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Multiple wavelength laser workstation

Multiple wavelength laser workstation description/claims

The invention relates to the field of lasers, particularly to lasers utilized in the treatment of skin and skin conditions.

The use of electromagnetic radiation in the visible and infrared regions of the spectrum has become commonplace in many areas of industry, medicine and research. For example, such radiation is of growing importance in the field of dermatology. In many cases, laser sources are used to generate the desired radiation level at the needed wavelength.

There are a myriad of lasers that are commonly used for dermatological applications such as treatment of vascular lesions or pigmented lesions, hair removal and skin resurfacing. The principle of selective photothermolysis underlies many laser therapies and is used to treat such diverse conditions such as varicose veins, portwine stain birthmarks, other ecstatic vascular lesions, and pigmented lesions including tattoos. The dermal and epidermal layers containing the targeted structures are irradiated with light, usually from lasers or flashlamps. The wavelength of this light is chosen so that its energy will be preferentially or selectively absorbed in the structures. This creates localized heating with the intent of raising the temperature to a point at which constituent proteins will denature or pigment particles will disperse.

Recently, the treatment of aged skin has become an important aspect of cosmetic dermatology. This treatment, often referred to as “skin rejuvenation,” includes elements of many of the commonly performed treatments. The goal of skin rejuvenation is to improve the appearance of aged skin by, for example, improving skin pigmentation, removing facial vessels, reducing wrinkles and fine lines, and improving skin elasticity and texture. Although numerous single-laser techniques have been proposed, there is a growing consensus that skin rejuvenation is best addressed by using multiple laser modalities. It follows that a single laser workstation that provides multiple lasers to address all of the components of skin rejuvenation would be desirable.

Presently, there are three lasers that have been shown to be particularly useful in the treatment of aged skin. These are the pulse dye laser (PDL), operating at a wavelength in the range of 585-600 nm; the Nd:YAG laser operating at 1064 nm; and the Nd:YAG laser operating at 1320 nm. The PDL improves pigmentation, can treat small facial vessels and promotes collagen stimulation. The results, particularly on fine lines and wrinkles, however, are often only subtle. The 1064 nm Nd:YAG laser can treat larger vessels and stimulate collagen, but does not have an acceptable effect on pigmentation. Finally, the 1320 nm Nd:YAG laser improves skin elasticity and reduces wrinkles and fine lines.

Generally, dermatological treatments utilizing multiple wavelengths involve separate laser systems having separate controls and separate delivery devices. An exposure is made using one laser, and subsequently the same area is exposed with a second laser. With such a method, the timing between the laser pulses is difficult to control exactly, and the time between pulses is usually seconds, rather than fractions of a second. Such timing problems may affect the clinical outcome.

A work station that included all three of these lasers would allow the practitioner to achieve optimal results in all aspects of treatment. Such a work station that merely packaged one of each of these lasers together would not be commercially attractive, however, as it would offer little to no cost advantage over three individual lasers.

It is an object of the present invention to provide a laser workstation that reduces or wholly overcomes some or all of the difficulties inherent in prior known devices. It is a further object of the invention to provide a laser workstation that provides laser output at 585-600 nm, 1064 nm and 1320 nm. Particular objects and advantages of the invention will be apparent to those skilled in the art, that is, those who are knowledgeable or experienced in this field of technology, in view of the following disclosure of the invention and detailed description of certain preferred embodiments.

In accordance with a first aspect, lasers capable of lasing at least two wavelengths are provided. The laser has a lasing medium which is capable of lasing at a first wavelength and at a second wavelength. In certain embodiments, the lasing medium is capable of lasing at the first and second wavelengths each to a sufficient degree to produce laser output of sufficient power for the intended purpose(s) to which the laser is being applied. The lasing medium has a longitudinal axis, along which an output coupler resides at a first end of the lasing medium. At a second end of the lasing medium, a first mirror and a second mirror are located along the longitudinal axis, the second mirror being located between the first mirror and the lasing medium. The first mirror is highly reflective at a first wavelength, and the second mirror is highly reflective at a second wavelength while being transparent at the first wavelength. A beam block shutter is arranged to be movable between a first position along the longitudinal axis of the lasing medium and between the first and second mirrors and a second position away from the longitudinal axis of the lasing medium.

Under operation, the second mirror reflects radiation at the second wavelength while allowing radiation at the first wavelength to pass through it. When the beam block shutter is in the first position, along the light path of the lasing medium, the beam block shutter prohibits radiation that passes through the second mirror from reaching the first mirror and being reflected back into the lasing medium. Thus, only radiation at the second wavelength is reflected, amplified and ultimately emitted. When the beam block shutter is in the second position, out of the longitudinal axis of the lasing medium and thus out of the light path, radiation at the first wavelength passes through the second mirror to the first mirror and is reflected back into the lasing medium. Simultaneously, radiation at the second wavelength is reflected back into the lasing medium. The output coupler is selected to permit the emittance of radiation at either or both of the first and second wavelengths. Such an arrangement advantageously permits the laser resonator to have all of the critical optical components (the lasing medium, the mirrors and the output coupler) mounted in a stationary fashion rather than requiring a tuning element or switching of mirrors, resulting in a robust and relatively maintenance-free workstation, capable of emitting two wavelengths from a single lasing medium.

In accordance with a second aspect, laser workstations are provided having two lasers and a single electronics drive system. The single energy drive system is operatively connected by a switch to a first laser pump chamber that excites a first lasing medium and to a second laser pump chamber that excites a second lasing medium. In certain embodiments, the laser pump chambers are each connected to the single energy storage network by high voltage trigger transformers, secondary windings of which are in series with excitation sources within the pump chambers, for example, lamps such as flashlamps, and thus are inductors in the excitation source discharge circuits. These high voltage trigger transformers are each operative to ionize the excitation sources in the pump chambers. Upon closing the switch, stored energy from the single energy drive system flows into whichever excitation source has been ionized and causes the laser associated with that lamp to discharge its energy.

