ImageMaster^® Universal Line

The ImageMaster^® Universal Series has been specifically developed to cover a wide spectral range. It is designed to measure the complete set of optical parameters over the extended wavelength range.

Virtually any existing lens system ranging from high performance photographic imaging lenses to high resolution telescopes can be accurately measured in: IR, Visible, UV. To fulfill these demands the system provides a flexible and modular structure which allows the user to adapt and expand it to different test requirements. As an example the whole system can be reconfigured from an infinity conjugate to a finite conjugates setup, or from measurements in the visible spectrum to the infrared spectrum in the twinkle of an eye. ImageMaster^® Universal consists of several main opto-mechanical assemblies. In particular these are the Object Generator, the Mirror Collimator, the Sample Holder, the Swinging Arm assembly and the Image Analyzer. Optionally the system can be equipped with a Finite Stage which makes the measurement at finite conjugates feasible. Also available as an option: the automated ultra-precision Afocal Unit.

For the operation of the system a powerful software package has been developed which processes all measurement data and controls all motorized stages and position feedback encoders. The Object Generator comprises a halogen light source for generating spectra in the extended visible regime. It can be easily exchanged for an infrared light source. A kinematic mount facilitates the exchange of several light sources without the need for a realignment of the source.

The output spectrum can be optionally narrowed with high performance optical filters. The illuminated target can be a single or double slit as well as crosshairs or USAF 1951 and other resolution targets. The exchange of the targets is very simple with a novel slider technique or it can be motorized for automation. Optionally the object generator can be mounted onto the finite stage for positioning the target at finite conjugates.

Reflecting Collimator Assembly

The target is imaged to infinity by a precisely aligned mirror collimator of remarkable surface quality. This guarantees diffraction-limited performance to highest precision. TRIOPTICS is the only company in the market that exclusively uses high quality diffraction limited collimators completely covered with stable, vibration damping, dust free and internally black matte-coated housings, eliminating the wavefront distortion due to air turbulences and ambient light influences.

Heavy Duty Precision Sample Holder

A high performance MTF-Test station requires a precision rotary sample holder featuring negligible radial and axial run out, extreme stability and reference surfaces machined with highest accuracy. TRIOPTICS has invested a lot of efforts in the design and manufacturing a sample holder fulfilling these requirements.

The heart of the holder is an ultra accurate, heavy duty rotary bearing. The precision, steel ground reference surfaces, square and parallel to the optical axis, allow for an accurate positioning of the sample. Rotation facilities over 360° can be motorized and software controlled. Fine adjustment in X, Y direction permits the accurate centering of the sample to the optical axis. Height adjustment of the sample holder and a linear stage for translation of the sample holder further increase the flexibility of the system.

Set of filters and collimators for short focal distance

Set of alignment tools

By default the sample under test is clamped to the Sample Holder by a self-centering chuck. As a matter of fact this can be replaced by a custom made bearing surface manufactured for the specific sample mount.

Precision Swinging Arm Assembly

The main parts of the swinging arm include:

• Stepper motor precision swinging arm with rotation facilities for very large field angles (up to +/-140 degrees rotation).
• High precision gear and arc rail with angular scale for backlash free rotation of the swinging arm.
• Precision Angular Encoder with resolution 0.18 arcsec
• Linear optical rail for IR Image Analyzer Unit and sample holder

Automated Ultra-Precision Afocal Unit

It includes:

• Semicircular guide ways, made of high stiffness, corrosion resistant materials and featuring exceptional straightness and running tolerances
• Precision drive with stepper motor and controller
• PC-controlled rotation of the optical head to the required angle, range +/-30°
• Guide ways for translation of the afocal unit along the optical axis in order to accurately position the image analyser in the centre of the exit pupil of the sample (telescope)
• Decollimators for the spectral ranges specified
• Software module for afocal systems

Image Analyzer

The Image analyzer can be equipped either with a CCD camera for measurements in the visible spectrum as well as with InSb- or- MCTdetectors to cover the infrared spectrum from SWIR to LWIR. The imaging device for the visible range is equipped with a high performance apochromatic relay lens. This lens focuses to the image plane of the lens under test and magnifies the target image onto the detector chip.

As the present technical development does not permit using CCD-like cameras in the UV or SWIR to LWIR region, TRIOPTICS made much effort in developing “scanning aperture” methods with point-like sensor chips for the these regions.

A high-precision air slit or pinhole of a few microns width is scanned in the image plane of the sample and the intensity profile of the line spread function (LSF) is recorded by the UV- or IR- detector. The intensity profile can be either scanned in tangential or in sagittal direction. The captured data is transferred to a computer which performs the data analysis. State of the art signal acquisition equipment with optical light choppers, low-noise preamplifiers and digital lock-in amplifiers is used to obtain the optimum signal-to-noise ratio and MTF results of highest precision.