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We present a micrograting-based injection force sensor integrated with a surface micromachined silicon-nitride injector. The injector is supported by springs of known spring constant, and the injection force is determined from displacement measurements using a high-resolution, miniaturized optical encoder. The sensor exhibits configurable sensitivity and dynamic range, allowing monitoring over a wide range of forces. The periodicity of the encoder response can be used for calibration and to obtain information about the deformation of the target. We used an injector with a measured spring constant of 1.85 N/m for penetration experiments on Drosophila embryos, and found a penetration force of 52.5/spl plusmn/13.2% /spl mu/N and a membrane displacement of 58/spl plusmn/5.2% /spl mu/m.

A technique for positioning and immobilization of Drosophila embryos in 2-D arrays for use in high throughput microinjection experiments has been characterized. The method is based on fluidic microassembly and immobilization yield, the number of misplaced embryos, and adhesion force of the embryos have been measured for samples with two different pad geomtries. For samples with 250 /spl mu/m/spl times/400 /spl mu/m sized pads an immobilization yield of 85% was achieved. The adhesion force of the embryos was estimated at 36 /spl mu/N/spl plusmn/22 /spl mu/N. A substantial amount of clustering was, however, observed. By reducing the pad size to 200 /spl mu/m/spl times/200 /spl mu/m and changing the pad pitch the number of misplaced embryos was reduced to less then 5%. The immobilization yield was, however, lower for these samples. The adhesion force of embryos immobilized at the smaller pads was estimated at 14 /spl mu/N/spl plusmn/5.5 /spl mu/N.

Cataloged from PDF version of article. Higher harmonics in tapping-mode atomic force microscopy offers the potential for imaging and sensing material properties at the nanoscale. The signal level at a given harmonic of the fundamental mode can be enhanced if the cantilever is designed in such a way that the frequency of one of the higher harmonics of the fundamental mode ~designated as the resonant harmonic! matches the resonant frequency of a higher-order flexural mode. Here we present an analytical approach that relates the amplitude and phase of the cantilever vibration at the frequency of the resonant harmonic to the elastic modulus of the sample. The resonant harmonic response is optimized for different samples with a proper design of the cantilever. It is found that resonant harmonics are sensitive to the stiffness of the material under investigation.

We describe a batch-assembled optoelectronic packaging technology based on silicon surface-micromachined alignment mirrors and demonstrate that these mechanical structures have the functionality, stability and accuracy required for active semiconductor laser-to-filter (single mode) coupling. In initial experiments, we measure an open-loop position accuracy of 0.2 /spl mu/m, and we achieve repeatable 45% coupling efficiency with good mechanical stability. >

Routers built around a single-stage crossbar and a centralized scheduler do not scale, and (in practice) do not provide the throughput guarantees that network operators need to make efficient use of their expensive long-haul links. In this paper we consider how optics can be used to scale capacity and reduce power in a router. We start with the promising load-balanced switch architecture proposed by C-S. Chang. This approach eliminates the scheduler, is scalable, and guarantees 100% throughput for a broad class of traffic. But several problems need to be solved to make this architecture practical: (1) Packets can be mis-sequenced, (2) Pathological periodic traffic patterns can make throughput arbitrarily small, (3) The architecture requires a rapidly configuring switch fabric, and (4) It does not work when linecards are missing or have failed. In this paper we solve each problem in turn, and describe new architectures that include our solutions. We motivate our work by designing a 100Tb/s packet-switched router arranged as 640 linecards, each operating at 160Gb/s. We describe two different implementations based on technology available within the next three years.

In this paper, we report on a FIR (finite impulse response) dispersion compensator made using optical MEMS (micro-electro-mechanical systems) technology. An array of micromirrors is used in a Gires-Tournois (GT) interferometer to obtain the desired dispersion value of the device. This type of device had earlier been shown to function as an optical WDM interleaver/deinterleaver. The proposed device has a periodic transfer function in the frequency domain with a well-defined free spectral range (FSR). Because of the large number of channels in dense WDM systems, periodic filters are advantageous to avoid the need for unique filters for each WDM channel.

