US 3792535 A
A marksmanship training system combining with a rifle a laser beam transmitter and receiver including an optics system and an indicator means, all of small size and weight and mounted on the barrel of the rifle to form a self-contained unit and including also a target having retroreflective means to provide in the combined system immediate information on hit or miss of the aimed attitude of the rifle toward the target when the rifle trigger is depressed.
Description (OCR text may contain errors)
United States Patent Marshall et a1.
LASER RIFLE SIMULATOR SYSTEM  Inventors: Albert H. Marshall, Maitland;
George A. Siragusa, Winter Park, both of Fla.
 Assignee: The United States of America as represented by the Secretary of the Navy, Washington, DC.
 Filed: Dec. 11, 1972 21 1 Appl. No.: 313,704
 Int. Cl. G09b 9/00  Field of Search 35/25;273/101.l, 101.2
 References Cited UNITED STATES PATENTS 3,633,285 I 1/1972 Sensney 35/25 3,657,826 4/1972 Marshall et al. 35/25 1 [4 1 Feb. 19, 1974 3,452,453 7/1969 Ohlund 35/25 3,499,650 3/1970 Lemelson 273/l0l.l 3,655,192 4/1972 Hall et a1. 273/101.]
Primary Examiner-Robert W. Michell Assistant ExaminerJ. H. Wolff Attorney, Agent, or FirmR. S. Sciascia; J. W. Pease 57 ABSTRACT A marksmanship training system'combining with a rifle a laser beam transmitter and receiver including an optics system and an indicator means, all of small size and weight and mounted on the barrel of the rifle to form a self-contained unit and including also a target having retroreflective means to provide in the combined system immediate information on hit or miss of the aimed attitude of the rifle toward the target when the rifle trigger is depressed.
6 Claims, 4 Drawing Figures PATENTEBFEB 1 91914 SHEET 1 IF 2 FIG.
1 LASER RIFLE SIMULATOR SYSTEM BACKGROUND OF THE INVENTION This invention relates to weapon simulators, and more particularly to a laser, rifle firing simulator for use in training personnel in marksmanship.
Heretofore, lasers have been used on weapons such as tanks or rifles to direct a beam to a target upon which receiver-indicator means provide the necessary means for indicating a hit or miss. Also in the past retroreflective means have been employed on the target to redirect a laser beam, originating from a weapon, back to a receiving photo detector unit for activating a radio transmitter-receiver system to indicate a hit or miss condition. I
Each of the above systems have been limited in application due to size, weight and cost of the required equipment and lack of a self-contained rifle unit which would produce instant visual or audio response to the trainee without extraneous equipment.
SUMMARY OF THE INVENTION In satisfying the above cited needs, according to the subject invention an especially simple and efficient transmitter and receiver circuitry is provided to be mounted with an appropriate lens system on the rifle itself and of such weight and size as to provide the actual feel and weight characteristics of the normal M-l6 rifle. Combined with the above mentioned equipment is an LED light indicator mounted directly on the sight of the rifle or alternatively an audio system such as the sonalert to provide instant response to the marksman as to a hit or miss when the rifle is aimed and the rifle trigger squeezed. A retroreflective means on the target provides for redirecting the laser beam from the target to the rifle mounted receiver adjacent the rifle mounted laser transmitter.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic perspective view of a laser, weapon simulator embodying the invention shown in the position of use in relation to an associated target;
FIG. 2 is an enlarged perspective view of the rifle mounted equipment shown in lesser detail in FIG. 1;
FIG. 3 is a diagrammatic illustration of a laser transmitter circuit employed in the invention; and
FIG. 4 is a diagrammatic illustration of a photodetector receiver, triggering circuit and hit indicator means.
DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a system configuration generally indicated at and incorporating the invention. The system includes a rifle 12 having a trigger l4, sight 16 and barrel 18. On the barrel 18 is mounted, by suitable means, as for example brackets 20, a laser beam transmitter 22, photodetector receiver and amplifier means 24 and on the sight 16 is mounted an indicator means 26 which can be a sonalert audio system or an LED for visual response. The aforementioned elements form with the rifle a self-contained unit, the transmitter and receiver each housing its battery power supply as indicated in FIGS. 3 and 4.
