Volume 1, Issue 6

This tutorial provides a brief introduction to the ISO 10110 optical drawing standard. The indications included on an ISO 10110 optical drawing are defined, and an example drawing is provided to illustrate how the information is commonly presented. To aid the designer who may not be familiar with the capabilities of optical shops, a set of specification values are provided, which illustrate easy, typical, and difficult values to achieve in fabrication. The same type of information is presented for lens dimensions. Finally, a set of design best practices are presented to aid in reducing fabrication difficulty and cost.

Autocollimators are versatile devices for the contactless measurement of the tilt angles of reflecting surfaces. In their practical application, e.g., in deflectometric profilometers for the precision form measurement of optical surfaces, the autocollimator beam is deflected in two orthogonal angular directions simultaneously. The concurrent engagement of both measuring axes results in errors in their angle response due to the crosstalk between them, which need to be calibrated. In this contribution, the capabilities of autocollimator calibration at the Physikalisch-Technische Bundesanstalt (PTB) are presented. The measurement of spatial angles is discussed in detail with a focus on achieving traceability of this measurand and reaching lowest uncertainties. A novel concept is introduced, which makes use of an innovative Cartesian arrangement of three autocollimators (two reference autocollimators and the autocollimator to be calibrated) facing a reflector cube. Each of the two reference autocollimators, which are used for the precise measurement of the cube’s angular orientation, is primarily sensitive to rotations of the cube around one of the two relevant axes and can, thus, be calibrated and traced back to PTB’s national primary standard for the plane angle in a conventional manner. In this way, the measurement of spatial angles is effectively divided into two separate measurements of plane angles. The mechanical realisation of the setup at PTB is described.

The assembly effort of optical systems can be reduced immensely by the use of appropriate manufacturing technologies. For refractive optical systems with a common axis of symmetry, lens centering allows a final system assembly with high accuracy and minimal effort, but is today mostly limited to spherical optical elements only. To overcome the current restrictions, a lens centering process for one-sided aspherical lenses was investigated both in theory and practice. The deviation of the rotational aspheric axis from a reference spindle axis is measured precisely with an electronic autocollimator and an additional distance sensor at the same time. Displacements can be minimized by a combination of lateral and rotational alignment motions, aiming at a coaxiality of both axes. In order to achieve a high performance of the entire optical system, the centered lens housings are machined with a diamond tool at their outer diameter, ground, and top surfaces. The feasibility of the complete process was proved by machining several aspherical lenses and measuring the final assemblies with a coordinate measuring machine. Thereby, a residual decenter <1 μm for the aspheric vertex and a tilt <0.5 arcmin between the aspheric axis and the axis of symmetry of the lens housing could be verified. The achievable manufacturing tolerances prove the practicability of the proposed lens-centering process for a majority of high-quality optical applications.

The effect of correct lens thermal optical path difference (OPD) on the optical performance of the Cassegrain telescope system is presented. The correct lens assembly includes several components such as a set of correct lenses, lens mount, spacer, mount barrel, and retainer. The heat transfer from the surrounding environment to the correct lens barrel will cause optical system aberration. The temperature distribution of the baffle is from 20.546°C to 21.485°C. Meanwhile, the off-axis ray’s path of the OPD has taken the lens incidence point and emergence point into consideration. The correct lens temperature distribution is calculated by the lens barrel heat transfer analysis; the thermal distortion and stress are solved by the Finite Element Method (FEM) software. The temperature distribution is weighted to each incidence ray path, and the thermal OPD is calculated. The thermal OPD on the Z direction is transferred to optical aberration by fitting OPD into a rigid body motion and the Zernike polynomial. The aberration results can be used to evaluate the thermal effect on the correct lens assembly in the telescope system.

A concept and design method of a dual-band flat-field spectrograph is presented. In the proposed optical scheme, the working range of wavelengths is divided into two subranges. A reflection holographic grating is used in the first subrange, and a transmission concave holographic grating is used in the second one. Both of them are aberration-corrected flat-field gratings. As an example, a scheme of spectrograph for spectral range from 278 to 560 nm is considered.

Metal island films are a matter of research in different branches of applied physics and technology. One possible future application field is their use as a substantial part of optical interference coatings, forming metal-dielectric composite multilayer coatings. This tutorial provides background on optical specifics of metal island films and ideas how these specifics could be exploited in coating technology. Consideration is given to effective optical constants of copper and silver island films, characterization methods and design strategies pursuing neutral density filters, asymmetric beamsplitters and decorative coating specifications.

Laser displays have been attractive because extremely wide color expression can be realized by choosing the wavelength of laser sources. The high efficiency and small etendue of laser sources contribute to downsizing, and a long lifetime is also another merit for users. In this paper, laser display technologies using efficient red, green, and blue lasers are reviewed. Also, applications of laser displays using these laser display technologies are introduced.