MEMS devices and related scanned beam devices

Embodiments relate to a MEMS device including a scanner rotatable about at least one rotation axis, with the scanner having a characteristic resonant frequency. According to one embodiment, the MEMS device includes drive electronics operable to generate a drive signal that causes the scanner to oscillate at an operational frequency about the at least one rotation axis. The drive signal has a drive frequency selected to be about equal to the characteristic resonant frequency or a sub-harmonic frequency of the characteristic resonant frequency. According to another embodiment, the drive electronics are operable to generate a drive signal having a plurality of drive-signal pulses that moves the scanner at an operational frequency and sensing electronics are operable to sense a position of the scanner only when the drive-signal pulses of the drive signal are not being transmitted by the drive electronics. The MEMS device embodiments may be incorporated in scanned beam imagers, endoscopes, and displays.

BACKGROUND

Micro-electro-mechanical systems (“MEMS”) are currently employed in a variety of different applications. A few widely used applications for MEMS devices include scanned beam displays, scanned beam imagers, and scanned beam endoscopes.

A typical scanned beam display includes a MEMS die formed from a semiconductor substrate having a reflective scanner supported by torsion arms about which the scanner may rotate. In operation, an image may be generated by modulating light emitted from a light source (e.g., a light-emitting diode, a laser, etc.) and scanning the emitted light by rotating the scanner. Various optical components (e.g., lenses) may be used to modify the light before scanning, after scanning from the scanner, or both. For example, in a head-mounted display, a beam may be scanned through a viewer's pupil to generate the image on the viewer's retina.

In a scanned beam imager, a beam may be scanned across a field-of-view (“FOV”) and affected by the FOV, such as being reflected by an object to be imaged. The affected light may be collected and an image may be generated that is characteristic of the FOV.

In order to accurately generate the image, the rotational position of the reflective scanner should be accurately determined. In one conventional approach, the position of the scanner may be determined using photodetectors. Another conventional approach for determining the scanner position is by mounting resistive material on the torsion arms that changes resistance as the torsion arms are twisted. The change in resistance may be correlated with the position of the scanner. For comb-drive MEMS scanners, dedicated sensor-comb fingers different than the drive comb fingers may be provided. Capacitance between a fixed sensor comb fingers of the MEMS scan frame and the moving sensor-comb fingers may be determined. The rotational position of the scanner may be correlated to the measured capacitance. The aforementioned approaches typically rely on adding additional components to the system (e.g., photodetectors), additional electrical connections, requires separate components (e.g., the sensor comb fingers) that consume valuable space on a MEMS die, among other problems.

SUMMARY

Embodiments relate to a MEMS device including a scanner rotatable about at least one rotation axis, with the scanner having a characteristic resonant frequency. According to one embodiment, the MEMS device includes drive electronics operable to generate a drive signal that causes the scanner to oscillate at an operational frequency about the at least one rotation axis. The drive signal has a drive frequency selected to be about equal to the characteristic resonant frequency or a sub-harmonic frequency of the resonant frequency. According to another embodiment, the drive electronics are operable to generate a drive signal having a plurality of drive-signal pulses that moves the scanner at an operational frequency and sensing electronics are operable to sense a position of the scanner only when the drive-signal pulses of the drive signal are not being transmitted by the drive electronics.

In other embodiments, the principles of the above-described MEMS devices may be incorporated in scanned beam imagers, scanned beam endoscopes, scanned beam displays, and other MEMS applications.

DETAILED DESCRIPTION

Embodiments described herein relate to MEMS devices including sensing electronics operable to determine a rotational position of a MEMS scanner when drive electronics thereof are not transmitting drive-signal pulses and MEMS devices including drive electronics operable to generate a drive signal having a frequency that is about equal to a fundamental resonant frequency of the MEMS scanner or a sub-harmonic frequency of the MEMS scanner fundamental resonant frequency. Additional embodiments relate to scanned beam imagers, scanned beam endoscopes, scanned beam displays, and other MEMS applications that incorporate principles of such MEMS devices.

