FR2727767A1 - LASER SYSTEM WITH EYE PROTECTION. - Google Patents

Abstract

The present invention relates to a laser system safe for the eye. - According to the invention, the system comprises detection means (11, 19) to ascertain whether a person is present up to the distance at which a high power laser beam (11) will cause damage to the eye , and means (13) for activating the high power laser (11) only if no person is present up to such a distance.

Description

The invention relates to laser systems and, in particular

  a process to make the eyes safe for use

  a laser system which is otherwise dangerous to the eyes by an auxiliary device or a modification of the existing laser apparatus.

  Lasers and laser-based systems are used

  intensively in many fields of application.

  including telemetry, remote sensing and others. All of these systems include a laser transmitter that emits a relatively high intensity light beam that is generally a potential hazard to the human eye. The problem of eye safety in the operation of lasers and laser-based systems

  restricts the use of such systems.

  There is a growing demand for eye-safe lasers and it has proved more difficult to apply this in the industrial and military fields. Despite the fact that the military uses a variety of unsafe equipment on the battlefield, in training, the safety criterion is very important and there is a

  need to be able to use equipment to

  size and for training. As another example, telemetry used in civil engineering is performed at low energy levels, for reasons of eye safety, and a retroreflector is used at the location of the target. The possibility of increasing the energy level

  of the transmitter without compromising the safety of the eyes

  significantly increase the efficiency of the equipment

and its deployment.

  To solve the problems concerning the use of high power lasers without putting the eye in danger, three

approaches exist today.

  - The use of an emission wavelength for which relatively high intensity radiation can be used without permanent damage to the retina. Current wavelengths are 1.54 y and 10.6 M. This solution is not always optimal because it decreases the efficiency of the system and increases the costs and in some applications it is not possible to implement it because there is interdependence with external systems whose wavelengths do not match. The case of laser designation means is an example of such systems. In addition, these wavelengths can cause temporary damage to the cornea or vitreous humor. - The use of temporary laser beam attenuators, at a safe rate of radiation, in potentially dangerous situations. This method is prevalent in military training situations and is accompanied by an increase in the reflectivity of the training target to compensate for energy lost in transmission. The attenuation of the laser beam during training is not a true reproduction of combat conditions because it prevents targeting random targets successfully. She also suffers

  complication of the logistics to fix a retro-

  special reflector for each potential target.

  - a clearly visible mark of potential equipment-

  dangerous for users to take external precautions or avoid the laser beam. This minimum mandatory equipment is a very low cost solution to the safety problem, but it is operator dependent and subject to accidents. The solutions that are available today to solve the problem of eye safety are thus, in many cases, only partial solutions to this problem.

  problem, are expensive, impractical or reduce

  fictitiously the efficiency of the system.

  It is an object of the present invention to provide a

  detection mechanism and control logic

  existing laser systems and laser-based equipment, which makes the use of these

safe for the human eye.

  The present invention relates to a laser system for the eye comprising detection means for ascertaining whether a human being is present up to the distance at which the laser beam will cause damage to the eye, and means for operate the high power laser only

  if no human being is present until such

  tance. Preferably, it comprises means for actuating the laser at a reduced power output and scanning means by said beam to establish the presence or

  the absence of a human being in the area where the full

  The laser will cause damage to the eye and, depending on the results of this test, means to operate the laser at full power only if no human being is in the danger zone. According to one embodiment, the system of the invention comprises a subsystem having a laser with a low power output, means for using

  its low power beam to ensure the pre-

  the presence or absence of a human being in the area where damage to the eye will be caused by the high-power laser, and means to direct the low-power beam in the direction of the target through the system optics of the main laser or through a separate optical system. The low power laser beam source may be a laser diode, and the auxiliary laser may be operated in pulsed or continuous mode. The invention further relates to a method for protecting the eyes of a human at a certain location from damage by laser radiation, which comprises: scanning a zone to which a laser to

