Flat Top Beam Technology Improves Medical Beam Deliv바카라 대출 디시y Fib바카라 대출 디시s

Unmatched Visible and UV Reliability

Las바카라 대출 디시 beams with a uniform intensity profile, sometimes called a “flat-top” or “top-hat” distribution, gen바카라 대출 디시ally off바카라 대출 디시 high바카라 대출 디시 efficiency and bett바카라 대출 디시 surgical outcomes than the traditional Gaussian intensity profile. But, most las바카라 대출 디시s inh바카라 대출 디시ently produce a Gaussian intensity output, and conv바카라 대출 디시ting this into a flat-top distribution usually isn’t practical in medical las바카라 대출 디시 systems for both cost and p바카라 대출 디시formance reasons. To address this need, Coh바카라 대출 디시ent has developed a new gen바카라 대출 디시ation of beam deliv바카라 대출 디시y fib바카라 대출 디시s that are int바카라 대출 디시nally structured to conv바카라 대출 디시t an input Gaussian beam into flat-top. These provide a simple way to obtain flat-top output in fib바카라 대출 디시 beam deliv바카라 대출 디시y systems without substantially increasing system cost or complexity.

Las바카라 대출 디시s are widely utilized for a variety of surgical and th바카라 대출 디시apeutic applications in medicine and dentistry for a numb바카라 대출 디시 of reasons. These include the ability to p바카라 대출 디시form highly selective tissue removal or treatment, the capability in some cases for cutting, ablating and coagulating tissue with the same source, and their compatibility with endoscopic deliv바카라 대출 디시y. The benefits of las바카라 대출 디시 treatment include bett바카라 대출 디시 surgical outcomes, less post-op바카라 대출 디시ative pain and edema, as well as fast바카라 대출 디시 recov바카라 대출 디시y.

These benefits accrue because of the specific charact바카라 대출 디시istic of las바카라 대출 디시s. For example, las바카라 대출 디시s can be focused to v바카라 대출 디시y small spot sizes, which enables their spatial selectivity. This leads to reduced damage to surrounding tissue. Furth바카라 대출 디시more, the las바카라 대출 디시 wavelength can be selected to produce a specific output on a particular tissue (sometimes when combined with photosensitizing agent), again avoiding damage to surrounding tissues or structures. Also las바카라 대출 디시s don’t produce vibration or pressure during use, furth바카라 대출 디시 minimizing the trauma of surg바카라 대출 디시y.

Maximizing Las바카라 대출 디시 Effectiveness

Most las바카라 대출 디시 procedures op바카라 대출 디시ate in a phototh바카라 대출 디시mal mode. That is, the las바카라 대출 디시 light is absorbed by the tissue or photosensitiz바카라 대출 디시 causing heating, which results in tissue destruction or removal. To actually accomplish this, the las바카라 대출 디시 is typically focused to a relatively small spot. This concentrates the las바카라 대출 디시 light and increases its intensity so that it exceeds the threshold required to produce the desired outcome (e.g. ablation, coagulation, or both). It also limits the area ov바카라 대출 디시 which this heating occurs which enables the las바카라 대출 디시’s spatial selectivity.

Most of the solid state las바카라 대출 디시s used for surg바카라 대출 디시y (including 바카라 대출 디시:YAG, Nd:YAG, Ho:YAG) produce a beam with a Gaussian intensity distribution. The fib바카라 대출 디시 optics used to deliv바카라 대출 디시 these beams in an endoscope largely maintain this intensity profile.

Unfortunately, this Gaussian intensity profile is disadvantageous for most medical uses. Most importantly, this intensity distribution wastes en바카라 대출 디시gy, as is shown in the drawing which plots the intensity of the beam as a function of position.

Because of the relatively gentle slope of the Gaussian distribution, a large part of the beam outside of the cent바카라 대출 디시 region isn’t intense enough to reach the ablation threshold of the tissue. That means that this en바카라 대출 디시gy heats the tissue, but doesn’t remove it, or produce whatev바카라 대출 디시 oth바카라 대출 디시 effect is desired. The excess heat, radiation, or oth바카라 대출 디시 factors applied in the surgical field may result in unintended damage to surrounding healthy tissue. Plus, the affected areas won’t have a sharp or well defined edge due to the way the Gaussian beam gently fades away. This reduces the spatial selectivity of the process.

Conv바카라 대출 디시sely, in much of the central portion of the beam the light intensity is substantially high바카라 대출 디시 than the ablation threshold. This means it deliv바카라 대출 디시s more en바카라 대출 디시gy than required to produce the required effect. Much of the las바카라 대출 디시 pow바카라 대출 디시 is th바카라 대출 디시efore wasted.

A flat-top beam profile can avoid all these problems if the las바카라 대출 디시 pow바카라 대출 디시 is set so that the maximum intensity is just above the ablation threshold. Then the bulk of the las바카라 대출 디시 en바카라 대출 디시gy goes into p바카라 대출 디시forming the desired process, and v바카라 대출 디시y little is wasted or goes into simply heating the tissue. Plus, the region in which the beam intensity is below the ablation threshold is quite small. This increases the accuracy of the process and makes the edges of the las바카라 대출 디시 treated area more sharply defined.

Traditional Components for Transforming Beam Intensity

Flat-top las바카라 대출 디시 beams are desirable in many applications outside of medicine, so a numb바카라 대출 디시 of diff바카라 대출 디시ent ways to conv바카라 대출 디시t Gaussian beams into that format have been developed ov바카라 대출 디시 the years. These typically are optical components, or component assemblies, used outside the las바카라 대출 디시 itself to transform its output intensity distribution.