FIG. 1is a diagrammatic view of a MEMS device100, according to one embodiment, operable to sense a rotational position of a MEMS scanner when drive electronics thereof are not transmitting drive-signal pulses. The MEMS device100includes a MEMS scanner102having a characteristic resonant frequency fr, at least one light source104operable to emit a beam of light106(e.g., a converging, diverging, or generally collimated beam), and control electronics108operably coupled to the MEMS scanner102and the light source104. For example, the at least one light source104may be a laser, an LED, or another suitable light source. The MEMS scanner102may be a uniaxial or a biaxial MEMS scanner driven electrostatically, magnetically, or by combinations thereof. The MEMS scanner102is positioned to receive the beam106and oscillate at an operational frequency foto reflectively scan the beam106(represented as scanned beam110). The operational frequency fois typically about equal to the resonant frequency fr(e.g., equal to the resonant frequency or slightly larger or smaller than the resonant frequency fr). For example, the MEMS scanner102may scan the beam106to generate a video image according to a video image signal as in a scanned beam display or scan the beam106across a FOV and collect affected light from the FOV to generate an image characteristic of the FOV as in a scanned beam imager. Although not shown, additional optical components may be positioned in the path of the beam106, scanned beam110, or both, such as lenses, mirrors, diffractive elements, refractive elements, or other suitable optical components configured to modify a characteristic of the beam106, scanned beam110, or both.

Still referring toFIG. 1, the control electronics108of the MEMS device100include a light-source control electronics114operably coupled to the at least one light source104. For example, the light-source control electronics114may be configured to modulate the intensity of the beam106output from the at least one light source104. The control electronics108further include drive electronics116configured to generate a drive signal DSfor oscillating the MEMS scanner102about a selected axis between a rotational position A and B (the zero crossing or neutral position of the MEMS scanner102shown as position Z) at the operational frequency fo. The control electronics108also include sensing electronics118configured to generate a sensing signal SSfor sensing a rotational position (i.e., angle) of the MEMS scanner102only when drive-signal pulses of the drive signal DSare not being transmitted by the drive electronics116. In operation, responsive to instructions from the control electronics108, the at least one light source104outputs the beam106, which is received by the MEMS scanner102and scanned as the beam110.

The operation of the MEMS scanner102is described with reference to the various drive signals shown inFIGS. 2A-2Cin conjunction with the sensing signal shown inFIG. 3. For ease of understanding, inFIGS. 2A-2Cand3, the rotational position of the MEMS scanner102(FIG. 1) is indicated with identifiers A, B, and Z along the horizontal time axes of the graphs and corresponds to the rotational positions A, B, and Z shown inFIG. 1.FIG. 2Ashows a conventional drive signal200that may be used to drive the MEMS scanner102. The drive signal200includes a plurality of drive-signal pulses202exhibiting a drive period P1corresponding to a drive frequency that is approximately equal to two times the operational frequency foof the MEMS scanner102(FIG. 1). When the MEMS scanner102is at the rotational position A, one drive-signal pulse202may be transmitted to rotate the MEMS scanner102to the zero crossing Z. The MEMS scanner102continues to rotate to the rotational position B without application of one of the drive-signal pulses202, followed by another drive-signal pulse202being transmitted that rotates the MEMS scanner102back to the zero crossing Z. The MEMS scanner102continues to rotate to the rotational position A. Thus, the drive signal200causes the MEMS scanner102to oscillate at the operational frequency fobetween the rotational positions A and B to scan the beam110(FIG. 1).

