IL111852A

IL111852A - System for eye protection from laser radiation

Info

Publication number: IL111852A
Application number: IL11185294A
Authority: IL
Inventors: Eytan Keydar
Original assignee: Elop Electrooptics Ind Ltd
Priority date: 1994-12-02
Filing date: 1994-12-02
Publication date: 2002-07-25
Also published as: SG64358A1; DE19544770A1; GB2295740B; FR2727767A1; FR2727767B1; IL111852A0; GB9523835D0; GB2295740A

Abstract

An eye-safe laser comprising proximity range-measurement sensing means utilizing a low power light source (19) for ascertaining whether a person is present up to the range at which the laser beam will cause eye damage, and means for actuating a high power laser (11) only if no person is present within such a range. 1852 ט" ז באב התשס" ב - July 25, 2002

Description

EYE PROTECTION SYSTEM FROM LASER RADIATION Field of the Invention The invention relates to laser systems and in particular to a method of rendering the use of a laser system which is otherwise This by way of an auxiliary device or modification of existing laser Background of the Invention Lasers and systems are used extensively in many field applications including remote sensing and All of these systems comprise a laser transmitter which emits a relatively high intensity light beam which generally is a potential hazard to the human The eye safety issue in the operation of lasers and system poses a restriction on the use of such There exists a growing demand for lasers and it proves more difficult to implement this for the industrial and the military In spite of the fact that the military is using a variety of unsafe equipment in the in the safety issue is most and there is a need to be able to use equipment for battle and for In another civil engineering type range finding is performed at low energy for eye safety reasons and a retroreflector is used at the target The possibility to increase the transmitter energy level without compromising eye safety would improve significantly the equipment performance and its To solve problems of using high power lasers without endangering the three approaches exist The use of a wavelength of emission where a relatively high intensity radiation can be used without a permanent damage to the Popular wavelengths are and solution is not always as it reduces system performance and increases and in some applications it is impractical to as there is a cross dependence with external systems which are not wavelength The case of laser designators is an example to such these wavelengths may cause temporary damage to the Cornea or to the Vitreous The use of temporary attenuators of the laser to a safe radiation in potentially hazardous This method is popular in military training situations and is accompanied by a boost in reflectivity to the training to compensate for the lost energy in the The attenuation of the laser beam during training is not a true replication of the combat condition as it prevents the opportunity to aim at random targets It also suffers from a of the logistics of attaching special retroref lector to each potential A clearly visible marking of the potentially hazardous to induce the users to take external precautions or avoidance of the laser This minimum mandatory requirement is a very low cost solution to the safety issue but it is operators sensitive and is prone to The solutions that are available today to solve the eye safety issue are in many cases only partial solutions to the eye safety are impractical or reduce significantly system Summary of the It is an object of the present invention to provide a sensing mechanism and a control logic to use with existing laser systems and laser based which renders the use of these safe to the human It is a further object of the present invention to provide a sensing mechanism and control logic to new lasers and laser based which renders these safe to the human It is a further object of the present invention to provide a substitute for existing laser transmitters for short distance range finding The sensing mechanism consists of a low intensity light pulse possibly a laser whose beam is optically combined or optically aligned with the laser beam of an existing or a different mode of operation of the existing The mechanism further comprises optical receiver and processing which could be a modification of the existing receiver or an addition to such The novel mode of operation comprises initiating a low intensity light that will precede the release of the existing high power laser and establishing the distance of a person in its optical path by calculating the time delay of the returned echo from this Such mode of operation prevents the actuation of the high power laser beam if the measured distance is below the distance for such a laser Such operation ensures by using an light that there is no specifically a human eye in the path of the anticipated laser beam of high A system of this invention comprises in addition to the existing laser an auxiliary comparatively light pulse source that emits its beam through one of the existing optical channels the transmitting optics through its own optics collimated onto the target of the existing The present invention also provides a power supply to drive the pulse The invention is illustrated with reference to the enclosed 1 which illustrates a conventional laser combined with an auxiliary system of the As shown in this the entire system comprises a conventional laser transmitter 11 which is powered by power supply 12 and which is controlled by control logic and processor which laser emits a light beam via beam splitter 15 and via transmitting optics 16 as beam 17 to the object There is further provided a light pulse power supply connected to control logic and processor which powers light pulse source 19 which emits a low power light pulse 20 via beam splitter 15 and the same transmitting optics 16 to the Light reflected from the object passes via optics 21 to receiver 22 which is connected with the control logic and processor The sensing light pulse from source returned from the object and received by receiver 22 is evaluated by control logic and processor which evaluation is the basis of the decision whether to actuate the Laser Transmitter Prior to the initiation of the existing laser transmitter by control logic 13 this control logic 13 initiates a triggering signal 13 to the Light pulse power supply which drives the light pulse spurce to emit a short light pulse This by way of beam will be transmitted through the transmitting optic 16 of the main transmitter and will reach same object the laser system was aimed Any especially a within the path will return a light echo that after going through receiving optics 21 will be detected by the receiver For some applications the receiver 22 will be modified to act at short down to zero The receiver 22 sends a signal to the contol logic 13 that uses the delay between the arrival of the echo and the initiation of the light pulse to establish its Unit 13 compares the distance of the as deduced from the to the distance required by the and will initiate the trigger to operate the laser transmitter only if the distance of the person is greater than the distance for the main In some the use of t e above described sequence of steps will be as the energy required to sense and measure distance to objects at the minimum distance of the existing will call for the use of a pulse source which in itself is not at zero distance from the transmitting optics For such systems the sequence of steps can be enhanced so that light pulse source can be emitted and processed in a number of consecutive Each step shall be as described but the light pulse intensity will be progressively increased with each The first pulse will be absolutely down to zero If the result of the first pulse shows that there is no person in the optical path up to a distance L1 than a stronger second pulse will be emitted to verify that there is no person up to a distance of where L1 The second pulse can be more as its requirement for eye safety have to be met only down to This can be repeated a number of times with an increasing power from pulse to pulse until full conditions are As an using a Watts pulsed laser diode as the light pulse source enables to sense objects to 100 is zero range and will verify safety for pulsed laser transmitters of about 10 per Such 10 mj transmitter is above 100 meters and can serve in rangefinders for km maximum insufficientOCRQuality