Date of Conference: 8-12 June 2003 Conference name: TRANSDUCERS '03. 12th International Conference on Solid-State Sensors, Actuators and Microsystems. Digest of Technical Papers We present a micromachined scanning probe cantilever, in which a specific higher order flexural mode is designed to be resonant at an exact integer multiple of the fundamental resonance frequency. We have demonstrated that such cantilevers enable sensing of nonlinear mechanical interactions between the atomically sharp tip at the free end of the cantilever and a surface with unknown mechanical properties in tapping-mode atomic force microscopy.

We present an analytical solution to the problem of finding a diffractive surface relief that generates a specific optical amplitude and phase spectral reflection in a particular direction. We show that any discrete finite impulse response filter can be generated to within a multiplicative constant at nonzero frequencies. We propose an implementation of such a filter that works in the visible and the near infrared, based on a two-dimensional array of dual-state tiltable mirrors. A 1024 x 1024 array results in a 1024-tap filter with 10-bit quantization of the impulse response. The applications of such a device include spectroscopy and wavelength-division multiplex switching.

The National Science Foundation Center for Adaptive Optics (CfAO) is coordinating a program for the development of spatial light modulators suitable for adaptive optics applications based on micro-optoelectromechanical systems (MOEMS) technology. This collaborative program is being conducted by researchers at several partner institutions including the Berkeley Sensor & Actuator Center, Boston Micromachines, Boston University, Lucent Technologies, the Jet Propulsion Laboratory, and Lawrence Livermore National Laboratory. The goal of this program is to produce MEMS spatial light modulators with several thousand actuators that can be used for high-resolution wavefront control applications that would benefit from low device cost, small system size, and low power requirements. The two primary applications targeted by the CfAO are astronomy and vision science. In this paper, we present an overview of the CfAO MEMS development plan along with details of the current program status.

The authors show that using a phaselocked loop, stable optical pulses can be generated from a monolithic, passively modelocked semiconductor laser. A phase noise of -100dBc/Hz at 46GHz and a pulse width of 1.3ps are achieved, and the limits of the pulse stability using this approach are discussed.

This paper describes the design and fabrication of micromachined resonant scanners that have large scan angles at fast scan speeds. Driven by an electrostatic comb motor, these 200 /spl mu/m by 250 /spl mu/m scanning-micromirrors can scan about 12/spl deg/ (optical) at the resonance frequency of 3 kHz with a sinusoidal voltage input of 20 V in amplitude. Fabricated with a four-poly-layer silicon-surface-micromachining process, these resonant scanners are compact, extremely light in weight, and potentially very low in cost. The power consumption is also minimal since the capacitive motor draws very little current. We have demonstrated the scanner as a laser-beam deflector in a barcode reader, a potentially important application that has a growing popularity in many industries.

Electrostatic actuation has received much attention recently for its potential application in microelectromechanical systems. However, in order to generate the forces needed in many applications, very high voltages (>100 V) are often required. Actuators based on impact have been shown to be a feasible alternative. With impact, a very large force of short duration can be delivered to move a microelement. We describe a surface-micromachined linear-motion microvibromotor to perform this function. The microvibromotor offers: large range of motion, high velocity and precise positioning. Our initial application is to position optical elements, such as mirrors or diffraction gratings, in a micro-optical system on silicon. >

