Security device with compact mid-ir laser

Abstract

A compact mid-IR laser device utilizes a quantum cascade laser to provide mid-IR frequencies suitable for use in molecular detection by signature absorption spectra. The compact nature of the device is obtained owing to an efficient heat transfer structure, the use of a small diameter aspheric lens and a monolithic assembly structure to hold the optical elements in a fixed position relative to one another. The compact housing size may be approximately 20 cm×20 cm×20 cm or less. Efficient heat transfer is achieved using a thermoelectric cooler TEC combined with a high thermal conductivity heat spreader onto which the quantum cascade laser is thermally coupled. The heat spreader not only serves to dissipate heat and conduct same to the TEC, but also serves as an optical platform to secure the optical elements within the housing in a fixed relationship relative on one another. A small diameter aspheric lens may have a diameter of 10 mm or less and is positioned to provided a collimated beam output from the quantum cascade laser. The housing is hermetically sealed to provide a rugged, light weight portable MIR laser source.

1 . A handheld security device viewable by a thermal imaging system, the device comprising:
 (a) a handheld housing having an interior and an exterior;   (b) a quantum cascade laser retained in the interior of the housing for emitting a beam at a thermal infrared wavelength along a beam path, a portion of the beam path extending from the housing to a target being substantially optically direct, the beam forming part of a thermal image of the target;   (c) a driver retained within the housing and operably connected to the quantum cascade laser causing the quantum cascade laser to emit the beam along the beam path   (d) a lens located in the beam path; and   (e) a power supply retained within the housing and operably connected to at least one of the driver and the quantum cascade laser.   
     
     
         2 . The handheld security device of  claim 1 , wherein the wavelength of the beam is between approximately 2-30 microns. 
     
     
         3 . The hand held security device of  claim 1 , wherein the device comprises an aiming device. 
     
     
         4 . The handheld security device of  claim 1 , further comprising a temperature controller thermally coupled to the quantum cascade laser. 
     
     
         5 . The handheld security device of  claim 4 , wherein the temperature controller is one of a Peltier module and a Stirling module. 
     
     
         6 . The handheld security device of  claim 4 , wherein the temperature controller maintains a substantially uniform temperature across the quantum cascade laser. 
     
     
         7 . The handheld security device of  claim 1 , wherein the power supply is operably connected to the both the quantum cascade laser and the driver. 
     
     
         8 . The handheld security device of  claim 1 , wherein the driver is controlled in response to a temperature of the quantum cascade laser. 
     
     
         9 . The hand held security device of  claim 1 , wherein humidity within the housing is controlled during operation of the laser. 
     
     
         10 . The handheld security device of  claim 1 , wherein the beam exiting the housing is generated by a single emitting structure. 
     
     
         11 . The hand held security device of  claim 1 , wherein the quantum cascade laser is retained within a sealed subhousing in the interior of the housing. 
     
     
         12 . The handheld security device of  claim 1 , wherein the housing defines an aperture and the lens comprises a collimating lens disposed at the aperture of the housing. 
     
     
         13 . The handheld security device of  claim 12 , wherein the lens comprises a collimating lens forming an interface between the interior and the exterior of the housing. 
     
     
         14 . The hand held security device of  claim 13 , wherein the substantially optically direct portion of the beam path extends from a collimating lens to the target. 
     
     
         15 . A method of marking a target comprising:
 (a) intersecting a thermal infrared beam from a quantum cascade laser retained in handheld housing at room temperature with the target, a portion of a beam path extending from the housing to the target being substantially optically direct;   (b) capturing a portion of the beam; and   (c) forming part of a thermal image of the target with the captured portion of the beam.   
     
     
         16 . The method of  claim 15 , further comprising forming the infrared beam to have a wavelength between approximately 8 microns and 30 microns. 
     
     
         17 . The method of  claim 15 , further comprising forming the infrared beam to have a wavelength between approximately 2 microns and 5 microns. 
     
     
         18 . The method of  claim 15 , further comprising sealing the quantum cascade laser in the housing. 
     
     
         19 . The method of  claim 15 , further comprising hermetically sealing the quantum cascade laser in the housing. 
     
     
         20 . The hand held security device of  claim 15 , further including maintaining a substantially uniform temperature across the quantum cascade laser. 
     
