Piezo-Based Mechanisms Provide Necessary Precision Required for Laser Eye Surgery

Introduction

Piezo motion-based mechanisms deliver a range of features preferred in medical engineering and life science applications, such as lubricant-free drives and sterile ceramic designs. The non-magnetic nature of ceramics is an advantageous characteristic in high-energy scanning/imaging based on strong magnetic fields. Precise motion along with incredible speed can be achieved with piezo mechanisms.

The use of optical glass for vision defect correction has been successfully carried out since medieval times. The first clinical studies exploring the use of surgical methods to “shape” the cornea were initiated in the last century.

Laser technology

The arrival of laser technology has replaced the steel scalpel with high energy photons. Today, many different well-established laser methods are available that correspondingly influence the cornea’s curvature to correct visual acuity.

The common decisive factor in all these laser methods is the need for high-precision positioning systems to control and focus the laser beam. Piezo-based mechanisms are not only fast and reliable but are also capable of working with the necessary precision. Due to the availability of compact and different designs, piezo-based mechanisms can be easily integrated into today’s laser systems. Moreover, gimbal actuation is offered in a compact package.

Controlling a laser beam requires maximum precision. Piezo-based nanopositioning systems are ideal for all these applications.

The S-334 shown in the below picture is a compact piezo laser beam steering mirror unit. It has two orthogonal axes and a parallel kinematics design, which eliminates polarization rotation by allowing for a single pivot point.

Piezo advantage

Scanners must be optically conjugate. Extra optics are required between the scanners when two independent galvanometer scanners are used, further increasing complexity, aberrations, and losses.

S-334, Tip/Tilt Mirror (Image: PI)

Piezoelectric scanner tubes for endoscopy/bio-imaging of the eye

High-resolution two-photon endoscopy and microscopy use mini piezoelectric XY scanner tubes. In a recently published research paper, biological imaging of the eye using a two-dimensional fiber scanner-mechanism based on a bespoke, compact piezoelectric scanner tube with an outer diameter of 1.5mm is discussed in detail. The small instrument can be placed within a 2mm diameter, providing a spatial resolution down to 1.5μm.

Mini piezoelectric XY scanner tubes (left) and standard piezoelectric ring-shaped actuator.

Design of the two-photon excitation fluorescence endoscope. (a) shows the piezo scanner tube; the complete 2 photon probe is shown in (d). (Source: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3018080)

About PI

PI is a leading manufacturer of precision motion control systems such as Piezo Nanopositioning Systems, Air Bearings, Linear Motor Stages, Microscope Stages, Motion Controllers, Piezo Flexure Mechanisms, Piezo Ceramic Motors and Hexapod 6-Axis Stages -- for photonics, bio-nanotechnology, medical device & semiconductor applications.

PI recently acquired the majority of ACS, a global leader in high-end motion controllers for precision industrial automation. PI USA is also specialized in Air Bearing positioning systems boasting over 200 man-years of in-house air bearing design experience.

Linear, planar XY, and rotary air bearing stages and custom turnkey systems are available to serve industrial and research markets. Piezo actuators from our PI Ceramic division and precision stages from our PI miCos division were selected by NASA for the Mars Mission and are employed on in the Curiosity rover science lab. PI has been developing and manufacturing standard & custom precision products with piezoceramic and electromagnetic drives for 40 years.


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Last updated: Sep 8, 2017 at 8:49 AM

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