In certain embodiments, one or more of the lasers comprises a laser capable of lasing at least two wavelengths in accordance with the first aspects described above. In certain embodiments, the laser workstation comprises a pulse dye laser (PDL) and an Nd:YAG laser. The pulse dye laser in certain embodiments has an output of 575-650 nm, for example about 585 nm. The Nd:YAG laser comprises an Nd:YAG laser resonator having an Nd:YAG lasing medium with a longitudinal axis along which laser energy is emitted. An output coupler is located at a first end of the Nd:YAG lasing medium along the longitudinal axis of the Nd:YAG lasing medium. A first mirror is located along the longitudinal axis of the Nd:YAG lasing medium at a second end of the lasing medium, and a second mirror is located along the longitudinal axis of the Nd:YAG lasing medium between the first mirror and the lasing medium. The first mirror is highly reflective at least 1064 nm. The second mirror is highly reflective at 1320 nm and is substantially transparent at 1064 nm. The second mirror in certain embodiments is treated to be substantially transparent at 1064 nm, for example, by being coated with a coating that is anti-reflective at 1064 nm. The Nd:YAG laser resonator further comprises a beam block shutter that is opaque and nonreflective. The beam block shutter is movable from a first position along a longitudinal axis of the Nd:YAG lasing medium between the first and second mirrors to a second position away from the longitudinal axis of the Nd:YAG lasing medium. The Nd:YAG lasing medium emits at both 1064 nm and at 1320 nm. Such an arrangement advantageously permits the laser resonator to have all of the critical optical components (the lasing medium, the mirrors and the output coupler) mounted in a stationary fashion rather than requiring a tuning element or switching of mirrors, resulting in a robust and relatively maintenance-free workstation.

Under operation, the second mirror reflects the 1320 nm radiation while permitting the 1064 nm radiation to pass. When the beam block shutter is in the first position, along the light path of the lasing medium, the beam block shutter prohibits the 1064 nm radiation that passes through the second mirror from reaching the first mirror and being reflected back into the lasing medium. Thus, only the 1320 nm radiation is reflected, amplified and ultimately emitted. When the beam block shutter is in the second position, out of the longitudinal axis of the lasing medium and thus out of the light path, the 1064 nm radiation passes through the second mirror to the first mirror and is reflected back into the lasing medium. The Nd:YAG lasing medium has a stimulated emission cross-section at 1064 nm that is much greater than the stimulated emission cross-section at 1320 nm. Accordingly, an output coupler can be selected such that the laser operates at 1064 nm.

In accordance with another aspect, laser workstations are provided having two lasers and a single electronics drive system. The single energy drive system is operatively connected by active semiconductor switches to a first laser pump chamber that excites a first lasing medium and to a second laser pump chamber that excites a second lasing medium. The active semiconductor switches allow for the selective release of portions of energy from a single energy storage network, for example, a capacitor bank, to its associated lamps and ultimately to the associated laser. The release of less than the total amount of stored energy allows for the rapid or immediate firing of either the first laser or the second laser in a series of partial-energy releases, resulting in a series of “sub-pulses” of laser energy of different wavelengths.

In certain embodiments of the various aspects described above, the laser workstation further comprises a handpiece operatively connected, for example, by means of a optical fiber or a wave guide, to the pulse dye laser and to the Nd:YAG laser. The handpiece in certain embodiments comprises a plurality of lenses operative to image the laser radiation, optionally adjustably.

Methods of treating skin problems utilizing laser systems disclosed herein are also provided. In one aspect, a laser system in accordance with the first aspect is used to apply laser energy at a first wavelength to an area of skin affected by a skin problem. The same laser system is used to apply laser energy at a second wavelength to the same area of skin. In this way, the skin problem is treated with two different wavelengths of laser energy from the same laser system, indeed from the same laser itself.

In another aspect, a laser system in accordance with those disclosed herein is used to treat skin affected by a skin problem. Laser energy from both the first laser and the second laser is applied to the area of skin affected by a skin problem. Typically, the wavelength of the laser energy from the first laser differs from the wavelength of the energy from the second laser, such that the area of skin can be treated with each of two beneficial wavelengths of laser energy of different wavelengths in a single treatment session. In certain embodiments, sub-pulses of laser energy are utilized to treat skin affected by a skin problem. Such a method has the advantage of permitting greater control over the duration of time between applications of the different wavelengths of laser energy, as well as permitting the two wavelengths to be applied in a much shorter period of time, perhaps instantaneously. These factors may lead to improved results in the treatment of skin problems.

A more specific example of using multiple wavelength pulses to treat a skin lesion is having a 595 nm wavelength generated with a pulse dye laser and a 1064 nm wavelength generated with a solid-state laser. To eradicate a vascular lesion, a pulse of 595 nm is followed by another pulse at 1064 nm radiating at the same area of the skin lesion. The pulse at 595 nm at an effective fluence converts the oxy-hemoglobin contained in the red blood cells in the ecstatic vascular lesion to met-hemoglobin that has a much higher absorption coefficient at a 1064 nm wavelength. With the wavelength multiplexing technique mentioned, the treatment efficacy is dramatically improved. The energy or fluence required is thus dramatically reduced.

These and additional features and advantages of the invention disclosed here will be further understood from the following detailed disclosure of certain preferred embodiments.

• Provisional Patent
• Utility Patent

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