Samurai Scientists has experience in all sorts of cutom optical design, from simple optical telescopes through arrays of infrared telescopes, from ultraviolet flash detectors to millimeter-wave imaging systems, from large off-axis mirrors to nanoscale-patterned lens arrays. We have also developed electro-optical and mechanooptical systems, including some described on our night vision and long-range sensing pages. We have applied these design skills to scene generators, 3D displays, resolution enhancement, and electro-optical sensors. Most of our efforts in optical design, however, occur as part of a system; most of our nondestructive evaluation systems, for example, have optical portions, implementing our custom optical design skills. Some of our applications are described in the following publications.

1. Gulses, A.A.; Rai, S.; Padiyar, J., et al. “Laser Beam Shaping with Computer-Generated Holograms for Fiducial Markings.” In: Dudley, A.; Laskin, A.V., editors. Laser Beam Shaping XIX. San Diego, California: SPIE; 11107, 2019. p. 1110716.
         The laser marking method has obvious advantages over other available marking methods in speed, accuracy, and flexibility. Mask marking and beam deflection marking are typical methods, each having advantages and disadvantages. In the former, an opaque mask is directly imaged to create the desired mark. This method is practical and relatively fast, but most of the marking energy is blocked, losing efficiency. Additionally, this method requires a precise and bulky lens system. In the latter method, the focused beam is steered onto the sample, writing point by point. This technique has higher flexibility between marks, but it is slow, requires micro-movements, and accurate micro-motion parts are very expensive.
         We propose an innovative, holographic approach in laser marking. In the new system, a holographic projection system based on a digitally designed computer-generated hologram (CGH) is employed. This specially designed, fully transparent, phase only CGH modulates the high-power writing beam to create any desired image in the far field, where the beam etches a permanent mark of that image onto the designated silicon wafer substrate. Holographic marking combines the advantages of mask and beam deflection marking methods, such as high speed and stationary operation with minimal power loss, in a relatively simple and inexpensive setup. Also, since the holographic projection maintains its image quality after a certain distance, the setup is less prone to spatial alignment errors. We believe that the proposed technique will make significant contributions in the field of laser marking.
2. Jannson, T.P.; Shnitser, P.I.; Kostrzewski, A.A., et al. “HWIL LIDAR Imaging Sensor, 3-D Synthetic and Natural Environment, and Temporal ATR.” In: Murrer Jr., R.L., editor. Technologies for Synthetic Environments: Hardware-in-the-Loop Testing VII. Orlando, Florida: SPIE; 4717, 2002. p. 68-76. doi:10.1117/12.474708.
         In this paper, LIDAR imaging sensors, 3-D synthetic and natural object-centric environment, and temporal (progressive) ATR (Automatic Target Recognition), are discussed in the context of Modeling and Simulation (M&S) and Hardware-in-the-loop (HWIL) testing.
3. Kurtz, R.M. “The Manufacturability of OLED Encapsulation and Light Extraction.” Vector. Muldersdrift, South Africa: EE Publishers; 2017.
    
4. Kurtz, R.M.; Parfenov, A.V.; Pradhan, R.D., et al. “A New Approach to Wideband Scene Projection.” Multisensor, Multisource Information Fusion: Architectures, Algorithms, and Applications 2005. Orlando, Florida: SPIE; 5813, 2005. p. 312-320.
        Advances in the development of imaging sensors depend upon (among other things) the testing capabilities of research laboratories.  Sensors and sensor suites need to be rigorously tested under laboratory and field conditions before being put to use.  Real-time dynamic simulation of real targets is a key component of such testing, as actual full-scale tests with real targets are extremely expensive and time consuming and are not suitable for early stages of development.  Dynamic projectors simulate tactical images and scenes.  Several technologies exist for projecting IR and visible scenes to simulate tactical battlefield patterns – large format resistor arrays, liquid crystal light valves, Eidophor type projecting systems, and micromirror arrays, for example.  These technologies are slow, or are restricted either in the modulator array size or in spectral bandwidth.  In addition, many operate only in specific bandwidth regions.  Physical Optics Corporation is developing an alternative to current scene projectors.  This projector is designed to operate over the visible, near-IR, MWIR, and LWIR spectra simultaneously, from 300 nm to 20 µm.  The resolution is 2 megapixels, and the designed frame rate is 120 Hz (40 Hz in color).  To ensure high-resolution visible imagery and pixel-to-pixel apparent temperature difference of 100°C, the contrast between adjacent pixels is >100:1 in the visible to near-IR, MWIR, and LWIR.  This scene projector is designed to produce a flickerless analog signal, suitable for staring and scanning arrays, and to be capable of operation in a hardware-in-the-loop test system.  Tests performed on an initial prototype demonstrated contrast of 250:1 in the visible with non-optimized hardware.