     
         21 . The method of  claim 15 , wherein the beam exiting the housing is generated by a single emitting structure. 
     
     
         22 . The method of  claim 15 , further including modifying control of the quantum cascade laser in response to a temperature change profile unique to the quantum cascade laser. 
     
     
         23 . A security device viewable by a thermal imaging system, the device comprising:
 (a) a housing mounted to a firearm, the housing having an interior and an exterior;   (b) a quantum cascade laser retained in the interior of the housing for emitting a beam at a thermal infrared wavelength along a beam path, the beam forming part of a thermal image;   (c) a driver retained within the housing and operably connected to the quantum cascade laser;   (d) a lens located in the beam path; and   (e) a power supply retained within the housing and operably connected to the quantum cascade laser.   
     
     
         24 . The security device of  claim 23 , wherein the wavelength of the beam is between approximately 2-30 microns. 
     
     
         25 . The security device of  claim 23 , wherein the device comprises an aiming device. 
     
     
         26 . The security device of  claim 23 , further comprising a temperature controller thermally coupled to the quantum cascade laser. 
     
     
         27 . The security device of  claim 26 , wherein the temperature controller is one of a Peltier module and a Stirling module. 
     
     
         28 . The security device of  claim 26 , wherein the temperature controller maintains a substantially uniform temperature across the quantum cascade laser. 
     
     
         29 . The security device of  claim 23 , wherein the quantum cascade laser is retained within a sealed subhousing in the interior of the housing. 
     
     
         30 . The security device of  claim 23 , wherein the beam exiting the housing is generated by a single emitting structure. 
     
     
         31 . A handheld security device viewable by a thermal imaging system, the device comprising:
 (a) a handheld housing having an interior and an exterior;   (b) a quantum cascade laser retained in the interior of the housing for emitting a beam at a thermal infrared wavelength along a beam path, a portion of the beam path extending from the housing to a target being substantially optically direct, wherein the quantum cascade laser is retained within a sealed subhousing in the interior of the housing;   (c) a driver retained within the housing and operably connected to the quantum cascade laser causing the quantum cascade laser to emit the beam along the beam path;   (d) a lens located in the beam path; and   (e) a power supply retained within the housing and operably connected to at least one of the driver and the quantum cascade laser.   
     
     
         32 . A security device viewable by a thermal imaging system, the device comprising:
 (a) a housing mounted to a firearm, the housing having an interior and an exterior;   (b) a quantum cascade laser retained in the interior of the housing for emitting a beam at a thermal infrared wavelength along a beam path, wherein the quantum cascade laser is retained within a sealed subhousing in the interior of the housing;   (c) a driver retained within the housing and operably connected to the quantum cascade laser;   (d) a lens located in the beam path; and   (e) a power supply retained within the housing and operably connected to the quantum cascade laser.   
     
     
         33 . A method of marking a target comprising:
 (a) intersecting a thermal infrared beam from a handheld housing at room temperature with the target, a portion of a beam path extending from the housing to the target being substantially optically direct;   (b) viewing the intersected beam with a remote thermal imaging device;   (c) capturing a portion of the beam; and   (d) forming part of a thermal image of the target with the captured portion of the beam.   
     
     
         34 . A method of marking a target comprising:
 (a) intersecting a thermal infrared beam from a quantum cascade laser retained in a housing mounted to a firearm at room temperature with the target;   (b) capturing a portion of the beam; and   (c) forming part of a thermal image of the target with the captured portion of the beam.   
     
     
         35 . A method of marking a target comprising:
 (a) intersecting a thermal infrared beam from a housing mounted to a firearm at ambient temperature with the target;   (b) viewing the intersected beam with a remote thermal imaging device;   (c) viewing the intersected beam comprises capturing a portion of the beam; and   (d) forming part of a thermal image of the target with the captured portion of the beam.   
     
     
         36 . A portable security device configured to create a mark viewable by an imaging instrument, the device comprising:
 (a) a portable housing having an interior and an exterior;   (b) a quantum cascade laser retained in the interior of the housing for emitting a beam at a thermal infrared wavelength along a beam path, a portion of the beam path extending from the housing to a target being substantially optically direct, the beam forming part of a thermal image of the target;   (c) an electronic sub-assembly retained within the housing and operably connected to the quantum cascade laser causing the quantum cascade laser to emit the beam along the beam path   (d) a lens located in the beam path; and   (e) a drive current within the housing operably connected to at least one of the electronic sub-assembly and the quantum cascade laser.   
     
