CCD Image Sensor Research Articles

Miniature integrated micro-spectrometer array for snap shot multispectral sensing.

An array of micro spectrometers for parallel spectral sensing is designed, set up and tested. It utilizes a planar prism grating combination to obtain an almost linear optical system of 6 mm length only. Arranging such micro spectrometers in an array configuration yields 2'000 spectrometers when utilizing a common 4/3" CCD image sensor well adapted to e.g. microscopic image dimensions. The application in microscopic imaging in the 450-900nm spectral range is demonstrated as proof of concept, which can be adapted to massively parallel sensing in the frame of integrated sensor concepts.

Injection Compression Molded Microlens Arrays for Hyperspectral Imaging.

In this work, a polymer microlens array (MLA) for a hyperspectral imaging (HSI) system is produced by means of ultraprecision milling (UP-milling) and injection compression molding. Due to the large number of over 12,000 microlenses on less than 2 cm², the fabrication process is challenging and requires full process control. The study evaluates the process chain and optimizes the single process steps to achieve high quality polymer MLAs. Furthermore, design elements like mounting features are included to facilitate the integration into the final HSI system. The mold insert was produced using ultraprecision milling with a diamond cutting tool. The machining time was optimized to avoid temperature drifts and enable high accuracy. Therefore, single immersions of the diamond tool at a defined angle was used to fabricate each microlens. The MLAs were replicated using injection compression molding. For this process, an injection compression molding tool with moveable frame plate was designed and fabricated. The structured mold insert was used to generate the compression movement, resulting in a homogeneous pressure distribution. The characterization of the MLAs showed high form accuracy of the microlenses and the mounting features. The functionality of the molded optical part could be demonstrated in an HIS system by focusing light spectrums onto a CCD image sensor.

Gated-Viewing System with an Electronic Shutter on a CCD Image Sensor

The results of the development and experimental investigation of the gated-viewing method without the using an image intensifier as a fast shutter are presented. The device for implementing the method consists of an interline CCD image sensor with an input lens and 906 nm pulsed laser diode with an output lens that forms an illumination beam. The gated-viewing method is based on the original CCD control procedure, which allows observing multiple pulses without lowering the frame rate. Experimental studies have shown the method feasibility under conditions of smoke and fog.

Insect-Mimetic Imaging System Based on a Microlens Array Fabricated by a Patterned-Layer Integrating Soft Lithography Process.

In nature, arthropods have evolved to utilize a multiaperture vision system with a micro-optical structure which has advantages, such as compact size and wide-angle view, compared to that of a single-aperture vision system. In this paper, we present a multiaperture imaging system using a microlens array fabricated by a patterned-layer integrating soft lithography (PLISL) process which is based on a molding technique that can transfer three-dimensional structures and a gold screening layer simultaneously. The imaging system consists of a microlens array, a lens-adjusting jig, and a conventional (charge-coupled device) CCD image sensor. The microlens array has a light screening layer patterned among all the microlenses by the PLISL process to prevent light interference. The three-dimensionally printed jig adjusts the microlens array on the conventional CCD sensor for the focused image. The manufactured imaging system has a thin optic system and a large field-of-view of 100 degrees. The developed imaging system takes multiple images at once. To show its possible applications, multiple depth plane images were reconstructed based on the taken subimages with a single shot.

Development of a CMOS-based optical computed tomography system (CMOS-OCT) for 3D radiotherapy dosimetry

