We present the development of a 5 mm, piezo-actuated, ultrafast laser scalpel for microsurgery with a capability to deliver energies in excess of 1 μJ per pulse. Having previously established that the maximum energy deliverable was limited by cladding damage in photonic badgap fibers, we utilized a large, 35μm cored inhibited-coupling Kagome fiber that allowed the delivery of micro-Joule energy femtosecond pulses. To maintain diffraction limited performance over the entire scan range of the piezo-actuated fiber tip, special objective lenses were developed and manufactured out of a high-refractive index Zinc Sulfide (ZnS) crystal. The probe was packaged in hypodermic 304SS stainless steel with a form factor minimizing in-line configuration. The probe’s performance was tested via metal and tissue ablation studies, characterizing highspeed ablation parameters and uniformity of ablation over the scan area. Additionally, we studied the nonlinear performance of ZnS and Calcium Fluoride (CaF2) as materials for refractive optics and determined the maximum energy deliverable through our probe using these optical materials. The high energy delivery through the probe system should allow for fast and effective tissue ablation.
A miniature laser ablation probe relying on an optical fiber to deliver light requires a high coupling efficiency objective with sufficient magnification in order to provide adequate power and field for surgery. A diffraction-limited optical design is presented that utilizes high refractive index zinc sulfide to meet specifications while reducing the miniature objective down to two lenses. The design has a hypercentric conjugate plane on the fiber side and is telecentric on the tissue end. Two versions of the objective were built on a diamond lathe—a traditional cylindrical design and a custom-tapered mount. Both received an antireflective coating. The objectives performed as designed in terms of observable resolution and field of view as measured by imaging a 1951 USAF resolution target. The slanted edge technique was used to find Strehl ratios of 0.75 and 0.78, respectively, indicating nearly diffraction-limited performance. Finally, preliminary ablation experiments indicated threshold fluence of gold film was comparable to similar reported probes.
Miniature piezoelectric actuators are commonly used as a compact means to relay images for numerous endoscopic applications. These scanners normally consist of an electrically driven lead zirconate titanate (PZT) tube that oscillates an optical fiber at its resonant frequency. The diameter and length of the PZT and fiber, the attachment of the fiber to the PZT, as well as the driving signal determine the main characteristics of the scan—frequency and amplitude of vibration. We present a new, robust, and repeatable method for producing miniature PZT actuators. The described technology allows for continuous tuning of the scanner mechanical properties during the assembly stage, enabling adjustment of resonant frequency and subsequent amplitude of vibration without a priori knowledge of the fiber’s mechanical properties. The method consists of manufacturing high-precision fiber-holding plastic inserts with diamond turning lathes that allow for the fiber length to be quickly varied and locked during operation in order to meet the preferred performance. This concept of tuned PZTs was demonstrated with an imaging technique that combined two scanners oscillating in unison at the ends of a single optical fiber to relay images without the need to correlate the driving signal with a detector.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.