Downward compatible laser transmission system

Abstract

A downward compatible laser transmitter of radiant energy at a 990 nm wavelength. The transmitter is usable with receivers of 905 nm radiant energy. The transmitted beam is less susceptible to humidity or temperature variations than a beam of radiant energy transmitted at 905 nm.

1 . A method of combat simulation comprising: 
 providing a first plurality of radiant energy transmitters with each transmitter having a beam wavelength with substantially zero atmospheric absorption due to water vapor;    providing a plurality of receivers having a bandwidth between 850 and 1050 nm;    moving the transmitters relative to, at least some of the receivers in a simulated combat scenario;    directing beams of various transmitters toward selected receivers,    generating electrical outputs, indicative of incident beams, from each of those receivers which are sensing an incoming beam.    
   
   
       2 . A method as in  claim 1  which includes setting the beam wavelength to a value substantially equal to 990 nm.  
   
   
       3 . A method as in  claim 1  which includes selecting the beam wavelength from a range that includes 970-1070 nm.  
   
   
       4 . A method as in  claim 2  which includes providing a second plurality of radiant energy transmitters having a beam wavelength on the order of 905 nm, and directing beams from members of the second plurality toward various of the receivers, the receivers being responsive to incident beams from both the first plurality and the second plurality of transmitters  
   
   
       5 . A method as in  claim 4  where beams from transmitters of the first plurality are transmitted with a nominal ocular hazard distance parameter that is less than a corresponding parameter for beams from transmitters of the second plurality.  
   
   
       6 . A method as in  claim 1  where the provided beam wavelength is substantially longer than a cut-off wavelength for selected night vision equipment.  
   
   
       7 . A method as in  claim 1  which includes filtering radiant energy incident on the receivers so as to exclude wavelengths less than 950 nm.  
   
   
       8 . A transmitter/receiver combination comprising: 
 a transmitter of radiant energy at a wavelength in a range of 970-1070 nm;    a receiver of radiant energy, the receiver having a bandwidth between at least 900 and 1000 nm where the receiver includes an optical filter which substantially excludes wavelengths less than 900 nm.    
   
   
       9 . A combination as in  claim 8  where the transmitter emits radiant energy at a wavelength on the order of 990 nm.  
   
   
       10 . A method comprising: 
 providing a plurality of radiant energy transmitters having a transmission wavelength on the order of 905 nm;    providing a plurality of receivers having a bandwidth between 850 and 1050 nm;    producing in respective receivers electrical signals in response to incident radiant energy from the transmitters;    providing a second plurality of radiant energy transmitters having a transmission wavelength on the order of 990 nm;    producing in respective receivers electrical signals in response to incident radiant energy from the members of the second plurality.    
   
   
       11 . A method as in  claim 10  which includes moving the transmitters and the receivers relative to one another, and, directing radiant energy emissions of 990 nm toward respective receivers.  
   
   
       12 . A method as in  claim 10  which includes minimizing absorption of radiant energy emitted from members of the second plurality due to atmospheric humidity.  
   
   
       13 . A method as in  claim 12  which includes minimizing temperature variation effects on radiant energy emitted from members of the second plurality.  
   
   
       14 . A method as in  claim 13  which includes reducing the numbers of the members of the plurality of transmitters thereby reducing human eye safety hazards.  
   
   
       15 . A method as in  claim 10  which includes reducing the number of 905 nm transmitters thereby reducing human eye safety hazards.  
   
   
       16 . A method as in  claim 10  which includes reducing the sensitivity of night vision equipment to the 990 nm radiant energy relative to the sensitivity of the same night vision equipment to the 905 nm radiant energy.  
   
   
       17 . A method as in  claim 10  which includes substantially excluding any radiant energy incident on the receivers that has a wavelength less than 900 nm.  
   
   
       18 . A method as in  claim 13  which includes substantially excluding any radiant energy incident on the receivers that has a wavelength less than 900 nm.  
   
   
       19 . A method as in  claim 17  which includes reducing the nominal ocular hazard distance for radiant energy transmitted at the 990 nm on the order of 15-20% below the nominal ocular hazard distance for radiant energy transmitted at 905 nm.  
   
   
       20 . A combat simulation system comprising: 
 a portable transmitter of laser emitted radiant energy having a wavelength on the order of 990 nm;    a source of energy for the transmitter;    control circuits for energizing the transmitter with energy from the source;    a housing for the transmitter, the source and the control circuits;    a receiver, movable relative to the transmitter, having a reception band between 850 nm and 1050 nm;    circuitry coupled to the receiver for producing a beam incident indicium responsive to incident beams having respective wavelengths of 905 nm and 990 nm.    
   
   
       21 . A system as in  claim 20  which includes night vision goggles, the laser emitted radiant energy is substantially invisible when in a receiving range of the goggles.  
   
   
       22 . A system as in  claim 21  which includes an optional filter for the receiver with a transmission cut-off wavelength on the order of 950 nm.  
   
   
       23 . A system comprising: 
 a plurality of transmitters of beams of radiant energy having about a 990 nm wavelength where the transmitters exhibit a reduced nominal ocular hazard distance when compared to a corresponding parameter of a transmitter of radiant energy at a 905 nm wavelength; and    at least one detector of the transmitted radiant energy, the detector having a predetermined frequency response, the detector including an optical filter to limit the response of the detector to incident radiant energy having a wavelength of at least 900 nm.    
   
   
       24 . A system as in  claim 23  where the detector and filter combination has a passband on the order of 900-1075 nm.  
   
   
       25 . A system as in  claim 24  which includes a plurality of night vision goggles and where the 990 nm transmissions are substantially not visible with the night vision goggles.  
   
   
       26 . A system as in  claim 23  which includes a plurality of detector and filter combinations where each detector includes a radiant energy sensor that has a predetermined bandwidth and an optical filter with a cut off wavelength on the order of 950 nm.  
   
   
       27 . A system as in  claim 25  which includes a second plurality of detectors, the members of the second plurality are responsive to at least 905 nm and 990 nm laser transmissions.  
   
   
       28 . A system as in  claim 26  which includes a plurality of night vision goggles and where the 990 nm transmissions are substantially not visible with the night vision goggles.  
   
   
       29 . A system comprising: 
 a plurality of transmitters of beams of radiant energy having a first wavelength at which virtually no atmospheric absorption occurs due to water vapor and where the transmitters exhibit a reduced nominal ocular hazard distance when compared to a corresponding parameter of a transmitter of radiant energy at a 905 nm wavelength; and    at least one detector of the transmitted radiant energy, the detector having a predetermined frequency response, the detector including an optical filter to limit the response of the detector to incident radiant energy having a wavelength of at least 900 nm.    
   
   
       30 . A system as in  claim 29  which includes a plurality of night vision goggles and where the goggles substantially do not respond to transmissions at the first wavelength.  
   
   
       31 . A system as in  claim 30  where the optical filter substantially blocks incoming radiant energy at wavelengths shorter than about 950 nm.