Claims

1 11852/3 - 6 - CLAIMS:

1. An eye-safe laser comprising proximity range-measurement sensing means utilizing a low power light source for ascertaining whether a person is present up to the range at which the laser beam will cause eye damage, and means for actuating a high power laser only if no person is present within such a range.

2. A system according to claim 1, which comprises a proximity range-measurement means for actuating the laser at a reduced power output and means for establishing the presence or absence of a person within the range where full laser-power will cause eye damage, and depending on the results of this test, means for actuating the full power laser only if no person is within the dangerous range.

3. A system according to claim 1, comprising a subsystem with a low-power output laser, means for using its low power beam for range-measuring to ascertain the presence or absence of a person in the range where eye damage will be caused by the high-power laser, and means for directing said low-power beam in the direction of a target though an optical system for the high-power laser.

4. A system according to claim 3, where the low-power laser beam source is a laser diode.

5. A system according to claim 3, where the low-power output laser is a laser operated at a pulse mode or in a continuous mode.

6. A system according to claim 1, comprising an auxiliary laser of weak power and means to operate it in a mode of operation different from that of the high power laser.

7. A system according to claim 1, comprising means for remote sensing using microwaves, millimeter waves or acoustic waves.

8. A system according to claim 1, incorporated in a range finding or target designating device. 111852/3

9. A method for protecting a person against damage by laser radiation, which comprises examining a range up to which a high power laser is likely to cause eye damage to the eyes of a person, said examination being effected by proximity range-measurement detecting means utilizing a low power light source selected from a low power laser beam, microwaves, millimeter waves and acoustic waves, and according to the determination that no person is within said range, actuating a high power laser.

10. A method according to claim 9, where a high-power laser is actuated at such reduced power so as not to cause eye damage to a person within a certain range, and after ascertaining that no person is present within said range, actuating said high-power laser at full power.

11. A method according to claim 9, where the low power laser beam is produced by a laser diode.

12. A method according to claim 9, which comprises operating the low-power laser in a pulse mode or in a continuous one, or in a mode of operation different from the mode of operation of the high-power laser. For the Applicant, itan, Pearl, Latzer & Cohen-Zedek .dvocates, Patent Attorneys & Notaries