Volumetric additive manufacturing and vat-polymerization 3D printing methods rapidly solidify freeform objects via photopolymerization, but problematically raises the local temperature in addition to degree-of-conversion (DOC). The generated heat can critically affect the printing process as it can auto-accelerate the polymerization reaction, trigger convection flows, and cause optical aberrations. Therefore, temperature measurement alongside conversion state monitoring is crucial for devising mitigation strategies and implementing process control. Traditional infrared imaging suffers from multiple drawbacks such as limited transmission of measurement signal, material-dependent absorptions, and high background signals emitted by other objects. Consequently, a viable temperature and DOC monitoring method for volumetric 3D printing doesn’t exist.To address this opportunity, UC Berkeley researchers have developed a tomographic imaging technique that detects the spatiotemporal evolution of temperature and DOC during volumetric printing. The invention lays foundations for the development of volumetric measurement systems that uniquely resolve both temperature and DOC in volumetric printing.This novel Berkeley measurement system is envisaged as an integral tool for existing manufacturing technologies, such as computed axial lithography (CAL, Tech ID #28754), and as a new research tool for commercial biomanufacturing, general fluid dynamics, and more.

Photonic integrated circuits (PICs) have emerged as an encouraging platform for many fields due to their compact size, phase stability, and can be mass produced in semiconductor foundries at low cost. As such, PIC enabled waveguide-to-free-space beam delivery has been demonstrated towards ion trap quantum computing, atomic clocks, optical tweezers, and more. Grating couplers are commonly used, as through careful design, they can generate diffraction-limited focused spots into free space from a waveguide input. However, they suffer from many drawbacks – they have a narrow optical bandwidth, limited efficiency, are sensitive to light polarization and the emission angle is sensitive to fabrication variation.Quantum systems require stable delivery of multiple wavelengths, often spanning the near ultraviolet (NUV), visible, and near infrared (NIR) spectrum, to multiple locations tens to hundreds of micrometers above the PIC. This requirement exacerbates the pitfalls of grating couplers; their single-wavelength operation necessitates multiple gratings per unit cell. With more gratings to fabricate, fabrication variance takes a greater toll on device performance. UC Berkeley researchers have devised a new approach and device to deliver light from in-plane waveguides to out-of-plane free space beams in a low-loss, broadband manner. In particular, this device is used for controlling qubits in a trapped ion quantum computer, but in general the system is suitable for other integrated beam delivery applications.

 The dynamic patterning of 3D optical point clouds has emerged as a key enabling technology in volumetric processing across a number of applications. In the context of biological microscopy, 3D point cloud patterning is employed for non-invasive all-optical interfacing with cell ensembles. In augmented and virtual reality (AR/VR), near-eye display systems can incorporate virtual 3D point cloud-based objects into real-world scenes, and in the realm of material processing, point cloud patterning can be mobilized for 3D nanofabrication via multiphoton or ultraviolet lithography. Volumetric point cloud patterning with spatial light modulators (SLMs) is therefore widely employed across these and other fields. However, existing hologram computation methods, such as iterative, look-up table-based and deep learning approaches, remain exceedingly slow and/or burdensome. Many require hardware-intensive resources and sacrifices to volume quality.To address this problem, UC Berkeley researchers have developed a new, non-iterative point cloud holography algorithm that employs fast deterministic calculations. Compared against existing iterative approaches, the algorithm’s relative speed advantage increases with SLM format, reaching >100,000´ for formats as low as 512x512, and optimally mobilizes time multiplexing to increase targeting throughput. 

Dynamic patterning of light is used in a variety of applications in imaging and projection. This is often done by spatial light modulation, in which a coherent beam of input light is modified at the pixel level to create arbitrary output patterns via later interference. Traditional approaches to spatial light modulation suffer from a high operating burden, especially as the number of pixels increases, and incomplete coverage of the optical surface. This results in high device complexity, and cost, as well as enormous real-time computation requirements, reduced optical performance, and optical artifacts.To address these problems, researchers at UC Berkeley have developed a method for wiring groups of pixels, such as annular rings, parallel strips, or radial strips. This takes advantage of the fact that most spatial light modulation tasks can be accomplished by combining a number of simple “primitive phase profiles”, in which not all pixels need be independent of each other. In this co-wiring method, individual optical elements remain at the pixel level, but are wired together in a way that they move in precisely the coordinated manner to produce one of these primitive phase profiles. This allows for high frame rates, high coverage of the optical plane, and a degree of sensitivity impossible to produce with large, geometric optical elements that exist in prior art.

