The proliferation of camera technology in small aperture devices such as webcams, vehicle cameras, and cell phones has created a need for high-speed optical test equipment that is capable of qualifying the alignment and focus of a lens to a camera in just a single snapped frame. This requirement necessarily means that all pertinent field points within the image must be presented to the unit under test simultaneously. Some camera manufacturers will make use of large printed test charts for this purpose, but this approach can consume considerable space, is unsuited to presenting targets at infinity, and is difficult to incorporate in a modular test cell configuration.
Optikos has developed and deployed the Meridian suite of products in answer to this need. Designed for rapid customization, the Meridian product line offers a revolutionary hardware and software approach to production camera testing. It’s a flexible test tool kit that’s compact, cost-effective and easy to incorporate in your production line: the graphical user interface facilitates setup and selection of metrology parameters; and a library of functions integrates easily into your testing software.
The Meridian ArchThe primary advantage of the Meridian Arch mounting scheme is that it consists of just two different types of machined plates (one top plate and four identical wings) each of which may be fabricated using a 3-axis CNC milling machine. This makes CAM programming time relatively short and the qualification of the machining program largely unnecessary. All of the positioning accuracy in these plates arises from the planarity of a single surface and the locational accuracy of several dowel pins.The Arch assembly is a textbook example of exact constraints. It uses the barrel of the center target projector to locate each of four wings that radiate out along the diagonals or the cardinal directions of the field of view. Each wing holds the required number of projectors, each of which is located on the wing by being pulled into the corner established by the plane of the plate and two dowel pins. Tangency to these features and the roundness of the tightly-toleranced projector barrel are sufficient to accurately locate the field angle for each projector. The radial directions of the four wings are set by the locations of dowel pins pressed into the top plate.
The Meridian Arch mount is well suited to customers who require just a few projector assemblies or to those customers who need a test setup for evaluation purposes or production use with the shortest possible delivery time.
The Meridian Starfield
If the number of test setups is relatively large and the delivery schedule may be somewhat more extended then the Meridian Starfield may be the mounting scheme of choice. Whereas the Arch consists of an assembly of machined plates, a Starfield mount is a monolithic design consisting of a thick plate into which precision bores are machined to receive the target projector barrels. This machining operation necessarily requires a 5-axis CNC machining center and the CAM programming, prototype machining, and fixturing for the machining operation take longer and are more expensive than is the case for the Arch. On the other hand, these costs are non-recurring and are less significant when amortized over several Starfield plates.
The Meridian product line is an entire solution for camera testing and includes the Meridian Prime software package for analyzing the images captured by the camera under test. The Prime software also provides direct control of the illuminators used in the target projectors. There are two components to the Prime software namely a Graphical User Interface (GUI) and a library of functions. The GUI provides users with an interface for configuring and testing the measurement setup. Results are displayed in graphical and text formats and images may be saved and loaded for analysis. In cases in which the Prime software has been customized to access video from the UUT directly, live video with an overlay of the sampled regions of an image may also be viewed from the GUI.In production environments it is not uncommon for the system integrator to control the entire sequence of part handling and measurement steps from a higher level application. In these instances, the Prime library of functions may be called by the user’s software to retrieve test results and to perform other functions that are accessible through the GUI.
Imatest now supports the analysis of images captured using the Meridian system, including sharpness tested at infinity with Imatest 4.2, and may augment or be used in place of the Meridian Prime software provided with the test suite according to the client’s test needs. Read more