Features

• Single- and Dual-Axis Systems
• Moving Magnet Motor Design for Faster Response
• High-Precision Optical Mirror Position Detection
• Analog PD Control Electronics with Current Damping
  and Error Limiter
• Choice of Mirror Coatings:
  • Protected Silver (GVS001 and GVS002)
    500 nm to 2.0 µm
  • Protected Gold (GVS101 and GVS102)
    800 nm to 20.0 µm
  • Broadband Dielectric E02 (GVS201 and GVS202)
    400 nm to 750 nm
  • High-Power Dual-Band K13 (GVS301 and GVS302)
    532 and 1064 nm
• Custom Coatings (e.g., Aluminum) Available upon Request
  Contact Tech Supportfor More Details

These high-speed Scanning Galvanometer Mirror Positioning Systems are designed for integration into OEM or custom laser beam steering applications that utilize laser beams smaller than 5 mm in diameter. Each system includes a single- or dual-axis galvo motor and mirror assembly, associated driver card(s), and driver card heatsink(s). A low noise, linear PSU (GPS011) and motor/mirror assembly heatsink (GHS003) are available separately.

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 silver, gold, broadband or high power dual band coatings. 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 GVS301 1D galvo mirror and driver card with heatsink. The mirror assembly feature multiple mounting holes and a rotatable collar mount for the mirror/motor. These small 5 mm galvo mirrors feature a plug style connector to the mirror assembly. Please see below for additional mounting options and accessories.

Servo Driver Board (All Systems)
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, either 0.5, 0.8 or 1. When set to 0.8, the ±10 V input will rotate the mirror over its full range of ±12.5°. 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 systems can be driven to scan their full mechanical range of ±12.5° at a frequency of 100 Hz when using a square wave control input voltage or at 350 Hz when using a sine wave. For a single small-angle step of 0.2°, it takes the mirror 300 μs to come to rest at the command position.
The scan frequency range is DC to 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 coated mirrors supplied with the GVS series galvo systems. The shaded regions denote the ranges over which we recommend using the respective coating.

Click to Enlarge
Excel Spreadsheet with Raw Data for Protected Silver, 45° AOI

Click to Enlarge
Excel Spreadsheet with Raw Data for Protected Gold, 45° AOI

Click to Enlarge
Excel Spreadsheet with Raw Data for -E02 Coating, 8° and 45° AOI

Click to Enlarge

Click to Enlarge

Excel Spreadsheet with Raw Data for NB1-K13, 45° AOI

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