Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
  • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
  • H01S3/005—Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
  • G02B27/0905—Dividing and/or superposing multiple light beams
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
  • G02B27/0938—Using specific optical elements
  • G02B27/0994—Fibers, light pipes
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/30—Collimators
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/02—Diffusing elements; Afocal elements
  • G02B5/0273—Diffusing elements; Afocal elements characterized by the use
  • G02B5/0278—Diffusing elements; Afocal elements characterized by the use used in transmission
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/26—Optical coupling means
  • G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
  • G02B6/2804—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals forming multipart couplers without wavelength selective elements, e.g. "T" couplers, star couplers
  • G02B6/2808—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals forming multipart couplers without wavelength selective elements, e.g. "T" couplers, star couplers using a mixing element which evenly distributes an input signal over a number of outputs
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
  • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
  • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
  • H01S3/06—Construction or shape of active medium
  • H01S3/07—Construction or shape of active medium consisting of a plurality of parts, e.g. segments
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
  • H01S5/00—Semiconductor lasers
  • H01S5/20—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/48—Laser speckle optics

Definitions

• the present inventive concept relates generally to lasers and applications thereof and, more particularly, to laser applications involving large field of view (FOV) laser illumination.
• FOV field of view
• Laser illumination provides an advantage in that energy from a laser beam can be confined optically into a narrow, collimated beam due to its narrow wavelength to produce high energy intensity, which is desirable in many imaging scenarios.
• this high energy intensity may result in injury to a user or equipment when directly exposed to the collimated laser beam.
• the laser beam is expanded to illuminate an area that covers a sample (target region) to be investigated.
• this can be any field of view (FOV) larger than, for example, 1cm x 1cm, and in some cases extending up to 10cm x 10cm.
• FOV field of view
• a crystal light pipe or optical fiber is used to expand the light beam, so that at certain object distance (>10cm) the beam is large enough to cover the entire target region.
• this expansion results in a cone-shaped beam profile, where the tip of the cone is at the laser energy exit point from the fiber.
• the irradiance i. e.
• laser power per unit area can be dangerously high, even if the irradiance at the surface of the imaged object 10cm away is not dangerous and within laser standard specifications. Thus, there is a risk that the skin of the user could get in close proximity to the tip of the cone, resulting in an injury, even if the exposure time is small.
• Passive devices such as a distance sensor, can be used to ensure the laser energy is delivered within tolerance levels to the samples (image object) surface at a pre- specified distance range. Thus, if the distance is too short or becomes too short, the laser will automatically shut off. Furthermore, with these devices, if any other objects appear in the space between the laser source and the target region, the laser will shut off. Use of these devices, however, has the tendency to cause sporadic unanticipated interruptions to the normal operation of the image acquisition process. Moreover, since the injury from the laser exposure is time-dependent and the exposure may be inadvertently unrecognized, occult injury may occur with delicate tissues even with safety features such as distance sensors and short exposure times because the principle of irradiance.
• Some embodiments of the present inventive concept provide a fiber assembly including a laser input end configured to receive an input signal having a first laser beam intensity.
• the fiber assembly further includes a plurality of channels attached to the laser input end and a plurality of laser safety adaptors.
• Each of the plurality of laser safety adaptors is configured to receive a corresponding one of the plurality of channels.
• a laser beam exiting each of the plurality of laser safety adaptors has a second laser beam intensity that is less than the first laser beam intensity.
• each the plurality of laser safety adaptors may include a collimator, a diffuser and a sleeve.
• the collimator maybe configured to receive the laser beam having the first intensity and re-shape the laser beam to provide a collimated, expanded, and less intense laser beam.
• the diffuser may be configured to receive the laser beam from the collimator and expand the laser beam such that a deflected beam output from the diffuser is diverged at an angle to cover a relatively large imaging area at a certain distance.
• the sleeve may be attached to the diffuser configured as a spacer, wherein the laser beam having the second laser beam intensity exits the sleeve.
• the sleeve may be one of a circular, box shaped or rectangular illumination pattern.
• the assembly may improve laser safety and improves beam homogeneity in single or multi-spectral wavelengths from 350 nm to 1100 nm imaging technologies.
