Instrument & Grating
These sections define the core optical components of the spectrograph.
Table of contents
- Instrument
- Collimator
- Focusing Lens
- Mosaic
- Grating Rotation
Instrument
| Parameter | Description |
| Name | A human-readable label saved in the TOML file |
| Grating groove density | Ruling density of the diffraction grating (lines mm⁻¹) |
Collimator
| Parameter | Unit | Description |
| Focal length | mm | Effective focal length of the collimating optic |
| X offset | mm | Lateral displacement from the optical axis |
| Y offset | mm | Vertical displacement from the optical axis |
| Rotation | ° | In-plane rotation of the collimator |
| Distance to grating | mm | Physical separation between the collimator rear principal plane and the grating |
Focusing Lens
| Parameter | Unit | Description |
| Double Pass | toggle | Enable double-pass mode (light reflects back through the focusing lens) |
| Focal length | mm | Effective focal length of the camera/focusing optic |
| X offset | mm | Lateral displacement from the optical axis |
| Y offset | mm | Vertical displacement from the optical axis |
| Rotation | ° | In-plane rotation of the focusing lens |
| Distance | mm | Distance from the grating to the focusing lens |
Mosaic
Defines the overall extent of the detector mosaic that receives focused light.
| Parameter | Unit | Description |
| Center X | ° | Angular center of the mosaic along the dispersion axis |
| Center Y | mm | Physical center of the mosaic along the spatial axis |
| Width | mm | Total detector width |
| Height | mm | Total detector height |
| Scale | µm px⁻¹ | Detector pixel size |
| Enabled | toggle | Include the mosaic outline in the focal-plane plot |
Grating Rotation
See Layout View → Grating Rotation for full details.
| Parameter | Range | Description |
| α offset | 0 – 90° | In-plane grating tilt |
| γ offset | −30 – +30° | Out-of-plane conical diffraction angle |
| Angular grid samples | 51 – 801 | Segment resolution |
| Angular step | 0.001 – 10° | Step size for angle sweep |