5. Kurtz, R.M.; Lu, W.; Piranian, J., et al. “The Fast Photorefractive Effect and Its Application to Vibrometry.” J Hologr Speckle. 5: 149-155; 2009. doi:10.1166/jhs.2009.1008.
         We previously reported on what we describe as the “fast photorefractive effect,” photorefractive signal amplification at much greater frequencies than predicted by its grating formation speed. In this paper we explain the effect and its potential for application to vibrometry. We demonstrated photorefractive amplification in Cu:KNSBN (whose grating formation speed is <5 Hz), matching the standard model with CW illumination. We then demonstrated photorefractive amplification of vibrometric signals at frequencies up to 4 MHz. Our theory of the fast photorefractive effect indicates that the amplification bandwidth of Cu:KNSBN at 488 nm illumination could exceed 800 GHz.
6. Kurtz, R.M.; Pradhan, R.D.; Aye, T.M., et al. “Development of an Automultiscopic True 3D Display.” Future Display Technologies: SPIE; 5801B, 2005. p. 287-294.
        True 3D displays, whether generated by volume holography, merged stereopsis (requiring glasses), or autostereoscopic methods (stereopsis without the need for special glasses), are useful in a great number of applications, ranging from training through product visualization to computer gaming.  Holography provides an excellent 3D image but cannot yet be produced in real time, merged stereopsis results in accommodation-convergence conflict (where distance cues generated by the 3D appearance of the image conflict with those obtained from the angular position of the eyes) and lacks parallax cues, and autostereoscopy produces a 3D image visible only from a small region of space.  Physical Optics Corporation is developing the next step in real-time 3D displays, the automultiscopic system, which eliminates accommodation-convergence conflict, produces 3D imagery from any position around the display, and includes true image parallax.  Theory of automultiscopic display systems is presented, together with results from our prototype display, which produces 3D video imagery with full parallax cues from any viewing direction.
7. Kurtz, R.M.; Pradhan, R.D.; Aye, T.M., et al. “Image Tiling for a High-Resolution Helmet-Mounted Display.” Helmet- and Head-Mounted Displays X: Technologies and Applications. Orlando, Florida: SPIE; 5800, 2005. p. 130-137.
         Head-mounted or helmet-mounted displays (HMDs) have long proven invaluable for many military applications.  Integrated with head position, orientation, and/or eye-tracking sensors, HMDs can be powerful tools for training.  For such training applications as flight simulation, HMDs need to be lightweight and compact with good center-of-gravity characteristics, and must display realistic full-color imagery with eye-limited resolution and large field-of-view (FOV) so that the pilot sees a truly realistic out-the-window scene.  Under bright illumination, the resolution of the eye is ~300 µr (1 arc-min), setting the minimum HMD resolution.  There are several methods of achieving this resolution, including increasing the number of individual pixels on a CRT or LCD display, thereby increasing the size, weight, and complexity of the HMD; dithering the image to provide an apparent resolution increase at the cost of reduced frame rate; and tiling normal resolution subimages into a single, larger high-resolution image.  Physical Optics Corporation (POC) is developing a 5120 x 4096 pixel HMD covering 1500 x 1200 mr with resolution of 300 µr by tiling 20 subimages, each of which has a resolution of 1024 x 1024 pixels, in a 5 x 4 array.  We present theory and results of our preliminary development of this HMD, resulting in a 4k x 1k image tiled from 16 subimages, each with resolution 512 x 512, in an 8 x 2 array.
8. Kurtz, R. “Manufacturability of OLED Encapsulation and Light Extraction.” Presented at OLED Stakeholders Meeting. Pittsburgh, Pennsylvania: 2015.