• the assembly may substantially increase laser safety by reducing irradiance levels in close proximity to an imaging device and laser energy exit sources from the imaging device.
• the assembly may provide homogeneity of a beam profile on an imaging target.
• the assembly may further provide improvement in image quality.
• the plurality of safety adaptors may reduce shadows on the imaged object.
• the assembly may improve laser safety and beam homogeneity in single or multi-spectral wavelength imaging technologies.
• the imaging technologies may include reflectance imaging, Laser Speckle Imaging, Laser Doppler Imaging, Near-infrared Fluorescence Imaging, and any combination thereof.
• Some embodiments of the present inventive concept may provide safety adaptors for a laser.
• the safety adaptors include a collimator configured to receive a laser beam having a first intensity and re-shape the laser beam to provide a collimated, expanded, and less intense laser beam; a diffuser configured to receive the laser beam from the collimator and expand the laser beam such that a deflected beam output from the diffuser is diverged at an angle to cover a relatively large imaging area at a certain distance; and a sleeve attached to the diffuser configured as a spacer, wherein a laser beam having the second laser beam intensity exits the sleeve.
• FIG. 1 For embodiments of the present inventive concept, provides methods of providing less intense laser beams using a fiber assembly.
• the method includes receiving an input signal at a first end of a laser input having a first laser beam intensity; providing the input signal having the first laser beam intensity, from a second end of the laser input, to a plurality of channels attached to the second end laser input end, wherein each of the plurality of channels has a corresponding one of a plurality of laser safety adaptors associated therewith; and providing a laser beam from each of the plurality of laser safety adaptors having a second laser beam intensity that is less than the first laser beam intensity.
• Figure 1 is a block diagram illustrating a fiber in combination with N safety adaptors in accordance with some embodiments of the present inventive concept.
• Figure 2 is a block diagram illustrating functionality of the laser safety adaptor in accordance with some embodiments of the present inventive concept.
• Figure 3 is a diagram illustrating assembly of the laser safety adaptor in accordance with some embodiments of the present inventive concept.
• Figures 4A and 4B are diagrams illustrating laser light directly out of the fiber (4A) and laser light that out of the laser safety adaptor (4B) in accordance with some embodiments of the present inventive concept.
• Figure 5 is a diagram illustrating aspects of the laser safety adaptor in accordance with some embodiments of the present inventive concept.
• embodiments of the inventive concept relate generally to lasers and applications thereof and, more particularly, to laser applications involving large field of view (FOV) laser illumination.
• embodiments of the present inventive concept may be used with single and multi-spectral laser imaging to increase laser safety, and improve beam profile in tissue/organ blood flow and perfusion imaging techniques, such as Laser Speckle Imaging (LSI), Laser Doppler Imaging (LDI), near-infrared fluorescence imaging, and combinations of these imaging techniques with each other or with reflective imaging techniques.
• LSI Laser Speckle Imaging
• LPI Laser Doppler Imaging
• NIR near-infrared fluorescence imaging
• Some embodiments of the present inventive concept use special optics to reduce the laser energy concentrated into a small area when exiting from the tip of a fiber. This concentrated, focused laser energy can be harmful with exposure to skin or the retina of the eye.
• a safety adaptor in accordance with embodiments discussed herein installed at the exit point of a fiber or laser illumination device, the laser energy to which an operator of the imaging device might be exposed is diverged in a very short distance so as to significantly spread out the laser energy.
• the laser energy exposure to the operator is much lower than a hazard threshold, even if the operator inadvertently touches the illumination system.
• Embodiments of the present inventive concept provide safety without sacrificing the attributes of laser intensity or imaging capabilities of the device.
• some embodiments of the present inventive concept provide a number of optics elements to form a special beam expander attached to an exit point of the laser energy source, for example, a laser port, a tip of a fiber, a tip of a light pipe, and the like.
• the laser beam energy may be dispersed into a large area in a very short distance, for example, a few centimeters.
• custom optical fibers are used to split the light into different channels to cover illumination of the field of view (FOV) of the imaged object.
