Diffractive Optical Element (DOE) composed of repetitive patterns is necessary for 3D measurement, or for converting a laser beam into several spots. In this study, DOEs were fabricated through a direct laser lithographic system of which it is easy to fabricate a pattern on the specimen at low cost and under relatively simple process conditions. A commonly used method in laser direct laser lithography is the thermochemical technique. In this way, a single-line can be produced. At this time, when the high power of the laser is used, the laser ablation phenomenon occurs, so that a dual-line can be produced. As a result, it is possible to fabricate a pattern quickly with the proposed process method. And especially, it can increase the effect in repetitive patterns production. To fabricate repetitive fine patterns using dual-line, hexagonal and tripleshaped patterns were fabricated, by using the writing speed and laser intensity appropriately. Optical performance evaluation was performed by comparing the diffracted image of the fabricated hexagonal repetitive patterns with the simulation result.

Tunable lasers have played an important role in a variety of industrial fields, by supplying stable output over a wide range of wavelengths. The external-cavity diode laser (ECDL) is widely used, because it provides a relatively broad tuning range, compact configuration, and easy control. In this paper, a new design is proposed for the Littman ECDL. The new design possesses a mode-hop-free single mode which is capable of tuning over a wide range of 17 nm, as a result of reconfiguring the pivot point location. Simulation and experimental studies were performed to verify our proposed method.

A direct laser lithography system is widely used to fabricate various types of DOEs (Diffractive Optical Elements) including lenses made as CGH (Computer Generated Hologram). However, a parametric study that uniformly and precisely fabricates the diffractive patterns on a large area (up to 200 mm X 200 mm) has not yet been reported. In this paper, four parameters (Focal Position Error, Intensity Variation of the Lithographic Beam, Patterning Speed, and Etching Time) were considered for stabilization of the direct laser lithography system, and the experimental results were presented.

The computer controlled optical surfacing (CCOS) technique provides superior fabrication performance for optical mirrors when compared to the conventional method, which relies heavily on the skill of the optician. The CCOS technique provides improvements in terms of mass production, low cost, and short polishing time, and are achieved by estimating and controlling the moving speed of the tool and toolpath through a numerical analysis of the tool influence function (TIF). Hence, the exact estimation of various TIFs is critical for high convergence rates and high form accuracy in the CCOS process. In this paper, we suggest a new model for TIFs, which can be applied for various tool shapes, different velocity distributions, and non-uniform tool pressure distributions. Our proposed TIFs were also verified by comparisons with experimental results. We anticipate that these new TIFs will have a major role in improving the form accuracy and shortening the polishing time by increasing the accuracy of the material removal rate.

Scanning white-light interferometry is an important measurement option for many surfaces. However, serious profile measurement errors can be present when measuring free-form surfaces being highly curved or tilted. When the object surface slope is not zero, the object and reference rays are no longer common path and optical aberrations impact the measurement. Aberrations mainly occur at the beam splitter in the interference objective and from misalignment in the optical system. Both effects distort the white-light interference signal when the surface slope is not zero. In this paper, we describe a modified version of white-light interferometry for eliminating these measurement errors and improving the accuracy of white-light interferometry. Moreover, we report systematic errors that are caused by optical aberrations when the object is not flat, and compare our proposed method with the conventional processing algorithm using the random ball test.

We propose a new variant of lateral shearing interferometer with a tunable laser source that enables 3D surface profile measurements of freeform optics with high speed, high vertical resolution, large departure, and large field-of-view. We have verified the proposed technique by comparing our measurement result with that of an existing technique and measuring a representative sample of freeform optics. Moreover, we propose a new algorithm that is able to compensate the rotational inaccuracy.