This paper describes a 2D raster scanning system incorporating two surface-micromachined mirrors fabricated on separate chips: a fast mirror for horizontal and a slow mirror for vertical scanning. The mirrors are tilted out-of-plane on polysilicon hinges and are connected to their supporting frames with torsional polysilicon beams. The tilt-up mirror design accommodates large mirror areas and allows integration of optical components on the same chip. Prior work on tilt-up micromirrors has demonstrated the feasibility of resonant mirrors for 1-D barcode scanning. The raster scanning mirrors are nearly circular, measuring 565 /spl mu/m along the scan axis and 500 /spl mu/m along the perpendicular axis. The mirror surfaces are linked to comb drive actuators, and both have a resonant frequency of 4.54 kHz. The measured optical scan angle of the fast mirror is 5.3/spl deg/ when operated at resonance, driven with a 116 Vpp sine wave and zero DC offset. The scan axis of the fast mirror is oriented perpendicular to the slow mirror. The slow mirror is identical to the fast mirror, except bidirectional comb drives allow it to be driven in opposing directions. Triangular voltage waveforms at 167 Vpp rotate the mirror, deflecting the optical beam through 5.7/spl deg/. The slow mirror governs the image refresh rate.

We have designed, implemented and characterized a switchable optical (de)interleaver based on a Gires-Tournois interferometer geometry. Less than 1 /spl mu/m piston motion of the individual mirrors of the array is required for tuning of the center wavelength, and for switching of (de)interleaved output ports. The concept can be extended to more complex filtering functions with a variety of applications in optical communication and sensing.

We demonstrate remote data acquisition from an autonomous sensor module over a low power wireless optical link. The communication link is based on a grating light modulator. The high data rate, low power consumption, compactness and ease of fabrication make this wireless optical link a promising candidate for a wide range of remote-sensing and sensor-network applications.

This paper describes two optical devices based on linear arrays of micro mirrors. The first is a phased array of micro mirrors that can be rotated as well as translated vertically to maintain coherence across the array. We demonstrate experimentally that such micro mirrors are capable of high-diffraction-efficiency, phased-array scanning of laser beams. The second device is a Gires- Tournois interferometer with a micro mirror array that provides tunable phase modulation for the multitude of partially reflected beams within the interferometer. We demonstrate experimentally that the MEMS-GT interferometer can operate as a tunable deinterleaver for dense Wavelength Division Multiplexed fiber optic communication.

We have developed surface micromachined hollow silicon nitride needles, specifically designed for injection of DNA and proteins into fruit fly embryos. Precisely controlled calibration of the injected volume is possible using an integrated membrane-based pressure sensor with interferometric read out. The membrane can withstand pressures in excess of 3 bar. The excellent mechanical stability of the hollow needle was verified in fruit-fly embryo injection experiments and the injection of water and a solution of GFP (green fluorescent protein) were successfully performed. Flow measurements of air through a needle with channel dimensions: 75 μm x 15 μm x 2.5 μm, resulted in a flow rate of rair = 1.4 nl / (s bar).

A technique for positioning and immobilization of fruit fly embryos in 2-D arrays is developed for use in high throughput microinjection of genetic material or drugs. The method is based on fluidic microassembly, and the results indicate that over 90% of the immobilized embryos would be injected with a matching array of microinjectors. The adhesion force of the immobilized embryos was estimated at 36 μN ± 22 μN.

The buildup of pulses in a passively mode‐locked monolithic semiconductor laser is investigated experimentally and theoretically. A simple model, based on competition between the fundamental and higher order mode‐locking ‘‘supermodes,’’ gives a time constant for the buildup in good agreement with the experimental values, which are on the order of 3.5 ns. The theory shows that to minimize the pulse buildup time, the photon life time and the width of the gain spectrum should be minimized, and the gain and the gain modulation, should be maximized.

Resonant mirrors introduce large spectral gradients in reflected phase while maintaining high reflectivity, allowing synthesis of optimized reflected phase for many practical applications. In this paper we show theoretically that asymmetry is required for negative group delay in lossless mirrors and explore the limits of reflected phase in resonant mirrors through the use of coupled mode theory and rigorous couple wave analysis. Our coupled mode theory shows that the phase response of resonant mirrors is determined by interacting resonances and gives insight into tradeoffs in design of mirrors with desired phase response.

