LLTF Python Wrapper

A Python wrapper for the Photon etc / NKT Photonics Laser Line Tunable Filter (LLTF) DLL. This wrapper provides a clean, class-based interface for controlling LLTF devices with automatic grating selection and comprehensive error handling.

Features

• Error Handling: Comprehensive error checking
• Simulation Mode: Virtual device support for development and testing without hardware
• Type Hints: Full type annotation support for better IDE integration
• Context Manager: Supports with statement for automatic resource cleanup
• XML Configuration: Reads device specifications directly from manufacturer-provided XML files
• Automatic Grating Selection: Automatically selects the appropriate grating (0 or 1), with option for manual override.

Installation

1. Clone this repository:

   git clone https://github.com/evanbray1/LLTF-tools.git
   cd LLTF-tools

2. Install PE_Filter SDK: You must install the PE_Filter SDK provided by Photon Etc. This includes the PE_Filter_SDK.dll library that must be accessible to your Python environment (either in your system PATH or in the same directory as the running script).

3. Place XML Configuration: Place your device's XML configuration file in the xml_files/ directory:

   • Your XML file should be named with your device's serial number (e.g., M000010263.xml)
   • This file is provided by NKT Photonics and contains critical device specifications
   • The wrapper will automatically detect XML files in the xml_files/ directory

Quick Start

Basic Usage

from lltf_wrapper import LLTF

# Initialize LLTF (automatically finds XML file in xml_files/ directory)
lltf = LLTF()

# Connect to device
lltf.initialize()

# Set wavelength (auto-selects appropriate grating)
lltf.set_wavelength(550)  # nm

# Get current wavelength
current_wl = lltf.get_wavelength()
print(f"Current wavelength: {current_wl} nm")

# Close connection
lltf.close()

Using Context Manager

from lltf_wrapper import LLTF

with LLTF() as lltf:
    lltf.initialize()
    lltf.set_wavelength(650)
    wavelength = lltf.get_wavelength()
    print(f"Set to: {wavelength} nm")
# Connection automatically closed

Simulation Mode (for Development)

from lltf_wrapper import LLTF

lltf = LLTF()
lltf.initialize(simulate=True)  # No hardware required

# All methods work the same way
lltf.set_wavelength(750)
current = lltf.get_wavelength()
lltf.close()

Demo Scripts

Basic Demo

For quick start with minimal code:

python examples/demo_basic.py

Advanced Demo

For comprehensive examples and features:

python examples/demo_advanced.py

The demo scripts demonstrate:

• Basic initialization and connection
• Wavelength setting with automatic grating selection
• Manual grating selection
• Error handling for invalid wavelengths
• Context manager usage
• Simulation mode

Requirements

• Python 3.6+
• Windows
• PE_Filter SDK supplied by Photon Et
• Device XML configuration file (placed in xml_files/ directory)

Grating Selection Logic

The LLTF has two internal gratings, each covering different wavelength ranges:

1. Automatic Selection (default): The wrapper automatically chooses the grating based on your target wavelength and the ranges defined in your device's XML file.

2. Manual Selection: You can force a specific grating using the grating parameter:

   lltf.set_wavelength(600, grating=0)  # Force grating 0

3. Range Validation: The wrapper validates wavelengths against both regular and extended ranges, issuing warnings for extended range usage.

Troubleshooting

"No XML configuration files found"

• Ensure your device's XML file is in the xml_files/ directory
• Check that the file has a .xml extension

"Failed to load PE_Filter_SDK.dll"

• Ensure you have installed the PE_Filter SDK from Photon Etc
• Make sure PE_Filter_SDK.dll is in your system PATH or in a locatable directory. The .dll path can also be supplied during initialization with LLTF(xml_config_path="/path/to/xml/file")

"Wavelength [X] nm not supported"

• Check your device's specifications using get_grating_ranges()
• Verify the wavelength is within your device's capabilities