Referring for the moment to FIG. 2, there is shown enlarged and in perspective the mounting of the transmitter 22, receiver 24 and hit indicator 26 on the barrel end of the rifle 12. The hit indicator shown in this view is an LED arranged aligned on the sight 16 to provide immediate visual indication of hit to a marksman firing the rifle when the rifle is correctly aimed and the trigger squeezed.
Referring again to FIG. 1, in accordance with the invention the transmitter 22 and receiver 24 are used in conjunction with a target 28 having attached thereto retroreflective means of different sizes exemplified at 30, 32 and 34. Retroreflective targets of different sizes are provided so that the trainee may progress from large to small diameter reflectors as his skill increases.
Referring to FIG. 3, the laser transmitter provided in accordance with the invention provides the advantages of safety, small size and cost, and reliability. The laser transmitter comprises a collimating lens 36, laser diode 38, laser pulser circuit to be described, and battery power source 40. The laser diode selected is the Gallium Arsenide type wherein the holes and electrons in the p-n junction of the diode are brought in close proximity by injection of carriers caused by a narrow high current pulse. Within a few ns (nanoseconds) they recombine and radiation occurs in the near-infrared region, 9050 at 125 C. As shown in FIG. 3, an SCR 42 is provided as a one-shot pulser being connected by lines 44, 46 and 48 to pass current through the laser 38 to ground indicated. Current is obtained from the battery 40 by charging of a capacitor 50 which is discharged through the SCR 42 to the laser diode 38 when the SCR 42 is conditioned to fire. Thus, battery 40 is connected via lines 72 and 52, resistor 54, line 56 and line 58 to one side of capacitor 50, the other side of which is connected by a line 60 to ground indicated.
The SCR 42 is triggered to ON condition from a capacitor 62 which is charged from the battery 40 via a trigger switch 64 having a normally closed contact 66 and a normally open contact 68 and a contact arm 70. Thus, battery 40 is connected via a line 72, resistor 74, contact 66, arm 70 and a line 76 to one side of capacitor 62, the other side thereof being connected by a line 78 to ground indicated. Normally open contact 68 is connected by a line 80 and a line 82 to the gate 84 of the SCR 42 and by line 80 and a resistor 86 to ground indicated. When the rifle trigger is squeezed to close trigger switch 64 by moving arm 70 to contact 68, the charge on capacitor 62 passes current to ground via resistor 86 and establishes a bias on the gate 84 of SCR 42 to momentarily condition SCR 42 to ON condition. Resistor 54 in series with SCR 42 is selected in value to act as a current limiting resistor such that when bias is removed from the gate 84 of SCR 42 the holding current to the SCR 42 from battery 40 is insufficient to maintain the SCR in ON condition and hence the SCR 42 is conditioned to OFF condition for the next cycle.
While the circuit as thus far described will operate to tire the laser 38, it is preferred to provide an additional identical parallel pulser circuit utilizing an additional SCR 88, capacitor 90 and resistor 92 connected in the same manner as described for elements 54, 50 and 42. Such additional pulser circuit provides additional power output from the laser 38. I
The pulser circuit provides a 20 ampere pulse with a current pulse width of 200 ns at the half-current points. Both current rise and fall times are 50 ns. A 5 watt peak power laser diode is used for laser element 38. The laser starts lasing at a nominal threshold current of seven amperes and the peak pulse output power of 5 watts is reached at 20 amperes at 27 C. Maximum allowable forward current pulse width is 200 ns. Optimum input to the laser diode is a perfect square wave of current. Minimum rise time of such a pulse reduces the time during which most of the current applied to the laser is used to heat the junction rather than to provide useful output. The maximum output pulse length that can be applied to the diode is limited to 200 ns.
To use the beam, indicated by the arrows A (FIG. 3), from the laser 38, it is necessary to collimate the beam by a lens means, indicated at 36. To collect the maximum amount of energy from the laser 38, a lens with an f number of approximately 1.5 is required and to obtain a minimum beam divergence, a long focal length lens is desirable. Thus, a lens with a diameter of 30 mm and with a focal length of 25.5 mm is provided. The detectable beam size at 300 meters is 25 cm.