Dynamic patterning of light is used in a variety of applications in imaging and projection. This is often done by spatial light modulation, in which a coherent beam of input light is modified at the pixel level to create arbitrary output patterns via later interference. Traditional approaches to spatial light modulation suffer from a fundamental restriction on frame rate which has led manufacturers to seek the diminishing returns of continually increasing pixel number, resulting in impractical device sizes, complexity, and cost, as well as enormous real-time computation requirements. Additionally, these devices inherently produce monochromatic and speckled frames due to the requirement that the input beam be coherent.To address these problems, researchers at UC Berkeley have developed a device which can perform spatial light modulation with a frame rate ~20 times higher than existing technologies. This allows for a smaller number of pixels to produce high resolution, full color images by interleaving images of different colors and scanning rapidly across a screen in a similar way to the operation of CRT televisions Researchers have also developed an efficient and robust fabrication method, which combined with the smaller pixel number of these devices could cause them to be much more cost effective than existing technologies.

Silicon photonics is increasingly used in an array of communications and computing applications. In many applications, photonic chips must be coupled to optical fibers, which remains challenging due to the size mismatch between the on-chip photonics and the fiber itself. Existing approaches suffer from low alignment tolerance, sensitivity to fabrication variations, and complex processing, all of which hinder mass manufacture.To address these problems, researchers at UC Berkeley have developed a coupling mechanism between a silicon integrated photonic circuit and an optical fiber which uses a microlens to direct and collimate light into the fiber. Researchers have demonstrated that this device can achieve low coupling loss at large alignment tolerances, with an efficient and scalable manufacturing process analogous to existing manufacture of electronic integrated circuits. In particular, because the beam is directed above the silicon chip, this method obviates dry etching or polishing of the edge of the IC and allows the silicon photonics to be produced by dicing in much the same way as present electronic integrated circuits.

For decades, researchers have been developing “cool roof” materials to cool buildings and save on energy usage from air conditioning. Cool roof materials are engineered to maximize infrared thermal emission, allowing heat to be effectively radiated into outer space and the building to cool down. Conventional cool roof materials emit heat even when it is cold outside, which exacerbates space heating costs and can outweigh energy-saving benefits. A temperature adaptive radiative coating (TARC) material was developed in 2021 that adapts its thermal emittance to ambient temperatures using metal-insulator transitions in vanadium oxide. TARC is projected to outperform existing roof materials in most climate areas, but the complicated structure required high-cost fabrication techniques such as photolithography, pulsed laser deposition, and XeF2 etching, which are not scalable.To address this problem, UC Berkeley researchers have developed a new scalable temperature-adaptive radiative coating (STARC). STARC has the same thermal emittance switching capability as TARC, allowing the thermal emittance to be switched between high- and low- emittance states at a preset temperature. However, STARC can be produced using high-throughput, roll-to-roll methods and low-cost materials. The STARC material also has an improved lifetime. As an added benefit, while cool roof materials are often engineered with uniformly low solar-absorption, the color and solar absorption of STARC can be tuned for aesthetic purposes or to meet local climate-specific needs.

The inventors have developed a scalable laser aperture that emits light perpendicular to the surface. The aperture can, in principal, scale to arbitrarily large sizes, offering a universal architecture for systems in need of small, intermediate, or high power. The technology is based on photonic crystal apertures, nanostructured apertures that exhibit a quasi-linear dispersion at the center of the Brillouin zone together with a mode-dependent loss controlled by the cavity boundaries, modes, and crystal truncation. Open Dirac cavities protect the fundamental mode and couple higher order modes to lossy bands of the photonic structure. The technology was developed with an open-Dirac electromagnetic aperture, known as a Berkeley Surface Emitting Laser (BKSEL).  The inventors demonstrate a subtle cavity-mode-dependent scaling of losses. For cavities with a quadratic dispersion, detuned from the Dirac singularity, the complex frequencies converge towards each other based on cavity size. While the convergence of the real parts of cavity modes towards each other is delayed, going quickly to zero, the normalized complex free-spectral range converge towards a constant solely governed by the loss rate of Bloch bands. The inventors show that this unique scaling of the complex frequency of cavity modes in open-Dirac electromagnetic apertures guarantees single-mode operation of large cavities. The technology demonstrates scaled up single-mode lasing, and confirmed from far-field measurements. By eliminating limits on electromagnetic aperture size, the technology will enable groundbreaking applications for devices of all sizes, operating at any power level. BACKGROUND Single aperture cavities are bounded by higher order transverse modes, fundamentally limiting the power emitted by single-mode lasers, as well as the brightness of quantum light sources. Electromagnetic apertures support cavity modes that rapidly become arbitrarily close with the size of the aperture. The free-spectral range of existing electromagnetic apertures goes to zero when the size of the aperture increases. As a result, scale-invariant apertures or lasers has remained elusive until now.  Surface-emitting lasers have advantages in scalability over commercially widespread vertical-cavity surface-emitting lasers (VCSELs). When a photonic crystal is truncated to a finite cavity, the continuous bands break up into discrete cavity modes. These higher order modes compete with the fundamental lasing mode and the device becomes more susceptible to multimode lasing response as the cavity size increases. 

