Thorlabs' ODL220-FS Free-Space Optical Delay Line Kit offers customers a tested set of Thorlabs components to build an optical delay line. The kit is based on our DDS220 long-travel, low-profile direct drive stage, capable of tuning the optical delay up to 1466 ps. Repeatable delay shifts down to 0.67 fs are achievable. The high accuracy and long-term stability of the stage make this system a suitable choice for pump-probe spectroscopy, THz spectroscopy, interferometry, and related applications.

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90° V-Block Contains Mirror Mounts and Irises

The direct-drive technology used in this delay line kit eliminates the need for a lead screw, which enables backlash-free operation. The absolute position of the stage is determined using a high-resolution, closed-loop optical feedback signal that provides bidirectional repeatability of 0.25 µm. The stage also features twin, precision-grooved linear bearings that provide superior linearity and on-axis accuracy, which makes the stage an ideal choice for a delay line setup.

In addition, the stage in this kit can be driven at speeds of up to 300 mm/s, making this kit well suited for studying experimental phenomena in a single-shot scanning mode. High-speed scans can also be used to minimize the effects of slow changes in a system (such as thermal drifts) on experimental data.

Optical Alignment
The optical delay line kit includes an RS99 Periscope Assembly that can accommodate input beam heights from 2.4" to 6" (60 mm to 152 mm). By purchasing additional Ø1" (Ø25 mm) Pillar Posts, the input beam height that can be accommodated is easily increased. The periscope's input and output mirrors are easily rotated through a full 360° using the included handles. The first POLARIS-K1^TM Low-Drift Kinematic Mirror Mount is used to align the beam parallel to the translation axis of the DDS220 stage. The stage's V-block contains two kinematic mirror mounts and two irises for beam alignment. The iris mounts are based on our FiberBench mounts, and many of our FiberBench accessories may be used in place of the irises. Finally, a second POLARIS-K1 mount is then used to steer the output beam. The optical path is shown in the figure below.

Six Ø1" protected silver mirrors, which provide an average reflectivity in excess of 96% over the entire 450 nm to 2 µm range, are included. If your application would benefit from gold, aluminum, broadband dielectric, dielectric laser line, or ultrafast mirrors, please contact Technical Support to discuss the various options.

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GUI Controls Time Delay of Stage
(See Software Tab for More Details)

Optical Delay Specifications

*Based on minimum incremental motion of the stage.

Custom GUI Software for Optical Delay Control

The optical delay line includes GUI software to control timing changes of the stage. With this software, it is possible to precisely choose the optical delay you wish to add or subtract from your beam path. For interferometry experiments, the option to scan the stage continuously or in discrete steps is available, with each step's position being held for a specific time period.

The kit also includes the apt^TM software package for computer control of the stage. The apt software also allows for advanced custom control applications and sequences in various programming languages through ActiveX.