Industries Information

Vision sensors are video cameras with integrated signal processing and imaging electronics. They are used in industrial inspection, quality control, and design and manufacturing diagnostic applications. They often include interfaces for programming and data output, and a variety of measurement and inspection functions.

When specifying vision sensors, it is important to determine whether a monochrome or color sensor is needed.  Monochrome vision sensors present the image in black and white, or grayscale.  Color sensing vision sensors are able the read the spectrum range using varying combinations of different discrete colors.  One common technique is sensing the red, green, and blue components (RGB) and combining them to create a wide spectrum of colors.  Multiple chip color is available on some vision sensors.   It is a method of capturing color in which multiple chips are each dedicated to capturing part of the color image, such as one color, and the results are combined to generate the full color image.  They typically employ color separation devices such as beamsplitters rather than having integral filters on the sensors.

Important specifications to consider when searching for vision sensors include number of images stored and maximum inspection rate.  The number of images stored represents captured images that can be stored into on-board memory or non-volatile storage.  The maximum inspection rate is the maximum number of parts or process steps that can be inspected or evaluated per unit time.  This is usually given in units of inspections per second.  Other important parameters include horizontal resolution, maximum frame rate, shutter speed, sensitivity, and signal to noise ratio.

Inspection functions include object detection, edge detection, image direction, alignment, object measurement, object position, bar or matrix code, optical character recognition (OCR), and color mark or color recognition.  Imaging technology used in vision sensors includes CCD, CMOS, tube, and film.  Charge Coupled Devices (CCD) use a light-sensitive material on a silicon chip to detect electrons excited by incoming light. They also contain integrated microcircuitry required to transfer the detected signal along a row of discrete picture elements (or pixels) and thereby scan an image very rapidly.  CMOS image sensors operate at lower voltages than CCDs, reducing power consumption for portable applications.  Analog and digital processing functions can be integrated readily onto the CMOS chip, reducing system package size and overall cost.   In a tube camera, the image is formed on a fluorescent screen.  It is then read by an electron beam in a raster scan pattern and converted to a voltage proportional to the image light intensity.  With film technology the image is exposed onto photosensitive film, which is then developed to be played or stored.  The shutter, a manual door that admits light to the film, typically controls exposure.

Other parameters to consider when specifying vision sensors include performance features, physical features, lens mounting, shutter control, sensor specifications, dimensions, and operating environment parameters.

 Video cameras are used in machine vision, quality monitoring, security, and remote monitoring for industrial and commercial operations. Consumer video cameras are not covered in this search form. Video cameras can operate in monochrome or color.  Monochrome is black and white, or grayscale; the image is presented in black, white, and grayscale.  The range of colors is generated with varying combinations of different discrete colors.  One common technique is sensing the red, green, and blue components (RGB) and combining them to create a wide spectrum of colors.  Multiple chip color is a method of capturing color in which multiple chips are each dedicated to capturing part of the color image, such as one color, and the results are combined to generate the full color image.  They typically employ color separation devices such as beamsplitters rather than having integral filters on the sensors.  Choices for imaging technologies for video cameras include CCD, CMOS, tube, and film. Charge Coupled Devices (CCD) use a light-sensitive material on a silicon chip to detect electrons excited by incoming light. CMOS image sensors operate at lower voltages than CCDs, reducing power consumption for portable applications. In a tube camera, the image is formed on a fluorescent screen. Image is exposed onto photosensitive film, which is then developed to be played or stored.

Important performance specifications to consider when searching for video cameras include horizontal resolution, maximum frame rate, shutter speed, sensitivity, and signal-to-noise ratio.  Horizontal resolution is the maximum number of individual picture elements that can be distinguished in a single scanning line. It is most common to characterize horizontal video resolution corrected for the image aspect ratio, or specify the resolution in the largest circle than can fit in a rectangular image.  Thus, for example a 640 x 480 image would be specified as 480 horizontal lines.  Maximum frame rate is the number of frames that can be captured per unit time, typically frames per second.  Shutter time is the time of exposure or light collection.  Typically may be set across a wide range.  Sensitivity refers to minimum scene illumination for good image quality.  The standard unit for illuminance is lux, or lumens per square meter (lm/m2).  Signal-to-Noise ratio is defined as the peak-to-peak camera signal output current to the RMS noise in the output current.  This ratio represents how prevalent the noise component of a signal, and thus the image uncertainty, is in the total signal.  Noise sources include sensor "dark current," electromagnetic interference, and any other spurious non-image signal elements.  Higher SNR numbers represent less image degradation from noise.