One embodiment for driving and sensing a rotational position of the MEMS scanner102is described with reference toFIGS. 2B and 3.FIG. 2Bshows a drive signal204that may be generated by the drive electronics116(FIG. 1) to drive the MEMS scanner102and includes a plurality of drive-signal pulses206. The drive signal204exhibits a drive period P2corresponding to a drive frequency that is approximately equal to the characteristic resonant frequency fr(i.e., the fundamental resonant frequency) or a sub-harmonic frequency of the resonant frequency frof the MEMS scanner102. A sub-harmonic frequency of a characteristic resonant frequency is an integer fraction of the characteristic resonant frequency. For example, the frequency of the drive signal204may be a sub-harmonic frequency of the MEMS scanner102and equal to 2·fr/n, where n is an integer equal to or greater than three, such as n=3, 4, 5, etc. However, when the drive frequency of the drive signal204is about equal to a sub-harmonic frequency of the characteristic resonant frequency fr, the MEMS scanner102still oscillates at the operational frequency fothat is approximately equal to the resonant frequency fr.

Referring toFIG. 3, the sensing electronics118generate a sensing signal300including a plurality of sensing-signal pulses302. For example, respective sensing-signal pulses302may comprise a plurality of discrete pulses. The timing and period of the sensing signal300is selected so that the sensing-signal pulses302are transmitted during the period of time between consecutive drive-signal pulses206(FIG. 2B) of the drive signal204in order to sense a physical parameter that may be correlated to a rotational position of the MEMS scanner102. In one embodiment, the sensing signal208may be used to sense a physical parameter indicative of when the MEMS scanner102passes through the zero crossing Z. For example, as will be discussed in more detail with respect to the electrostatically-driven MEMS scanners shown inFIGS. 4 and 5, the sensing electronics118may generate the sensing signal300so that capacitance between fixed comb fingers of a MEMS frame and moving comb fingers of a MEMS scanner may be measured and correlated to a specific rotational position of the MEMS scanner.

FIG. 2Cshows a drive signal208according to another embodiment that may be used to drive the MEMS scanner102in conjunction with the sensing signal300shown inFIG. 3for determining a rotational position of the MEMS scanner102. The drive signal208includes a plurality of drive-signal pulses210exhibiting a drive period P3corresponding to a drive frequency that is approximately equal to two times the operational frequency foof the MEMS scanner102(FIG. 1) that oscillates the MEMS scanner102at the operational frequency fo. However, random or selected drive-signal pulses202may be omitted. For example, one of the drive-signal pulses is omitted between the drive-signal pulses210aand210b. The sensing signal300transmitted from the sensing electronics118may still be used to determine a rotational position of the MEMS scanner102, except only the sensed parameter measured during periods in which the sensing electronics118has sufficient sensitivity is used to determine the rotational position of the MEMS scanner102. For example, the parameter sensed between the drive signals210aand210bmay be correlated with a rotational position of the MEMS scanner102.

FIG. 2Dshows a drive signal212according to another embodiment that may be used to drive the MEMS scanner102. The drive signal212includes a plurality of drive-signal pulses214exhibiting a drive period P4corresponding to a drive frequency that may be approximately equal to two times the operational frequency foof the MEMS scanner102(FIG. 1). The drive signal212oscillates the MEMS scanner102at the operational frequency fo. Respective drive-signal pulses214may be terminated prior to the MEMS scanner102reaching the zero crossing Z. The sensing signal SStransmitted from the sensing electronics118may be used to measure a parameter related to the rotational position of the MEMS scanner102between consecutive drive-signal pulses214. For example, the sensing electronics118may measure a parameter related to the rotational position as the MEMS scanner102passes through the zero crossing Z.

In another embodiment, the drive electronics116may generate the drive signal200shown inFIG. 2Aand the sensing-signal pulses302generated by the sensing electronics118may be used to measure a parameter related to the rotational position of the MEMS scanner102during the time periods between consecutive drive-signal pulses202.

It should be noted that embodiments of other waveforms are contemplated for the drive signals that drive the MEMS scanner102, such as a sinusoidal-type waveform or another suitable waveform, while still allowing sensing of the rotational position of the MEMS scanner102during “dead periods” between drive-signal pulses.

