Archives for April 2022
Nikon Z 800mm f6.3 VR S review
April 6, 2022 By Leave a Comment
The Z 800mm f6.3 VR S is Nikon's longest telephoto prime for Z-mount so far. It has a large f6.3 focal ratio and is aimed at pro sports and wildlife photographers. Here's my review.…
Nikon releases the NIKKOR Z 800mm f/6.3 VR S, a super-telephoto prime lens for the Nikon Z mount system
April 6, 2022 By Leave a Comment
Accsoon M1 HDMI recorder review
April 5, 2022 By Leave a Comment
The Accsoon M1 is an adapter that lets you use an Android phone as an HDMI monitor, recorder, or streamer. It could save you money and weight over a dedicated recorder, so find out if it's right for you in my review!…
Hamamatsu videos
April 4, 2022 By Leave a Comment
Image Sensors World Go to the original article...
Hamamatsu has published new videos on their latest products and technologies.
ORCA-Quest quantitative CMOS (qCMOS) scientific camera: With ultra-low read noise of 0.27 electrons (rms), a high pixel count of 9.4 megapixels, and the ability to detect and quantify the number of photoelectrons, discover how our new camera can revolutionise scientific imaging applications.
Automotive LiDAR technologies - TechBites series: How recent advances in photonics, specifically in LiDAR, have played a major role in the move towards autonomous vehicles
InGaAs Cameras - TechBites Series: Short-wave infrared cameras and their applications today and in the future
Mini Spectrometers: What are mini-spectrometers and how can they be used in the medical industry?
Canon Group bolsters Label & Packaging growth strategy with acquisition of Edale
April 4, 2022 By Leave a Comment
Better Piezoelectric Light Modulators for AMCW Time-of-Flight Cameras
April 3, 2022 By Leave a Comment
Image Sensors World Go to the original article...
A team from Stanford University's Laboratory for Integrated Nano-Quantum Systems (LINQS) and ArbabianLab present a new method that can potentially convert any conventional CMOS image sensor into an amplitude-modulated continuous-wave time-of-flight camera. The paper titled "Longitudinal piezoelectric resonant photoelastic modulator for efficient intensity modulation at megahertz frequencies" appeared in Nature Communications.
Intensity modulators are an essential component in optics for controlling free-space beams. Many applications require the intensity of a free-space beam to be modulated at a single frequency, including wide-field lock-in detection for sensitive measurements, mode-locking in lasers, and phase-shift time-of-flight imaging (LiDAR). Here, we report a new type of single frequency intensity modulator that we refer to as a longitudinal piezoelectric resonant photoelastic modulator. The modulator consists of a thin lithium niobate wafer coated with transparent surface electrodes. One of the fundamental acoustic modes of the modulator is excited through the surface electrodes, confining an acoustic standing wave to the electrode region. The modulator is placed between optical polarizers; light propagating through the modulator and polarizers is intensity modulated with a wide acceptance angle and record breaking modulation efficiency in the megahertz frequency regime. As an illustration of the potential of our approach, we show that the proposed modulator can be integrated with a standard image sensor to effectively convert it into a time-of-flight imaging system.
a) A Y-cut lithium niobate wafer of diameter 50.8 mm and of thickness 0.5 mm is coated on top and bottom surfaces with electrodes having a diameter of 12.7 mm. The wafer is excited with an RF source through the top and bottom electrodes. b) Simulated ∣s11∣ of the wafer with respect to 50 Ω, showing the resonances corresponding to different acoustic modes of the wafer (loss was added to lithium niobate to make it consistent with experimental results). The desired acoustic mode appears around 3.77 MHz and is highlighted in blue. c) The desired acoustic mode ∣s11∣ with respect to 50 Ω is shown in more detail. d) The dominant strain distribution (Syz) when the wafer is excited at 3.7696 MHz with 2 Vpp is shown for the center of the wafer. This strain distribution corresponds to the ∣s11∣ resonance shown in (c). e) The variation in Syz parallel to the wafer normal and centered along the wafer is shown when the wafer is excited at 3.7696 MHz with 2 Vpp.
a) Schematic of the characterization setup is shown. The setup includes a laser (L) with a wavelength of 532 nm that is intensity-modulated at 3.733704 MHz, aperture (A) with a diameter of 1 cm, neutral density filter (N), two polarizers (P) with transmission axis t^=(a^x+a^z)/2–√, wafer (W), and a standard CMOS camera (C). The wafer is excited with 90 mW of RF power at fr = 3.7337 MHz, and the laser beam passes through the center of the wafer that is coated with ITO. The camera detects the intensity-modulated laser beam. b) The desired acoustic mode is found for the modulator by performing an s11 scan with respect to 50 Ω using 0 dBm excitation power and with a bandwidth of 100 Hz. The desired acoustic mode is highlighted in blue. c) The desired acoustic mode is shown in more detail by performing an s11 scan with respect to 50 Ω using 0 dBm excitation power with a bandwidth of 20 Hz. d) The fabricated modulator is shown. e) The depth of intensity modulation is plotted for different angles of incidence for the laser beam (averaged across all the pixels), where ϕ is the angle between the surface normal of the wafer and the beam direction k^ (see “Methods” for more details). Error bars represent the standard deviation of the depth of intensity modulation across the pixels. f) Time-averaged intensity profile of the laser beam detected by the camera is shown for ϕ = 0. g) The DoM at 4 Hz of the laser beam is shown per pixel for ϕ = 0. h) The phase of intensity modulation at 4 Hz of the laser beam is shown per pixel for ϕ = 0.
