the application of galvo scanner in optical coherence tomography beauty
optical coherence tomography is a kind of no contact to biological tissue and non-invasive new laser diagnostic image technology with the advantages of high resolution and sensitive etc. oct is based on low-coherent interferometry theory, which is integrated laser technology, heterodyne detection, precision machine control and computer image processing. it has great prospects in the field of biomedical imaging. at present, in the field of biomedical, oct is mainly used in ophthalmology because the near infrared light can easily penetrate the human eyes media. it obtains the tomographic image of the tissue, distinguish the internal structure
of the organization through detecting different tissues to reflectance of light (reflectance, light absorption, scattering and reflection related)
oct is an important breakthrough of biological imaging towards non-invasive, high resolution development. it is called “optical biopsy” in medicine. as a new tomography technology with high speed and resolution, the scanning speed can reach hundreds of meters per second and resolution a few microns. it can meet the need for real-time, non-invasive and high resolution in biomedical diagnosis, which cannot replaced by other tomography techniques.
since oct successfully demonstrated human retina structure, it developed rapidly. the application in other fields also expands. it developed from axial detection of transparent biological tissue to the imaging of high non-transparent tissue, and from the detection of transparent biological tissue to the application of no-biological materials. the main application of the oct is as following:
to ensure the oct with best performance, the galvo scanner and the whole system performance are needed to test. at the same time, how to reduce the image distortion through oct image processing is also introduced. oct system uses galvo scanners to text with a real-quick scanning. the image rate of the system, the quality of imaging are directly related to the scanning of galvo scanners. the two major factors that affect the performance of scanners are response time and linearity. the response time determines the scanning frequency of scanner. the linearity direct reflect the linear relationship between signal control and linear movement. so, the main factor of increasing the system performance is to choose a suitable galvo scanners. figure 4-1 is an optical path photo for testing scanner. projecting a beam onto the scanner, after scanning, the beam is received by linear ccd of detection module. ccd collect the strongest point signal on the spot at various time and determine the spot position at that time. in this way, the movement of the scanner under the input signal driveing can be obtained.
the application of scanning galvanometer in fractional laser system
laser emits a single wavelength laser. for this characteristic, laser technology can transfer all kinds of energy and information to various biological tissue through a single wavelength laser. human is a complex biological organism, and the pigment and moisture content of body’s each tissue are different, so the absorption for different wavelength lasers are different. for this characteristic of human body, laser treatment means transferring laser energy to different body issues with different wavelength and achieving accurate treatment.
skin tissue has the ability to self-recover. when the skin suffered trauma, it can recover itself. if the trauma is too large, it will have scars after recovering. if the trauma is small, the skin can recover fully. each tiny dot of fractional laser means a minor trauma to skin tissue. this micro trauma is sufficient to finish tissue regeneration and the skin can recovery perfectly. fractional laser technology ihas been paid most attention and it is the newest skin beauty technology in the global skin boundary. it is a kind of minimally invasive treatment between invasive and noninvasive. fractional photothermolysis is published firstly by harvard university medical laser specialist dr. rox anderson in 2004 which was recognized by experts from all over the world and applied to clinical treatment immediately. fractional photothermolysis not only has the advantage of fast and significant effect of invasive treatment, but also less adverse effect of noninvasive treatment and shorter recovery time.
fractional laser is a new laser resurfacing mode. it has an obvious treatment on face whitening, scars, acne scars, wrinkles, pigmentation, large pores, rough skin, photo aging skin etc. this technology has the characteristics of noninvasive, easy operation, short recovery period and obvious effect, so it applied very extensive overseas, and became the latest popular in the minimally invasive and beauty. at present, cosmetology in clinical use super pulse co2 laser. the pulses of these lasers are shorter than 1ms, and the depth of peeling skin is about 100μm one time. the more canning or stronger of laser energy, the deeper of peeling skin, and the better treatment effect. in addition to direct exfoliation effect, co2 laser can also prompt skin recovery, collagen remodeling or regeneration through indirect heat conduction.
from the laser development trend, fractional laser represents a new technology which is a new treatment between invasive and noninvasive treatment.