It is also contemplated that in other embodiments, the drive signal204(FIG. 2B), which may have a drive frequency that is about equal to the characteristic resonant frequency fror a sub-harmonic frequency of the resonant frequency frof the MEMS scanner102, may be used to drive the MEMS scanner102and the rotational position of the MEMS scanner102may be determined in a conventional fashion (e.g., using a resistive material, photosensors, separate sensor comb fingers, etc.). Moreover, in such an embodiment, the sensing may be performed during periods in which the drive signal204is not transitioning from a high value to a low value or vice versa, or during periods other than the periods between consecutive drive pulses206. In certain embodiments, the drive frequency of the drive signal204may be selected to be a sub-harmonic frequency of the resonant frequency frof the MEMS scanner102that does not excite undesirable resonant responses in the MEMS scanner102. For example, undesirable resonant responses in the MEMS scanner102may be resonant responses other than the desired rotational mode.

FIG. 4is a schematic plan view of a MEMS device400that incorporates principles of the MEMS device100shown inFIG. 1, according to one embodiment, and includes an electrostatic comb drive configured to rotate a scanner about a single axis. The MEMS device400comprises a MEMS die401including a substrate402(e.g., a single-crystal silicon substrate or other semiconductor substrate that functions as a frame) having a scanner404formed therein with a reflective surface406. The scanner404is rotatably connected to the substrate402via respective torsion arms408and410that, together, define a rotation axis412. The MEMS die401includes an electrostatic comb-drive actuator comprising comb fingers414aand414bextending from the scanner404and corresponding fixed comb fingers416aand416bextending from the substrate402.

In operation, the drive electronics116of the control electronics108may apply a time-varying voltage drive signal DSbetween the comb fingers414aand416aand the comb fingers414band416b. For example, the drive signal DSmay have a waveform similar to any of the drive signals200,204,208, or212shown inFIGS. 2A-2D, such as having a frequency selected to be about equal to a sub-harmonic frequency of the scanner404or other frequency. The application of the drive signal DScauses the comb fingers414aand414bto be periodically electrostatically attracted to corresponding fixed comb fingers416aand416bthereby twisting the torsion arms408and410and causing the scanner404to oscillate about the rotation axis412at an operational frequency fo. Oscillating of the scanner404responsive to the drive signal DSenables scanning the beam106output from the light source104(represented as the scanned beam110) in a one-dimensional scan pattern that may be used for image generation as in a scanned beam display or to scan and image a FOV as in a scanned beam imager.

Additionally, as previously described with respect to the MEMS device100shown inFIG. 1, the sensing electronics118may determine a rotational position of the scanner404. For example, the sensing electronics118may generate the sensing signal SSin order to sense a capacitance between the comb fingers414aand414band corresponding fixed comb fingers416aand416b, which may be correlated to the rotational position of the scanner404. Such capacitance sensing may be performed at or near the zero crossing, or at another time period in which the sensing electronics118has sufficient sensitivity to measure capacitance. Furthermore, the sensing electronics118may transmit pulses of the sensing signal SSonly when the drive electronics116are not transmitting drive-signal pulses of the drive signal DS.

It is noted that in the MEMS die401shown inFIG. 4, the comb fingers414a-band416a-bare employed for both effecting rotation of the scanner404and sensing capacitance, to determine a rotational position of the scanner404. Thus, dedicated sensor-comb fingers may be omitted, which may provide for a relatively more compact MEMS die401.

FIG. 5is a schematic plan view of a MEMS device500that incorporates principles of the MEMS device100shown inFIG. 1, according to one embodiment, and includes electrostatic comb drives configured to rotate a scanner about a fast-scan axis and a slow-scan axis. The MEMS device500comprises a MEMS die501including a substrate502(e.g., a single-crystal silicon substrate or other semiconductor substrate that functions as a frame) having a scanner504formed therein with a reflective surface506. The scanner504is rotatably connected to a gimbal frame507via respective torsion arms508and510that, together, define a fast-scan rotation axis512. The gimbal frame507is rotatably connected to the substrate502via respective torsion arms514and516that, together, define a slow-scan rotation axis518that is generally perpendicular to the fast-scan rotation axis512.

