The speed of current microprocessors permits real time correction of galvanometer's imperfections and have become an integral elements of scanning systems. Consequently the critical parameters of scanning galvanometers have been reduced to speed, first mechanical resonance and power dissipation. This paper examines armature rigidity and the copper density of various coil designs. External fiducial sensors and capacitive pick-off imbedded fiducial sensors shall be reviewed.

Flexures are quite ancient, and their use as pivots is also ancient. Long before the use of the most primitive sleeve bearings leather strap flexures were used as trunk lidhinges and the like. Early engines of war, including the ballista of the Romans, technically advanced hand bows, and the cross bows of the fourteenth century all employ flexure pivots as their enabling technology. Designers of modern scientific instruments, including optical and laser scanning equipment exploit the same attributes of the flexure which appealed to their forefathers: simplicity, reliability, lack of internal clearance, long service life, ease of construction, and often, it's high mechanical Q. A special case of the flexure pivot, the torsional pivot, has made possible very long lived scanners at speeds which are far out of the reach of other bearing types. Since success with flexures requires consideration of some simple but non-intuitive issues such as stress distribution and stress corrosion, this talk will emphasize the practicum of flexure design and application.

In scanning display systems, high horizontal and vertical resolution, and high refresh rate requirements translate into large mirror-size scan-angle product and high scanner-frequency requirements. A comparison between published scan-angle mirror-size product values for MEMS scanners and a steel mechanical scanner is presented. Current performance levels of steel mechanical scanners are better; however, Silicon MEMS scanners have good material properties and should be able to reach and exceed the performance levels of conventional mechanical scanners. The resolution limitations of mechanical and MEMS scanners are established using dynamic mirror deformation, flexure stress, and other oscillation mode frequencies. Analytical formulas for torsional, vertical deflection mode, lateral deflection mode, and rocking mode natural frequencies are derived using mechanical beam deflection theory.

Given a prismatic polygonal scanner with a rotation axis at a fixed location O, and an incident beam with a finite width at an offset angle 2β to the optical scan-axis, it is required to determine with respect to O the location of the optical scan-axis, the coordinates of the point of incident P on a mirror-facet, and the orientation of the polygonal scanner mirror-facet, for when the incident beam is reflected along the optical scan-axis. Conversely, given a fixed location of the point of incidence P somewhere on a mirror-facet, and a fixed position of an incident beam at an offset angle 2β to a fixed location of an optical scan- axis, it is required to determine with respect to P the location and coordinates of the rotation axis O of the polygonal scanner, and the orientation of the polygonal scanner mirror-facets in the nominal position. This paper diagrammatically describes a geometrical construction procedure to provide precise analytical solutions to these problems. Most importantly the objective is to give a comprehensive visual insight into the effects and limits of changing the incident beam width, the beam offset angle, and the number of mirror-facets on a prismatic polygonal scanner.

As excellent performance is difficult to achieve in traditional laser beam scanner, which adopt cumbersome transmission mechanisms, this paper will propose a novel type, which employs permanent magnetic suspension structure. Static stability of such a scanning system will be analyzed fully based on magnetic theory and 3D-FEM tools. Finally, typical experiments verify that high static stability can be realized by this novel permanent magnetic suspension scanner. Other techniques involved in this type of laser beam scanner, including the scanning theory, precision control and dynamic stability, will be referred in later papers.

The surface of technical materials is playing an ever more important part in modern production processes. However, standard roughness values, which are obtained from a profile, frequently no longer provide sufficient descriptions. What are desired are three-dimensional measurements of surfaces over a macroscopic range with a high degree of vertical and lateral resolution. This has become necessary to be able to describe both deterministic and non-deterministic structures in the same fashion. Due to increased requirements for data and the measuring speed demanded by industry, only optical systems are a possibility. Using the example of tribology, the capability of this technology is shown in this article on the basis of the commercial confocal 3D white light microscope, the NanoFocus^TMμSurf^TM. On the one hand, the technology and data preparation used are discussed, and on the other, a comparison is drawn with other standard optical measuring methods.

The Nomad^TM Personal Display System is a head-worn display (HWD) with a see-through, high-resolution, high-luminance display capability. It is based on a single bi-axial scanning MEMS mirror. In the Nomad HWD system, a red laser diode emits a beam of light that is scanned bi-axially by a single MEMS mirror. A diffractive beam diffuser and an ocular expand the beam to form a 12mm exit pupil for comfortable viewing. The Nomad display has an SVGA (800x600) resolution, 60Hz frame rate, 23-degree horizontal field of view (FOV) and 3:4 vertical to horizontal aspect ratio, a luminance of 800~900 foot-Lamberts, see-through capability, 30mm eye-relief distance, and 1-foot to infinity focusing adjustment. We have characterized the performance parameters, such as field of view, distortion, contrast ratio (4x4 black and white checker board), modulation depth, exit pupil size, eye relief distance, maximum luminance, dynamic range ratio (full-on-to-full-off ratio), dimming ratio, and luminance uniformity at image plane. The Class-1 eye-safety requirements per IEC 60825-1 Amendment 2 (CDRH Laser Notice No. 50) are analyzed and verified by experiments. The paper describes all of the testing methods and set-ups as well as the representative test results. The test results demonstrate that the Nomad display is an eye-safe display product with good image quality and good user ergonomics.

In the current state of the prepress industry, high power laser beams (800 nm - 1064 nm, 10 to 40 Watts output) are used to expose Infra-red (IR) sensitized media to create half-tone images. These media are then chemically processed and fed into press systems for printing and publishing. In this paper, the basic physics of a high power IR imaging system recently introduced into the prepress industry is discussed. More specifically, we focus our attention to the spatial light modulator used in the imaging system. This modulator is called the Grating Light Valve^TM(GLV^TM), invented by David Bloom, and further developed and manufactured by Silicon Light Machines (SLM), Inc. The GLV-imaging system principle is described in terms of basic partial coherence and Fourier optical ideas. Although the fundamental physics of the GLV is based on the coherent superposition of diffracted waves, simple experimental observations imply that a high degree of spatial coherence from the illumination source is not required for the practical application of the GLV technology in imaging systems.

