UV Micro-Objectives

UV Micro-Objectives

Catadioptric, long working distance micro-objectives are designed for use down to Deep Ultraviolet wavelengths. The µCAT’s superior design attributes outperform Schwarzschild objectives. Before considering an all-mirror system, take a closer look at the Tropel µCAT.

Benefits of the µCAT Design

The µCAT design incorporates reflective and refractive elements, resulting in a micro-objective with high numerical aperture, long working distance and low obscuration. High resolution and advantaged light collection, with a working distance that can work with a pellicle, the µCAT’s features combine performance and flexibility in a cost effective solution.

Broad-Bandwidth

The µCAT designs can provide sufficient bandwidth to accommodate lamp-based

systems, eliminating the need for expensive laser sources; lowering the overall cost of your system.

Less Obscuration Equals Improved Performance

Central obscuration within the lens has a direct effect on the mid-frequency

modulation transfer function (MTF) (i.e. image contrast). The µCAT’s design reduces the amount of obscuration, and improves the mid-frequency MTF. The amount of central  obscuration in the µCAT design can be as low as 15%, while typical Schwarzschild

objectives have greater than 35% central obscuration.

Another feature of the  µCAT design is the use of a "floating" secondary mirror, thereby

eliminating mechanical struts or "spiders", which when present in other micro-objectives, obstruct some light from passing through the system. By eliminating these struts, there is also a reduction in unwanted diffraction effects that are present in many reflective

micro-objective systems.

Well Designed for a Long Life

Our expertise in contamination control, optical materials selection, high

transmission coatings, and low outgassing materials combine to offer a robust design - which translates into lenses with longer lifetimes for our customers.

The  µCAT is an enclosed system designed to be purged with high purity nitrogen.

Controlling the internal atmosphere by purging with high purity nitrogen prevents harmful environmental contaminants from depositing on the internal components.

Purge design enhances internal cleanliness and maintains UV transmission while maximizing system life.

All materials selected for use in the µCAT objectives are ultra-low outgassing to minimize sources of contamination. µCAT designs are free of cemented surfaces which are known to degrade system performance and reduce lifetime by lowering transmission in UV applications.

Our designs include materials specifically selected to optimize transmission at wavelength and specially developed coatings are applied to the optical surfaces to maximize transmission and lifetime.

UV Micro-objectives for High Performance Applications

Because of the low obscuration incorporated into the design, the  µCAT can be used in

inspection applications with partial coherent illumination conditions, or to inspect images on reticles and wafers. µCAT objectives are currently utilized in OEM applications

including photomask and wafer inspection and writing.

UV Optics for High Performance Imagery, Interferometry, and Inspection Applications

All µCATs are corrected at specified wavelength ranges and are certified at those UV

wavelengths to verify their performance. A Certificate of Conformance and wavefront map are included with every micro-objective manufactured. All µCATs are certified for diffraction limited performance. Standard wavelengths are 193 nm, 213 nm, and 248 nm, with additional wavelengths and configurations available with special orders.

Micro-objectives are available to special order at different wavelengths, numerical apertures and mechanical configurations. Please contact us for your specific requirements. Specifications are subject to change.

Specifications

NOTE: inquire about a custom tube lens to support your magnification requirements.