Still referring toFIG. 5, the MEMS die501includes a fast-scan electrostatic comb-drive actuator comprising comb fingers520aand520bextending from the scanner504and corresponding comb fingers522aand522bextending from the gimbal frame507. The MEMS die501also includes a slow-scan electrostatic comb-drive actuator comprising comb fingers524aand524bextending from the gimbal frame507and corresponding comb fingers526aand526bextending from the substrate502.

In operation, the drive electronics116of the control electronics108may apply a time-varying voltage fast-scan drive signal DSFbetween the comb fingers520aand522aand the comb fingers520band522b. For example, the drive signal DSFmay have a waveform similar to any of the drive signals200,204,208, or212shown inFIGS. 2A-2D), such as a waveform having a frequency selected to be about equal to a sub-harmonic frequency of the scanner504or other frequency.

The application of the drive signal DSFcauses the comb fingers520aand520bto be periodically electrostatically attracted to corresponding fixed comb fingers522aand522b. The periodic attraction between the comb fingers520aand522aand the comb fingers520band522bthereby twists the torsion arms508and510and causes the scanner504to oscillate about the fast-scan rotation axis512at a fast-scan operational frequency. The drive electronics116of the control electronics108may also apply a time-varying voltage fast-scan drive signal DSSbetween the comb fingers524aand526aand the comb fingers524band526b. For example, the drive signal DSSmay have a waveform similar to any of the drive signals204,208, or212shown inFIGS. 2A-2D), such as a waveform having a frequency selected to be about equal to a sub-harmonic frequency of the scanner504or other frequency. The application of the drive signal DSScauses the comb fingers524aand524bto be periodically electrostatically attracted to corresponding fixed comb fingers526aand526b. The periodic attraction between the comb fingers524aand526aand the comb fingers524band526bthereby twists the torsion arms514and516and causes the scanner504to oscillate about the slow-scan rotation axis518at a slow-scan operational frequency less than that of the fast-scan operational frequency. Oscillating the scanner504about the fast-scan rotation axis512and the slow-scan rotation axis518responsive to the drive signals DSSand DSFenables scanning the beam106output from the light source104(represented as the scanned beam110) in a two-dimensional scan pattern that may be used for image generation as in a scanned beam display or to scan and image a FOV as in a scanned beam imager.

Additionally, as previously described with respect to the MEMS device100shown inFIG. 1, the sensing electronics118may determine a rotational position of the scanner504about the fast-scan rotation axis512. For example, the sensing electronics118may generate the sensing signal SSFin order to determine a capacitance between the comb fingers520aand520band corresponding fixed comb fingers522aand522b, which may be correlated to a rotational position of the scanner504about the fast-scan rotation axis512. The sensing electronics118may also determine a rotational position of the scanner504about the slow-scan rotation axis518. For example, the sensing electronics118may generate the sensing signal SSSin order to determine sense a capacitance between the comb fingers524aand524band corresponding fixed comb fingers526aand526b, which may be correlated to a rotational position of the scanner504about the slow-scan rotation axis518. Furthermore, the sensing electronics118may only transmit pulses of the sensing signal SSFfor sensing the fast-scan rotational position when the drive electronics116are not transmitting drive-signal pulses of the fast-scan drive signal DSFand the sensing electronics118only transmits pulses of the sensing signal SSSfor sensing the slow-scan rotational position only when the drive electronics116are not transmitting drive-signal pulses of the fast-scan drive signal DSS. In certain embodiments, the sensing signal SSSmay be transmitted when both the drive signal DSFand DSSare not being transmitted.

As with the MEMS device400, the fast-scan comb drive and slow-scan comb drive of the MEMS device500may be employed for both effecting rotation of the scanner504and sensing a parameter related to a rotational position of the scanner504. Thus, dedicated sensor-comb fingers may be omitted, which may provide for a relatively more compact MEMS die501.

