Akihiro Kanno

Laser treatment of cutaneous lesions with image-guided fine spot-scanning irradiation

We propose a new laser irradiation method for the treatment of cutaneous lesions in plastic surgery. In general, lasers with a spot size of 1 to 10 mm are used in irradiation on diseased skin. Although the target absorbs more light energy according to the theory of selective photothermolysis, the surrounding tissue, however, is still somewhat damaged. In proposed method, an f-theta lens, which is assembled by a shrink fitter, focuses the irradiation laser beam to a very fine spot with the size of 125 μm. Guided by the captured object-image, such laser beam is conducted by a pair of galvanometer-driven mirrors to irradiate only the desired tissue target without thermal damage to surrounding tissue. Moreover, an optical coherence tomography, whose probe is capable of wide field of view, can be used to provide the guidance information for the best treatment. The usefulness of the developed laser therapy apparatus was demonstrated by performing an experiment on the removal of tattoo pigment.

Development of the Laser Fine Processing Equipment with Wide Process Area Using a Shrink Fitter Technology

diameter using a shrink fitter made it possible to process with great accuracy across the wide area. In this paper, we examined the process accuracy of this equipment by measuring the marks processed by this equipment. And in order to examine the process quality across the wide process area, the surface of the process marks were measured with a stylus profilometer. In addition, we considered an influence of a decentering of each lens in the scanning lens unit on positioning accuracy of the laser spots and field curvature on an image plane.

Development of Pinpoint Laser Therapy Apparatus by Scanning a Fine Laser Spot (Wide Laser Scanning using the Shrink Fitter Method)

To improve unwanted pigments in the skin laser light is irradiated on the pigmented lesion. Melanin, locally existing in the skin, selectively absorbs the laser light. At the present time, the laser guns used in dermatology are manually operated and their laser spots are as large as 3 to 7 mm in diameter. It is thought that normal tissues, which do not contain melanin so much, are hardly damaged by the laser irradiation. However, in reality terrible burns appear after the laser irradiation even in the normal tissue. We have developed a new type of laser apparatus for removing only the pigmented lesions with laser scanning technology. A fθ lens unit assembled by a shrink fitter can focus the laser beam well over a wide scanning width. The effect of the laser pinpoint irradiation to only the pigmented lesions on the pigmentation therapy was experimentally examined with the developed apparatus. As a result, the pigmented lesions were able to be removed without affecting any damage to the surrounding tissue. Thus, the laser pinpoint irradiation was proved to be effective in the pigmentation therapy.

Ultra-Precision Method of Joining a Polygon Mirror Using a Shrink Fitter. Effect of Out-of-Roundness of Joining Surfaces on the Flatness of Mirror Surfaces.

In a previous paper, a new simple and ultra-precision method of joining a polygon mirror onto a SiC self-acting air bearing has been developed by using a shrink fitter as a new machine element. In this new joining method, mirror surfaces were deformed beyond a desired flatness of 100 nm, because of contact pressure applied at inner surface of the polygon mirror. This distortion of the mirror surfaces is considerably affected by form errors or surface accuracy of the joining surfaces and sizes of the polygon mirror. Therefore a secondary cut after the joining is needed to finish the mirror surfaces to the desirable level. In order to dispense with the secondary cut, we must know how the form errors affect the deformation of the mirror surfaces. In this paper, we considered only an out-of-roundness as the form error. The effect of the out of-roundness on the deformation of the mirror surfaces was examined theoretically and experimentally. The calculated profiles of the mirror surfaces were in agreement with the experimented ones. In addition, the range of the out-of- roundness, in which the mirror surfaces were not deformed seriously, was shown in a 3-dimensional diagram.