Optical Computed Tomography (OCT) was developed as a 3D imaging system for measuring radiotherapy dose delivered to radiochromic dosimeters. The imaging system reconstructs dose distributions delivered to a radiochromic dosimeter such as PRESAGE that changes its colour when irradiated. Current optical CT systems in the market are based on CCD image sensor and have slow imaging speed. The study exploited recent advances in CMOS image sensor (CIS) technology to improve the imaging speed of the OCT system. The study characterised the components in the in-house developed CMOS-based Optical CT (CMOS-OCT) imaging system and investigates the feasibility of the system for imaging 3D radiochromic dosimeters. A green dye solution of various concentration was used to mimic colour variation in a PRESAGE radiochromic dosimeter from its response to radiation dose. The solution was filled in a plastic cylinder to study the linearity and uniformity of the system. A rotary stage was constructed using a stepper motor to hold and rotate the dosimeter between the CIS and a large area LED. The components of the imaging system were integrated and controlled using LabVIEW (National Instrument, Austin, TX). A graphical user interface (GUI) was also developed to acquire projection images of the dosimeter. The measured field of view (FOV) of the CIS is 125 mm by 90 mm that can cover the whole PRESAGE dosimeter. A projection image is captured at every 1.8 degree rotation of the dosimeter, at every second, that amounted to 200 projection images for a 360 degree rotation. Current limitation of the imaging speed is the rotation speed of the motor of 1.8 degree per second which can be improved with upgrading the stepper motor. At an imaging speed only limited by the maximum sensor frame rate of 28.5 fps, the scanning time will be reduced to 7 s compared to 200 s. The results show that the system is capable of capturing the projection images of a 3D translucent object with good linearity and uniformity. Further experiments will be carried out to optimise the development of the system to reconstruct dose distributions in 3D from a PRESAGE dosimeter.

Single-shot multispectral imager using spatially multiplexed Fourier spectral filters

We demonstrate a single-shot multispectral imaging system using a fundamentally different approach compared with present-day methods. Conventional multispectral imagers utilize narrowband spectral filters, which makes the system application-specific. By using filters with sinusoidally varying transmittance, known as Fourier filters, we demonstrate an application-agnostic multispectral system. We designed and fabricated this Fourier filter array, integrated it with a commercial CCD image sensor, and acquired and reconstructed the spectral information from multiple targets. Compared with narrowband multispectral imagers, this system generalizes well to applications where we lack a priori knowledge of the spectral content of the scene, which makes it a versatile acquisition device for a wide range of applications.

System Design for Evenness Measurement of Raw Silk

The evenness of raw silk is one of its most valuable qualities. Seriplane inspection is a common test for raw silk evenness but is prone to human error and lacks accurate repeatability; the Uster evenness tester is another common approach but is costly and vulnerable to environmental factors. An image-based raw silk evenness detection system is proposed in this paper. The system is comprised of an image acquisition segment with a CCD image sensor, telecentric lens, light source, over feeding device, and raw silk winding device, plus an image processing segment tasked with threshold segmentation and morphology operations. Images of the raw silk are first captured with the image acquisition segment, then the images are processed by threshold segmentation and morphology processing; the diameters obtained in this segment are then used to calculate the variation coefficient (CV), which characterises the evenness of the raw silk. We conducted three experiments to test the stability, repeatability, and accuracy of the system. The results showed that the system proposed is stable, repeatable, and accurate.

Research on an Automatic Tracking Strategy Based on CCD Image Sensor in Micromanipulation

In this paper, an automatic tracking strategy based on a CCD image sensor is proposed to achieve the real-time tracking of embryonic cells with the MR-6 micromanipulator. The optical characteristics of the micro-vision sensor are systematically studied. Dark field is formed by the optical microscope imaging principle under the low rate objective lens. The global information of the embryo cells is tracked automatically using the improved Hungarian algorithm, so that the motion parameters of the batch of embryo cells and the interested area can be obtained. Then, the detailed information of the interested area is obtained in the bright field using the automatic conversation device. In addition, the feasibility of the algorithm is further verified by automatic experimental research.

Способ активно-импульсного видения с электронным затвором на CCD-фотоприемнике

AbstractThe results of the development and experimental investigation of the gated-viewing method without the using an image intensifier as a fast shutter are presented. The device for implementing the method consists of an interline CCD image sensor with an input lens and 906 nm pulsed laser diode with an output lens that forms an illumination beam. The gated-viewing method is based on the original CCD control procedure, which allows observing multiple pulses without lowering the frame rate. Experimental studies have shown the method feasibility under conditions of smoke and fog.

Remote sensing of atmospheric NO2 by employing the continuous-wave differential absorption lidar technique.