  high power is likely to cause

  the eyes of said human being in this area, said scanning being carried out by proximity detection means selected from a low power laser beam, microwaves, millimeter waves and acoustic waves and, in accordance with the determination that 'No human being is in this area, operate a high power laser. Preferably, the high power laser is operated at a reduced power such that it does not cause damage to the eye of a human being in a certain area and, after making sure that no human being is present in said zone, said high power laser is operated at full power. A low power laser subsystem can be used which is directed in the direction of a target through the optical system of the high power laser or through a separate optical system. The power source at low power can be a laser diode. The low power laser can be operated in pulsed mode or in continuous mode, or in a mode of operation different from the operating mode of the laser

at high power.

  The invention also relates to a laser telemetry method in which scanning is performed by a low power laser and wherein the high power laser and the scanning means are integrated into the laser range finder. It is another object of the present invention to provide a detection mechanism and control logic for novel high power lasers and apparatus based on the present invention.

  on lasers, which make them safe for the human eye.

  It is another object of the present invention to provide a substitute for existing laser emitters for

  short range telemetry applications.

  The detection mechanism consists of a low intensity light pulse emitter, possibly a laser diode, whose beam is optically combined or optically aligned with the laser beam of an existing design or a different mode of operation of the laser. existing. The mechanism further includes an optical receiver

  and means of treatment, which could be a modification

  cation of the existing receptor or an addition to such an apparatus. The new mode of operation includes initiating a low intensity light pulse, which will precede the emission of the existing high power laser beam, and establishing the distance of a person in his optical path by calculating the delay. the echo returned from that person. Such a mode of operation prevents

  the emission of the high-power laser beam if the

  measured speed is below the safe distance for the eye for such a laser beam. Such an operation ensures, by using a light beam for the eye, that there is no object, in particular a human eye, on the

  advanced laser beam of high intensity

tible to damage the eye.

  A system of this invention further comprises the laser

  existing pulsed light source of relative power-

  low beam which emits its beam through one of the existing optical channels, the optical transmission through its own optical collimated on the target of the existing device.

  As. The present invention also provides a food

  power supply to power the pulse source

luminous at low power.

  The invention is illustrated by the single figure of the accompanying drawing which shows a conventional laser combined with a system

auxiliary of the invention.

  As shown in this figure, the system as a whole comprises a conventional laser emitter 11 which is powered by a power supply 12 and which is controlled by a processor and a control logic 13, which laser emits a light beam 14 via a separator beam 15 and via transmission optics 16, as beam 17 to

the object (person).

  There is further provided a pulsed light power supply 18, connected to the processor and the control logic 13, which supplies a pulsed light source 19 which emits pulsed light 20 via the beam splitter and the same transmission optics. 16 towards the object. The light reflected by the object (person) passes via an optical 21 to the receiver 22 which is connected to the processor and the control logic 13. The light pulse detection of the source 19, returned by the object (nobody ) and received by the receiver 22, is evaluated by the processor and the control logic 13, which evaluation makes it possible to

  decide whether the laser transmitter 11 should be actuated.

  Prior to the start of the existing laser transmitter 11 by the control logic 13, this control logic 13 initiates a trigger signal 24 to the pulsed light power supply 18 which supplies the source of power.

  pulsed light 19 for emitting a short pulsed light 20.

  This beam, via the optical multiplexer 15, will be transmitted through the transmission optics 16 of the main transmitter 11 and will reach the same object as that targeted by the laser system. Any object, in particular a person, on this path will return a light echo 23 which, after passing through the reception optics 21, will be detected

  22. For some applications, the receiver

  22 will be modified to act at short distances to zero distance. The receiver 22 sends a signal to the control logic 13 which uses the delay between the arrival of the echo and the initiation of the light pulse to establish its distance. The unit 13 compares the distance of the object, deduced from this delay, to the safe distance for

  the eye required by the standard, and will trigger the function

  11 only if the person's distance is greater than the safe distance to the eye

for the main laser.