Referring to the diagrammatic view ofFIG. 6, principles of any of the above-described MEMS device embodiments may be employed in a scanned beam imager600for imaging a FOV. The scanned beam imager600includes a light source602(e.g., a laser, an LED, or another suitable light source) operable to emit a beam of light604. A MEMS scanner606is positioned to receive and scan the beam604across a FOV605as a scanned beam608. For example, the MEMS scanner606may be configured and operated as the aforementioned MEMS scanners100,400, and500. The scanned beam imager600includes control electronics610comprising drive electronics612that outputs a drive signal with a drive frequency to drive the motion of the MEMS scanner606at an operational frequency, sensing electronics614that determines a rotational position of the MEMS scanner606by sensing a parameter related to the rotational position (e.g., capacitance), and light-source control electronics616that controls the output of the beam604from the light source602. The drive electronics612and sensing electronics614function the same or similarly to the drive electronics116and sensing electronics118of the MEMS device100shown inFIG. 1. For example, the drive signal may have a waveform similar to any of the drive signals200,204,208, or212shown inFIGS. 2A-2D.

Still referring toFIG. 6, instantaneous positions of the scanned beam608are designated as608aand608b. The scanned beam604sequentially illuminates locations618in the FOV at locations618aand618b, respectively. While the scanned beam608illuminates the locations, a portion of the illuminating scanned beam608is reflected (e.g., specular reflected light and diffuse reflected light also referred to as scattered light), absorbed, refracted, or otherwise affected according to the properties of the object or material at the locations to produce reflected light620aand620b. At least a portion of the reflected light620aand620bis received by one or more detectors622(e.g., PIN photodiodes or other suitable photodetectors), which generates electrical signals corresponding to the amount of light energy received. The control electronics610processes the electrical signals and generates a digital representation of the FOV605, which is transmitted for further processing, decoding, archiving, printing, display, or other treatment or use via interface624. Because the sensing electronics614may determine a rotational position of the scanner606during “dead periods” in which the drive-signal pulses are not being transmitted, the position information may be more accurate and may be utilized to more accurately relate the received reflected light620to a location on the FOV605in order to generate relatively more defined digital representation of the FOV605.

Referring toFIGS. 7-9, principles of any of the above-described MEMS device embodiments may also be employed in a scanned beam endoscope700for imaging a FOV according to one embodiment. Specialized endoscopes have been developed to best accomplish their intended function. For example, upper endoscopes are used for examination of the esophagus, stomach and duodenum, colonoscopes are used for examining the colon, angioscopes are used for examining blood vessels, bronchoscopes are used for examining the bronchi, laparoscopes are used for examining the peritoneal cavity, and arthroscopes are used for examining joint spaces. Instruments to examine the rectum and sigmoid colon, known as flexible sigmoidoscopes, have also been developed. The discussion of endoscopes herein generally applies to these and other types of endoscopes, and the term “endoscope” as used herein may encompass all these and other such devices

Referring to the diagrammatic view ofFIG. 7, the scanned beam endoscope700includes a control module702and monitor704, all of which may be mounted on a cart726, and collectively referred to as console724. The control module702includes control electronics706for controlling the operation of a scanning tip720that comprise drive electronics707for driving a MEMS scanner742(FIG. 9) and sensing electronics709for determining a rotational position of the scanner742. The control module702further includes an image processor708for processing image data signals associated with light reflected from a region of interest being imaged, a light source710coupled to the control electronics706, and a light-detector module712. A handpiece714is operably coupled to the control module702through an external cable716to enable an operator to manipulate a position and image collection functions of an endoscope tip718.