Researchers at UC Berkeley have developed techniques for optical voltage sensing of power grids as well voltage sensing within a human or animal subject. The safe, accurate and economical measurement of time-varying voltages in electric power systems poses a significant challenge. Current systems for measuring power grid voltages typically involve instrument transformers. Although these systems are accurate and robust to environmental conditions, they are bulky, heavy, and expensive, thus limiting their use in microgrids and sensing applications. An additional drawback is that some designs explode when they fail. Optical methods for direct measurement of high voltages have gained attention in recent years, mainly due to the high available bandwidth, intrinsic electrical isolation, and the potential for low cost and remote monitoring. Stage of Research The inventors have developed a low-Q resonant optical cavity-based voltage sensor based on a piezoelectric AIN thin film that transduces a voltage applied across the piezo terminals into a change in the resonant frequency of the cavity. This sensor can be fabricated with high yield and low cost (<$1), which makes it uniquely well-suited to reduce the cost of grid voltage measurement.

Electromagnetic noise from surfaces is one of the limiting factors for the performance of solid state and trapped ion quantum information processing architectures. This noise introduces gate errors and reduces the coherence time of the systems. Accordingly, there is great commercial interest in reducing the electromagnetic noise generated at the surface of these systems.Surface treatment using ion bombardment has shown to reduce electromagnetic surface noise by two orders of magnitude. In this procedure ions usually from noble gasses are accelerated towards the surface with energies of 300eV to 2keV. Until recently, commercial ion guns have been repurposed for surface cleaning. While these guns can supply the ion flux and energy required to prepare the surface with the desired quality, they are bulky and limit the laser access, making them incompatible with the requirements for ion trap quantum computing.To address this limitation, UC Berkeley researchers have developed an ion gun that enables in-situ surface treatment without sacrificing high optical access, enabling in situ use with a quantum information processor.

This materials platform enables flexible engineering of infrared (IR) emissivity and development of thermal radiation devices beyond the Stefan-Boltzmann law. The materials structure is based on thin films of vanadium oxide (VO2) with judiciously designed graded W doping across a thickness less than the skin depth of electromagnetic screening (~100 nm). The infrared emissivity can be engineered to decrease in an arbitrary manner from ~ 0.75 to ~ 0.35 over a temperature range up to 50 C near room temperature. The large range of emissivity tuning and flexible adjustability is beyond the capability of regular materials or structures. This invention provides a new platform for unprecedented manipulation of thermal radiation and IR signals with a wide variety of applications, such as:  The emissivity can be programmed to precisely counteract the T^4 dependence in the Stefan-Boltzmann law and achieve a temperature dependent thermal radiation. Such a design enables a mechanically flexible and power-free infrared camouflage, which is inherently robust and immune to drastic temporal fluctuation and spatial variation of temperature. By tailoring structure and composition, the materials platform can create a surface with robust and arbitrary IR temperature image, regardless of the actual temperature distribution on the targets. This design of infrared "decoy" not only passively conceals the real thermal activity of the object, but also intentionally fools the camera with a counterfeited image. The materials platform can achieve strong temperature dependence of reflectivity over a broad wavelength from near-IR to far-IR, which is promising for high-sensitivity remote temperature sensing by thermoreflectance imaging, or active reflectance modulation of IR signals. 

Most pulse oximeters are linked with one or two LEDs, depending on which scheme was used.  In this invention, we demonstrate pulse oximetry with no controlled LEDs, utilizing ambient light as the light source, and use two spectrally-selective OPDs. Organic absorbers are selected so that the fabricated OPDs will be able to sense green, red, and NIR.

