Standard Operating Procedure
Thermo Scientific GeneSys-20 Spectrophotometer
The Genesys-20 Spectrophotometer, combined with custom Windows software, provides a simple tool to analyze photonic filters and other optical devices. The unit may be also be used manually (from the front panel controls) to quickly scan for peaks.
Manual (Front Panel) Usage
To use the unit, power it on and wait until self-calibration is complete and the unit becomes ready (about 5 minutes). Press the A/T/C button to select % Transmission on the display.
Readings may now be taken as follows:
- Press nm-Up or nm-Down to select the wavelength on the display.
- Remove the filter holder, insert a blank (e.g. glass substrate), place the sample holder back into the unit, and close the sample door.
- Press the 100%T button. The unit will display 'Setting Blank ...' and then display 100%
- Remove the filter holder, insert the sample (e.g. glass substrate with coating), place the sample holder back into the unit, and close the sample door.
- Read the transmission of the filter at that wavelength directly as displayed on the LCD.
The above procedure (beginning with selecting wavelength) must be repeated for each reading required. Start taking readings across the entire spectrum at 25 nm apart then take more readings at 5 nm intervals around the peak transmission (to precisely determine center wavelength for the filter). As well, take readings near the half-maximum point to allow a precise determination of the FWHM of the filter.
The Genesys-20 Controls (including wavelength selector, ZERO button, and units selection) as well as the filter holder for the unit with a dielectric filter installed.
Custom Windows software allows automated scanning of the transmission curve of an optical filter in the range 365nm to 100nm inclusive and is the preferred mode of operation.
To use the unit, power it on and wait until self-calibration is complete and the unit becomes ready (about 5 minutes).
Start the program on the PC (via an icon on the desktop).
- The SPECTROPHOTOMETER menu has three option: START, RUN NEW SAMPLE, and RESTART COMMS. When starting scans for the first time this session, select START - this will scan the blank and determine the 100% reference point for all further measurements, storing it in memory. The graph will remain gray and progress will be indicated by an incrementing wavelength indication on the bottom of the screen.
- If the unit is unresponsive, it may be required to RESTART COMMS from the Spectrophotometer menu first - this often depends on the order in which the unit and program were powered-up.
- You will be prompted to insert a blank substrate into the machine after which a background reference will be run (approximately seven minutes). This defines the "100%" level at all wavelengths in the region 365nm to 1100nm. After the background has been acquired the background will change to a graph and the program will prompt you to insert a sample.
- Insert the sample filter, close the door, and allow the program to acquire the entire spectrum (progress can be seen as the wavelength increases and the graph is drawn in real-time).
- After the sample has been completed, select SAVE DATA from the FILE menu. The file must be saved before starting another scan otherwise it will be overwritten on the next scan. This file is in CSV format which may then be opened with ExcelTM - you will get two columns: wavelength and % transmission.
- If scanning a subsequent sample, there is no need to run the background again as it is in memory, simply select RUN NEW SAMPLE from the SPECTROPHOTOMETER menu and insert the new sample substrate when prompted. If the unit is powered-off, a new background/reference will be required.
- During operation, it may be required to RESTART COMMS from the Spectrophotometer menu should the unit become unresponsive - this often depends on the order in which the unit and program were powered-up.
A screen shot of the Genesys-20 software as it acquires data on a filter.
Technical Note: The program accepts a single argument (e.g. "/3") on the command line. This selects the COM port to use. If no arguments are specified, the default is COM1. A CMD batch file is the easiest way to include this argument is required.