Analog video formats used by video cameras include NTSC, PAL, SECAM, RS170, RS330, and CCIR.  Digital output interfaces common to vision sensors include RS232, RS422, RS485, parallel interfaces, Ethernet, DeviceNet, ARCNET, PROFIBUS, CANbus, Foundation Fieldbus, IEEE 1394 (Firewire), Modem, SCSI, TTL, USB, and radio or wireless.  Choices for bits or pixels include 8 bits, 10 bits, 12 bits, 14 bits, or 16 bits.  Color outputs are typically RGB, Y PbPr, Y/C (S-video), or composite.

Other parameters to consider when specifying video cameras include specialty applications, performance features, physical features, lens mounting, shutter control, sensor specifications, dimensions, and operating environment parameters.

Imaging workstations are vision systems with integrated camera, image capture, processing, storage, analysis and control systems for automated inspection, metrology or image analysis end-uses in production, manufacturing, inspection, laboratory or clean room settings. Typically, imaging workstations are stationary with high magnification optics as well as high-resolution imagers and precision sample stages or positioners. The high resolution is required for the 2D or 3D measurement of semiconductor wafers, electronics or other high precision components or in capturing microstructural or biological features.

Imaging workstations are provided in both modular and turnkey forms. Turnkey imaging workstation systems are complete, off-the-shelve (COTS) vision systems with all of the required components to provide an application ready product.  These units do not require additional hardware such as a computer or cameras.

With modular systems, the engineer or system integrator selects or configures the components to produce a product tailored to meet the application’s requirements. To replicate a complete, highly flexible vision systems, it may be necessary to integrate some or all of the following compatible modules: cameras/imagers, lenses, computers/processors, frame grabber boards, image processing boards, image analysis software and illuminators.

Imaging workstations are used in a wide range of applications including all of the following: alignment and guidance in web applications, to verify assembly quality, to read bar codes and matrices, for biological or medical imaging and sample testing, color marking and color marking recognition, conveyor line identification and product counting, edge detection, semiconductor and electronics inspection, flaw detection, gaging and dimensioning, ID detection and verification, seal integrity examination, and many other industrial applications.

 High speed cameras are designed for very fast image acquisition. They are used in scientific and industrial applications in which a process or inspection function is changing or moving rapidly. High speed cameras can operate in monochrome or color.  Monochrome is black and white, or grayscale; the image is presented in black, white, and grayscale.  The range of colors is generated with varying combinations of different discrete colors.  One common technique is sensing the red, green, and blue components (RGB) and combining them to create a wide spectrum of colors.

Important performance specifications to consider for high speed cameras include maximum frame rate, horizontal resolution, and shutter speed.  The maximum frame rate is the frames that can be captured per unit time, typically frames per second.  Horizontal resolution is the maximum number of individual picture elements that can be distinguished in a single scanning line. It is most common to characterize horizontal video resolution corrected for the image aspect ratio, or specify the resolution in the largest circle than can fit in a rectangular image.  Thus, for example a 640 x 480 image would be specified as 480 horizontal lines.  Shutter speed is the time of exposure or light collection, typically may be set across a wide range.

Choices for imaging technology for high speed cameras include CCD, CMOS, tube, and film.  Charge Coupled Devices (CCD) use a light-sensitive material on a silicon chip to detect electrons excited by incoming light. They also contain integrated microcircuitry required to transfer the detected signal along a row of discrete picture elements (or pixels) and thereby scan an image very rapidly. CCD cameras use two-dimensional CCD arrays with many thousands of pixels.  CMOS image sensors operate at lower voltages than CCDs, reducing power consumption for portable applications.  Analog and digital processing functions can be integrated readily onto the CMOS chip, reducing system package size and overall cost.  In a tube camera, the image is formed on a fluorescent screen.  It is then read by an electron beam in a raster scan pattern and converted to a voltage proportional to the image light intensity.  In film high speed cameras, the image is exposed onto photosensitive film, which is then developed to be played or stored.  The shutter, a manual door that admits light to the film, typically controls exposure.

