A compressive force is applied to a conventional air-spaced etalon filter to fine tune the thickness of the spacers to a precise and uniform optical length. The etalon is coupled to a housing device capable of adjusting the thickness of each spacer, thereby tuning the etalon to the desired filter wavelength. The resulting assembly is permanently set to the desired parameters for direct use in optical applications.

Disclosed is a laser system including a high reflector and an output coupler defining a resonator; a gain medium positioned in the resonator that produces optical gain at more than two desired wavelengths; a coarse selection system, positioned in the resonator and coupled to the gain medium, that produces single transverse modes at the desired wavelengths, with transmission values at the desired wavelengths selected such that power output at the desired wavelengths is maximized, and with transmission values at undesired wavelengths selected to retard lasing at the undesired wavelengths; and a fine selector positioned in the resonator and coupled to the gain medium, having a optical length such that all of the desired wavelengths are substantially simultaneously resonant within the optical length; whereby an output beam is generated. Also disclosed are full-color holography systems and three-dimension laser Doppler velocimetry systems incorporating the inventive laser system.

A conversion efficiency of 42% and slope efficiency of 60% relative to absorbed pump power are obtained from a continuous wave diode-pumped Tm, Ho:YLiF.sub.4 laser at 2 .mu.m with output power of 84 mW at a crystal temperature of 275 K. The emission spectrum is etalon tunable over a range of 7 nm (16.3 cm.sup.-l) centered on 2.067 .mu.m with fine tuning capability of the transition frequency with crystal temperature at a measured rate of -0.03 cm.sup.-1 .K.sup.-1. The effective emission cross-section is measured to be 5.times.10.sup.-21 cm.sup.2. These and other aspects of the laser performance are disclosed in the context of calculated atmospheric absorption characteristics in this spectral region and potential use in remote sensing applications. Single frequency output and frequency stabilization are achieved using an intracavity etalon in conjunction with an external reference etalon.

The present invention provides a compliant mechanism that can be used to make a variety of devices, such as tunable optical devices that are more reliable, more cost effective and/or exhibit better performance than prior art devices.

A cost-effective tunable optical component uses entropic, rather than enthalpic, materials to provide a compliant member that supports the optical element and is driven by an electrostatic actuator. Entropic materials exhibit an entropic plateau region over a wide frequency range with a Young's modulus much lower than enthalpic materials, linear elastic behavior over a wide deformation range, and, in certain geometries, energy and stress behavior that tend to stabilize the optical element during deformation. The compliant member can be configured in a variety of geometries including compression, tension, tensile/compressive and shear and of a variety of materials including elastomers, aerogels or other long chained polymers.