     
         37 . The portable security device of  claim 36 , wherein the wavelength of the beam is between approximately 2-30 microns. 
     
     
         38 . The portable security device of  claim 36 , wherein the device comprises an aiming device. 
     
     
         39 . The portable security device of  claim 36 , further comprising a cooler thermally coupled to the quantum cascade laser. 
     
     
         40 . The portable security device of  claim 39 , wherein the cooler is a Peltier module. 
     
     
         41 . The portable security device of  claim 39 , wherein the cooler maintains a substantially stable temperature across the quantum cascade laser. 
     
     
         42 . The portable security device of  claim 36 , further comprising an optical beam collimator in the beam path. 
     
     
         43 . The portable security device of  claim 42 , wherein the optical beam collimator comprises a collimating lens. 
     
     
         44 . The portable security device of  claim 42 , wherein the optical beam collimator is fixed relative to the beam path. 
     
     
         45 . The portable security device of  claim 36 , wherein the drive current is operably connected to the both the quantum cascade laser and the electronic sub-assembly. 
     
     
         46 . The portable security device of  claim 36 , wherein the drive current is controlled in response to a temperature of the quantum cascade laser. 
     
     
         47 . The portable security device of  claim 36 , wherein humidity within the housing is controlled during operation of the laser. 
     
     
         48 . The portable security device of  claim 36 , wherein the beam exiting the housing is generated by a single emitting structure. 
     
     
         49 . The portable security device of  claim 36 , wherein the quantum cascade laser is retained within a laser device housing in the interior of the housing. 
     
     
         50 . The portable security device of  claim 36 , wherein the housing comprises a transmissive element and the beam path is directed through the transmissive element of the housing. 
     
     
         51 . The portable security device of  claim 50 , wherein the transmissive element comprises a window which forms an interface between the interior and the exterior of the housing. 
     
     
         52 . The portable security device of  claim 51 , wherein the lens is located in the beam path before the window. 
     
     
         53 . The portable security device of  claim 36 , wherein the housing defines an output window and the lens comprises a collimating lens disposed at the output window of the housing. 
     
     
         54 . The portable security device of  claim 36 , wherein the substantially optically direct portion of the beam path extends from a collimating lens to the target. 
     
     
         55 . A method of impinging an infrared beam on a substance comprising:
 (a) intersecting a thermal infrared beam from a quantum cascade laser retained in portable housing at room temperature with a substance, a portion of a beam path extending from the housing to the substance being substantially optically direct;   (b) capturing a portion of the beam; and   (c) forming part of a thermal image of the substance with the captured portion of the beam.   
     
     
         56 . The method of  claim 55 , wherein the method of impinging an infrared beam on a substance comprises a method of detecting a molecular substance and wherein the substance is a molecular substance to be detected. 
     
     
         57 . The method of  claim 55 , further comprising forming the infrared beam to have a wavelength between approximately 8 microns and 30 microns. 
     
     
         58 . The method of  claim 55 , further comprising forming the infrared beam to have a wavelength between approximately 2 microns and 5 microns. 
     
     
         59 . The method of  claim 55 , further comprising sealing the quantum cascade laser in the housing. 
     
     
         60 . The method of  claim 55 , further comprising hermetically sealing the quantum cascade laser in the housing. 
     
     
         61 . The method of  claim 55 , further including maintaining a substantially stable temperature across the quantum cascade laser. 
     
     
         62 . The method of  claim 55 , wherein the beam exiting the housing is generated by a single emitting structure. 
     
     
         63 . The method of  claim 55 , further including modifying control of the quantum cascade laser in response to a temperature change profile unique to the quantum cascade laser. 
     
     
         64 . A security device configured to create a mark viewable by an imaging instrument, the device comprising:
 (a) a housing mounted to a second security device, the housing having an interior and an exterior;   (b) a quantum cascade laser retained in the interior of the housing for emitting a beam at a thermal infrared wavelength along a beam path, the beam forming part of a thermal image;   (c) an electronic sub-assembly retained within the housing and operably connected to the quantum cascade laser;   (d) a lens located in the beam path; and   (e) a drive current within the housing operably connected to the quantum cascade laser.   
     