Choices for analog video format for high speed cameras include NTSC, PAL, SECAM, RS170, RS330, and CCCIR.  The digital output interface can be RS232, RS422, RS485, parallel, Ethernet, DeviceNet, ARCNET, PROFIBUS, CANbus, Foundation Fieldbus, IEEE-1394, modem, SCSI, TTL, USB, and radio or wireless.  Choices for number of bits or pixels include 8 bits, 10 bits, 12 bits, 14 bits, and 16 bits.  The color output can be RGB, Y PbPr, Y/C (S-Video), and composite.  Physical features for high speed cameras include outdoor rated, underwater rated, radiation hardened, pan or tilt, dome, gooseneck, remote head, and board mount.

Filter wheels are used on microscopes, cameras, and video systems to position a selection of filters quickly and accurately over a lens or array of lenses.  They are used in machine vision, part inspection and research applications, especially those involving fluorescent microscopy, spectrophotometry, photometry, color CCD photography, laboratory applications, and optical and infrared imaging.  This area focuses on the wheels themselves.  For replacement lenses, or varied configurations, it is best to check with the manufacturer.

Filter wheels are generally available in configurations with between three and twelve lenses or filters.  Normally, the first lens is a simple clear filter.  The other lenses in the wheel may be of different colors, lens thickness, lens materials, or any combination thereof.  Custom and specialized filter wheels are available with more than twelve filters.

In addition to the number of filters, filter wheels may be configured in systems with more than one wheel.  This allows for additional colors or views to be used, as well as, the possibility of overlapping filters to allow for widely varied views. A system with two six-filter wheels could provide twelve separate, individual views, with the potential for as many as thirty-six overlapping views.  However, it is very rare that this many options would be available, as many lens types will not work together.

Filter wheels are available in manual, motorized via controller, and motorized via computer interface designs.  Manual wheels are simply tuned by hand.  They are generally used in situations where filter changes are infrequent.

Motorized via controller systems are designed with a packaged control unit for wheel indexing, typically with keypad, buttons, or other local interface.

When using motorized via computer interface driven systems, the wheel can communicate directly with the computer via communication such as RS232 or GPIB, and run set modes, or function within set parameters.

Neutral Density (ND) filters are available with some styles of filter wheels.  ND filters attenuate the light passing through the subsequent optics.  They can provide enhanced color balance and allow for aperture adjustment for depth-of-field effects.  Sets of ND filters are often graduated in degrees of light absorption.

CMOS image sensors (complementary metal oxide semiconductors) operate at lower voltages than CCDs, reducing power consumption for portable applications. Each CMOS active pixel sensor cell has its own buffer amplifier, and can be addressed and read individually. A commonly used cell has four transistors and a photo-sensing element. The cell has a transfer gate separating the photo sensor from a capacitive "floating diffusion," a reset gate between the floating diffusion and power supply, a source-follower transistor to buffer the floating diffusion from readout-line capacitance, and a row-select gate to connect the cell to the readout line. All pixels on a column connect to a common sense amplifier.

In addition to their lower power consumption when compared with CCDs, CMOS image sensors are generally of a much simpler design; often just a crystal and decoupling.  For this reason, they are easier to design with, generally smaller, and require less support circuitry.

There are two categories of CMOS sensors, analog and digital, as defined by their manner of output.  Analog sensors feed their encoded signal in a video format, such as PAL, NTSC, etc. The signal can be fed directly to standard video equipment.  Digital CMOS image sensors provide digital output, typically via a 4/8 or 16 bit bus.  The digital signal is direct, not requiring transference or conversion via a video capture card.

The video and imaging equipment and components category covers devices that either use video technology to record or display data, or read data or are powered by imaging technologies such as lasers and infrared scanners. In industrial applications, these products are used for automated inspection and measurement, quality control, image sensing; and in specific applications, reading, analyzing and displaying data. Video and imaging equipment and components are divided into seven different families: machine vision and inspection equipment, video cameras and lenses, video equipment, image sensors  – including CMOS image sensors, bar code equipment, and meters, readouts and indicators.

Video equipment includes those devices used to process or display captured video data. This family includes digital video recorders (used to transform the video data into digital output), monitors, multiplexers (to handle a number of signals at one time) and switchers (to control video camera sequence).

Video cameras and lenses include all video devices that are used in industrial applications – including CMOS image sensors. These items are different from the consumer market camcorders and lenses in that they are structured to survive in rigorous factory or industrial environments. Video cameras and lenses include not only video cameras and vision sensors for visual inspection and surveillance, but thermal and infrared imagers to track heat changes within systems, or in security operations.