Flexible semiconductors are far less costly, resource and energy intensive than conventional silicon production. Yet, as an unintended consequence of semiconductor printing, the films produced contain structural heterogeneities, or defects, which can limit their capacity to shuttle energy, or, information, over device-relevant scales. To be able to fully embrace this new, greener process, it is essential to elucidate which physical material properties most influence energy flow and which defects are most deleterious to efficient energy transport so that they can be targeted for elimination at the materials processing stage. Although some rather complex approaches have recently been used to track energy flow, the applicability of each one depends on specifics of the semiconductor properties (bandgap, excitonic vs charge carrier form of excitation, strong absorption or emission). Existing techniques cannot therefore be applied to a broad range of materials, and often necessitate adapting samples to fit the specific requirements of the technique. A broadly applicable approach is therefore needed to non-invasively and simultaneously reveal and correlate material morphology and energy flow patterns across many scales.    Researchers at the University of California, Berkeley have developed a new high-sensitivity, non-invasive, label-free, time-resolved optical scattering microscope able to map the flow of energy in any semiconductor, and correlate it in situ to the semiconductor morphology. This device has been shown as a far simpler approach to spatio-temporally characterize the flow of energy in either charge or exciton form, irrespective of the electronic properties of the material, and with few-nm precision. Furthermore, built into this approach is the unprecedented capability to perform in situ correlation to the underlying physical structure of the material. 

Silicon photovoltaic (“Si-PV”) modules currently dominate the solar energy market. Increased progress into Si-PV efficiency enhancements combined with historically low module costs aim to decrease the overall Levelized Cost of Electricity (“LCOE”) to a point competitive with non-renewable energy sources. Despite recent LCOE reductions, Si-PV technology remains economically inferior to fossil fuels. Additionally, flat-plate Si solar modules generally require geographical locations with high direct normal incidence (“DNI”) sunlight conditions in order to maintain module performance. Both the strict DNI requirement and the high LCOE of Si-PV cells ultimately limit the dissemination of solar power into the global energy market. A solution for the capturing of diffuse sunlight includes the use of optical concentrators.  One class of optical concentrators includes luminescent solar concentrators (“LSCs”).  Luminescent solar concentrators have garnered interest due to their ability to utilize diffuse light and their potential for use in architectural applications such as large area power-generating windows. However, LSCs have not yet reached commercialization for photovoltaic power generation, largely due to their comparatively low power conversion efficiencies (“PCEs”) and lack of scalability.     Researchers at UC Berkeley and other educational institutions have developed luminescent solar concentrators that  can be designed to minimize photon thermalization losses and incomplete light trapping using various novel components and techniques.

Neurotransmitters play a central role in complex neural networks by serving as chemical units of neuronal communication.  Quantitative optical methods for the detection of changes in neurotransmitter levels has the potential to profoundly increase our understanding of how the brain works. Therapeutic drugs that target neurotransmitter release are used ubiquitously to treat a vast array of brain and behavioral disorders.  For example, new methods in this sphere could provide a new platform by which to validate the function of drugs that alter modulatory neurotransmission, or to screen antipsychotic and antidepressant drugs.  However, currently in neuroscience, few optical methods exist that can detect neurotransmitters with high spatial and temporal resolution in vitro or in vivo.  Brain tissue also readily scatters visible wavelengths of light currently used to perform biological imaging, and neuronal tissue and has an abundance of biomolecules that are chemically or structurally similar and therefore hard to specifically distinguish.  Furthermore, neurotransmission relevant processes occur at challenging spatial  and temporal scales.    UC Berkeley investigators have developed polymer-functionalized carbon nanotubes for in vitro and in vivo quantification of extracellular modulatory neurotransmitter levels using optical detectors. The method uses the fluorescent optical properties of polymer-functionalized carbon nanotubes to selectively report changes in concentration of specific neurotransmitters. The scheme is novel in that the detection method applies to wide variety of specific neurotransmitters, it is an optical method and therefore gives greater spatial information, and enables the potential for imaging of one or more neurotransmitters. The optical method also produces less damage to the surrounding tissue than methods that implant electrodes or cells and allows high resolution localization with other methods of optical investigation. The invention takes advantage of favorable fluorescence properties of carbon nanotubes, such as carbon nanotube emission in the near infrared and infinite fluorescence lifetime.  The near infrared emission scatters less than shorter wavelengths, enabling greater signal recovery from deeper tissue, and allows greater compatibility with other techniques. The optical properties also enable long term potentially even chronic use. 

