Acousto-Optical Single Pulse Selector
pulseSelect is an acousto-optical pulse picker, developed for the special demands of femtosecond laser technology. Pulse distortion is minimized by a low dispersive design and the use of reflective optics. High repetition rates and high contrast rates are achieved by using acousto-optical elements.
The pulse repetition rate can be reduced by an adjustable internal frequency divider or by external triggering. Pulse picking with low division ratios down to fREP/2 are possible. pulseSelect has an integrated RF power limitation and protection circuit to prevent modulator damage. For highest stability the phase of the RF carrier frequency is locked to the repetition rate of the laser in use.
The Single pulseSelect consists of an optical module and control electronics. A Bragg cell represents the most important part of the optics, which selects individual pulses from the laser beam due to the acousto-optical effect. Focusing mirror, collimator mirror and a beam stop for the zero-order beam complete the setup. The driver electronics supplies the modulated RF signal for the Bragg cell with a carrier frequency that corresponds to the multiple of the laser repetition rate.
pulseSelect in a double configuration is available in two variants, Serial and Parallel. The Serial variant offers an improved contrast ratio of over 200,000:1. The Parallel version allows the simultaneous picking of pulses from two synchronized laser sources.
Double pulseSelect Serial : This version is designed to achieve for highest contrast ratio of over 200,000:1 for non-adjacent pulses (5000:1 for adjacent pulses) by placing two Bragg cells in sequence. Both are synchronized to one common clock (in serial configuration; i.e. one beam through two Bragg cells).
Double pulseSelect Parallel : This variant is designed for simultaneous picking of pulses from two synchronized laser sources. The system is equipped with two synchronized Bragg cells. Independent picking settings are possible for both Bragg cells.
| pulseSelect | Broadband | Dualband |
| Wavelength
range (other on request) |
500 nm … 1600 nm | 340 nm … 540 nm + 680 nm … 1080 nm |
| Max. input power | 5 W at 800 nm | |
| Input frequency (fREP) | 72 MHz … 81 MHz to be specified with an accuracy of 0.5 MHz when ordering |
|
| Input polarization | Linear, horizontal - polarization rotator optional | |
| Division ratio (internal trigger) | 2 … 260,000 | |
| Output repetition rate | Internal trigger based: ~308 Hz
… 40 MHz (based on fREP = 80 MHz) External trigger based: Single-shot … 3 MHz |
|
| Contrast ratio (at 800 nm, fREP/20) |
>500 : 1 for non-adjacent
pulses >75 : 1 for adjacent pulses |
|
| Diffraction efficiency* (at 800 nm, fREP/20) |
>50% | |
| pulseSelect Dual - Serial: High-contrast performance | ||
| Contrast ratio (at 800 nm, fREP/20) |
>200,000 : 1 for
non-adjacent pulses >5000 : 1 for adjacent pulses |
|
| Diffraction efficiency* (at 800 nm, fREP/20) |
>25% | |
| pulseSelect Dual - Parallel: Simultaneous picking of pulses from two synchronized laser sources | ||
| Contrast ratio (at 800 nm, fREP/20) |
>500 : 1 for non-adjacent
pulses >75 : 1 for adjacent pulses |
|
| Diffraction efficiency* (at 800 nm, fREP/20) |
>50% | |
| Options: | ||
| Input frequency (fREP) | 35 MHz … 90 MHz to be specified with an accuracy of 0.5 MHz when ordering |
|
| High diffraction efficiency* | >60% (36% for pulseSelect
Dual - Serial), only available for max. average input power of 0.5 W at 800 nm |
|
| Polarization rotator | Changing input polarization to horizontal | |
* Ratio of the diffracted pulse energy to the pulse energy incident into Bragg cell.
APE_pulseSelect Datasheet (pdf / English)