• the special beam expander and optical fibers in accordance with some embodiments discussed herein may decrease the light energy per unit area, increase the homogeneity of the laser illumination of the target, maintain the irradiance at the surface of the imaged target, but reduce the risk of excessive irradiance exposure at close proximity to the imaging system and laser source(s) as will be discussed further below with respect to Figures 1 through 5.
• FIG. 1 a diagram illustrating a processor splitting a fiber in accordance with some embodiments of the present inventive concept will be discussed.
• an end of a fiber laser beam 101 is split into N channels (1Q2A-102N) to decrease the light intensity.
• Each channel 102A-102N is then provided to a corresponding laser safety adaptor 103A-103N.
• the fiber is split into four channels in Figure 1, embodiments of the present inventive concept are not limited to this configuration. For example, more or less than four channels may be present without departing from the scope of the present inventive concept.
• the laser source for illumination is provided into the only input end of a custom made fiber assembly 104.
• the laser beam is split into N output channels 102A-102N. Each channel has a laser intensity of 1 N of the total input energy, wherein N is the number of output fiber legs (channels).
• each fiber leg (channel) enters a corresponding laser safety adaptor 103A-103N.
• embodiments of the present inventive concept not only provide decreased laser energy per unit area but also increased quality of the beam profile by making the illumination more homogenous. Furthermore, shadows may be reduced, or possibly eliminated, by shedding the light onto the target from different angles, which is desired in many laser imaging applications.
• the laser safety adaptor 203 includes a laser source 210, a collimator 215, a diffuser 220 and a sleeve 220.
• the laser light is launched from the source 210, for example, a laser port, fiber tip or light pipe, it is collected and collimated by a collimator 215.
• the collimator 215 re-shapes the laser beam, which becomes collimated.
• the laser beam exiting the collimator 215 still has a nearly Gaussian energy distribution across the region it shines on and the laser intensity in the center is significantly stronger than the peripheral regions.
• the collimator 215 may be any commercially available laser collimator without departing from the scope of the present inventive concept.
• the laser beam enters a diffuser 220, which expands the laser beam so that the deflected beam output from the diffuser 220 is diverged at a certain angle to cover a relatively large imaging area at a certain distance, for example, 30cm.
• the diffuser 220 can be any commercially available laser diffuser without departing from the scope of the present inventive concept.
• the laser intensity profile within the illumination area after the diffuser 220 is regulated into a uniform
• the sleeve 230 may be a circular sleeve, however, embodiments of the present inventive concept are not limited to this configuration.
• the sleeve may be box shaped or rectangular without departing from the scope of the present inventive concept.
• a laser safety adaptor 303 includes a laser source 310, a collimator 315, a diffuser 320 and a sleeve 330 as discussed above with respect to Figure 2. It is clear how these elements of the safety adaptor 303 fit together from Figure 3.
• Figure 4 A illustrates laser light that comes directly out of the fiber
• Figure 4B illustrates laser light that comes out of a laser safety adaptor in accordance with some embodiments of the present inventive concept.
• Figure 4A illustrates a green laser directly shining a piece of paper. It is clear from Figure 4A how intense the laser beam is when it directly comes out of the laser. It is also clear that the laser energy is concentrated in a small area and the beam profile is more intense in the center.
• Figure 4B illustrates laser light exiting a laser safety adaptor in accordance with some embodiments of the present inventive concept.
• Figure 4B illustrates that the laser light that comes out of the laser safety adaptor is expended into a relatively large area and the beam profile is significantly more uniform across the illumination area.
• Experiments have been performed with a 450m W Class 3b laser in accordance with some embodiments of the present inventive concept. Results showed that a laser light that passes through as laser safety adaptor can directly shine on a human hand without causing any discomfort.
• the optical fiber used for this imaging configuration to launch the laser is a multi-mode optical fiber with a numerical aperture (NA) of, for example, 0.22.
• NA numerical aperture
• the outgoing beam after the collimator has a diameter of about 16mm.
• a collimated laser beam is still featured by a Gaussian profile, and the light intensity in the central region of the beam is significantly higher than the peripheral regions.
• the central portion of the laser beam will create physical damage to the living tissue.