Differential absorption lidar (DIAL) technique employed for remote sensing has been so far based on the sophisticated narrow-band pulsed laser sources, which require intensive maintenance during operation. In this work, a continuous-wave (CW) NO2 DIAL system based on the Scheimpflug principle has been developed by employing a compact high-power CW multimode 450 nm laser diode as the light source. Laser emissions at the on-line and off-line wavelengths of the NO2 absorption spectrum are implemented by tuning the injection current of the laser diode. Lidar signals are detected by a 45° tilted area CCD image sensor satisfying the Scheimpflug principle. Range-resolved NO2 concentrations on a near-horizontal path are obtained by the NO2 DIAL system in the range of 0.3-3 km and show good agreement with those measured by a conventional air pollution monitoring station. A detection sensitivity of ± 0.9 ppbv at 95% confidence level in the region of 0.3-1 km is achieved with 15-minute averaging and 700 m range resolution during hours of darkness, which allows accurate concentration measurement of ambient NO2. The low-cost and robust DIAL system demonstrated in this work opens up many possibilities for field NO2 remote sensing applications.

A fast multiple shutter for luminescence lifetime imaging

A new fast readout mode for off-the-shelf CCD image sensors is presented. It provides the capability to record two consecutive frames of short exposure time with multiple exposure cycles in fast succession. This is advantageous for measurements of recurrent low light events. A main application is the lifetime measurement of luminescence emissions such as those used for temperature- or pressure-sensitive paint measurements.

CCDイメージセンサにおけるフォトダイオード特性向上技術 : 感度改善、VODシャッター電圧低減

CCDイメージセンサにおけるフォトダイオード特性向上技術 : 感度改善、VODシャッター電圧低減

30fps VGA相当動画読み出し対応330万画素CCDイメージセンサとその応用(固体撮像技術および一般)

30fps VGA相当動画読み出し対応330万画素CCDイメージセンサとその応用(固体撮像技術および一般)

4-2 アナログホワイトバランス機能を持つCCD用プログラマブルゲインアンプの試作と評価

4-2 アナログホワイトバランス機能を持つCCD用プログラマブルゲインアンプの試作と評価

Intrapixel effects of CCD and CMOS detectors

Intrapixel nonuniformity is known to exist in CCD and CMOS image sensors, though the effects in backside illuminated (BSI) CCDs are too small to be a concern for most astronomical observations. However, projects like the Large Synoptic Survey Telescope require precise knowledge of the detector characteristics, and intrapixel effects may need more attention. By scanning CCD and CMOS cameras with a small light spot (unresolved by the optics), we find in the images that the spot's flux, centroid displacement, and ellipticity vary periodically on the pixel scale in most cases. The amplitude of variation depends on not only the detector but also how well the spot is sampled by the pixels. With a spot radius of 2 pixels (encircling 80% energy) as measured, the flux and the ellipticity extracted from the BSI CCD camera vary by 0.2–0.3% (rms) and 0.005 (rms), respectively, while the deviation of the centroid position (rms ∼ 0.01 pixel) is not correlated with the pixels. The effects are more pronounced for the BSI CMOS camera and even worse for the frontside illuminated CMOS camera. The results suggest that a closer examination of the intrapixel effects is needed for precision astronomy.

Fibrin Network Formation and Thrombolysis using a Birefringence Measuring

Background: Fibrin is a fibrous plasma protein, which is known as precursor of clot. The polymerized fibrin network together with platelets forms a thrombus which causes fatal thromboembolism especially in the extracorporeal circulation using heart-lung machine or dialyzer. Because the length of fibrin is shorten than visible ray wavelength, we cannot detect fibrin using an optical microscope. Objective: To develop early phase thrombus detection system, we proposed fibrin imaging method using the birefringence properties. In this study, the relationship between fibrin network formation/resolution and optical birefringence properties was evaluated. Method: Birefringence imaging system was consisted of halogen light source, red light interference filter, polarizer, quarter wave plate, optical condenser, sample flow pass, ×10 objective lens, and CCD image sensor. Experimental plasma, which was kept at temperature of 36°C and coagulated gradually, was set in flow tube and guided by continuous flow pump to the sample flow pass. The retardation of the sample plasma was calculated from CCD images which was obtained by system at every 5 seconds. After confirming sufficient aggregation of fibrin, heparin was injected to the sample flow pass so as to activate fibrinolytic system of blood. Result: The retardation of plasma increased over time within 5 minutes. In contrast, fibrinolytic system reduced phase differences by melting aggregated fibrin within 6 minutes.

