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Anatomy of the Ocean Optics FLAME spectrometer

Flame Spectrometer’s Flexible Design

Our new Flame Spectrometer employs the classic Ocean Optics model of modular design and build to order options that let you optimize the system to best meet your needs!

Better manufacturing techniques, faster, quieter electronics and even greater modularity are incorporated. The legacy of this approach goes back to the original S1000 spectrometer invented in 1992. With the options now available, the number of primary model variations is 4,680! If we include the option of starting wavelength, the number of variations grows even bigger.

We set out to build Flame spectrometers that could meet ANY need, and we come very close to meeting that goal.

Flame Spectrometer

– Function and Options

Click on the item below to expand and view all the details

Fiber Optic Port

Light from a fiber enters the optical bench through the SMA 905 Connector. The SMA 905 bulkhead provides a precise location for the end of the optical fiber, slit, absorbing filter and fiber clad mode aperture. While we supply SMA connectors as standard, FC connectors are also available. We also offer a screw on lens to convert the optical fiber port into a free-beam port on this Flame spectrometer.

Interchangeable Slit

Light passes through the installed slit, which acts as the entrance aperture. Slits come in various widths from 5 µm to 200 µm. The slit is fixed in the SMA 905 bulkhead to sit against the end of a fiber. Smaller slit sizes achieve the best optical resolution while larger slits have higher light throughput. The slit size of our Flame spectrometer is labeled as shown.

SlitDescriptionPixel Resolution
INTSMA-55-µm wide x 1-mm high~3.0 pixels
INTSMA-1010-µm wide x 1-mm high~3.2 pixels
INTSMA-2525-µm wide x 1-mm high~4.2 pixels
INTSMA-5050-µm wide x 1-mm high~6.5 pixels
INTSMA-100100-µm wide x 1-mm high~12 pixels
INTSMA-200200-µm wide x 1-mm high~4.2 pixels
INTSMA-2525-µm wide x 1-mm high~24 pixels
INTSMA-000Interchangeable bulkhead with no slitNA
INTSMA-KITInterchangeable SMA Kit connectors;
5µm; 10µm; 25µm; 50µm; 100µm and 200µm


Ocean Optics also offers a range of FC connector slits in the same slit widths, with the product code INTFC-XXX. An INTFC-KIT is also available. Note that these items are made to order and have a longer lead time.

Longpass Filter
If selected, an absorbing filter is installed between the slit and the aperture in the SMA 905 bulkhead. The filter is used to limit bandwidth of light entering the Flame spectrometer or to balance color. Filters are installed permanently. A filter is for a specific slit. If you anticipate needing the filter with multiple slit sizes, then you must specify this at the time you order. You will know which filter is installed in each slit because of the color-coded dots on the outside as shown in the figure and described in the table below.

Item CodeDescriptionDot 1Dot 2
OF1-BG28Bandpass filter, transmits >325 and <500 nmBlueRed
OF1-WG305Longpass filter; transmits light >305 nmBlackWhite
OF1-U325CBandpass filter, transmits >245 and <390 nmWhiteGreen
OF1-GG375Longpass filter; transmits light >375 nmRedBlack
OF1-GG395Longpass filter; transmits light >395 nmWhiteRed
OF1-CGA420Longpass filter; transmits light >420 nmOrangeWhite
OF1-GG475Longpass filter; transmits light >475 nmGreenGreen
OF1-OG515Longpass filter; transmits light >515 nmPinkYellow
OF1-OG550Longpass filter; transmits light >550 nmOrangeOrange
OF1-OG590Longpass filter; transmits light >590 nmRedPink
OF1-RG695Longpass filter; transmits light >695 nmWhiteBlue
OF1-RG830Longpass filter; transmits light >830 nmBlackBlue
OF1-CGA1000Nonfluorescing longpass filter, transmits >1000 nmRedGreen
OF1-CGA760Nonfluorescing longpass filter, transmits >760 nmBlueBlack
OF1-CGA780Nonfluorescing longpass filter, transmits >780 nmWhiteYellow
OF1-CGA830Nonfluorescing longpass filter, transmits >830 nmGreenOrange
OF1-CGA475Nonfluorescing longpass filter, transmits >475 nmYellowPink
Collimating Mirrors standard or enhanced
The collimating mirror is matched to the 0.22 numerical aperture of our standard optical fibers. Light reflects from this mirror, as a collimated beam, toward the grating. You can opt to install a standard Al mirror or a NIR-enhancing, but the Flame spectrometer has a UV absorbing special coated Ag (SAG+) mirror.

