receiver telescope comprising further:
• a primary reflector, said primary reflector disposed to reflect at least some radiation scattered inelastically from a target;
• a focusable secondary reflector disposed to reflect and focus said inelastically scattered radiation toward a first focal point;
• a secondary reflector focusing mechanism to move said focusable secondary reflector along said focal direction;
• a spectrograph fixedly disposed on said structure, said spectrograph receiving said inelastically scattered radiation from said receiver telescope;
• a range-finder fixedly disposed on said structure and outputting a distance-to target signal;
• wherein said focusing mechanism focuses said secondary reflector based on said distance-to-target signal.

An apparatus for laser interrogation of surface agents moving relative to the apparatus, said apparatus comprising:

• a laser, said laser outputting an output beam;
• a beam-focusing telescope having an axis of transmission, said beam-focusing telescope receiving and focusing substantially said output beam;
• a first reflector substantially aligned with said axis of transmission for directing said output beam in a first direction, said first direction being substantially perpendicular to the axis of transmission;
• a second reflector substantially aligned with said first direction for directing said output beam in a second direction, said second direction being substantially perpendicular to said first direction;
• a receiver telescope, said receiver telescope having a focal direction substantially opposite to said second direction, said receiver telescope comprising further:
• a primary reflector, said primary reflector disposed to reflect at least some radiation scattered inelastically from a target;
• a focusable secondary reflector disposed to reflect and focus said inelastically scattered radiation toward a first focal point;
• a secondary reflector focusing mechanism to move said focusable secondary reflector along said focal direction;
• an optical fiber having a first end and a second end coupling said inelastically scattered radiation from said receiver telescope to a spectrograph;
• said first end being substantially coincident with said first focal point to collect said inelastically scattered radiation;
• said spectrograph comprising further:
• a parabolic reflector, said second end being substantially coincident with a focal point of said parabolic reflector to disperse said inelastically scattered radiation;
• said parabolic reflector disposed to reflect said dispersed inelastically scattered radiation toward a diffraction grating said second end being integral to said diffraction grating, said diffraction grating diffracting said dispersed inelastically scattered radiation;
• and
• a focal plane array detector receiving said diffracted inelastically scattered radiation;
• a range-finder outputting a distance-to-target signal;
• wherein said focusing mechanism focuses said secondary reflector based on said distance-to-target signal.

An apparatus for laser interrogation of a target moving in a direction of motion relative to the apparatus, the apparatus comprising:

• a laser that supplies a beam that strikes the target upon the target entering a predetermined sensing location;
• a focusable receiver that receives a portion of radiation scattered inelastically from the target in response to the laser beam striking the target and focuses the inelastically scattered radiation at a focal point;
• a spectrograph that receives the focused inelastically scattered radiation from the focusable receiver;
• and
• a range-finder that determines a distance-to-target in response to the target entering a location that is a predetermined distance from the sensing location in the direction of relative motion;
• wherein the focusable receiver is focused based on the determined distance-to-target signal and a rate of the relative motion to focus the received inelastically scattered radiation at the focal point.

An apparatus for laser interrogation of surface agents moving relative to the apparatus, said apparatus comprising:

• a laser that generates an output beam;
• a beam-focusing telescope having an axis of transmission in a first direction, the beam-focusing telescope focusing the output beam;
• a reflector substantially aligned with the first direction for directing the output beam in a second direction;
• a receiver telescope having a focal direction substantially opposite to the second direction, the receiver telescope comprising:
• a primary reflector disposed to reflect at least some radiation scattered inelastically from a target;
• a focusable secondary reflector disposed to reflect and focus the inelastically scattered radiation toward a first focal point;
• a secondary reflector focusing mechanism that moves the focusable secondary reflector along the focal direction;
• a spectrograph that receives the inelastically scattered radiation from the receiver telescope;
• a range-finder that generates a distance-to-target signal in a third direction;
• wherein the third direction is at a predetermined non-zero angle to the second direction in a direction of the relative motion;
• and
• wherein the focusing mechanism moves the secondary reflector based on the distance-to-target signal and a rate of the relative motion to focus substantially the inelastically scattered radiation at the first focal point.