Guiding Method	Movement Accuracy	Load Capacity	Rigidity
V-Groove and Cross roller (HG-VCR Method)	☆	☆	☆
V-Groove and Cross roller (V-CR Method)	◎	◎	◎
Roller way	◎	◎	◎
Ball way	○	○	◎
Ball bushing	△	△	△
Rotary bearing	◎	○	○

Table 1 Guiding method comparison. ☆: Superior　　◎: Great　　○: Good　　△: Possible

Instead of the traditional worm gear, we have adopted a feed screw mechanism for out complex coupling mechanism that is used to drive tilt stages.
By coupling this feed screw and the tilting part to a device that switches over between translatory and angular movement, this mechanism is able to pass on the straight line trajectory of the feed screw to a circular trajectory of the tilting part.
This mechanism takes advantage of the preciseness of using screws, resulting in high resolution, smooth motion, and superior durability.

■ Worm Gear Method
This is a general drive mechanism that uses a worm gear and worm-wheel. In this arrangement, part of the tilt stage upper table is made into part of a worm-wheel which is then driven by a worm gear. This mechanism has a fixed amount of backlash and if sufficient lapping adjustment is not performed, during operation, the worm gear can become heavy or uneven rotational torque can come about due to eccentricity.
In addition, the small area of contact between the worm gear and wheel can lead to problems with abrasion resistance.

■ Actuator + Spring Method
This is a mechanism used for general microscope stages that works by using an actuator and spring.
This backlash-free mechanism uses an actuator that pushes on the upper table and a spring that tries to return it back in the direction of the actuator.
There are several identified problems when using this mechanism. For example, the load on the actuator becomes quite high if a very powerful spring is used, the table can become unresponsive if it experiences a high load when being driven, or the table may not return to its original position if the spring force is to weak.

The complex coupling mechanism is driven by a feed screw and a specially designed coupling part. When compared with conventional technology, this design has the following features:

• Higher resolution when compared with the worm gear method.
• A specially designed coupling part allows free movement which absorbs any rotation irregularities.
• The small drive torque enables smooth movement.
• Durability is improved due to having a larger contact surface area than worm gears.
• Reliable movement control is possible due to the spring-free design.
• By changing the feed screw lead, the resolution and movement speed can be varied.

When the straight line motion is converted into angular motion, there are angular positioning errors along the tangent curve between the amount of feed screw movement and the tilting part that actually moves, as well as along the sine curve of the distance between the feed screw and the tilting part. However in reality, microscopic positioning errors are within ±3° of the amount of movement which is much less that the ±5° you get with worm gear positioning. It is also possible to achieve high positioning precision by performing error compensation.

The “Complex Coupling Mechanism” has been registered under patent number 3848304 as a “Table position adjuster”.