96 Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:Calibri; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;} The ∼10% optical contrast of graphene on specialized substrates like oxide-capped silicon substrates, together with the high-throughput and noninvasive features of optical microscopy, have greatly facilitated the use and research of graphene research for the past decade.  However, substantially lower contrast is obtained on transparent substrates. Visualization of nanoscale defects in graphene, e.g., voids, cracks, wrinkles, and multilayers, formed during either growth or subsequent transfer and fabrication steps, represents yet another level of challenge for most device substrates.     UC Berkeley researchers have developed a facile, label-free optical microscopy method to directly visualize graphene on transparent inorganic and polymer substrates at 30−40% image contrast per graphene layer.  Their noninvasive approach overcomes typical challenges associated with transparent substrates, including insulating and rough surfaces, enables unambiguous identification of local graphene layer numbers and reveals nanoscale structures and defects with outstanding contrast and throughput. We thus demonstrate in situ monitoring of nanoscale defects in graphene, including the generation of nano-cracks under uniaxial strain, at up to 4× video rate.  

The use of electric fields for signaling and manipulation is widespread, mediating systems spanning the action potentials of neuron and cardiac cells to battery technologies and lab-on-a-chip devices. Current FET- and dye-based techniques to detect electric field effects are systematically difficult to scale, costly, or perturbative. Researchers at the University of California Berkeley have developed an optical detection platform, based on the unique optoelectronic properties of two-dimensional materials that permits high-resolution imaging of electric fields, voltage, acidity, strain and bioelectric action potentials across a wide field-of-view.

The ability to see depth is a key visual function, as three-dimensional vision is used to guide body movements. Although many visual cues are used to infer spatial relationships, depth perception relies primarily on stereopsis, or the perception of depth based on differences in the images in the two eyes. More than 5% of the US population, however, is unable to see in three dimensions due to stereo-blindness and stereo-anomaly. Without depth perception, basic activities such as catching a ball or driving a car are not possible. Current therapeutic methods to address this issue include a set of eye-training exercises that aim to equalize the input from the eyes to the brain, which are collectively called orthoptics.   Researchers at UC Berkeley have developed an orthoptic method to train stereo depth perception. This method includes devices and systems for implementation, and it can be used in the home. 

Better understanding the brain's architecture and the behavior of neural networks requires non-invasive probes capable of monitoring brain activity at the scale of individual neurons.  Functional neuro-imaging methods have the advantage of being minimally invasive and can potentially resolve individual action potentials.  An ideal imaging method would be capable of quantifying many neurons simultaneously, have high spatial and temporal resolution, be non-invasive, and be accurate even in deep layers of brain tissue. There are a variety of current techniques available, many of which use mechanical scanning to reduce the effects of optical scattering and therefore have low temporal resolution. UC Berkeley researchers have developed a device capable of quantitative functional neuro-imaging in the thick brain tissue of live animals. By combining a detection method with algorithmic data processing, this device achieves single neuron resolution and fast sampling rates with high spatial and temporal resolution.  

Cathodoluminescence (CL) is used for nanoscale imaging by detecting the light generated in the sample by the application of an electron beam. Direct CL has also been used to image biological samples, but typically causes damage to the sample and can result in poor imaging quality.  Methods which incorporate inorganic cathodoluminescent nanoparticle labels into a biological sample result in less sample damage, but imaging with nanoparticle labels requires the electron beam to penetrate into the sample, which precludes repeated measurements or observations of dynamics. A UC Berkeley researcher has developed an optical imaging system and method for producing nanoscale images with high resolution, images of fragile samples without damaging the samples and that can be used for repeated imaging of a sample which allows observation of sample dynamics.  

Almost 170 million people in the United States (~55% of the total U.S. population) wear vision correction. Of this population, more than 63 million people (53%) up to age 64 have presbyopic vision. Eyeglasses have been the primary tool to correct such aberrations since the 13th century. In more modern times, contact lenses and refractive surgery have become viable alternatives to wearing eyeglasses. Unfortunately, these approaches require the observer to either use eyewear or undergo surgery, which is often uncomfortable and costly, and can lead to complications, in the case of surgery. To address these challenges, researchers at the University of California, Berkeley, and MIT have developed vision correcting screen technology which involves digitally modifying the content of a display so that the display can be seen in sharp focus by the user without requiring the use of eyeglasses or contact lenses. By leveraging specialized optics in concert with proprietary prefiltering algorithms, the display architecture achieves significantly higher resolution and contrast than prior approaches to vision-correcting image display. The teams have successfully demonstrated light field displays at low cost backed by efficient 4D prefiltering algorithms, producing desirable vision-corrected imagery even for higher-order aberrations that are difficult to be corrected with conventional approaches like eyeglasses.