     
         65 . The security device of  claim 64 , wherein the wavelength of the beam is between approximately 2-30 microns. 
     
     
         66 . The security device of  claim 64 , wherein the device comprises an aiming device. 
     
     
         67 . The security device of  claim 64 , further comprising a cooler thermally coupled to the quantum cascade laser. 
     
     
         68 . The security device of  claim 67 , wherein the temperature controller is a Peltier module. 
     
     
         69 . The security device of  claim 67 , wherein the temperature controller maintains a substantially stable temperature across the quantum cascade laser. 
     
     
         70 . The security device of  claim 64 , further comprising an optical beam collimator in the beam path. 
     
     
         71 . The security device of  claim 70 , wherein the optical beam collimator comprises a collimating lens. 
     
     
         72 . The security device of  claim 70 , wherein the optical beam collimator is fixed relative to the beam path. 
     
     
         73 . The security device of  claim 64 , wherein the quantum cascade laser is retained within a laser device housing in the interior of the housing. 
     
     
         74 . The security device of  claim 64 , wherein the beam exiting the housing is generated by a single emitting structure. 
     
     
         75 . A portable security device configured to create a mark viewable by an imaging instrument, the device comprising:
 (a) a portable housing having an interior and an exterior;   (b) a quantum cascade laser retained in the interior of the housing for emitting a beam at a thermal infrared wavelength along a beam path, a portion of the beam path extending from the housing to a target being substantially optically direct, wherein the quantum cascade laser is retained within a sealed subhousing in the interior of the housing;   (c) an electronic sub-assembly retained within the housing and operably connected to the quantum cascade laser causing the quantum cascade laser to emit the beam along the beam path;   (d) a lens located in the beam path; and   (e) a drive current within the housing operably connected to at least one of the electronic sub-assembly and the quantum cascade laser.   
     
     
         76 . A security device configured to create a mark viewable by an imaging instrument, the device comprising:
 (a) a housing mounted to a second security device, the housing having an interior and an exterior;   (b) a quantum cascade laser retained in the interior of the housing for emitting a beam at a thermal infrared wavelength along a beam path, wherein the quantum cascade laser is retained within a sealed subhousing in the interior of the housing;   (c) an electronic sub-assembly retained within the housing and operably connected to the quantum cascade laser;   (d) a lens located in the beam path; and   (e) a drive current within the housing operably connected to the quantum cascade laser.   
     
     
         77 . A method of impinging an infrared beam on a substance comprising:
 (a) intersecting a thermal infrared beam from a portable housing at room temperature with a substance, a portion of a beam path extending from the housing to the substance being substantially optically direct;   (b) viewing the intersected beam with a remote thermal imaging device;   (c) capturing a portion of the beam; and   (d) forming part of a thermal image of the substance with the captured portion of the beam.   
     
     
         78 . The method of  claim 77 , wherein the method of impinging an infrared beam on a substance comprises a method of detecting a molecular substance and wherein the substance is a molecular substance to be detected. 
     
     
         79 . A method of impinging an infrared beam on a substance comprising:
 (a) intersecting a thermal infrared beam from a quantum cascade laser retained in a housing mounted to a security device at room temperature with a substance;   (b) capturing a portion of the beam; and   (c) forming part of a thermal image of the substance with the captured portion of the beam.   
     
     
         80 . The method of  claim 79 , wherein the method of impinging an infrared beam on a substance comprises a method of detecting a molecular substance and wherein the substance is a molecular substance to be detected. 
     
     
         81 . A method of impinging an infrared beam on a substance comprising:
 (a) intersecting a thermal infrared beam from a housing mounted to a security device at ambient temperature with a substance;   (b) viewing the intersected beam with a remote thermal imaging device;   (c) viewing the intersected beam comprises capturing a portion of the beam; and   (d) forming part of a thermal image of the substance with the captured portion of the beam.   
     
     
         82 . The method of  claim 81 , wherein the method of impinging an infrared beam on a substance comprises a method of detecting a molecular substance and wherein the substance is a molecular substance to be detected.