Herriott Cell (Multipass Cell) Setup and Configuration (Viewer Inspired) | Thorlabs Insights

Описание: In a Herriott cell (Multipass Cell), light reflects multiple times between two concave mirrors. The reflected beams cross the volume between the two mirrors at different angles, tracing out different paths and creating linear, elliptical, or circular spot patterns on the mirrors. To allow the beam to enter and exit the cell, one or both of the mirrors typically has a hole at its center or near its edge. Herriott cells are used in a variety of applications that benefit from folding a long optical path length into a compact space. Gas-absorption spectroscopy is a popular application, since every additional pass of the beam through the sample volume increases the signal-to-noise ratio of the measurement data.

This demonstration begins with a roughly aligned setup, in which one mirror has a hole near its edge and the other has no hole. Both mirrors have the same focal length. A non-polarizing beamsplitter and a pair of irises are used to set the mirror orientations so they are parallel to each other and perpendicular to a line of screw holes in the table. After this procedure is completed, the angular orientations of the mirrors are no longer adjusted. The demonstration then shows how to achieve different reflections patterns on the mirrors by changing the input beam orientation and cell length.

Both the input beam angle and mirror spacing affect the number of reflections the beam experiences before exiting the cell. A special case is when the two mirrors have the same focal length and are separated by a distance equal to the focal length. This configuration always provides six passes through the cell, regardless of the orientation of the input beam. This mirror spacing is used to illustrate the effects of changing the input beam’s pitch and yaw angles, as well as the beam’s X-axis and Y-axis position. In addition, the input beam is aligned parallel to the cell’s optical axis as a starting point. Then, the cell length is adjusted to increase the number of passes through the cell. Further adjustments to the input beam orientation are demonstrated to create linear, elliptical, and circular reflection patterns.

References:
D. Herriott et al., Appl. Opt. 3, 523-526 (1964).
C.G.Tarsitano et al., Appl. Opt. 46, 6923-6935 (2007).

00:00 - Introduction
00:46 – Herriott Cell Overview
02:37 – Mirror Alignment
04:54 – Transfer Laser Input
06:20 – Adjustments at Reference Distance
07:20 – Obtain a Linear Pattern
08:45 – Obtain Elliptical Patterns
09:36– Obtain a Circular Pattern

Components used in this Demonstration Include:
CM508-200EH4-M02 Gold-Coated Herriot Cell Mirror with Off-Axis Hole, Ø2”: https://www.thorlabs.com/newgrouppage...
CM508-200-M02 Gold-Coated Herriot Cell Mirror, No Hole, Ø2”: https://www.thorlabs.com/newgrouppage...
KS2 Kinematic Mirror Mount for Ø2” Optics: https://www.thorlabs.com/newgrouppage...
XRN25C Linear Translation Stage, 25 mm Travel: https://www.thorlabs.com/newgrouppage...
-XRN25-RC2 Quick-Connect Stage Platform: https://www.thorlabs.com/newgrouppage...
S1FC637 Benchtop 637 nm Laser Source: https://www.thorlabs.com/newgrouppage...
--P1-630A-FC-1 Single Mode Fiber Patch Cable: https://www.thorlabs.com/newgrouppage...
K6XS Six-Axis Kinematic Mount (For Input to Cell Collimator): https://www.thorlabs.com/newgrouppage...
KM100 Kinematic Mount (For Mirror Alignment Collimator): https://www.thorlabs.com/newgrouppage...
BA2F Flexure Clamping Base (For Input to Cell): https://www.thorlabs.com/newgrouppage...
F230FC-B Collimator for FC/PC Fiber Connectors: https://www.thorlabs.com/newgrouppage...
AD11NT Unthreaded Adapter (Collimator to Mount): https://www.thorlabs.com/newgrouppage...
-SM1D12C and SM1D12D Irises with Ring Actuators: https://www.thorlabs.com/newgrouppage...
LMR1 Mount (for Iris): https://www.thorlabs.com/newgrouppage...
CM1-BS013 Cube-Mounted Non-Polarizing Beamsplitter: https://www.thorlabs.com/thorproduct....
BE1R Magnetic Pedestal Base Adapter (For Beamsplitter): https://www.thorlabs.com/newgrouppage...
Post Collars: https://www.thorlabs.com/newgrouppage...
BHM3 Magnetic Ruler: https://www.thorlabs.com/newgrouppage...

For more photonics how-to videos, visit https://www.thorlabs.com/newgrouppage...