Jenoptik Laser, Optik, Systeme GmbH has developed a new mounting technology for optical elements. It is free of any
glue or other organic material whereby it is excellently appropriate to the use for DUV Systems, especially if high intensity occurs as it is to be found in illuminating systems. The new technology has been successfully applied in high quality lenses e.g. in a high NA inspection lens @266nm and several ultra high quality imaging systems @193nm. The so called Clamp Mount Technology is characterized by high accuracy and stability under environmental influence such as shock, vibration or thermal effects. There is no limitation in use with any optical material e.g. fused silica or calcium fluoride. The lens cells are routinely optimized by finite element method. Thus in advance clamp force is optimized having regard to deformation of optical surfaces, lens shape, lens weight, gravity and shock load. Additionally stress induced polarization effects are predictable. The FEM simulation results can be transferred to optical design tools which are used for lens design as much as for comparing design data with experimental results.
For about 200 years surface shape specification for optical components always had one goal only, to make an individual
optical component comparable with other pieces of the same type. If the specification is met, the component should
fulfill the requested behavior in the related optical system. Nomenclature of specification did not differ in dependence on
the components different position in the system or on different used beam diameters vs. components clear aperture. With
increasing performance of designed optical systems, surface shape tolerances of components became tighter more and
more. Such requirements either lead to inadequate expenses or to the absence of equipment to manufacture and test them
in a controlled process.
But in reality, only a small part of optical system components are used as they are measured - within full clear aperture.
Moreover, the light beam has a significant smaller diameter than the clear aperture has. Typically, this kind of
components we find in scanning systems and lenses with large Field of View (FOV).
As far as designed surface shape tolerances are derived from maximal acceptable wave front deviation for individual
light beams passing through the system, the related method for optical components acceptance test procedures is to
analyze wave front deviation in sub apertures caused by surface shape deviation. In this case designed values and
manufactured results are comparable to each other. To get the comparable values, surface shape analysis must be done in
a gliding sub-aperture area instead of analysing full clear aperture.
We show how sophisticated optical systems components may be specified, manufactured and tested in gliding subaperture
areas for any term described in normative papers, such as ISO
10110-Part 5 "Surface Form Tolerances", to
assure the final function in system.
The chosen examples correspond with "classic specified" optical component surface shapes down to 3/ - (0.02)@546nm.
Shack-Hartmann wave front sensors (SHS) are an accurate and highly versatile tool for
characterizing and adjusting high performance optical systems, especially in the DUV
The conventional set-up uses a single path approach. An illuminated pinhole is placed in the
object plane and the sensor in the exit pupil of the system under test. This approach is applicable
up to a NA of about 0.9 because of the limited ability of a pinhole to illuminate high numerical
apertures. Beyond the limit a double pass set-up is necessary. The double pass approach also
allows a higher precision and the application of multi-position tests well-known from
A set-up will be shown which can be easily integrated into existing Shack-Hartmann test
benches. Some exemplary data will be given comparing results from single pass and double pass
The fast development of sensors with high sensitivity and growing pixel numbers for the IR range drives the
development of suitable optical systems. This is enforced by the growing demands of the defense and security sector.
JENOPTIK LASER, OPTIK, SYSTEME GmbH serves this market based on many years of experience. The product
spectrum contains all usual types of optical components. Most of the typical IR transmitting and reflecting materials are
machined. The quality scale reaches from medium to high-end, where the latter is mostly needed for defense
applications. High-efficiency, highly durable and environmentally stable anti-reflection coatings for the complete
spectrum of substrate materials are developed and produced in-house. JENOPTIK is developing and manufacturing
custom-tailored lens systems and electro-optical modules for civil and military applications. This includes optical
modules for IR cameras and for long range surveillance and target recognition, which fulfill the highest demands with
respect to imaging quality, aperture, stray light, compactness, and durability. The testing and the verification of
performance parameters include interferometrical testing, transmission, scattering, and MTF measurement at working
temperature. A combination of design, manufacturing and measurement techniques is needed for the fabrication of IR
lens systems meeting the highest performance requirements.
Aside from steppers also inspection systems in the semiconductor industry as well as in micro
material processing require DUV imaging optics with very high optical requirements.
