FAQ - Spectrometers


1: Can the software show integrated irradiance(uW/cm2) and illuminance(lux) over a wavelength range?

2: How do I display chromaticity calculations?

3: Your spectrometer has a GPIO port, but we could not find the corresponding API in your SDK.

4: Your ETC calibration is performed with only a small range of exposure time, how does it apply to different exposure times?

5: What is the difference between Dark Compensation and Dark Subtraction?

6: If we set a different Exposure Time (ET), will the software use a different dark spectrum for Dark-Subtracted display?

7: Why there are ripples and distortions in the measured spectrum?

8: How do I upgrade the spectrometer software?

9: What do I do if I have more than one spectrometers?

10: Where does the software look for calibration information?

11: What's the wavelength calibration accuracy of Mightex's spectrometers?

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  1. Can the software show integrated irradiance(uW/cm2) and illuminance(lux) over a wavelength range?

User can specify a wavelength range in the Setup/Illuminance Wavelength Range menu. The spectrometer software will then show the integrated irradiance and illuminance in the status bar at the bottom of the main window.

  1. How do I display chromaticity calculations?

Chromaticity is computed only on either %T/R or irradiance data. Therefore in the main spectrum view please choose either %T/R or Absolute Irradiance in the Display Option panel.

From View menu select Chromaticity. In the top tool bar click > button to acquire a single spectrum. Chromaticity calculations will be displayed in the right-side panel. Please note that chromaticity calculation is not implemented in the …> continuous acquiring mode.

  1. Your spectrometer has a GPIO port, but we could not find the corresponding API in your SDK.

In the current SDK version, we don't have GPIO related function. We will add GPIO control (including IO Pin config and Out/In control) in our SDK.

  1. Your ETC calibration is performed with only a small range of exposure time, how does it apply to different exposure times?

Our ETC is for correcting the non-linearity of the CCD pixels (in reality, it also includes non-linearity of the analog front end such as ADC). It is important that the pixel values span the entire measurement range (this is, from ADC value 0 - 65xxx).

We have assumed that the nonlinearity behavior is the same under different ranges of exposure time. When possible you should choose ETC exposure time range so that it covers the exposure time values that you will be using in you measurements.

  1. What is the difference between Dark Compensation and Dark Subtraction?

Dark compensation is based on the CCD sensor itself. The sensor has several OB(optical black) pixels on both sides of the pixel array, and the values of these OB pixels are considered "Dark" signal. When dark compensation is ON, the "Dark" signal will be deducted from the normal CCD signal.

Dark Subtraction is a display mode where a background spectrum is first taken and then subtracted from subsequent spectra.

  1. If we set a different Exposure Time (ET), will the software use a different dark spectrum for Dark-Subtracted display?

No, the software will still use the old dark spectrum. For this reason in order to achieve the most accurate Dark-Subtracted measurement user should take a new dark spectrum whenever ET is changed.

  1. Why there are ripples and distortions in the measured spectrum?

The ripples are caused by a thin-film layer on the CCD sensor.  Diffraction efficiency of the grating and the sensitivity of the silicon sensor also have strong wavelength dependence.  For HRS-BD1 spectrometers, the single small sharp dip is caused by the transition on the order-sorting filter.  This dip will become smaller when the cone of the input light is greater.  All these factors together distort the measured spectrum.

There's a simple solution to this issue.  The distortions can be all calibrated out by a radiometric calibration.  We provide the calibration service at our factory for a nominal fee.  The absolute irradiance calibration can be ordered at the time of or after your spectrometer purchase.

You can also perform the calibration if you have a light source with known spectrum (a radiometrically calibrated source).  The standard software that comes with the spectrometer includes the necessary calibration functions.

  1. How do I upgrade the spectrometer software?
1). Do not delete your existing software yet because it contains the wavelength calibration file specific to your spectrometer;
2). Download the new software from our website and save it in a separate folder;
3). Copy the para.ini file and the “ModuleNo_SerialNo” sub-directory from you OLD application/appdata/ folder to the NEW application/appdata/ folder. Here, "ModuleNo" and "SerialNo" are the Module Number (e.g. HRS-VIS-025) and the Serial Number (e.g. 13-100528-001) of the spectrometer, respectively. In this specific example, the sub-directory name will be "HRS-VIS-025_13-100528-001)". This operation replaces the new para file with the old para file which contains the wavelength calibration specific to your spectrometer. Other calibration data such as irradiance calibration are also copied through this operation;
4). Now run the new spectrometer software.

      9. What do I do if I have more than one spectrometers?

1). You can install the software by copying the content of the CDROM (of the first spectrometer) to a local directory (say "mySpectrometers"), and this installs the software for the first spectrometer;
2). For other following spectrometers, each should come with its own companion CD. All CD's contain the same software but with different calibration information. The device-specific calibration information is stored under the following directory: "\Application\Appdata\ModuleNo_SerialNo". Please note that, in the above directory name, "ModuleNo" and "SerialNo" are respectively the Module Number and the Serial Number of the particular spectrometer. If one has (for example) a spectrometer with model # HRS-VIS-025 and serial # 13-100528-001, the sub-directory name should be "\Application\Appdata\HRS-VIS-025_13-100528-001".
One can copy the above sub-directory into the local directory mentioned in Step 1) above (i.e. "mySpectrometer") and save it under "mySpectrometers\Application\Appdata".
Now, there should be multiple "\ModuleNo_SerialNo" sub-directories under "mySpectrometers\Application\Appdata" directory. For example, if one has two spectrometers as following:
  • Model#: HRS-VIS-025, and Serial #: 13-100528-001; and
  • Model#: HRS-VIS-025, and Serial#: 13-110221-003
There should be two sub-directories under "mySpectrometers\Application\Appdata" directory:
"\HRS-VIS-025_13-100528-001" and "\HRS-VIS-025_13-110221-003".
     10. Where does the software look for calibration information?

1). The spectrometer application software (either “Mightex_SSE_App.exe” or user's own application software developed based on SDK) will load “MT_Spectrometer_SDK.dll”;
2). “MT_Spectrometer_SDK.dll” will search for calibration info at the following locations:
a). .\Appdata\para.ini
b). .\Appdata\ModuleNo_SerialNo
(Note: “.\” above means the directory where “MT_Spectrometer_SDK.dll” is located.)
3). If “MT_Spectrometer_SDK.dll” is unable to find calibration data in either of the locations, it will show a warning box.

     11. What's the wavelength calibration accuracy of Mightex's spectrometers?

The wavelength calibration accuracy is 0.4nm for HRS-BD1-xxx spectrometers, and 0.2nm for other spectrometers.