# MERLIN IPDA Lidar Instrument
*sensor . products*

## Specifications
- **collection**: products
- **manufacturer**: dlr
- **deployment context**: orbital
- **sensor**: {"instrument_family":"lidar","measurement_principle":"active","wavelength_nm":1645}
- **entity type**: sensor
- **last verified date**: 2026-06-04
- **verified by**: agency-doc
- **claim status**: agency-sourced
- **provider**: dlr
- **attributes**: {"collection":"products","kind":"sensor","manufacturer":"dlr","deployment_context":"orbital","sensor":"{\"instrument_family\":\"lidar\",\"measurement_principle\":\"active\",\"wavelength_nm\":1645}"}
- **technology**: lidar

## Editorial
The MERLIN IPDA Lidar Instrument is the science payload for the MERLIN (MEthane Remote Sensing LIdar missioN) satellite, a joint mission of CNES and DLR. The instrument uses Integrated Path Differential Absorption (IPDA) lidar to measure the column-averaged dry-air mole fraction of methane (XCH4) from orbit. MERLIN operates at a near-infrared wavelength of approximately 1645 nm; eoPortal documentation gives the online and offline channel wavelengths as 1645.552 nm and 1645.846 nm respectively,[^merlin-eoportal] and SPIE 2023 conference proceedings confirm the 1645.55 nm methane absorption feature.[^merlin-spie-2023] The instrument transmits paired laser pulses at the two wavelengths alternately, and the ratio of the differential absorption gives the integrated methane column. DLR leads instrument development; CNES is the system prime for the mission.[^merlin-cnes-project] Airbus Defence and Space is reported as the satellite platform contractor, according to eoPortal documentation as of 2026-06-04.[^merlin-eoportal] Launch is planned for 2028 according to CNES and DLR official sources;[^merlin-methane-space][^merlin-eoportal] some secondary publications cite 2029. MERLIN is intended to provide global methane flux constraints relevant to greenhouse gas monitoring and climate modelling.

| Methodology | Evidence class | Demonstrated via |
|---|---|---|
| lidar-dial-trace-gas | capable-pending-review | (pre-launch) |[^merlin-eoportal]

## Compositional position
- merlin (missions) --[mission_payloads]--> MERLIN IPDA Lidar Instrument

## Sources
- [merlin-eoportal] | MERLIN Methane Remote Sensing Lidar Mission - eoPortal Directory | https://www.eoportal.org/satellite-missions/merlin | tier=community | accessed=2026-06-04
- [merlin-methane-space] | MERLIN Atmospheric Methane Lidar Mission official site | https://merlin-methane.space/ | tier=operator-marketing | accessed=2026-06-04
- [merlin-spie-2023] | MERLIN: heading towards PFM and observation of interesting effects - SPIE 2023 | https://www.spiedigitallibrary.org/conference-proceedings-of-spie/12777/127772T/MERLIN-MEthane-Remote-sensing-LIdar-missioN--heading-towards-PFM/10.1117/12.2690303.full | tier=peer-reviewed | accessed=2026-06-04
- [merlin-cnes-project] | MERLIN project - CNES | https://cnes.fr/en/projects/merlin | tier=operator-marketing | accessed=2026-06-04

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Source: https://eo-atlas.org/products/sensor/merlin-lidar
Maintainer: SpectraWorks B.V. (CC-BY 4.0)