CMOS cameras operate at lower voltages than CCDs, reducing power consumption for portable applications.  Analog and digital processing functions can be integrated readily onto the CMOS chip, reducing system package size and overall cost.  Each CMOS active pixel sensor cell has its own buffer amplifier, and can be addressed and read individually.  A commonly used cell has four transistors and a photosensing element.  The cell has a transfer gate separating the photosensor from a capacitive "floating diffusion", a reset gate between the floating diffusion and power supply, a source-follower transistor to buffer the floating diffusion from readout-line capacitance, and a row-select gate to connect the cell to the readout line.  All pixels on a column connect to a common sense amplifier.

CMOS cameras are available in either monochrome or color configurations.  Monochrome cameras capture images in black and white or grayscale.  In color CMOS cameras, a range of colors is generated with varying combinations of different discrete colors.  One common technique is sensing the red, green, and blue components (RGB) and combining them to create a wide spectrum of colors.  Some styles of color CMOS cameras capture color using multiple chips, where each chip is dedicated to capturing part of the color image, such as one color, and the results are combined to generate the full color image.  These cameras typically employ color separation devices such as beamsplitters rather than having integral filters on the sensors.

As with most camera styles, the important specifications for CMOS cameras include horizontal resolution, maximum frame rate, shutter speed and resolution.  Horizontal resolution is the maximum number of individual picture elements that can be distinguished in a single scanning line. It is most common to characterize horizontal video resolution corrected for the image aspect ratio, or specify the resolution in the largest circle than can fit in a rectangular image.  Thus, for example a 640 x 480 image would be specified as 480 horizontal lines. Frame rate refers to the number of frames that can be captured per unit time, typically expressed in frames per second. Shutter speed is the time of exposure or light collection.  Typically, this can be set across a wide range, resulting in very different forms of image composition.  Resolution in CMOS cameras refers to the bit numbers and signal levels presented in terms of the analog-to-digital resolution of the image.

 Charge injection device (CID) cameras are used in analytical instrumentation, industrial machine vision, medical, scientific and aerospace applications. CID cameras use photosensitive silicon capacitor components as image sensors, arranged in an addressable array. By using the electrical indexing of row and column electrodes in the array, each pixel in the CID camera can be individually addressed. The current between the capacitors is amplified and converted to voltage, providing a composite video or digitized video signal.

CID cameras offer a high degree of exposure control in low-light settings. An operator can suspend the charge injection and use the camera for time-lapse exposures. This technique is useful in a variety of scientific photography applications, including astronomy, inspection and measurement applications, laser beam profiling, semiconductor inspection and process manufacturing monitoring. CID cameras are also designed to be tolerant of radiation, including gamma, neutron, and proton radiation. CID digital camera systems use camera controller circuitry for data acquisition and real-time video processing.

CID cameras offer unique technical advantages over charge coupled device (CCD) imagers and other camera systems. A CCD camera is subject to image distortion called blooming or smearing that can occur with bright light intensities. CID cameras eliminate many distortion problems because the optical overloads in the array are confined to the illuminated pixels, and the excess charge is drawn into a charge collector.

Because CID cameras are capable of discerning weak optical signals from strong optical signals, they are commonly used in spectroscopy, X-ray crystallography, and biological imaging applications. A CID camera system for spectroscopic applications may also use a cooling system to reduce dark current, or the current that flows into a photosensitive detector when it is not exposed to light. CID video cameras can also capture images using a wide spectral response, making them useful to record images produced in the ultraviolet to near infrared range.

CCD image sensors (charge coupled device) are electronic devices that are capable of transforming a light pattern (image) into an electric charge pattern (an electronic image). The CCD consists of several individual elements that have the capability of collecting, storing and transporting electrical charge from one element to another. This together with the photosensitive properties of silicon, is used to design image sensors. Each photosensitive element will then represent a picture element (pixel). With semiconductor technologies and design rules, structures are made that form lines, or matrices of pixels. One or more output amplifiers at the edge of the chip collect the signals from the CCD. An electronic image can be obtained by - after having exposed the sensor with a light pattern - applying series of pulses that transfer the charge of one pixel after another to the output amplifier, line after line. The output amplifier converts the charge into a voltage. External electronics will transform this output signal into a form suitable for monitors or frame grabbers. CCDs have extremely low noise figures.

