OptiCentric^® MOT Extension Moduls

MultiLens^®

This complex software module is used either for the measurement, alignment and assembly of objective lenses or for measuring the centering errors of completely mounted optical assemblies. The inspection of mounted objective lenses provides precise data about the assembly quality. In this way, the MultiLens^® software becomes an indispensable tool for optimizing the manufacturing process. The MultiLens^® software delivers in a nondestructive way the complete information about the individual centering errors of all surfaces in an assembly. The PC controlled OptiCentric^® instrument per forms stepwise a reflection mode centering measurement starting with the first sur face closest to the measuring head and continuing with the following surfaces.

The MultiLens^® software performs a ray tracing through the optical system based on the lens design parameters and the measured centering values. Finally, the operator obtains a numerical and graphical output of the complete centering status regarding shift and tilt of each measured surface.

The module can calculate the best-fit optical axis of the objective lens and all surface centering data can be referenced to this axis. Combining these features with adequate assembly techniques, high performance objective lenses with tolerances in the micron range can be easily centered to best performance.

Advanced Analyzer

The Advanced Analyzer is a software tool in addition to the MultiLens^® software with even more analysis features and comprehensive 3D graphical output. When it is run on the instrument's PC, the measurement data is transferred automatically between the applications. As it is a self-contained software application a separate copy can be ordered to perform a detailed centering analysis independently from the instrument's PC.

The initial measurement data refer to the air bearing's axis of rotation, which is usually not the desired result. The Advanced Analyzer software therefore calculates the following situations:

• Calculation of the optical axis of a lens
• Calculate the optical axis passing through two or more centers of curvature. Weighting factors can be applied to calculate the regression line depending on the optical power of the surfaces
• Reference relatively to the mechanical axis
• Reference all other surfaces and optical elements relatively to any user defined optical axis
• Calculate angle and distance between two optical axes (e.g. two single lenses)
• Calculate the surface tilt error of any surface relatively to the axis of reference.

AspheroCheck^®

AspheroCheck^® (Patent application 10 2006 052 047.5-51) is a hardware and software module designed to measure the tilt and shift of an aspherical axis with respect to a defined reference axis. The module is available as an upgrade for all OptiCentric^® Systems equipped with a rotary air bearing sample stage.

The AspheroCheck^® module consists of a high-precision AspheroCheck^® distance sensor mounted on a x-z linear stage system. The angle of the sensor can be adjusted square to the sample surface by a rotary stage. Every point along the radius of the sample can thus be reached by the sensor. The standard module is operated manually, a motorized version is available on request.

Both values are then combined to determine the position and the tilt of the aspherical axis.

The following parameters of aspherical lenses can be measured:

1. Shift and tilt of the asphere axis in relation to the reference axis of rotation.
2. Shift and tilt of the asphere axis in relation to the optical axis of the lens. The "optical axis" is considered to be the line running through the centers of curvatures of the spherical portions.
3. When a lens consists of two aspherical surfaces the angle and shift of both aspherical axes are determined.

CylinderCheck^®

CylinderCheck^® is a module for the precise measurement of centering errors in cylindrical surfaces. Depending on the application, different parameters of the cylindrical surface can be measured using the CylinderCheck^® module.

• The angle (azimuth) between the cylindrical axis and a given edge or other reference line
• The offset of the cylindrical axis from a given edge
• The tilt of the cylindrical axis from a plano base surface (optional)

For this measurement task special sample holders are required, (see picture).

Furthermore, the OptiCentric^® system is capable of measuring the centering error of cylindrical surfaces in mounted anamorphotic lenses.

OptiSurf^® Center Thickness Measurement

Besides measuring centering errors, the OptiCentric® system is able to determine the distance between optical surfaces inside of an optical system.

An individual distance, e.g. the center thickness of a lens, but also a complete set of distances, including the center thickness of lenses and air gaps, can be measured non-destructively in an assembled objective lens. Similar as in the MultiLens measurement, this procedure requires the optical design data of the sample. OptiCentric^® offers two methods for this measurement.

The first method refers to the OptiSurf^® sensor, specifically developed for measuring distances inside optical systems. OptiSurf^® is based on low coherent interferometry and is able to measure all center thicknesses in an objective lens with an accuracy of about 1 μm. The OptiSurf^® low coherent interferometer measures lens distances within a range of 0 to 600 mm with an accuracy of 1 μm. Longer distance ranges i.e. optical paths are available on request.

The second method uses an autocollimator with a lens attachment in order to determine the cat's eye surface reflection position of the surface under test. The difference between two measured positions is used in conjunction with the design data (radii and refractive index) to calculate the actual distance. This method works extremely well with a limited number of surfaces but can be noticeable problematic when measuring optical systems with large numbers of optical elements. The OptiSurf^® sensor is the preferred choice for measurement of multilens optical systems.

OptiSpheric^®

With the extension module OptiSpheric^®, the measurement functionality of an OptiCentric^® instrument can be extended by the following optical parameters:

• EFL - Effective Focal Length
• BFL - Back Focal Length
• FFL - Flange Focal Length
• Radius of Curvature
• MTF on-axis

Besides the software functions, the OptiSpheric^® module consists of an additional collimator mounted with a 90° deflection mirror in the base of the instrument. It is equipped with a selection of test targets for the different measurement options.

OptiAngle^®

The software module OptiAngle^® and some additional mechanical fixtures convert the OptiCentric^® instrument into a powerful tool for angle measurements, including:

• Wedges
• 90°-prisms
• Parallelism of parallel plates
• Deviation angle through wedges and prisms
• Mirror tilt
• Alignment of CD/DVD optical heads
• Wobble of rotating disks