Phase imaging has applications in biology and surface metrology, since objects of interest often do not absorb light but cause measurable phase delays (e.g. biological cells or uneven surface heights).  Here, a new extension to an experimentally simple method for imaging quantitative phase information is described, which uses a Kalman filter algorithm with a stack of intensity images taken through focus. The extended method involves incorporation of information about the microscope source shape in Koeler configuration, so that the coherence of the illumination may be included into the phase retrieval algorithm in order to produce more accurate phase results with arbitrary source shapes and sizes. Investigators have optimized and extended the Kalman filtering method to reduce computational complexity and to produce images using partially coherent illumination. This new software and method is faster and more efficient than previous methods, and in addition is robust to noise. It is compatible with a range of imaging systems, including optical, electron, X-ray and synchrotron, for example. Further, modifications are described for variations on the phase contrast mechanism, such that any complex transfer function (including but not limited to defocus) may be used. 

Optical trapping systems are commercially available through several companies. In these systems, the optical trap precision relies on the passive stability of the instrument itself, and therefore demands costly engineering solutions to limit environmental noise that can be coupled into the optomechanical components. Consequently, high-resolution measurements are not possible in common biological laboratory settings that typically lack appropriate vibration isolation and temperature stability.  Researchers at the University of California, Berkeley have developed an invention that addresses a critical problem currently limiting the performance of high-resolution optical traps: that the mechanical drift of optical components often results in physical drift in the location of an optical trap that obscures the displacement-of-interest. The motion of biological motor proteins that are specific to interacting with DNA often take steps along the double helix that is on the order of 0.3 nanometers in size. Accurate measurement of displacements on this scale requires that drift of the trap positions be limited to no more than a few angstroms. However, the current best-performing optical traps suffer from instrumental drift that is almost twice what can be tolerated. Owing to the critical role of these components in all optical trapping systems, and the previously undetectable levels of mechanical drift they undergo, we sought to measure the trap drift with angstrom-level precision using a new approach. This new approach has successfully measured for and corrected for the mechanical drift of these components and demonstrated that this novel invention is capable of consistently reducing the noise floor to levels that have not previously been accomplished.       

Researchers at the University of California, Berkeley have developed an invention that consists of an angular interferometer able to measure angle variations of a coherent, collimated light source with an accuracy below 30 nrad. The optical setup is compact and consists of a few simple optical components. The novelty of this innovation lies in the use of a simple, cost-effect technique to amplify the sensitivity of the instrument. The disclosed invention is in principle capable of being integrated into more compact, high-sensitivity commercial instruments for a fraction of the cost of current, state-of-the-art instruments (currently exceeding $30,000).   Commercial devices used to measure the angular deviation of a single beam include autocollimators and interferometers. The highest resolution offered by a commercial system is 25 nrad. The disclosed angular interferometer is able to measure relative angle variations (of a sample beam relative to a reference beam) below 30 nrad, though the resolution is known to currently be limited by the specific details of the current application and can therefore be further reduced with minor, inexpensive improvements.

Commercially available optical tweezers can move objects using laser light, but they are generally not used to measure forces exerted on those objects, since accurate force calibration is difficult. Research in the field of optical trapping has led to the development of optical tweezers that measure forces (transverse to optic axis) by changes in light-momentum. Force calibration is greatly simplified by using this method. However, in measuring the light force on a trapped object, it is also desirable to obtain all three vector components of that force. Representing an improvement on the light-momentum force-sensor, researchers at the University of California, Berkeley have developed an axial light-force sensor. A system incorporating the Berkeley improvement permits simultaneous measurements of the axial and transverse forces acting on a trapped particle. Like the transverse sensor, the axial force sensor is calibrated from measured constant values: the speed of light, the objective focal length, and the power sensitivity of the planar photo-diode. Thus calibration is not affected by particle shape, laser power, particle refractive index, or sharpness of the trap focus. In addition, a highly-miniaturized, ultra stable, optical trap system has been developed that should permit a low cost instrument with force-measuring capabilities for use in normal lab environments.