This paper describes design and simulations of dielectric laser electron accelerators that achieve Gigavolt-per-meter (GV/m) accelerating gradients and wide electron channels (>1 μm). The accelerator design is based on a silicon buried grating structure that enables flexible phase synchronization, large electron channel fields, and low standing-wave ratio in the material. This design increases the accelerating gradients to more than double those of reported quartz grating accelerators, thereby reducing the input laser fluence by 60% for the same accelerating gradient. With a 100 fs pulsed laser, our silicon buried gratings can achieve a maximum gradient of 1.1 GV/m, indicating that these accelerators have potential for numerous electron-accelerator applications.

The modulation efficiency and bandwidth limitations of a new type of light modulator, the attenuated total internal reflection modulator (ATRM), are described. The ATRM is based on coupling a light beam to a surface plasmon wave, and its fabrication is compatible with GaAs integrated circuit technology. We demonstrate modulation to 22 GHz (the extrapolated 1.5 dB optical modulation bandwidth is 26 GHz) and show that devices with high modulation index can be built using existing materials.

The NSF Center for Adaptive Optics (CfAO) is coordinating a five to ten year program for the development of MEMS-based spatial light modulators suitable for adaptive optics applications. Participants in this multi-disciplinary program include several partner institutions and research collaborators. The goal of this program is to produce MEMS spatial light modulators with several thousand actuators that can be used for high-resolution wavefront control applications and would benefit from low device cost, small system size, and low power requirements. We present an overview of the CfAO MEMS development plan along with details of the current program status. Piston mirror array devices that satisfy minimum application requirements have been developed, and work is continuing to enhance the piston devices, add tip-tilt functionality, extend actuator stroke, create a large array addressing platform, and develop new coating processes.

We demonstrate a GaAs/AlGaAs multiple-quantum-well in-line fiber optic intensity modulator. Based on evanescent wave coupling between a GaAs/AlGaAs anti-resonant reflective optical waveguide and a side-polished single mode fiber, this device concept combines the inherent advantages of in- line fiber devices with high-performance GaAs integrated optoelectronics. The GaAs waveguide utilizes distributed Bragg reflector mirrors, which are designed to provide maximum reflection at a given more angle, to phase-match to the low-index fiber. Intensity modulation of the transmitted light through the fiber is achieved by changing the complex propagation constant of the GaAs waveguide through the quantum-confined Stark effect. Typical device shows an on/off ratio of 4:1, with an applied voltage of 9V. Calculations show that with a longer interaction region, an on/off ratio of more than 40dB is achievable with the same applied voltage.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A measurement system for static and dynamic characterization of silicon micromachines was developed. The computer- controlled system, using a HeNe-laser at 633 nm and a two- dimensional position sensor, allows simultaneous measurements of optical beam motion on two axes. To demonstrate the flexibility and functionality of the setup, measurements on various polysilicon surface-micromachined mirrors were performed. These measurements included tilt-angle versus driving-voltage curves, frequency responses, and motion perpendicular to the primary scan axis.

A GaAs/AlGaAs in-line fiber optic filter for wavelength division multiplexing applications is demonstrated. The device consists of a GaAs/AlGaAs anti-resonant reflecting optical waveguide (ARROW) evanescently coupled to a single mode fiber. At certain discrete wavelengths, light is coupled from the fiber to the ARROW, due to phasematching conditions. Sharp resonances are observed around the design wavelength of 830 nm. The 3 dB cutoff bandwidth for TE polarization is 0.5 nm and the rejection ratio is 9 dB.