A cantilevered optical fiber is micromachined to function as a miniature resonant opto-mechanical scanner. By driving the base of the cantilevered fiber at a resonance frequency using a piezoelectric actuator, the free end of the cantilever beam becomes a scanned light source. The fiber scanners are designed to achieve wide field-of-view (FOV) and high scan frequency. We employ a non-linearly tapered profile fiber to achieve scan amplitudes of 1 mm at scan frequencies above 20 KHz. Scan angles of over 120 degree(s) (full angle) have been achieved. Higher order modes are also employed for scanning applications that require compactness while maintaining large angular FOV. Etching techniques are used to create the non-linearly tapered sections in single mode optical fiber. Additionally, micro-lenses are fabricated on the tips of the etched fibers, with lens diameters as small as 15 microns. Such lenses are capable of reducing the divergence angle of the emitted light to 5 degree(s) (full angle), with greater reduction expected by employing novel lens shaping techniques. Microfabricated optical fiber scanners have display applications ranging from micro-optical displays to larger panoramic displays. Applications for micro-image acquisition include small barcode readers to medical endoscopes.

Advancements in Light Emitting Diode (LED) output have allowed the possibility for producing a TV display using LEDs as the source. This paper presents the design of an optical projection system that takes an array of LED sources and scans them onto the screen of a rear projection TV display. A spinning polygon provides the scanning motion.

As part of the Infrared Eye project, this article describes the design of large-deviation, achromatic Risley prisms scanning systems operating in the 0.5 - 0.92 and 8 - 9.5 μm spectral regions. Designing these systems is challenging due to the large deviation required (zero - 25 degrees), the large spectral bandwidth and the mechanical constraints imposed by the need to rotate the prisms to any position in 1/30 second. A design approach making extensive use of the versatility of optical design softwares is described. Designs consisting of different pairs of optical materials are shown in order to illustrate the trade-off between chromatic aberration, mass and vignetting. Control of chromatic aberration and reasonable prism shape is obtained over 8 - 9.5 μm with zinc sulfide and germanium. The design is more difficult for the 0.5 - 0.92 μm band. Trade-offs consist in using sapphire with Cleartran® over a reduced bandwidth (0.75 - 0.9 μm ) or acrylic singlets with the Infrared Eye in active mode (0.85 - 0.86 μm). Non-sequential ray-tracing is used to study the effects of fresnelizing one element of the achromat to reduce its mass, and to evaluate detector narcissus in the 8 - 9.5 μm region.

Ghost images are caused by both specular and scattered reflected rays from optical surfaces and are always unwanted, especially within the image format of the scanned field image plane. This paper illustrates the formation of stationary ghost images that are produced only by the reflected rays from the image plane itself. A large portion of these rays are directed back through the optical scanning system to the mirror-facets of a prismatic polygonal scanner, which returns them to form one or more stationary ghost images in the image plane. The goal is to determine the angular ranges of incident beam offset angles from the scan-axis that ensure that the ghost images lie outside the image format.

A novel video tracking system based on fringe tracking and camera tracking is developed to simultaneously measure the spatial position and the body deformation of a swimming fish. The system control module consists of a fringe pattern tracking system that includes one rotating tracking mirror and a fringe pattern projector, and a video tracking system that includes another rotating tracking mirror and a high-speed camera. The two mirrors are mounted on two step-motors respectively. In the control module, a tracking gate technique based on the target trajectory identification and prediction algorithm is developed. The control module, through the two tracking mirrors, drives the fringe pattern projector and a high-speed camera to track the swimming fish. The rotating angles of tracking mirrors are recorded simultaneously. Body position and deformation are measured from the distorted fringes by the triangulation. We successfully apply the system to a swimming fish.

As an optical focus detection technique, confocal microscopy has been received much attention in the last few years. It has not only the particular property of depth discrimination, but also the ability of enhancement of contrast by suppression of light scattered from defocused object location. Therefore, the techniques based on confocal microscopy have been developed as a powerful tool for surface profiling. However, in order to maintain the high resolution, it is difficult to make fiber-optic sensor as small as possible, and which restrict the measurement of small internal curve surface. For the purpose of uniting micromation and high-precision in profile, based on a fiber confocal microscopy theory, a new fiber optical scanning microscope made up of splitter and GRIN lens is presented. Compared with other confocal technique, it has smaller size, higher anti-jam, and higher axial resolution. Especially, it has the characteristic of absoluteness zero point, which can be used for 3D and super-glossy inner surface profile. Experiment results show that the axial resolution with 30nm and linearity range 40μm can be achieved. This linearity, high resolution and small cubage permit non-contacting surface profilometry to be readily obtained for specimens of uniform reflectivity and small internal curve surface profile.

The single-axis and two-axis, flexure mounted, fast steering mirror (FSM) represents a compact, low cost, high performance design solution for a variety of emerging optical scanning and beam stabilization applications. Such devices are used to correct for polygon cross scan errors in prepress photography, acquire and lock beams within free space laser telecom systems, modulate tilt and cavity control in interferometers, maintain beam stabilization in the presence of thermal drift and vibration, and provide general two axis beam scanning. This paper discusses the tradeoffs among range of motion, spring selection, actuator types, mirror designs, and control systems. Actual product design and performance data is presented for a single axis FSM used for polygon cross scan error correction, and a dual axis FSM used for free space laser telecom.