Still referring toFIG. 7, the endoscope tip718includes a scanning tip720and a hollow, elongated body722having a proximal end723attached to the handpiece714and a distal end725attached to the scanning tip720. The hollow, elongated body722encloses optical and electrical components, such as optical fibers and electrical wires, associated with the scanning tip720. Depending upon the endoscope application, the elongated body722may be flexible or rigid. The scanning tip720includes a scanning module734(FIGS. 8 and 9) configured to scan a beam across a FOV, and a plurality of detection optical fibers732(FIG. 8) that collect light reflected from a region of interest in the FOV and transmit optical signals to the light detection module712. The light-detector module712is operable to convert the optical signals received from the scanning tip720to electrical image data signals and transmit the electrical image data signals to the image processor708. As with the aforementioned scanned beam imager embodiments, the light-detector module712may include one or more photodiodes for converting the light received from the region of interest to electrical image data signals. Although the light-detector module712is shown located in the control module702, in another embodiment, one or more photodiodes may be physically integrated with scanning tip720and electrical image data signals converted thereby may be transmitted to the image processor708for processing via electrical wires instead of optical fibers.

FIGS. 8 and 9illustrate the scanning tip720and a scanning module734of the scanning tip720, respectively, in more detail. Referring to the schematic perspective view shown inFIG. 8, the scanning tip720includes a housing730that encloses and carries the scanning module734, the detection optical fibers732, and an end cap735affixed to the end of the housing730. The detection optical fibers732may be disposed peripherally about the scanning module734within the housing730and transmit reflected light received from the region of interest to the light-detector module112.

Referring to the schematic cross-sectional view shown inFIG. 9, the scanning module734has a housing738that encloses and supports a MEMS scanner742and associated components, an illumination optical fiber752affixed to the housing738by a ferrule750and coupled to the light source710, and a beam shaping optical element746. A dome740is affixed to the end of the housing730and may be hermetically sealed thereto in order to protect the sensitive components of the scanning module734. In some embodiments, the light source710may output polarized light and the dome740may be structured to only transmit the scanned beam744when the scanned beam744exhibits a selected polarization. In the illustrated embodiment, the detection optical fibers732or other collection optics may be used to collect light received from the FOV.

In operation, the scanning tip720is inserted into a body cavity to image a region of interest of an organ or tissue. The illumination optical fiber752receives light from the light source710and outputs a beam748that is shaped by the beam shaping optical element746to form a shaped beam736having a selected beam shape. The shaped beam736may be transmitted through an aperture in the center of the MEMS scanner742or another opening in the MEMS scanner742, reflected off a first reflecting surface738of the interior of the dome to the front of the scanner742, and then reflected off of the scanner742as a scanned beam744through the dome740. The scanned beam744is scanned across a FOV and reflected off the region of interest of the body cavity. The drive electronics707of the control electronics710(FIG. 7) drives the motion of the scanner742. For example, the drive electronics707may output a drive signal having a waveform similar to any of the drive signals200,204,208, or212shown inFIGS. 2A-2D. Additionally, the sensing electronics709of the control electronics710(FIG. 7) may determine a rotational position of the scanner742as the scanner742oscillates during “dead period” in which the drive electronics707of the control electronics710are not transmitting a drive-signal pulse using any of the previously described techniques.

At least a portion of the reflected light (e.g., specular reflected light and diffuse reflected light also referred to as scattered light) is collected by the detection optical fibers732of the scanning tip720, transmitted to the light detection module712for conversion to electrical image signals that are subsequently transmitted to the image processor708. The image processor708processes the image signals received from the scanning tip720to generate an image characteristic of the region of interest being imaged for display on the monitor704. It is noted that in other embodiments, the conversion of the reflected light to electrical signals may occur at the scanning tip720and transmitted to the image processor708via electrical wires.

Although many of the above-described embodiments relate to MEMS devices for use in beam scanning applications (e.g., scanned beam imagers, scanned beam endoscopes, or scanned beam displays), the principles may be employed in non-optical applications. For example, a body supported by a frame may be moved (e.g., oscillated) by the drive electronics116and the position thereof determined by the sensing electronics118. The body may be a body other than a scanner, such as a shutter for a MEMS valve, a MEMS gear, a MEMS mechanical actuator, or other MEMS application.

Although the present invention has been disclosed and described by way of some embodiments, it is apparent to those skilled in the art that several modifications to the described embodiments, as well as other embodiments of the present invention are possible without departing from the spirit and scope of the present invention.