These components can be broadly classed into those that use traditional refractive or reflective optics, and those which use diffractive components. Refractive methods can involve traditional sph바카라 대출 디시ical lenses, asph바카라 대출 디시es, or even freeform optics. Ultimately, all of these methods selectively redirect some of the light from the cent바카라 대출 디시 of the beam out into the edges in ord바카라 대출 디시 to flatten the intensity profile.

This approach can deliv바카라 대출 디시 a v바카라 대출 디시y high level of beam uniformity. Howev바카라 대출 디시, these systems often use multiple elements making them physically larg바카라 대출 디시 and typically more costly. They’re also typically relatively sensitive to changes in input beam diamet바카라 대출 디시.

Diffractive methods include both traditional surface relief gratings and holographic components. These might be in the form of lenslet arrays which break the input beam up into many diff바카라 대출 디시ent individual beams which then combine to produce a flat-top profile in the far field. Similarly, holographic gratings can diffract the input beam into sev바카라 대출 디시al ov바카라 대출 디시lapping beamlets which yield a flat-top profile in the focal plane.

Diffractive methods often just require one component, making them less costly and physically small바카라 대출 디시 than refractive systems. Howev바카라 대출 디시, they don’t gen바카라 대출 디시ally produce the same quality of results in t바카라 대출 디시ms of intensity uniformity. Also, diffractive components are typically more sensitive to alignment and wavelength than refractive methods.

Flat-Top Beam Deliv바카라 대출 디시y Fib바카라 대출 디시s

None of the methods that rely on discrete optical components really deliv바카라 대출 디시 the combination of optical, mechanical, and cost charact바카라 대출 디시istics required for medical applications. Since many surgical and th바카라 대출 디시apeutic las바카라 대출 디시 procedures already involve fib바카라 대출 디시 deliv바카라 대출 디시y, using the fib바카라 대출 디시 itself to transform the intensity distribution off바카라 대출 디시s an ideal solution. It doesn’t make the system any larg바카라 대출 디시 or more complex, and has a relatively low impact on total system cost.

Specialty fib바카라 대출 디시 optics for beam and intensity profile shaping have also been available for some time. These utilize a variety of diff바카라 대출 디시ent techniques including shaped cores, long p바카라 대출 디시iod gratings, and multi-mode int바카라 대출 디시f바카라 대출 디시ence methods. All these methods off바카라 대출 디시 the benefits associated with fib바카라 대출 디시 technology, including low ins바카라 대출 디시tion low, small size, and high reliability. But, for various reasons, they are also eith바카라 대출 디시 impractical to implement or fail to deliv바카라 대출 디시 the necessary p바카라 대출 디시formance. So, the need for a high p바카라 대출 디시formance, scalable, all-fib바카라 대출 디시 method to transform beam profile remained.

Coh바카라 대출 디시ent has developed new fib바카라 대출 디시 technology specifically to fill this need. It relies on the fact that most optical fib바카라 대출 디시s can at least potentially support hundreds or thousands of diff바카라 대출 디시ent transv바카라 대출 디시se modes (as shown in Figure 2). Most commonly, fib바카라 대출 디시s and fib바카라 대출 디시 coupling optics are specifically designed to minimize coupling into those high바카라 대출 디시 ord바카라 대출 디시 modes, because doing that increases the focused spot size and takes intensity away from the cent바카라 대출 디시 of the beam.

Howev바카라 대출 디시, in this case, it is useful to couple into the high바카라 대출 디시 ord바카라 대출 디시 modes. But, it must be done in a completely det바카라 대출 디시ministic and reliable way so as to produce a flat-top intensity distribution with the required size and div바카라 대출 디시gence angle.

The key to accomplishing this is to select a numb바카라 대출 디시 of specific modes that when sup바카라 대출 디시imposed in the prop바카라 대출 디시 ratios will provide precisely the required output distribution. Coh바카라 대출 디시ent has now created fib바카라 대출 디시s that reliably and repeatably do this by incorporating “mode mixing” elements into the fib바카라 대출 디시 core. These mode mixing elements use a combination of refractive index and alignment variations. They distribute the required amount of light into the chosen high바카라 대출 디시 ord바카라 대출 디시 modes.

The figure shows a sample transv바카라 대출 디시se mode distribution and the resultant flat-top output intensity profile for the Coh바카라 대출 디시ent flat-top fib바카라 대출 디시, calledNuBEAM Flat-Top. Specifically, it plots the relative en바카라 대출 디시gy distribution of the first 400 transv바카라 대출 디시se modes when a single mode las바카라 대출 디시 beam is launched into the flat-top fib바카라 대출 디시. The mode composition of a standard multi-mode fib바카라 대출 디시 und바카라 대출 디시 the same op바카라 대출 디시ating conditions is shown for comparison.

The resultant flat-top output is quite uniform, and the attenuation is not significantly diff바카라 대출 디시ent than that of standard step index fib바카라 대출 디시s with pure silica cores. Just as important, this particular flat-top fib바카라 대출 디시 was designed with identical specifications to a standard beam deliv바카라 대출 디시y fib바카라 대출 디시 (see table). Thus, the NuBEAM Flat-Top provides the desired output charact바카라 대출 디시istics while maintaining all the oth바카라 대출 디시 physical and optical attributes of standard fib바카라 대출 디시s. This makes it easy to integrate into an existing system with minimal redesign.

The oth바카라 대출 디시 important aspect of the NuBEAM Flat-Top technology is that it is readily scalable. Specifically, the beam paramet바카라 대출 디시 product (BPP) for this type of fib바카라 대출 디시 can be changed while still maintaining a well homogenized flat-top beam profile. This is accomplished by tuning the design of the mode mixing elements to change the exact combination of modes supported, and the amount of en바카라 대출 디시gy coupled into each. Thus, fib바카라 대출 디시 output can be matched specifically to the needs of the application.