Optical Mirror Mount Guide

An optical mirror mount generally consists of a movable front plate which holds the mirror, and a fixed back plate with adjustment screws. Adjustment screws drive the front plate about the axes of rotation in the pitch (vertical) and yaw (horizontal) directions. An optional third actuator often enables z-axis translation.

Summary of Options

The following table provides a quick snapshot of your main options for selecting a mirror mount.

Mirror Diameters & Shapes	ø0.5 in., ø0.75 in., ø1.0 in., ø30 mm, ø1.5 in., ø2.0 in., ø3.0 in., ø4.0 in., ø6.0 in., ø8.0 in., Square, D-Shape
Materials	Aluminum, Alloy Steel, Stainless Steel
Configurations	Clear Edge, Top Adjust, Gimbal, Flexure, Low Distortion, Platform, Corner, Fixed, Low Outgassing, Industrial
Adjustments	θxθy-(Pitch/Yaw), zθxθy-(Pitch/Yaw/Focus), (Mounts without adjusters also available)
Sensitivity (Adjuster TPI)	80-TPI, 100-TPI, 127-TPI, 170-TPI, 254-TPI
Actuator Types	Knob, Knob locking, Allen key, Allen key locking, Micrometer, Motor, No Actuator

Mount Configurations

Mirror mounts are configured in several different ways to suite a variety of applications. Below are some of the available options.

Corner Mounts

Corner Mounts hold the mirror in a unique corner location to provide both a clearer beam path and enable gimbal movement. To achieve gimbal movement, two adjacent adjustment screws must be actuated the exact same distance

Clear Edge Mounts

With the clear edge design, beams can be reflected from one mount to another at smaller incident angles, taking less space. Clear Edge Mounts ideal for creating multiple reflections on Chirped Mirrors to compensate for pulse dispersion effects

Top Adjust Mounts

Top Adjust mirror mounts provide adjustments access above the beam path so your hands never have to cross the beam. This configuration also lends itself for use in compact spaces

Industrial Mounts

Industrial mounts are specifically designed for "Set and Forget" OEM applications. They all have the key features that are required for Industrial Applications: 1) Slim and geometry 2) Hex Key (Knobless) Adjusters 3) Extra Stiff, 4) Optional Locking for added Long term Stability

Gimbal Mounts

A gimbal mount has axes of rotation which intersect at the center surface of the optic. When the mount is adjusted, only the beam's angle changes, not its length. In contrast, a non-gimbal mount will shorten or lengthen a beam path as angle is adjusted

Platform Mounts

Platform mounts have a flat, square, adjustable surface for mounting square optics, prisms, and beamsplitter cubes. One benefit all platform mounts have over aperture mounts is their ability to hold mirrors which are as large as or larger than the actual mount itself.

Flexure Mounts

Flexure mirror mounts are designed for "set and forget" OEM applications. Welded construction, stiff flexure pivots, and precision adjustment screws provide excellent mechanical stability

Low Wavefront Distortion (LWD) Mounts

LWD optical mounts are specifically designed to hold mirrors in a way that will not induce optical distortion. They use an axial three-point mounting method to gently, but securely, hold optics so as not to affect tight flatness tolerances

Optical Mount Stability & Performance

In most applications, mirror mounts have the greatest influence on the stability and performance of an optical system. We use thermal tests to quantify this stability. In our thermal deflection test, the mount's temperature is cycled 10C from ambient and the pitch and yaw movement is recorded.

Mirror Mount Thermal Deflection Test Graph

Two key pieces of test data are drift and shift. Drift is the maximum deflection of the mount over the duration of the test, which usually occurs at maximum temperature. Shift measures how well the mount returns to its original position following the thermal cycle. Newport optical mounts that perform best with the lowest shift and drift deflection include: Suprema® ZeroDrift™ Series, MFM Series Flexure Mounts

Adjustment Sensitivity

Adjustment sensitivity is a calculation of the smallest angular adjustment a mirror mount can make. It is determined by taking the inverse tangent of the adjuster's minimum incremental movement, (MIM), divided by the distance from the rotation axis of the actuator axis (R).

Mirror Mount axis of rotation TPI illustration

The adjuster's minimum incremental movement is determined primarily by the TPI of the screw. TPI stands for threads per inch and is the number of threads over 1 inch of the screw.

Fine Pitch Adjustment Screw TPI Illustration

The reciprocal of TPI (also called thread pitch) is the axial length of just one thread. Thread pitch also represents how far the adjustment screw will travel with one full rotation of the adjustment knob. For calculating adjustment sensitivity we say that the smallest rotation a person can make on an adjustment knob is 1 degree. Calculating the adjuster's minimum incremental movement is simply the reciprocal of TPI divided by 360.

For example, to determine the sensitivity of the Suprema SU100-F2K-254 mirror mount, we first need to get the mounts information:

The distance from the rotation axis of the actuator axis: R = 1.5 in
The threads-per-inch (TPI) value of the adjustment screws: TPI = 254

Next we calculate the minimum incremental movement of the adjustment screw:

Adjustment screw minimum incremental movement formula

Finally, we can now calculate the adjustment sensitivity of the mirror mount:

Newport mounts with the highest TPI adjusters and, likewise, highest relative adjustment sensitivity include those listed below.

Mounts with 254-TPI Adjusters

SU100-F2K-254

SU100-F3K-254

SN200-F2K-254

SN200-F3K-254

Mounts with 170-TPI Adjusters

U100-A2K-170N

U100-A3K-170N

Mirror Mount Actuator Lock Types


Jam Nut Lock	Set Screw Lock
Key Benefits Exerts an axial force on the screw to prevent rotation. The jam nut lock with this design can be retrofitted onto the mount and can be tightened by hand or hex-key.	Key Benefits Exerts a radial force against the screw to prevent rotation. The locking mechanism for this type of mount is space saving and compact.
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Flexure Lock		Lever Lock
Key Benefits Exerts a tangental force on the screw to prevent rotation. Both adjustment and locking actions are accomplished using a single tool from the same side of the mount.		Key Benefits Exerts a tangental force on the screw to prevent rotation. Both adjustment and locking actions are accomplished using a single tool from the same side of the mount.
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Mirror Mount Materials

Mirror mounts are typically made exclusively from aluminum or stainless steel. Generally speaking, aluminum mounts are less expensive and stainless steel mounts are more stable. Below are a few characteristics and benefits of each material type:

	Aluminum	Stainless Steel	Advantages
Stiffness	69 Gpa	200 Gpa	Stainless steel mounts are stiffer and easier to align.
Thermal Expansion	22 µm/mK	16 µm/mK	Stainless steel mounts have lower CTE and lower drift.
Density	2700 kg/m³	7500 kg/m³	Aluminum mounts have lower density and weight less.
Relative Machinability / Cost	LOW	HIGH	Mounts made with Aluminum are easier to machine thus costing less to manufacture.
Thermal Conductivity	205 W/mK	16 W/mK	Aluminum mounts have higher thermal conductivity and stabilize faster.

Recommended Optical Mirror Mounts

Most Popular	Most Stable	Most Value
ULTIMA® U100-A2K Mirror Mounts (U100-A2K, U100-A3K) are a longstanding customer favorite. Their full-featured design combines excellent stability and a competitive value.	Engineered with thermal drift compensation built-in, Suprema® ZeroDrift™ Series Mounts reduce mechanical drift by 85% compared with standard stainless steel mounts.	Priced 15-20% less than competing mounts, Newport's M Series Mounts (M05, M1, M1Q) are the industry's most cost effective. Save an additional 10% off individual prices with convenient 10-packs.