Laser Guidance System Research Articles

Development of new laser guidance system which improves accuracy of image-guided biopsy

Development of new laser guidance system which improves accuracy of image-guided biopsy

Potentials of laser guidance system for percutaneous musculoskeletal procedures.

Early experience using a new laser guidance device to assist CT-guided percutaneous musculoskeletal procedures is presented. We describe six cases which demonstrate typical musculoskeletal applications of laser guidance. In our experience laser guidance for these procedures resulted in improved accuracy with no significant increase in biopsy time when a short learning period is considered. Other musculoskeletal procedures may benefit from laser guidance compared with current standard CT-guided techniques, particularly when precision and accuracy are essential.

MRI-guided endoscopy in the brain: a feasability study.

For neuronavigation in neuroendoscopy conventional navigation systems cannot exclude tissue movements caused by loss of cerebrospinal fluid (CSF). Open MRI can serve as a real-time navigation system if special conditions of endoscopic instruments and equipment are followed. We adapted an endoscopic system to the MRI and installed a miniaturized laser guidance system to project the central transaxial and coronal planes onto the phantom. A human cadaveric model was examined with a flexible microendoscope marked with a titanium wire inside the open magnet. The procedures were guided by gradient echo sequences refreshing the image every 4.5 seconds to control position of the endoscope. Endoscopic and corresponding MRI-findings are presented. Results and technical conditions are discussed.

Laser guidance system for CT-guided procedures.

In a phantom and in 37 patients, a simple laser guidance system for computed tomography (CT)-guided procedures used the software program of the CT scanner and a laser beam mounted on the CT gantry without need for additional software or components. The skin entry point and angulation of the target path were determined. Then the system projected the desired needle path (including compound angulation), allowing accurate needle placement in all cases, even in small lesions.

Test of an Automatic Precision Guidance System for Cultivation Implements

By guiding implements accurately various field activities can be performed very precisely, such as row crumbling, band fertilizing, row spraying, drilling and hoeing. This means that no inputs are applied at places where they are not needed or would cause undue pollution of the environment. In the work reported here, the accuracy of a laser guidance system was examined when a hoe was used. On a level and slightly pressed band of soil approximately 1 m wide and full-field length, three paper sheets were spread with dimensions of approximately 15 m × 1 m. These pieces of paper were placed at approximately 35, 120 and 220 m from the laser transmitter. The centre element of the hoe carried a writing device, suspended to allow free vertical movement, which produced traces on the paper of the true path followed by the implement. Automatic guidance of an agricultural implement mounted on a vehicle by means of a side-shift facility, proved to be accurate within an average of ±6 mm on a track length of 220 m on arable land.

Evaluation of a laser method for guidance of field machinery

An electronics-based pulsed laser guidance system was developed, constructed and tested under static field conditions. A control algorithm was developed to determine system positioning and display directional steering information. The location and orientation of a 0.5 m wide × 1.0 m long frame, with various distances between the transmitter and receiver were checked and evaluated. Experimental results on two different pulse rate laser transmitters (250 Hz and 1000 Hz) indicated that greater accuracy was obtained at higher pulse rates. By applying the method presented in this paper with 1000 Hz pulse rate lasers and a 6 m × 6 m frame, accuracies of closer than 0.4 m in a 200 m range were predicted.

A compact laser beam guidance system for interventional CT.

We propose a simple, compact, and accurate light guidance system for interventional CT. The system using intersecting laser beams is mounted on the CT gantry and ensures precise needle guidance even when the gantry is tilted. The device does not require additional software/hardware. Phantom simulations and clinical experiments have demonstrated an accuracy of +/- 1 degrees and +/- 1 mm. The laser guidance system for CT makes the intervention safer, faster, and more accurate.

An image intensifier laser guidance system for the distal locking of an intramedullary nail

An image intensifier laser guidance system for the distal locking of an intramedullary nail

Measurement of the Electro-Optic Coefficient for Gallium Arsenide and Cadmium Telluride Modulator Rods

ABSTRACTCadmium telluride and gallium arsenide remain the only viable materials for electro-optic modulator applications in the 10 μm wavelength range. Primarily the modulators are used as Q switches, cavity dumpers, amplitude modulators, and frequency modulators for infrared applications, such as laser radar and guidance systems. Designers of optical and electrical systems incorporating these modulators require accurate values for the electro-optic coefficient, r41.A test arrangement, based on a modified version of the cross polarizer technique, was used to measure the electro-optic coefficients for cadmium telluride and gallium arsenide single crystals. The first part of this paper describes our test arrangement for measuring the r41 coefficient. The second part of the paper will discuss the test results. The r41 coefficient for CdTe was found to be 5.5 × 10−12 m/V in the unclamped region and 4.1 × 10−12 m/V in the clamped reion. Values for the r41 coefficient in GaAs were found to be 1.3 × 10−12 m/V and 1.9 × 10−12 m/V in the unclamped and clamped regions, respectively. All measurements were at 10.6 μm. Also investigated are the piezoelectric resonance values for both materials and the effect the resonances have on the measured r41 coefficient in the clamped and unclamped regions.

A Laser Guidance System for Rendezvous and Docking

Laser guidance system for rendezvous and docking providing data acquisition for guidance computer