The U400-AC ULTIMA® Aperture Base Precision Kinematic Optical Mount uses spring-loaded pawls to gently, but securely, hold high precision 4 inch (101.6 mm) diameter optics from the back against three points on the front plate of the mount. Wavefront distortion in the optic is minimized because the forces acting on the optic are axial, instead of radial and are more distributed. For applications requiring secure mounting, the pawls can be tightened further, compressing the springs, and clamping the optic between the three points on the front plate and the pawls.
Like all ULTIMA mounts, thick front and rear plates and optimized, stiff springs improve the long-term stability and provide greater protection against vibrations. This base model does not include actuators. various actuators can be quickly changed to accommodate a broad selection of adjustment screws, micrometers, and motorized actuators. ULTIMA Precision Kinematic Optical Mounts minimize mount-induced wavefront distortion. Side set screw mounting, found in most optical mounts, is fine for many applications but our tests have shown that this technique induces wavefront distortion in the optic if the set screw is tightened a little too much. Convenient clearance mounting holes on each of two sides are compatible with either 8-32 or M4 screws providing quicker, more precise, and more secure mounting.
With the axial 3-point mounting, because there are twice as many mounting points, the forces that would cause distortion are essentially cut in half, more distributed, and axially opposite to eliminate bending.
Interferometric testing results show the flatness of the mirrors held in these mounts, measure at 0.100 wave PV (peak to valley). Compare this to mirrors held in a mount with a nylon-tipped set screw where the flatness degrades to 0.600 to 0.800 wave PV. An unconstrained 1/10th wave mirror will typically measure 0.090 wave PV.
The ULTIMA's industry-standard clamp design allows many different types of actuators to be used to adjust the mirror position to meet the requirements for any application. Actuators can be replaced with ease by simply loosening two screws to allow the actuator to gently slide into and out of the mount. ULTIMA mounts are compatible not only with standard knob and hex-key adjustment screws, but also with micrometers and motorized actuators. See our Recommended Compatible Actuators in the Accessories section below.
For long-term stability, ULTIMA® Low Wavefront Distortion Mirror Mounts use a Flexure Lock built with an AJS bushing. Flexure Locks exert a tangential force on the screw to prevent rotation.
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