A test and adjustments set-up based on the Shack-Hartmann wave front sensor for objectives
and telescopes is presented. It allows primarily to characterize the image quality of systems
under test for both finite as well as infinite object and image distances.
From the wave front the modulation transfer function, point spread function or encircled
energy data can be derived. Also, other data such as magnifications, focal lengths and even
distortion with micrometer accuracy can be obtained with the test bench.
The test system consists of a spherical waves generator, the sensor including adapting optics
and the mechanical motion system. It is highly motorized and all essential functions are
computer controlled. The available wavelengths currently range from NIR to 193nm.
Machining of aspheres represents an extra field in the manufacturing of optical components. The deviation from the sphere has a big impact on machining and testing equipment, tools and technologies, achievable specifications and costs. The production of aspheres deals with special problems such as mid-spatial frequency errors, centering tolerances and slopes, not known in that degree from manufacturing of spheres. Over the past 20 years JENOPTIK Laser, Optik, Systeme GmbH has gained a wide experience of this application area. Recent results give a review on what is required to execute the transition from standard quality to high-precision aspheres, off-axis parts and free forms.
Computer generated holograms (CGH) are widely used in combination with standard Fizeau interferometers. The test of plane and spherical specimen is extended to the test of aspherical surfaces. The wave from a transmission flat or a transmission sphere is formed by the CGH to fit the surface of an asphere or a cylinder. There are some considerations for an advantageous design of this additional optical element in the beam path. The availability of a suitably designed CGH is often the limitation for the manufacturing of precision aspheres. JENOPTIK Laser, Optik, Systeme GmbH can provide a custom made CGH within a short time. We will show the design principles and the layout of the CGHs. The optical properties and the known limitations will be presented based on measurements of aspherical surfaces.
With computer generated holograms (CGH) the testing possibilities of interferometers for plane and spherical specimen is widened to the test of aspherical surfaces. The wave from a transmission flat or a transmission sphere is formed by the CGH to fit the surface of an asphere or a cylinder. The availability of suitable CGHs is often the limitation for the production of precision aspheres. JENOPTIK L.O.S. can provide a custom made CGH within a short time. We will show the design principles and the layout of the CGHs. The optical properties and the known limitations will be presented on the basis of measurements of aspherical surfaces.
The paper deals with challenges, solutions and results obtained by JENOPTIK Laser.Optik.Systeme GmbH (JO L.O.S.) while contriving and transferring knowledge gained in the field of manufacturing and testing high-end spherical and plan surfaces into manufacturing of complex optical surface shapes. During the last two years notable progress was made in the field of manufacturing optical components with constantly changing curvature and lack of symmetry by linking selected manufacturing equipment and testing methods to each other. We will show present results reached in industrial manufacturing of complex surface shapes on an accepted level of expanse.
JENOPTIK Laser, Optik, Systeme GmbH (JO L.O.S.) enlarged its product range in the field of cylinder lenses and crystal optics. These components are used in optical measuring technology and in various laser applications. The new cylinder components are a result of the state of the art manufacturing technology. For applications, where the quality of standard cylinders with a surface deviation of PV~Lambda/2 to ~Lambda/5 @632,8nm and tested with a reference glass only is not sufficient, the surface shape can be improved to PV Lambda/10 @632,8nm.
The presentation deals with Jenoptik's current state to produce cylinder optics, to reduce remaining surface shape deviations of semi-finished cylinder optics and to test these elements. Based on in-house developed machinery, cylinders are manufactured by means of blocking or drum. The required surface quality in the range of PV~Lambda/10 @632,8nm for cylindrical lenses can be reached by computer aided correction using mrf-polishing techniques in connection with an interferometer test set-up. Therefore, the polishing machine is equipped with an additional axis of movement. The interferometer measurement of the residual surface deviation is done by Computer Generated Holograms (CGH), which are designed and manufactured in-house. CGHs from JO L.O.S. for testing cylindrical lenses can be custom designed starting with F#1.0. They are related to the typical rectangular geometry of cylinder components. Using these measurement techniques, testing is no longer the limiting factor in achieving high quality cylindrical surfaces.
