Absolute Encoder Options

In order to meet the needs of the most demanding astro-imagers and researchers, we have integrated the optional Renishaw RESOLUTE Absolute Encoders into our 1600GTO mount. These encoders and readheads comprise a true absolute non-contact optical encoder system, which offers the latest in technological advances to ensure accurate and reliable performance in the field. What will this mean for you? Near perfect periodic error correction and your mount will never be lost, which will result in greater productivity and hassle-free imaging sessions. Your mount will be invisible, as it should be.

Consider these features when the absolute encoders are installed in both axes:

• Absolute encoder knows the exact position of the gear angle of the mount when the power is applied.
• No separate homing sensor is needed. Homing can be set to any gear angle via a simple software command.
• Adjustable software slewing limits based on the position of the gear angle allow you to safely image several hours past the meridian.
• The R.A. encoder is used to set the exact sidereal rate to eliminate periodic error of the worm gear. When used in conjunction with our Astro-Physics Command Center (APCC) Pro version software (purchased separately), the sidereal rate can be trimmed in small increments and adjusted to any rate necessary to counter R.A. and Dec. drift due to flexure, atmospheric refraction, polar misalignment, etc.
• High immunity to dirt, scratches and light oils to withstand real-world observatory conditions.
• Sealed readhead for high reliability in harsh environments.
• Integral set-up LED on readhead for quick set-up and instant “health check” any time.
• Built-in position-checking algorithm constantly monitors calculations for ultimate safety and reliability.
• Low temperature version available.

RESOLUTE uses a unique single optical absolute track (a world first) combined with sophisticated optics. The readhead acts like an ultra fast miniature digital camera, taking photos of the coded scale of the encoder ring. Photos are analyzed by a high-speed DSP to determine absolute position. The built-in position check algorithm actively checks every reading. Advanced optics and position determination algorithms are designed to provide low noise and low sub-divisional error. The result is unparalleled performance.

Specifications

• One-piece 4” diameter stainless steel ring with a single track, true absolute scale marked directly onto the periphery. High accuracy graduations ensure outstanding metrology and reliability.
• Resolution: 67 million pulses per rotation, 0.019 arc second per pulse.
• Accuracy is +- 3 arc seconds over the entire 24 hour, 360 degree rotation. +- 0.2 arc sec per hour typical accuracy.
• RESOLUTE Absolute Encoder:
  Operating: -20 degrees C to +80 degrees C (-4 F to +176 F)
  Storage: -20 degrees C to +80 degrees C (-4 F to +176 F)
• RESOLUTE ETR (Extended Temperature Range) Encoder:
  Operating: -40 degrees C to +80 degrees C (-40 F to +176 F)<
  Storage: -40 degrees C to +80 degrees C (-40 F to +176 F)
• Operation down to -40 degrees C (-40 degrees F) in non-condensing environments is guaranteed by Renishaw. The encoder is also tough enough to survive the physical punishment of harsh environments with solid steel ring scales