SAG+ mirrors are often specified for fluorescence. These mirrors absorb nearly all UV light, which reduces the effects of excitation scattering in fluorescence measurements. Unlike typical silver-coated mirrors, the SAG+ mirrors won’t oxidize. They have excellent reflectivity — more than 95% across the VIS-NIR.

Fixed Gratings, Range & Resolution
We install the grating on a platform that we then rotate to select the starting wavelength you have specified. Then we permanently fix the grating in place to eliminate mechanical shifts or drift.

Flame and USB Series Custom Configured Gratings and Wavelength Range

Gratings for Ocean Optics spectrometers are permanently fixed in place at the time of manufacture to ensure long-term performance and stability. Choose from among multiple gratings for your custom configured Flame spectrometer. When selecting your grating, consider groove density (resolution), spectral range (wavelength range) and blaze wavelength (determines the most efficient range). We offer ruled and holographic diffraction gratings. Holographic gratings produce less stray light while ruled gratings are more reflective, resulting in higher sensitivity.

Grating NumberIntended UseGroove DensityAllowable Start WavelengthTypical Spectral Range*(nm)Blaze WavelengthBest Efficiency (>30%) (nm)
1UV600150-400 nm700-670300 nm200-575
2UV-VIS600150-400 nm700-670400 nm250-800
3VIS-Color600300-500 nm680-660500 nm350-850
4NIR600400-700 nm670-630750 nm530-1100
5UV-VIS1200150-250 nm325Holographic UV200-400
6NIR1200425-880 nm320-250750 nm500-1100
7UV-VIS2400150-350 nm170-140Holographic UV200-500
9VIS-NIR1200330-600 nm325-300Holographic VIS400-800
10UV-VIS1800150-510 nm235-175Holographic UV200-635
11UV-VIS1800320-800 nm210-110Holographic VIS320-720
12UV-VIS2400150-640 nm170-70Holographic VIS260-780**
14NIR600450-725 nm670-6301000 nm650-1100
31UV-NIR500150-250 nm925250 nm200-450

* Spectral range will be smaller when starting wavelength is longer. Spectral range also depends on exact spectrometer model.

** For applications >720 nm, please consult an Application Sales Engineer.

Groove Density:

The Groove Density (mm-1) of a grating determines its dispersion, while the angle of the groove determines the most efficient region of the spectrum. The greater the groove density, the better the optical resolution possible, but the more truncated the spectral range.

Spectral Range

The dispersion of the grating across the linear array; also expressed as the “size” of the spectra on the array. The spectral range (bandwidth) is a function of the groove density and does not change. When you choose a starting wavelength for a spectrometer, you add its spectral range to the starting wavelength to determine the wavelength range. For several gratings, the Spectral Range of a grating varies according to the starting wavelength range. The rule of thumb is: the higher the starting wavelength, the more truncated the spectral range.

Blaze Wavelength:

For ruled gratings, the Blaze Wavelength is the peak wavelength in an efficiency curve. For holographic gratings, it is the most efficient wavelength region.

Best Efficiency (>30%):

All ruled or holographically etched gratings optimize first-order spectra at certain wavelength regions; the “best” or “most efficient” region is the range where efficiency is >30%. In some cases, gratings have a greater spectral range than is efficiently diffracted. For example, Grating 1 has about a 650 nm spectral range, but is most efficient from 200-575 nm. In this case, wavelengths >575 nm will have lower intensity due to the grating’s reduced efficiency.

Focusing Mirror - standard or enhanced

This mirror focuses first-order spectra on the detector plane. Both the collimating and focusing mirrors are made in-house to guarantee the highest reflectance and the lowest stray light possible. You can opt to install a standard Al or special coated Ag (SAG+) mirror. As with the collimating mirror, the mirror type needs to be specified when ordering.