• the laser safety adaptor includes an engineered diffuser attached to the laser fiber collimator to further diverge the laser beam to a larger area.
• the diffuser is capable of homogenizing the incoming laser beam, and converting it from a Gaussian profile to a top-hat profile, which means the laser intensity distribution within the beam is nearly uniform to avoid any hidden hot spots.
• the engineered diffuser used in safety adaptors in accordance with embodiments discussed herein has a diverging angle of about 20 degrees, which can project the laser beam to a circular spot of 120 mm in diameter at a distance of 30 cm away as illustrated in Figure 5.
• the engineered diffuser may be positioned in a tubular spacer to allow the beam to diverge freely to an enlarged spot before being launched.
• This spacer (sleeve) may have a length of 35 mm.
• the laser spot has an enlarged beam size of 28 mm in diameter at the exiting port of the tube.
• the maximum power level of a laser used is 1 W, and the laser was evenly split into 4 channels as illustrated.
• the laser power in each leg is 0.25W.
• the irradiance intensity at the exiting port of the spacer is uniformly 0.04 W/cm 2 across the illuminated area within the beam.
• ANSI Z136.1 -2000 the American National Standard for Safe Use of Lasers, the Maximal Permissible Exposure (MPE), o laser to human skin is roughly 0.2 W/cm2 in the visible wavelength region (0.4 - 0.7 ⁇ ).
• the irradiance at the exiting port of the laser safety adaptor in accordance with embodiments of the present inventive concept is 0.04 W/cm2, much lower than the MPE in corresponding wavelength regions. Therefore, human skin is safe during imaging manipulations if accidentally exposed to a laser in a wide range of wavelengths.
• Table 1 below summarizes the MPE (W/cm 2 ) and actual irradiance (W/cm ) for both visible wavelengths and Near infrared (NIR) wavelengths discussed above.
• some embodiments of the present inventive concept provide safety adaptors that improve the safety level of large Field of View laser imaging applications, such as Fluorescence Imaging, LSI, and LDI and the like. Some embodiments of the present inventive concept may also provide improved image quality of large Field of View laser imaging applications by making the beam more homogenous, removing the shadow of the target and decreasing the noise caused by laser instability. Thus, some embodiments of the present inventive concept provide systems that improve laser safety and beam homogeneity in laser-based imaging.
• Some embodiments of the inventive concept improve laser safety and improve beam homogeneity in single or multi-spectral wavelength (350 nm - 1100 nm) imaging technologies, consisting of the two components of a special optics design and device, and the splitting of the laser energy into multiple fibers.
• Some embodiments include a special optics design and device to achieve rapid beam expansion and diffusion over a short (several cm) distance.
• an optics design is provided that divides the laser fiber into N separate channels, each of which is attached to the special optics design device.
• These embodiments provide improvement in laser safety and beam homogeneity simultaneously. Improvements in laser safety and beam homogeneity in accordance with embodiments discussed herein can result in prolonged imaging exposure of physiologic processes in the imaged target without increased risk. Furthermore, multiple serial image acquisitions of physiologic processes in the imaged target may be provided without increased risk.

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• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Electromagnetism (AREA)
• General Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• Geometry (AREA)
• Laser Surgery Devices (AREA)
• Radiation-Therapy Devices (AREA)
• Investigating Or Analysing Materials By Optical Means (AREA)
• Optical Couplings Of Light Guides (AREA)
• Non-Portable Lighting Devices Or Systems Thereof (AREA)
• Lasers (AREA)

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• 2016
  • 2016-03-24 CA CA2977153A patent/CA2977153A1/en not_active Abandoned
  • 2016-03-24 WO PCT/US2016/023963 patent/WO2016154408A1/en not_active Ceased
  • 2016-03-24 CN CN201680017623.7A patent/CN107438927A/zh active Pending
  • 2016-03-24 EP EP16769669.9A patent/EP3243248A4/en not_active Withdrawn
  • 2016-03-24 JP JP2017550231A patent/JP2018517158A/ja active Pending
  • 2016-03-24 US US15/559,646 patent/US20180337507A1/en not_active Abandoned

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