  In some applications, the use of the algorithm described above will be lacking, because the energy required to detect and measure the distance to objects at the

  safe minimum distance for the eye of the existing design

  aunt, will require the use of a pulsed light source 19 which, in itself, is not safe for the eye to

  a zero distance from the transmission optics 16.

  For such systems, the algorithm can be developed so that the pulsed light source can be emitted and processed in a number of consecutive steps. Each step will be as in the previously described algorithm, but the intensity of the pulsed light will be gradually increased at each pulse. The first impulse will be absolutely safe for the eye until the zero distance. If the result of the first pulse shows that there is no person in the optical path to a distance L1, then a second stronger pulse will be emitted to verify that there is no one up to a distance L2, with L1 <L2. The second impulse can be more powerful, since its requirements for eye safety must only be met up to L1. it

  can be repeated a number of times with a

  increased pulse momentum until

  totally safe conditions for the eyes to be checked.

  As an example, the use of a pulsed laser diode of 10

  at 20 W, as a source of pulsed light 19, makes it possible to detect

  objects up to 100 meters, is safe for the eyes to

  zero distance and will check the security for transmissions

  pulsed lasers at 1.06 p of about 10 mJ per pulse.

  Such a 10 mJ transmitter is safe for the eyes above 100 meters and can be used in rangefinders for a range

up to 10 km.

Claims (15)

  1. Safe laser system for the eye, characterized in that it comprises detection means (11, 19) for ascertaining whether a person is present up to the distance at which a high power laser beam ( 11) will cause damage to the eye, and means   (13) for operating the high power laser (11) only   if no one is present to such a distance. 2. System according to claim 1, characterized in that it comprises means for actuating the laser (11) at a reduced power output to establish the presence or absence of a person in the area where the full power of the laser will cause eye damage and, depending on the results of this test, means (13) to operate the laser at full power only if   no one is in the danger zone.   3. System according to claim 1, characterized in that it comprises a subsystem having a laser (19) low output power, means for using its beam at low power to ensure the presence or the absence of a person in the area where eye damage will be caused by the high power laser (11), and means for directing said low power beam in the direction of the target through the optical system of the main laser or through a system separate optics.   4. System according to claim 1 or 3, characterized in that the source of the low-frequency laser beam power is a laser diode.   5. System according to claim 1, 3 or 4, characterized in that the auxiliary laser is a laser   operating in pulsed or continuous mode.   6. System according to any one of claims 1 and 3 at 5,   characterized in that a low auxiliary power laser beam source is coupled to a laser system existing high power.   7. System according to any one of claims 1 to 6,   characterized in that it comprises a low power auxiliary laser and means for operating it   in a different mode from that of the high power laser.   8. System according to claim 1, characterized in that it comprises detection means to   distance, using microwaves, millimeter waves   acoustic waves or other means of detection Proximity.   9. System according to any one of claims 1 to 8,   characterized in that it is incorporated in a range finder or   a target designation device.   10. A method of protecting the eyes against damage by high-power laser radiation, characterized in that it comprises: scanning the area to which the high-power laser (11) is capable of causing a damage to a person's eyes within this zone, said scanning being performed by proximity detection means selected from a low power laser beam, microwaves, millimeter waves and acoustic waves and, according to the determination that no one is present in said area, operate the laser at high power. Method according to claim 10, characterized in that the high power laser (11) is operated at a reduced power so that it does not cause damage to a person's eyes in a certain area and, after be assured that no person is present in said zone, said laser is actuated at   high power at full power.   12. Process according to claim 10,   characterized in that it comprises the use of a sub-   low power laser system (19), which is directed in the direction of a target through the optical system of the high power laser or through an optical system separate.   13. The method of claim 10, characterized in that the power source at low power is a laser diode.   14. Method according to claim 10, characterized in that it comprises the actuation of the laser at low power pulsed mode or in continuous mode, or according to   a mode of operation different from the operating mode high power laser.   Laser telemetry method, characterized in that a scanning is performed according to claim 10, the high power laser and the   scanning means being integrated in a laser range finder.