Rotary Scales
Precision Glass Rotary scales (Codewheels)
Maximize performance of any optical encoder with precision glass scales by VC America. Linear and Rotaryscales are manufactured using soda-lime glass with chrome reflective and absorptive layers optimized for 630-640nm (Red LED), with dimensional precision and low defect density.
Standard scales provide opportunity for fast evaluation and support production and we manufacture to customer specifications for unique patterns and dimensional requirements.
Track periods of 20µm, 40µm, 100µm are common. We'll manufacture scales to 2µm period (1µm reflective +1µm clear or anti-reflective) when needed.
| 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 700 | ±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 | ||
| 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 | % | |
Lifecycle
Active
Rotary Glass Scales.pdf
SMD-04B
SMD-01B
SM3414B
Linear Scales