The performance of a light modulator at a 1.3 mu m wavelength based on the plasma effect in silicon is described. The modulator is directly coupled to a single-mode fiber pigtail in a simple and robust package. The measured modulation index is 24% with a 3-dB bandwidth of 60 MHz, and the insertion loss is 5 dB. This modulator has applications in data acquisition from silicon sensors and other silicon ICs. >

The authors have developed an integrated silicon light intensity modulator based on polarization-independent free-carrier optical phase modulation and mode filtering in fibers. A novel push-pull complementary diode pair are used for a twofold increase in modulation depth over a single diode device. Operation is demonstrated at a wavelength of 1.32 mu m. >

The six invited and 30 contributed papers in this special issue focus on optical micro- and nanosystems. They are grouped into the following categories: spatial light modulators; resonators and waveguides; biophotonics; photonic crystals and plasmonics; optical scanning devices and systems; optical switches; lasers; sensors; and nanoelectromechanical systems (NEMS).

Summary form only given. We have demonstrated an inline fiber optic filter using a GaAs ARROW waveguide as the overlay. It has a rejection ratio of 11 dB and a bandwidth of 7 nm. The inclusion of quantum wells in the waveguide core will lead to a new class of integrated fiber devices, including modulators, detectors, amplifiers, and lasers.

We present the design and fabrication of surface- micromachined electrostatic-comb driven microscanners that have high angular precision over a large scan angle. When used as resonant scanners, these mirrors have fast scan rates with very low operating power. We use polysilicon microhinges, which allow the micromirrors to be lifted out of the plane of the substrate after processing is completed, to create high-aspect-ratio optical surfaces with dimensions in the hundreds of micrometers s while taking advantage of the planar surface-micromachining processing technology. Microscanners that are capable of high-speed scanning over large scan angles with high precision have been fabricated. Application of these actuated micromirrors in laser barcode scanning and optical-fiber switches have been demonstrated. These single-mirror scanners can be combined to form more complicated microscanners such as a two-mirror, two-axis raster scanner that have a wide range of applications in areas such as medicine, displays, printing, data storage, and communications.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We investigate, by simulations and experiments, the light scattering of small particles trapped in photonic crystal membranes supporting guided resonance modes. Our results show that, due to amplified Rayleigh small particle scattering, such membranes can be utilized to make a sensor that can detect single nano-particles. We have designed a biomolecule sensor that uses cross-polarized excitation and detection for increased sensitivity. Estimated using Rayleigh scattering theory and simulation results, the current fabricated sensor has a detection limit of 26 nm, corresponding to the size of a single virus. The sensor can potentially be made both cheap and compact, to facilitate use at point-of-care. © 2013 Optical Society of America. Open Access article.

We investigate theoretically and experimentally Fano resonances in integrated silicon Bragg reflectors. These asymmetric resonances are obtained by interference between light reflected from the Bragg waveguide and from the end facet. The Bragg reflectors were designed and modeled using the 1D transfer matrix method, and they were fabricated in standard silicon wafers using a CMOS-compatible process. The results show that the shape and asymmetry of the Fano resonances depend on the relative phase of the reflected light from the Bragg reflectors and end facet. This phase relationship can be controlled to optimize the lineshapes for sensing applications. Temperature sensing in these integrated Bragg reflectors are experimentally demonstrated with a temperature sensitivity of 77 pm/°C based on the thermo-optic effect of silicon.

We make the case for minimizing cavity length of extrinsic Fabry-Pérot (FP) cavities for use in fiber-tip sensors. Doing so mitigates multiple challenges that arise from using multimode fibers: mode averaging, phase uncertainty, amplitude reduction, and spectral modal noise. We explore these effects in detail using modal simulations, and construct pressure sensors based on this principle. We discuss the multimodal effects that we observe in our fiber sensors, and use simple filtering of the spectral signal to more easily measure pressure sensitivity. The concept of short-cavity FP interferometry is important for ensuring high quality and performance of multimode fiber sensors.