Cylindrical Detector Collection Lens
This optional cylindrical lens is fixed to the detector to focus the light from the tall slit onto the shorter detector elements of the Flame spectrometer. It increases light-collection efficiency and reduces stray light. The slit height in our Flame spectrometers is 1mm. However the illuminated portion of the slit is equal to the diameter of the fiber that is connected to the spectrometer. When using large fibers, the lens focusses more of the light onto the 200um tall sensor pixels. For small fibers, such as 50um core, the lens doesn’t appreciably affect signal strength.

Detectors: Sony or Toshiba

There are two choices of detector available for the Flame spectrometer. We offer a 2048-element FLAME-S (Sony ILX511B) or a 3648 element FLAME-T (Toshiba TCD1304AP) linear CCD array. These both have an effective range of 190-1100 nm. The optics split the light into its component wavelengths which fall across the different pixels. Each pixel responds to the wavelength of light that strikes it. The detector outputs an analog signal from each pixel that is converted via the ADC into a digital signal. The driver electronics process this signal and send the spectrum via the USB connection to the software. The best choice of detector will depend on the application.

SpecificationS Type (FLAME-S)T Type (FLAME-T)
Detector:Sony ILX511B linear silicon CCD arrayToshiba TCD1304AP linear silicon CCD array

Strong response < 350nm, good for UV measurements.

Fast data output rate.

Larger pixel size improves sensitivity

Slightly higher SNR due to well depth

Larger number of pixels can offer better resolution with small slits.

Electronic shutter

Watch for:N/A – Offers strong all-around performance

Signal lag at low integration times

Signal may bleed to neighboring pixels at high intensities (blooming)

Higher minimum integration time

Detector specifications sheets:


OFLV Linear variable detector order sorting filters

Our proprietary filters precisely block second- and third-order light from reaching specific detector elements. Light reflected off the grating can propagate 2nd and 3rd order effects at whole multiples of the incident light wavelength. So, for example, 250nm light hits the first order position at 250nm, and the second order position at 500nm. While 2nd order is generally weaker than first order signals, they are troublesome when looking at broad band spectra. Order sorting filters reject this stray light only allowing the desired 1st order wavelength through to the detector.

Order sorting filters are installed on detectors and are listed in the detector selection pane below. They are only available at set wavelength ranges, as the filters have to be fabricated to align all the proper blocking bands to specific ranges on the detectors. These must be specified at the time of ordering.

Detector, OFLV and window (UV or VIS) Options
The standard BK7 glass window on the detector absorbs light < 340nm. For applications in the UV, < 360nm, we recommend the UV quartz detector window upgrade. This replaces the BK-7 glass with Quartz. Typically these are used in conjunction with an OFLV order sorting filter to block the impact of 2nd and 3rd order effects at higher wavelengths.
DET2B-200-535Sony ILX511B detector, installed, with Custom OFLV Coated Window Assembly for Grating#5 and Grating#5U, S-benchFLAME-S

Sony ILX511 detector, installed, with 200 – 850 nm variable longpass filter and UV2 quartz window;

Best for UV-VIS systems configured with Grating #1 or #2


Sony ILX511 detector, installed, with 200 – 850 nm variable longpass filter and UV2 quartz window;

Best for UV-VIS systems configured with XR-1 grating


Sony ILX511 detector, installed, with 350 – 1000 nm variable longpass filter;

Best for VIS systems configured with Grating #2 or #3


Sony ILX511 detector, installed, with UV2 quartz window;

Best for systems configured for <360nm


Sony ILX511 detector, installed, with VIS BK7 window;

Best for systems configured for >400nm


Toshiba TCD1304AP detector, installed, with Custom OFLV Coated Window Assembly for Grating#5 and Grating#5U, S-bench

Toshiba TCD1304AP detector, installed, with 200 – 850 nm variable longpass filter and UV2 quartz window;


Toshiba TCD1304AP detector, installed, with 200 – 850 nm variable longpass filter and UV2 quartz window;

Best for systems configured with Grating #1 or #2


Toshiba TCD1304AP detector, installed, with 200 – 850 nm variable longpass filter and UV4 quartz window;

Best for systems configured with XR-1 grating


Toshiba TCD1304AP detector, installed, with 350 – 1000 nm variable longpass filter;

Best for VIS systems configured with Grating #2 or #3


Toshiba TCD1304AP detector, installed, with UV4 quartz window;

Best for systems configured for <360 nm


Toshiba TCD1304AP detector, installed, with VIS BK7 quartz window;