Rotary Scales

Precision Glass Rotary Scales (Codewheels)

Key Features

Precision Linear and Rotary Glass Scales
- Fine feature photolithography for maximum accuracy
- Multiple coating process options
  - Reflective and Anti-Reflective coatings for different wavelengths
  - Increase performance and lower power consumption
  - UV curing options
- Up to 700mm Linear, Up to 150mm Rotary diameter
- Soda lime glass standard, low CTE & special glass available

Typical Applications

Metrology, CMM
Laser optical axis control
Assembly machines
Measuring instruments
Precision rotary and linear encoders
Stages, Actuators
Robotics

Maximize performance of any optical encoder with precision glass scales by VC America Electronics.

VC America Electronics uses fine feature sub micron photolithography to create accurate and repeatable patterns. The process is capable of 2µm period (1µm reflective +1µm clear or anti-reflective) when needed. Common track periods between 20µm and 100µm benefit from the precise photolithography.

Production scales match the encoder, physical, environmental, and performance requirements. For applications requiring best accuracies over long lengths or temperature extremes, glass compositions with very low CTE are used.

Linear and Rotary scales are manufactured using soda-lime glass with chrome reflective and absorptive layers optimized for 630-640nm (Red LED) or 850nm, with dimensional precision and low defect density.

We offer standard scales for rapid evaluation and production and we also manufacture to custom specifications for unique pattern, material, and dimension requirements.

Code	Precision Rotary	Mounting Adhesives
CG	Reflective chrome on clear glass	Epoxy, UV
AR	Reflective chrome topside with Anti-reflective layer bottom side	Epoxy
AC	Reflective chrome and Anti-reflective layer top side (in track area) and clear center zone	Epoxy, UV

Rotary scales OD and ID are sawed and edges may be straight cut or beveled with chamfer or rounded edges.

Symbol	Material	Specification	Tolerance	Units
OD Maximum	Soda-Lime Glass	Up to 150	±0.1	mm
OD		Outside Diameter	±0.1	mm
ID		Inside Diameter	±0.1	mm
T		Thickness	±0.05	mm
TTV		Total Thickness Variation	10	µm
LTV		Local Thickness Variation	5	µm
CTE		Temperature coefficient of expansion	8.5	10^-6mm/mm°C

Parameter	Reference	Minimum	Typical	Maximum	Units
Pitch/Period Accuracy	Local			±1	µm
Pitch/Period Accuracy	Total			±2	µm
Metal pattern alignment to Axis				±20	µm
Chrome reflective layer	Standard	50	54	60	%
	Augmented	60	65	70	%
	Enhanced	88	93	98	%
Chrome absorptive(anti-reflective)@ 630nm	AR		<2	5	%