We present a two-axis electrostatic MEMS scanner with high-reflectivity monolithic single-crystal-silicon photonic crystal (PC) mirrors suitable for applications in harsh environments. The reflective surfaces of the MEMS scanner are transfer-printed PC mirrors with low polarization dependence, low angular dependence, and reflectivity over 85% in the wavelength range of 1490nm~1505nm and above 90% over the wavelength band of 1550~1570nm. In static mode, the scanner has total scan range of 10.2° on one rotation axis and 7.8° on the other. Dynamic operation on resonance increase the scan range to 21° at 608Hz around the outer rotation axis and 9.5° at 1.73kHz about the inner rotation axis.

High bandwidth interdigitated probes have enabled high-speed mapping of elastic properties of various samples in air. To extend this capability to imaging in fluids, we implemented a signal processing scheme to calculate the tip-sample interaction force as well as elastic properties from high-frequency photodiode signals. Using this method, we imaged a styrene-(ethylene/butylene)-styrene copolymer sample submerged in water and obtained spatial maps of elastic properties as well as maps of higher harmonics of the motion of the tip. We observed that multiple physical quantities contribute to the contrast observed in the phase and higher harmonic images.

Two types of polysilicon surface-micromachined actuators designed for moving hinged micromirrors are described. An electrostatic comb-drive actuator comprised of interdigitated capacitors has been used to move a mirror at frequencies of at least a kHz. Impact-actuated linear vibromotors allow mirrors to travel over large (> 100 micrometers ) ranges with submicron positioning.

The growing optical communications and measurement market requires low-cost, high- performance optoelectronic modules such as laser-to-fiber couplers, tunable lasers, scanners, interferometers, etc. Unlike integrated electronic circuits, integrated optical systems require precise alignment of components. A misalignment of less than 1 pm can dramatically decrease system performance. While silicon-optical-bench (SOB) technology provides for hybrid integration of semiconductor lasers, lenses, and optical fibers on a silicon chip, it is typically limited to +I pm alignment tolerances (without externa1 adjustment). Another limitation is the lack of on-chip actuated optical components (such as mirrors, gratings, lenses, etc.) As a result, SOB technology applications have been limited to simple systems with no more than three or four components. To overcome these limitations a micromachined free-space optical platform has been proposed [ 1, 21. By combining micromachined movable optical components with lasers, lenses, and fibers on a silicon substrate, we can produce complex self-aligning optical systems on a chip. In order to function in a self-contained optical module, the micromachined components must have sufficient precision and, where required, must have on-chip actuation. In this paper, we present an actuated micromachined microreflector with two degrees of freedom and on-chip resonant electrostatically driven impact actuations.

We have designed and built integrated, movable micromirrors for on-chip alignment in silicon- optical-bench technology. The mirrors are fabricated using surface micromachining with three polysilicon layers. A polysilicon-hinge technology was used to achieve the required vertical dimensions and functionality for alignment in hybrid photonic integrated circuits. The positioning accuracy of the mirrors is measured to be on the order of 0.2 micrometers . This precision is shown theoretically and experimentally to be sufficient for laser-to-fiber coupling. In the experimental verification, we used external actuators to position the micromirror and obtained 45% coupling efficiency from a semiconductor laser (operating at 1.3 micrometers ) to a standard single-mode optical fiber. The stability and robustness of the micromirrors were demonstrated in shock and vibration tests that showed that the micromirrors will withstand normal handling and operation without the need for welding or gluing. This micromirror technology combines the low-cost advantage of passive alignment and the accuracy of active alignment. In addition to optoelectronic packaging, the micromirrors can be expected to find applications in grating-tuned external-cavity lasers, scanning lasers, and interferometers.

We quantitatively map the surface forces and elastic modulus in tapping-mode atomic force microscopy (AFM). To achieve this, we use custom-built cantilevers with interferometric high-bandwidth force sensors that can resolve nonlinear tip-sample interaction forces, combined with a set of algorithms to process the force sensor signals in real-time. Our technique achieves quantitative mechanical measurements, while retaining nanoscale spatial resolution and minimal loading forces in tapping-mode AFM. Moreover, conventional tapping-mode AFM images are not affected and can simultaneously be acquired. As a practical demonstration, we use our technique to quantify the mechanical properties of a polystyrene and linear low-density polyethylene blend.