Referring to FIG. 4, at the receiver end a collector lens 94 directs the collected beam indicated by the arrow B, to a photodetector 96 of the receiver circuit indicated generally at 98. The photodetector 96 is supplied with energy from a power source, as for example battery 100, via lines 102 and 104 and resistor 106. The photodetector is grounded as indicated via a line 108. The photodetector 96 is coupled to an operational amplifier 110 through a capacitor 112 and lines 114, 116 and 118. A suitable amplifier is Fairchild UA 740. The capacitor 112 and resistor 106 in the circuit act as a high-pass filter with the -3dB point on the gain curve at the frequency of 700 Hz. A feedback resistor 120 is connected via lines 122 and 124 across the amplifier 110 to provide the necessary signal gain for use with the photodetector 96 and the amplifier output is coupled via line 126, capacitor 128 and line 130 to the gate 132 of an SCR 134 to trigger the SCR to ON condition. In series with the SCR 134 is provided the indicator 26 which may be a sonalert or an LED and a resistor 136. Power passes through the indicator 26 via lines 138, 140 and 142 to ground indicated when the SCR 134 is triggered to ON condition by action of the amplifier 110 responsive to an output from photodetector 96'. The anode of SCR 134 is connected through a capacitor 144 to the emitter of a unijunction transistor 146, the latter being connected to ground indicated via a line 148 and to power source 100 via resistors 150 and 152 and lines 154, 156, 140 and 138 as indicated. When SCR 134 conducts capacitor 144 is charged to bias unijunction transistor 146 to ON condition. Transistor 146 in conducting short cirucits SCR 134 to interrupt current to indicator 26. The duration of the ON condition of indicator 26 can be determined by the selection of the value of resistor 150.
Advantages of applicants laser rifle simulator system include the fact that the system is simple, inexpensive and effective in training combat personnel in weapon firing techniques. The system includes a transmitter, receiver and indicator combination which attaches to an MA-l6 rifle without adding noticeable bulk or weight to the standard rifle. Scoring is instantaneous without the use of complicated radio relay systems. It is effective against both moving and stationary targets. Safe training can be accomplished in both day and night conditions in inhabited areas and without the use of additional manned scoring equipment.
What is claimed is:
1. A laser rifle simulator system for training in rifle fire against a target comprising:-
a. a conventional rifle having a trigger, sight and barrel,
b. a laser beam transmitter, a laser beam receiver and amplifier means and means for fixedly attaching said transmitter, receiver and amplifier means to the barrel of said rifle to form with the rifle a selfcontained unit,
c. means operable from said trigger for activating said laser beam transmitter in short bursts,
d. indicator means mounted on said rifle and connected to said receiver to provide immediate response to actuation of said receiver while maintaining said self-contained feature, and
e. retroreflector means attached to the target to reflect the beam from said transmitter back to said receiver only when said rifle is properly aimed at the target and the trigger thereof is depressed to thereby actuate said indicator means to indicate a hit.
2. Apparatus according to claim 1, wherein said laser beam receiver and amplifier means comprise a. a photodetector, an operational amplifier and a high-pass filter,
b. said photodetector being coupled to said operational amplifier through said filter circuit to eliminate 60 Hz noise and other low frequency transients,
c. an SCR and an electrically responsive indicator means for connection in series between a source of voltage differential to actuate said indicator means when said SCR is actuated,
d. said SCR being connected for triggering to active condition from an output of said amplifier means, and V e. tum-off means connected to said SCR for interrupting the active state thereof comprising an PET and associated resistors and capacitors selected to determine the conducting period of said SCR and hence the period of activation of said indicator means.
3. Apparatus according to claim 2,
a. said indicator means being an audio system.
4. Apparatus according to claim 2,
a. said indicator means being a light emitting diode.
5. Apparatus according to claim 2, said transmitter means comprising:
a. a laser diode,
b. a laser pulser circuit for actuating said laser diode,
c. a collimating lens system for'collimating the beam from said laser diode, and
(1. battery means as a powersource for said transmitter means.
6. Apparatus as set forth in claim 5, wherein a. said laser pulser circuit comprises a current limiting resistor,
b. an SCR having its anode connected through said resistor to said power source and its cathode connected to the anode of said laser diode,
c. a first capacitor connected to the anode of said SCR for discharging therethrough to said laser when said SCR is conditioned to ON condition.
e. said current limiting resistor being selected in value to provide insufiicient holding current to said SCR whereby said SCR reverts back to OFF condition following the termination of capacitor discharge to the trigger gate thereof.