Improper selection of the correct quality and type of machine vision lens can make your camera selection useless!
In many cases, we see customers attempting to choose a low quality lens for a camera that really needs quality optics to resolve the pixel sizes. Conversely, we also see customers trying to over specify a lens, where you simply need a lens that’s “good enough”
1st Vision has a white paper to help in the lens selection and provide valuable knowledge on various topics to make the best decisions.
A successful, cost-effective application of a Machine Vision system is often dependent on the interplay of many individual elements, including machine vision lighting. As much as an Light Emitting Diode (LED) appears to be a basic electronic component, driving it in a fashion suitable for machine vision applications is non-trivial. LED’s have become the staple in industrial imaging applications in which consistent illumination is key. In order to achieve constant illumination and synchronization with cameras, controllers from Gardasoft should be utilized. Download the full white paper here NOW
Why use a LED Lighting Controller? LED Light Controllers are an essential element of any vision system which needs to optimize illumination intensity and precision trigger sequencing between vision cameras and lights. The following are the main areas where you will benefit from the use of an LED light controller: Pulse (or strobe) control Where you need to synchronize the ON time of your light with the camera and target product (controllers are available for nano-second timing resolution) Overdriving Where you require increased intensity from your LED light for a short, defined, period of time (with up to 10x over driving capability) Continuous current power supply (constant light) Where you require a highly stable constant current supply for constant on LED lighting Control of multi-lighting schemes For systems with multiple lighting configurations which require intensity control and high speed synchronization (from single or multiple triggers) Remote configuration changes For systems where it is advantageous to have remote setting of lighting system parameters – eg: to facilitate efficient set-up during system commissioning
LED Technology Overview LEDs are current driven devices. While LED Lights are specified as either 12V or 24V lights, the actual LEDs are semiconductor devices whose light output is a direct result of the current through the device, not the voltage. All LED device manufacturers specify that current control is advised for efficient use. Typically, LED datasheets will indicate that very small changes in LED voltage results in large changes in the LED current; and large changes in LED current results in large changes in light output intensity. As seen in the diagram to the right, small changes in forward voltage (Vf),greatly change current ( If ) Gardasoft LED controllers regulate the current, not the voltage, so that light output is stable, tightly controlled and highly repeatable. Controlling the current allows for precise control of the LED light output, with an additional benefit to users looking to overdrive their lights to increase light output. There are many advantages of accurate pulsing and over driving LED’s. However it is also extremely important to ensure LEDs are over driven safely to ensure long life and not catastrophic failure. In this white paper, the following topics are covered:
An overview of LED technology
How to pulse and overdrive LEDs safely using Gardasoft’s patented “SafeSense” technology
Three trigger modes from constant, pulses and switched for various applications.
How “SafeSense” technology determines the optimum current for consistent LED drive.
Advanced and custom controller functions. Example – allowing multiple pulses at different intensity levels over various LED channels.
In applications where high color precision and spatial resolution are required, there are distinct advantages of 3-CCD color cameras versus Bayer mosaic color alternatives. JAI cameras provide 3-CCD camera solutions to provide high color fidelity in various resolutions.
Color Fidlity Bayer mosaic color cameras use a pattern of color filters and an interpolation process to estimate the approximate RGB value of a give pixel. With a 3-CCD camera, a specific R, G and B value is captured for each pixel. This inherently produces higher color precision in the 3-CCD output. The spectral curves resulting from the hard dichroic prism coating are much steeper than the curves from the soft polymer dyes used in Bayer filters. This enables the 3-CCD cameras to produce exceptional accurate color data without the uncertainty that comes with the overlap regions (Area in grey below in the illustration )
High Dynamic Range In addition to reducing color precision, the overlap in the color filter response also results in part of each pixel’s well capacity filling with photons resulting from the cross-talk, thus decreasing the available well capacity. Precision responses from the dichroic coating enable each channel to efficiently use the full well capacity of the pixel, allowing the maximum possible dynamic range.
Color Space calibration JAI’s 3-CCD cameras include a sophisticated linear color matrix circuit which enables color matching between camera data and calibrated printers, monitors and other devices. Built in presets are provided to output the color information in the proper format for the sRGB or Adobe RGB industrial standard color space. The end Result The two images below compare results from a 5-megapixel Bayer color camera (left) with the 2- megapixel JAI AT-200 camera (right). Despite having 2.5X the resolution, the 5 megapixel cameras soft polymer dye color filters and the interpolation process result in significant color contamination, less differentiation between similar colors, and reduced sharpness of the image.
Additional images for comparison are below to demonstrate the fidelity of a 3-CCD camera vs Bayer cameras
Click on the video below now for a full presentation on detailing how 3-CCD cameras improve color accuracy
Need to discuss how a 3-CCD color camera will benefit your application? 1st Vision’s sales engineers all have 25+ years of experience in industrial imaging and can review this in detail. JAI also makes 2-CCD, 3-CMOS and 4-CCD line scan cameras. Click here now for more information (see multi-sensor tab) Need to understand more about Bayer color cameras? Download this white paper now Please do not hesitate toContact us! 1st Vision can provide a complete solution including cameras, lenses, lighting and cables.