    
9. Kurtz, R., inventor; Luminit, LLC assignee. Reducing the Optical Effects of Domes. Patent Application Publication US2020/0161752A1. 2020 May 21.
         This application discloses an apparatus for minimizing the optical effects of transmissive domes, and for using the dome surfaces to correct for other optical aberrations and distortions. Herein, the inner surface of the dome is designed to correct for unwanted optical effects of the outer surface of the dome and may also be used to correct for other anticipated effects in the overall optical system.
10. Ai, J.; Dimov, F.; Kurtz, R., inventors; Luminit, LLC assignee. Compound Eye Laser Tracking Device. Patent US010281551B2. 2019 May 9.
          The Compound Eye Laser Tracking Device(CELTD) is a tracking system used to guide items to point at a laser-illuminated target, with the illumination being either pulsed or modulated at either a specific rate or within a range of rates. The CELTD, comprising a multiaperture compound receiver optics (MACRO) to collect the signal, a set of light guides to combine the received light into light representing individual angular sectors and redirect it to detectors whose output represents the illumination signal in that quadrant, a spectral filter, an angle filter, the set of detectors, and processing electronics. The output is an electronic signal indicating the angular difference between the pointing direction of the signal and the pointing direction of the tracking device.
11. Ai, J.; Dimov, F.; Kurtz, R.M.; Gorce, E.J., inventors; Luminit, LLC assignee. Compound Eye Laser Illumination Seeker. Patent US010890417B2. 2021 Jan 12.
          The Compound Eye Laser Illumination Seeker (CELIS) is a tracking system used to guide items to point at a laser-illuminated target, with the illumination being either pulsed or modulated at either a specific rate or within a range of rates. The CELIS, comprising a multiaperture compound receiver optics (MACRO) to collect the signal, a set of light guides to combine the received light into light representing individual angular sectors and redirect it to detectors whose output represents the illumination signal in that quadrant, a spectral filter, an angle filter, the set of detectors, and processing electronics. The output is an electronic signal indicating the angular difference between the pointing direction of the signal and the pointing direction of the tracking device.
12. Ai, J.; Dimov, F.; Xia, X., et al., inventors; Luminit, LLC assignee. Quantum Wave-Converter. Patent US010591840B2. 2020 Mar 17. 6 p.
          A plug-and-play fiber-coupled nonlinear optical quantum wave-converter, optimized for quantum communications, comprises a commercial periodically-poled, waveguide-based, nonlinear optical chip, coupled with a pair of substrate-guided holographic (SGH) wavelength division multiplexers (WDM) and a pair of SGH filters; it offers bidirectional difference frequency conversion (DFG) and sum frequency conversion (SFG) simultaneously in a single packaged device.
13. Kurtz, R.M., inventor; Luminit, LLC assignee. Holographic Solar Coupler. Patent US009310593B2. 2016 April 12. 7 p.
          A method and system of collecting radiation with an array of lenses or a diffractive optical element are disclosed, the method includes: modifying angles of convergence and/or divergence, and a direction of propagation , with a diffractive element, and coupling the radiation into optical fibers, without separating the radiation into separate bands. The system includes an array of lenses or a diffractive optical element, a broadband holographic optical element, and at least one optical fiber, wherein the array of lenses or the diffractive optical element is configured to collect light and direct the light to the broadband holographic optical element, and wherein the broadband holographic optical element is configured to partially collimate and/or redirect light into the at least one optical fiber, and wherein the at least one optical fiber is configured to transmit the radiation away from the array of lenses or the diffractive optical element.
14. Kurtz, R.M., inventor; Samurai Scientists, LLC assignee. Directed Acoustic Shearography. Patent US008596128B2. 2013 Dec 3. 5 p.
          A nondestructive evaluation system, consisting of a metrology device and a directable acoustic transducer, is used to measure the variation of the surface when stress is applied. The directable acoustic transducer selects the location of the applied stress. The difference between the surface during stress application and in the absence of stress detects both surface and buried defects along the location of the stress. By scanning the beam from the acoustic transducer, the location of the stress can be adjusted, enabling the device to located the detected defect in three dimensions.