CCD image sensors can be a color sensor or a monochrome sensor.  In a color image sensor an integral RGB color filter array provides color responsivity and separation.  A monochrome image sensor senses only in black and white.  Choices for array type include linear array, frame transfer area array, full frame area array, and interline transfer area array.  Digital imaging optical format is a measure of the size of the imaging area.  Optical format is used to determine what size lens is necessary for use with the imager.  Optical format refers to the length of the diagonal of the imaging area.  Optical format choices include 1/7 inch, 1/6 inch, 1/5 inch, ¼  inch, 1/3 inch, ½ inch, 2/3 inch, ¾ inch, and 1 inch.  The number of pixels and pixel size is important to consider.  Horizontal pixels refer to the number of pixels in a row of the image sensor.  Vertical pixels refer to the number of pixels in a column of the image sensor. The greater the number of pixels, the better the resolution.  For example, VGA resolution is (640x480), this means the number of horizontal pixels is 640 and the number of vertical pixels is 480.  Pixels are usually square but can sometimes be rectangular.

Important image sensor performance specifications to consider when searching for CCD image sensors include spectral response, data rate, quantum efficiency, dynamic range, and number of outputs.  The spectral response is the spectral range (wavelength range) for which the detector is designed.  The data rate is the speed of a data transfer process, normally expressed in MHz.  Quantum efficiency is the ratio of photon-generated electrons that the pixel captures to the photons incident on the pixel area.  This value is wavelength dependent so the given value for quantum efficiency is generally for the peak sensitivity wavelength for the CCD.  Dynamic Range is the logarithmic ratio of well depth to the readout noise in decibels, the higher the number, the better.  Common features for CCD image sensors include antiblooming and cooled.  Some arrays for CCD image sensors offer an optional anti-blooming gate designed to bleed off overflow from a saturated pixel.  With out this feature, a bright spot, which has saturated the pixels, will cause a vertical streak. Some arrays are cooled for lower noise and higher sensitivity.  An important environmental parameter to consider is the operating temperature.

Charge coupled device (CCD) cameras contain light-sensitive silicon chips that detect electrons excited by incoming light. They also contain micro circuitry that transfers a detected signal along a row of discrete picture elements or pixels, scanning the image very rapidly. CCD cameras use two-dimensional CCD arrays with many thousand of pixels. They are often used in machine vision applications.

CCD cameras can operate in monochrome or color.  Monochrome is black and white, or grayscale; the image is presented in black, white, and grayscale.  The range of colors is generated with varying combinations of different discrete colors.  One common technique is sensing the red, green, and blue components (RGB) and combining them to create a wide spectrum of colors.  Multiple chip color is a method of capturing color in which multiple chips are each dedicated to capturing part of the color image, such as one color, and the results are combined to generate the full color image.  They typically employ color separation devices such as beamsplitters rather than having integral filters on the sensors.

Important performance specifications to consider when searching for CCD cameras include horizontal resolution, maximum frame rate, shutter speed, sensitivity, and signal-to-noise ratio.  Horizontal resolution is the maximum number of individual picture elements that can be distinguished in a single scanning line. It is most common to characterize horizontal video resolution corrected for the image aspect ratio, or specify the resolution in the largest circle than can fit in a rectangular image.  Thus, for example a 640 x 480 image would be specified as 480 horizontal lines.  Maximum frame rates for CCD cameras are the number of frames that can be captured per unit time, typically frames per second.  Shutter time is the time of exposure or light collection.  Typically may be set across a wide range.  Sensitivity refers to minimum scene illumination for the CCD camera to produce good image quality.  The standard unit for illuminance is the lux, or lumens per square meter (lm/m2).  Signal-to-Noise ratio is defined as the peak-to-peak camera signal output current to the RMS noise in the output current.  This ratio represents how prevalent the noise component of a signal, and thus the image uncertainty, is in the total signal.  Noise sources include sensor "dark current," electromagnetic interference, and any other spurious non-image signal elements.  Higher SNR numbers represent less image degradation from noise.

Analog video formats used by CCD cameras include NTSC, PAL, SECAM, RS-170, RS-330, and CCIR.  Digital output interfaces common to vision sensors include RS232, RS422, RS485, parallel interfaces, Ethernet, DeviceNet, ARCNET, PROFIBUS, CANbus, Foundation Fieldbus, IEEE 1394 (Firewire), Modem, SCSI, TTL, USB, and radio or wireless.  CCD cameras choices for bits or pixels include 8 bits, 10 bits, 12 bits, 14 bits, or 16 bits.  Color outputs are typically RGB, Y PbPr, Y/C (S-video), or composite.

Other parameters to consider when specifying CCD cameras include specialty applications, performance features, physical features, lens mounting, shutter control, sensor specifications, dimensions, and operating environment parameters.