Rate of Strabismus Detection on Digital Photographs Increases by Using Off-center Near Target.

To increase the detection rate of strabismus on digital photographs, with the ultimate aim of developing a new automated strabismus detection algorithm. In this prospective case series, the authors acquired digital face photographs of 409 children with manifest or latent strabismus, using a 14-million-pixel camera with CCD image sensor. Of the last 52 enrolled, 34 image sets were selected for this study: 29 with manifest and 5 with latent strabismus. Images were taken at a distance of 40 to 70 cm in primary position, with the camera lens as the fixation target and in slight off-center fixation, and using a novel target of small light-emitting diodes mounted onto the camera case. The location of the corneal light reflection was manually calculated in relation to the center of the pupil in both eyes and ocular deviation as the difference in corneal light reflection location between the two eyes. In orthotropia, the expected deviation is zero. In children with phorias, the mean corneal light reflection location difference between the eyes was -0.10 ± 0.14 mm in primary position and -2.02 ± 0.39 mm in off-center fixation. Using a threshold of ±0.5 mm on either side of zero for central and of 2 mm for off-center fixation, sensitivity to detect strabismus increased from 65.6% in central to 79.3% in off-center fixation, respectively. The calculation of specificity will require inclusion of a population of individuals without strabismus. Off-center fixation onto a near target ensures that participants are actively looking at the target and may increase accommodative effort, thereby increasing the detection rate of strabismus. [J Pediatr Ophthalmol Strabismus. 2017;54(2):90-96.].

Zoom lens design for 10.2-megapixel APS-C digital SLR cameras.

A zoom lens design for a 10.2-megapixel digital single-lens reflex (SLR) camera with an advanced photo system type-C (APS-C) CCD image sensor is presented. The proposed zoom lens design consists of four groups of 3× zoom lenses with a focal length range of 17-51 mm. In the optimization process, 107 kinds of Schott glass combined with 26 kinds of plastic materials, as listed in Code V, are used. The best combination of glass and plastic materials is found based on the nd-Vd diagram. The modulation transfer function (MTF) was greater than 0.509 at 42 lp/mm, the lateral chromatic aberration was less than 5 μm, the optical distortion was less than 1.97%, and the relative illumination was greater than 80.05%. We also performed the tolerance analysis with the 2σ (97.7%) position selected and given tolerance tables and results for three zooming positions, which made the design more practical for manufacturing.

Portable organic gas detection sensor based on the effect of guided-mode resonance

A novel organic gas detection sensor based on the effect of guided-mode resonance is proposed in this paper. The sensor is designed to operate in the visible light band. It contains four main sections: a light source, a miniature gas chamber composed of a guided-mode resonant filter, a diffraction grating, and a CCD image sensor. When bunched visible light is irradiated vertically to the gas chamber, it passes through the gas chamber and diffraction grating, and is then received by the CCD sensor. The optical signal received by the CCD sensor is then reduced to the spectrum using a specific algorithm. When organic gases are injected into the gas chamber, there is a shift in the wavelength of resonant reflection, and the magnitude of this shift is proportional to the refractive index of the gas. The large variation in the refractive indexes of industrially important organic gases means that their characteristic peak wavelengths can be easily identified. As a result, this system can quickly detect organic gases. To verify the feasibility of this technique, we use finite difference time domain solutions to simulate the results. The sensitivity of this type of sensor can reach wavelength differences of 0.001 nm, which means that the sensor has high potential for application in portable, high-precision detection systems.

基于CCD图像传感器的压缩成像方法

基于CCD图像传感器的压缩成像方法