Spectrometry: configurable spectroradiometers

Besides preconfigured spectroradiometers, Admesy offers the Rhea as configurable spectro[radio]meter, tailored to specific measurement needs between 200 and 1000nm. Depending on your specific measurement application, the Rhea spectrometer can be customized to perfectly match the measurement requirements and can be delivered with calibration as spectroradiometer. Various options in slit sizes, gratings and detectors allow almost unlimited options. For OEM customers we additionally offer customized electrical, mechanical and firmware designs as well as system integration support.

Rhea optical bench

System response & detector

The system response is mainly determined by the grating and the detector response. For our customizable Rhea series spectroradiometer, Admesy uses cooled CCD detectors from Hamamatsu and supports detectors for the range of 200-1100nm.

Slit size

The slit size defines the amount of light entering the optical bench and influence the FWHM. Admesy’s OEM spectrometer engines can be configured with various slit sizes. The table below shows the approximated FWHM values per slit size and grating type.

FWHM [nm] S7031-1006 detector (1024 pixels)
Grating Grooves/mm100um50um25um10um

The grating disperses the light into individual wavelengths. The amount of dispersion is determined by the number of grooves. The blaze wavelength determines the optimal efficiency at a certain wavelength. Admesy keeps on extending its stock of gratings. If a grating is not on the list or you require something different please contact our distributor or sales engineers to see what the possibilities are.

Dispersion range

The higher the number of grooves the wider the dispersion. However, this also limits the range of wavelengths which can be resolved because the detector has a fixed width. For a broad wavelength range low groove gratings can be used and for a detailed analysis of a small wavelength range high grooves gratings can be used. This range is defined as the dispersion range. The number of grooves also has influence on the FWHM.

Start & stop wavelength

Start and stop wavelength are depending on the grating choice and alignment. For example, a grating with a dispersion range of 200nm can be used from 300nm to 500nm as well as from 400nm to 600nm.

System configuration

The table below describes the currently available gratings for the Rhea spectroradiometer with its corresponding range. The Code is specified as the grooves per mm and Blaze wavelength. Both are divided by 10 in the code. Additionally the type of grating can be chosen. H stands for holographic and R for ruled. Currently Admesy supports only holographic gratings. Note 1: Combine this data with the system response graphs to check whether your required range is feasible with respect to the total spectral system efficiency. Note 2: The dispersion range includes a safety margin. More detailed information can be found in the Rhea specification.

TypeGrooves/mmBlaze WL [nm]Dispers. range [nm]Used range
060030HHologr.600300300 – 280UV-NIR
060060HHologr.600600300 – 280VIS-NIR
060100HHologr.6001000300 – 280VIS-NIR
090030HHologr.900300200 – 150UV-NIR
090060HHologr.900600200 – 150VIS-NIR
090080HHologr.900800200 – 150VIS-NIR
120020HHologr.1200200150 – 90UV-NIR
120040HHologr.1200400150 – 90UV-NIR
120080HHologr.1200800150 – 90VIS-NIR
160020HHologr.1600200100 – 30UV-NIR
160060HHologr.1600600100 – 30VIS-NIR
180040HHologr.180040090 – 25UV-NIR

More detailed information about the customizable Rhea series configurable spectroradiometers can be found on the Rhea product page.