JO L.O.S. has all the capabilities of effective manufacturing, testing and correcting cylindrical lenses. Latest results achieved in series production are shown.
A small distinction of some micron makes an awful difference between spheres and aspheres. It takes special technological equipment to manufacture and test aspheric optics. This equipment is clearly distinguished from that for classical optics manufacturing. This paper deals with equipment installed at JENOPTIK L.O.S. and give results based on serial manufacturing of aspheres.
Testing of spherical surfaces using the Twyman-Green interferometer with a laser source suffers from the presence of spurious interference fringes and dust diffraction. By reducing the spatial coherence while maintaining the temporal coherence a tremendous improvement of the fringe quality can be obtained. To conserve sufficient contrast, the reference mirror must be positioned to suitable locations relative to the test arm of the interferometer. These conditions are described and examples are presented.
Holographic optical lens elements (HOEs) are volume grating in thick material such as dichromated gelatine (DCG) which suffer from the wavelength mismatch between the recording process and the practical application e.g., at laser diode wavelengths. Wavelength mismatch between recording and reconstruction is caused by the fact that the best recording materials are sensitive only in the blue region of the spectrum. The advantage of volume gratings (thickness 13 micrometers ) is the large angle of deflection of the first diffraction order with a high diffraction efficiency. An optimized recording geometry using only spherical wave fronts allows on the one hand for the elimination of one of the third order aberrations (predominantly: astigmatism) or on the other hand for the fulfillment of the Bragg condition. To optimize the properties of holographic optical lens elements with one aspheric recording wave a kind of iterative procedure for the manufacturing is proposed. Each iteration consists of three different steps.
A shearing interferometer is proposed for the characterization of microlenses. The optical configuration of the test system enables the measurement of the wave aberrations, the focal length, and the deviations of the lens surface from an ideal sphere. In addition, a quantitative evaluation method is given that enables the calculation of the wave aberrations (e.g., the phase function) from the shearing interferometer data.
Refractive or diffractive microlenses have already been reported. Here we discuss two examples of microlenses where the generation process and the interferometric control are strongly interwoven. For refractive lenses we use lenses melted in photoresist and also reactive ion etched samples. The control is done with the help of a phase shifting interference microscope of the Mach-Zehnder type. We developed an evaluation software under Windows. The software allows for the evaluation of the wave aberrations and related functions as are psf and otf.
Phase-shift interferometry suffers from periodic systematic errors caused by erroneous reference phase adjustments and instabilities of the interferometer. A new method is described that uses only four interferograms and eliminates the errors caused by linear adjustment deviations of the reference phase or the mean phase in the interferometer. Test results confirm the theoretical predictions.
Switchable optical filters have been designed and fabricated for optical image processing applications. In particular, the case of filters producing a Gaussian PSF has been investigated. The filter functions are calculated using methods based on the stationary phase approximation and an iterative Fourier algorithm. The resulting phase functions are realized as continuous surface-relief gratings in photoresist by laser-beam lithography. The optical filters are then made electrically switchable by a liquid crystal layer on top of the grating.
Wave aberrations determine the quality of the focal spot and, more generally, the imaging quality of the lens under test. Here we propose the measurement of the wave aberrations with the help of a Twyman-Green interferometer adapted to the special requirements for testing holographic optical lens elements. The evaluation of the interferograms is done with the phase-shifting technique. The resulting wave aberrations are expanded as Zernike polynomials. In addition to this evaluation, the point spread function and the modulation transfer function are calculated from the wave aberrations. The setup, the evaluation method, and some exemplary results of a tested holographic optical element are presented.
The wave aberrations determine the quality of the focal spot and more general the imaging quality of the lens under test. Here we propose the measurement of the wave aberrations with the help of a Twyman-Green interferometer adapted to the special requirements for testing holographic optical lens elements. The evaluation of the interferograms is done with the phase-shifting technique. The resulting wave aberrations are expanded as Zernike polynomials. In addition to this evaluation the point spread function and the modulation transfer function are calculated from the wave aberrations. The setup the evaluation method and some exemplary results of a tested holographic optical element are presented.