Features

• Moving Magnet Motor Design for Faster Response
• High-Precision Optical Mirror Position Detection
• Analog PD Control Electronics with Current Damping
  and Error Limiter
• Protected Silver Mirror Coating
• Custom Coatings (e.g., Aluminum) Available upon Request
  (Contact Tech Support for More Details)

These high-speed Scanning Galvanometer Mirror Positioning Systems are designed for integration into OEM or custom laser beam steering applications with a beam diameter of <10 mm. Each system includes a single- or dual-axis galvo motor and mirror assembly, associated driver card(s), and driver card heatsink(s). Also provided is a base plate, which is a combined post adapter and tilt platform adapter. A low noise, linear PSU (GPS011); covers for the driver cards (GCE001); cage system adapter (GCM012); and heat sink (GHS003) are available separately (see below for details).

Galvo Motor/Mirror Assembly
The galvo consists of a galvanometer-based scanning motor with an optical mirror mounted on the shaft and a detector that provides positional feedback to the control board. The moving magnet design for the GVS series of galvanometer motors was chosen over a stationary magnet and rotating coil design in order to provide the fastest response times and the highest system resonant frequency. The position of the mirror is encoded using an optical sensing system located inside of the motor housing.

Due to the large angular acceleration of the rotation shaft, the size, shape and inertia of the mirrors become significant factors in the design of high performance galvo systems. Furthermore, the mirror must remain rigid (flat) even when subjected to large accelerations. All these factors have been precisely balanced in our galvo systems in order to match the characteristics of the galvo motor and maximize performance of the system.

The mirrors are available from stock with a silver coating. Custom coatings (e.g., aluminum) are available on request. Please contact Tech Support for more details.

Scanning Galvo Mirror Assembly and Driver Board
All Thorlabs scanning galvo mirror systems feature a mounted single- or dual-axis mirror/motor assembly and driver card(s). Shown to the left is the 10 mm 1D galvo mirror and driver card with heatsink. The mirror assembly features multiple mounting holes and a rotatable collar mount for the mirror/motor. A flying lead allows connection to the driver board. Please see below for additional mounting options and accessories.

Servo Driver Board
The Proportional Derivative (PD) servo driver circuit interprets the signals from the optical position detecting system inside the motor and then produces the drive voltage required to rotate the mirror to the desired position. The scanner uses a non-integrating, Class 0 servo that is ideal for use in applications that require vector positioning (e.g., laser marking), raster positioning (printing or scanning laser microscopy), and some step-and-hold applications. Furthermore, the proportional derivative controller gives excellent dynamic performance. The circuit includes an additional current term to ensure stability at high accelerations. The same driver board is used in all our galvo systems.

System Operation
The servo driver must be connected to a DC power supply, the galvo motor, and an input voltage source (the monitoring connection is optional). For continuous scanning applications, a function generator with a square or sine wave output is sufficient for scanning the galvo mirror over its entire range. For more complex scanning patterns, a programmable voltage source should be used. The ratio between the input voltage and mirror position is switchable between 0.5, 0.8, and 1. For the GVS011 and GVS012 systems, the ±10 V input produces the full angular range of ±20° with a scaling factor of 0.5. The control circuit also provides monitoring outputs that allow the user to track the position of the mirror. In addition, voltages proportional to the drive current being supplied to the motor and the difference between the command position and the actual position of the mirror are supplied by the control circuit.

Closed-Loop Mirror Positioning
The angular orientation (position) of the mirror is optically encoded using an array of photocells and a light source, both of which are integrated into the interior of the galvanometer housing. Each mirror orientation corresponds to a unique ratio of signals from the photodiodes, which allows for the closed-loop operation of the galvo mirror system.

The GVS011 and GVS012 systems can be driven to scan their full ±20° range at a frequency of 65 Hz when using a square wave control input voltage and 130 Hz when using a sine wave. For the same 0.2° small angle, the step response is 400 µs. The maximum scan frequency is 1 kHz and the angular resolution is 0.0008° (15 μrad).

Galvanometer System Specifications

*Measured with pulsed laser at 1064 nm, 10 ns, 10 Hz, and Ø1.000 mm beam diameter.

GPS011 Power Supply Specifications

The curves below show the reflection data for the silver-coated mirrors supplied with the GVS011 and GVS012 galvo systems.

Click to Enlarge
Protected Silver, 45° Reflectance Data

GVS Series Driver Connections

J10 Power Connector

Pin	Designation
1	+ 15 V
2	Ground
3	- 15 V

J6 Diagnostics Connector

Pin	Designation
1	Scanner Position
2	Internal Command Signal
3	Positioning Error x 5
4	Motor Drive Current
5	Not Connected
6	Test Input (NC)
7	Motor + Coil Voltage / 2
8	Ground

 

J9 Motor Connector

Pin	Designation
1	Position Sensor A Current
2	Position Sensor Ground
3	Position Sensor Cable Shield
4	Drive Cable Shield
5	Position Sensor B Current
6	Position Sensor Power
7	Motor + Coil
8	Motor - Coil

Galvo Assembly Motor Connector
GVS001/GVS002 Only

Pin	Designation
1	Motor + Coil
2	Not Used
3	Motor - Coil
4	Position Sensor Cable Shield
5	Not Used
6	Position Sensor Power
7	Not Used
8	Position Sensor A Current
9	Position Sensor B Current
10	Position Sensor Ground

J7 Command Input Connector

Pin	Designation
1	Command Input +ve
2	Command Input -ve
3	DRV OK
4	External Enable
5	-12 V Output (low impedence O/P)
6	+12 V Output (low impedence O/P)
7	Ground
8	Ground

 

JP7 Volts/Degree Scaling Factor Control

Servo driver cards manufactured after October 2009 have a jumper which is used to set the Volts per Degree scaling factor. The cards are shipped with the scaling set to 1.0 V/°, where the max scan angle is 10°, and is compatible with driver cards manufactured before October 2009.

To set the maximum scan angle to ±12.5°, set the scaling factor to 0.8 V/° by placing a jumper across the pins as shown above. Similarly, the 0.5 V/° scaling factor is provided to allow the full scan angle to be achieved using small input signals. In this case, the input voltage should be limited to ±6.25 V max.

External Enabling of the Driver Board

The drive electronics can be configured for external enabling by placing a jumper across pins 2 and 3 of JP4.

JP4

Once this has been done, the user can enable or disable the drive electronics by applying a 5 V CMOS signal to J7 pin 4.

If a logic high or no signal is applied, the drive electronics will be enabled. If a logic low signal is applied, then the driver will be disabled.

Pin	Designation
1	Command Input +ve
2	Command Input -ve
3	No Connect
4	External Enable
5	-12 V Output
6	+12 V Output
7	Ground
8	Ground

J7