Scanned beam medical imager

Abstract

We report on a conceptual design and feasibility demonstration for a scanned beam endoscope, with advantages over present CCD imaging technology in image resolution and quality, light source power, and package diameter. Theoretical calculations were made by optical modeling and finite element analysis of the performance projected for a design meeting size constraints. To verify the design target of 5 mm for the endoscope diameter, we conducted a design study of the deformation and resolution characteristics of a scan mirror small enough to fit within a 2.5 mm capsule within the endoscope. The results show that performance similar to the test system can be achieved. A functional prototype was then built and tested to validate the theory used. The test system consisted of a photonics module with red (635 nm), green (532 nm) and blue (473 nm) lasers, combined by dichroic mirrors and launched to a single mode fiber. The light emerging from the fiber is formed into a beam and reflected from a commercially available bi-axial MEMS scanner with a 1.56 mm square mirror, and a scan angle of 6 degrees zero to peak mechanical, at a frequency of 19.7 kHz. Scanned beam power from 1 to 3 mw impinges the test object at a range from 10 to 100 mm, and the scattered light is collected by several 3 mm diameter multimode fibers and conducted one-meter to detectors. The detected light was digitized and then reconstructed to form an image of the test object, with 800 by 600 output pixels. Several such images will be presented.

Update on MEMS-based scanned beam imager

“…By following the relationship for fast scan (FS) and slow scan (SS) drive frequencies shown in equation [1], the addressability is maximized while provided the desired video frame rate. Based on the fast scan axis resonant frequency, a desired operating frequency is chosen to give sufficient operating margin.…”

“…Based on the fast scan axis resonant frequency, a desired operating frequency is chosen to give sufficient operating margin. From this seed, a clock frequency is calculated that satisfies equation [1].…”

Scanning fiber endoscopy with highly flexible, 1 mm catheterscopes for wide‐field, full‐color imaging

“…However, to achieve sub-cellular spatial resolutions, FOV must be sacrificed, hindering broad clinical utility. A wide-FOV MEMS endoscopic device has been designed using a 0.5 mm scan mirror, however, the packaging enlarges the device size to greater than 2 mm [63]. Unique circumferential line scanning has been demonstrated using a dual-reflectance large scan MEMS mirror, but again the device footprint is 2×2 mm 2 [64].…”