Linear Scales
Precision Glass Linear scales
Precision scales track complement optical reflective read head encoder modules. Fine feature [nanometer] mask photolithography used creates accurate and repeatable patterns.
The majority of linear scale applications work well with soda-lime glass with reflective chrome metal pattern on top and anti-reflective chrome backside. Common pitches range from 100µm to 20µm or as required for specific industry encoders. Process capable of 1µm track pattern (2µm period).
Production scales match the encoder, physical, environmental, and performance requirements. Well process coatings for specific wavelengths matched to requirements. For applications requiring best accuracies over long lengths or over temperature range, glass compositions with very low CTE are used.
Track periods of 20µm, 40µm, 100µm are common. We'll manufacture scales to 2µm period (1µm reflective +1µm clear or anti-reflective) when needed.
Glass Scale | Standard | Extended Length |
---|---|---|
Base Material | Soda-Lime Glass | |
Length | Up to 160mm | >160 to 700mm |
Length Tolerances | ±0.1mm | ±0.2mm |
Width | As specified (3mm or 6mm are often used) | As Specified |
Width Tolerances | ±0.05mm | ±0.1mm |
Thickness Range | 0.3 to 1.1 | 1.0 to 6.0mm |
Thickness Tolerances | ±0.05mm | ±0.05mm |
Pitch (total tolerance) | ± 2.0µm | |
Pitch (local tolerance) | ±1.0 µm |
Parameter | Reference | Minimum | Typical | Maximum | Unit |
---|---|---|---|---|---|
Pitch/Period Accuracy | Local | ±1 | µm | ||
Total | ±2 | µm | |||
Chrome reflective layer | Standard | 50 | 54 | 60 | % |
Augmented | 60 | 65 | 70 | % | |
Enhanced(620-650 nm) | 88 | 93 | 98 | % | |
Chrome anti-reflective layer @ 620-650nm | AR | <2 | 5 | % |