An acoustic sensor and a method of fabricating an acoustic sensor are provided. The acoustic sensor includes at least one photonic crystal structure and an optical fiber having an end optically coupled to the at least one photonic crystal structure. The acoustic sensor further includes a structural portion mechanically coupled to the at least one photonic crystal structure and to the optical fiber. The at least one photonic crystal structure, the optical fiber, and the structural portion substantially bound a region having a volume such that a frequency response of the acoustic sensor is generally flat in a range of acoustic frequencies.

The ability to transmit millimeter-wave signals over fiber opens up new possibilities for distributed antenna networks and phased- array systems. Previous results have demonstrated the transmission of millimeter-wave signals at 40 Mbit/s around 35 GHz by using narrow-band resonant enhancement.1 In this paper we report a system demonstration of 300-Mbit/s binary-phase- shift-keyed (BPSK) signal transmission at a carrier frequency of 39 GHz through 2.2 km of optical fiber, using a recently reported feedforward modulation technique.2 A bit error rate (BER) of 10-9 at a received optical power of —9.8 dBm has been achieved. The experimental setup is shown in Fig. 1. The dotted enclosure represents the feedforward millimeter-wave optical modulator. Details of the operational principle of this modulation technique can be found in Ref. 2. In brief, a beat note at 36.5 GHz is generated by photomixing two 1.3-μιη distributed-feedback (DFB) lasers each with a free-running linewidth of 15 MHz and emitting at an optical power of 8 mW. The beat note is electrically-mixed with the input millimeter-wave signal that is centered at 39 GHz and contains pseudorandom (215 — 1) nonreturn-to-zero (NRZ) BPSK data at 150-300 Mbit/s. The resulting i.f. error signal at fD = 39.0 — 36.5 = 2.5 GHz is fed forward to an external optical modulator with a 4-GHz electrical bandwidth.

We present the optical design of a 9.6-mm diameter fiber-coupled probe for combined femtosecond laser microsurgery and nonlinear optical imaging. Towards enabling clinical use, we successfully reduced the dimensions of our earlier 18-mm microsurgery probe by half, while improving optical performance. We use analytical and computational models to optimize the miniaturized lens system for off-axis scanning aberrations. The optimization reveals that the optical system can be aberration-corrected using simple aspheric relay lenses to achieve diffraction-limited imaging resolution over a large field of view. Before moving forward with custom lenses, we have constructed the 9.6-mm probe using off-the-shelf spherical relay lenses and a 0.55 NA aspheric objective lens. In addition to reducing the diameter by nearly 50% and the total volume by 5 times, we also demonstrate improved lateral and axial resolutions of 1.27 µm and 13.5 µm, respectively, compared to 1.64 µm and 16.4 µm in our previous work. Using this probe, we can successfully image various tissue samples, such as rat tail tendon that required 2-3 × lower laser power than the current state-of-the-art. With further development, image-guided, femtosecond laser microsurgical probes such as this one can enable physicians to achieve the highest level of surgical precision anywhere inside the body.

Cantilevers with interferometric high bandwidth force sensors can resolve nonlinear tip-sample interaction forces in tapping-mode atomic force microscopy. In this paper, we provide a detailed analysis of time-resolved force measurements using such cantilever. We first model the probe as a coupled spring-mass system and investigate its steady state dynamics under tapping-mode imaging conditions. Next, we analyze the optical response of the interferometric force sensor: Diffraction patterns as a function of tip displacement are obtained both analytically and by simulations. Finally, the frequency response of the force sensor is calculated, and the effects of the sensor geometry variations on the sensor mechanical response are analyzed.