a) Schematic of the imaging setup is shown. The setup includes a standard CMOS camera (C), camera lens (CL), two polarizers (P) with transmission axis t^=(a^x+a^z)/sqrt(2), wafer (W), aperture (A) with a diameter of 4 mm, laser (L) with a wavelength of 635 nm that is intensity-modulated at 3.733702 MHz, and two metallic targets (T1 and T2) placed 1.09 m and 1.95 m away from the imaging system, respectively. For the experiment, 140 mW of RF power at fr = 3.7337 MHz is used to excite the wafer electrodes. The laser is used for illuminating the targets. The camera detects the reflected laser beam from the two targets, and uses the 2 Hz beat tone to extract the distance of each pixel corresponding to a distinct point in the scene (see “Methods” for more details). b) Bird’s eye view of the schematic in (a). c) Reconstructed depth map seen by the camera. Reconstruction is performed by mapping the phase of the beat tone at 2 Hz to distance using Eq. (3). The distance of each pixel is color-coded from 0 to 3 m (pixels that receive very few photons are displayed in black). The distance of targets T1 and T2 are estimated by averaging across their corresponding pixels, respectively. The estimated distances for T1 and T2 are 1.07 m and 1.96 m, respectively (averaged across all pixels corresponding to T1 and T2). d) Ambient image capture of the field-of-view of the camera, showing the two targets T1 and T2. e The dimensions of the targets used for ToF imaging are shown.
The paper points out limitations of other approaches such as spatial light modulators and meta-optics, but doesn't mention any potential challenges or limitations of their proposed method. Interestingly, the authors cite some recent papers on high-resolution SPAD sensors to make the claim that their method is more promising than "highly specialized costly image sensors that are difficult to implement with a large number of pixels." Although the authors do not explicitly mention this in the paper, their piezoelectric material of choice (lithium niobate) is CMOS compatible. Thin-film deposition of lithium niobate on silicon using a CMOS process seems to be an active area of research (for example, see Mercante et al., Optics Express 24(14), 2016 and Wang et al., Nature 562, 2018.)
Full article [open access]: https://www.nature.com/articles/s41467-022-29204-9
Two new papers on 55 nm Bipolar-CMOS-DMOS SPADs
April 1, 2022 By Leave a Comment
Image Sensors World Go to the original article...
The AQUA research group at EPFL together with Global Foundries have published two new articles on 55 nm Bipolar-CMOS-DMOS (BCD) SPAD technology in the upcoming issues of IEEE Journal of Selected Topics in Quantum Electronics.
Engineering Breakdown Probability Profile for PDP and DCR Optimization in a SPAD Fabricated in a Standard 55 nm BCD Process
Link [open access article]: https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=9543572
Abstract:
CMOS single-photon avalanche diodes (SPADs) have broken into the mainstream by enabling the adoption of imaging, timing, and security technologies in a variety of applications within the consumer, medical and industrial domains. The continued scaling of technology nodes creates many benefits but also obstacles for SPAD-based systems. Maintaining and/or improving upon the high-sensitivity, low-noise, and timing performance of demonstrated SPADs in custom technologies or well-established CMOS image sensor processes remains a challenge. In this paper, we present SPADs based on DPW/BNW junctions in a standard Bipolar-CMOS-DMOS (BCD) technology with results comparable to the state-of-the-art in terms of sensitivity and noise in a deep sub-micron process. Technology CAD (TCAD) simulations demonstrate the improved PDP with the simple addition of a single existing implant, which allows for an engineered performance without modifications to the process. The result is an 8.8 μ\mu m diameter SPAD exhibiting ∼\sim 2.6 cps/ μ\mu m 2^2 DCR at 20 ∘^{\circ} C with 7 V excess bias. The improved structure obtains a PDP of 62% and ∼\sim 4.2% at 530 nm and 940 nm, respectively. Afterpulsing probability is ∼\sim 0.97% and the timing response is 52 ps FWHM when measured with integrated passive quench/active recharge circuitry at 3 V excess bias.
On Analog Silicon Photomultipliers in Standard 55-nm BCD Technology for LiDAR Applications
Link [subscription needed]: https://ieeexplore.ieee.org/document/9739982
Abstract:
We present an analog silicon photomultiplier (SiPM) based on a standard 55 nm Bipolar-CMOS-DMOS (BCD) technology. The SiPM is composed of 16 x 16 single-photon avalanche diodes (SPADs) and measures 0.29 x 0.32 mm2. Each SPAD cell is passively quenched by a monolithically integrated 3.3 V thick oxide transistor. The measured gain is 3.4 x 105 at 5 V excess bias voltage. The single-photon timing resolution (SPTR) is 185 ps and the multiple-photon timing resolution (MPTR) is 120 ps at 3.3 V excess bias voltage. We integrate the SiPM into a co-axial light detection and ranging (LiDAR) system with a time-correlated single-photon counting (TCSPC) module in FPGA. The depth measurement up to 25 m achieves an accuracy of 2 cm and precision of 2 mm under the room ambient light condition. With co-axial scanning, the intensity and depth images of complex scenes with resolutions of 128 x 256 and 256 x 512 are demonstrated. The presented SiPM enables the development of cost-effective LiDAR system-on-chip (SoC) in the advanced technology.
