FSI Linear Array CMOS Spectrometer 200-1100nm | SIMTRUM Photonics Store

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You can refer to the table below to select the wavelength range and resolution you need. For specific details, please contact our sales staff for consultation.

During the selection process, you can first confirm the required wavelength range based on your own needs, and then confirm the corresponding slit size according to the resolution requirements.

The slit size specifications we can provide are: 10/25/50/100/200 μm. Generally, the smaller the slit, the narrower the image formed on the detector, and the higher the resolution. However, at the same time, the light flux passing through the slit is less, and the sensitivity will be lower.

We can offer the grating groove density are: 300/400/600/830/900/1200/1800/2400 l/mm. Generally, the higher the line density, the stronger the dispersion ability of the grating, that is, the narrower the wavelength range that can be detected, and the higher resolution.

Note:LVF(Linear variable filter), LP(LongPass), For the selection of filters, please refer to the explanations in the optional selection guide section.

In addition, we can also provide various related accessories. Customers can choose to purchase them according to their own needs. The list of optional accessories is as follows.

Tab 1. Mandatory Accessories

Note：

1. XSR: Refers to anti-negative sensing optical fiber;

2. All the above-mentioned models of straight-through optical fibers are silicone /PVC coated optical fibers. If you need, we can upgrade it to metal-armored optical fiber for you for free. In addition to the indicated models, we can also upgrade the optical fiber length from 1m to 2m according to your requirements.

Optional Accessories

	Integrating Sphere Wavelength 250 - 2500 nm Output port customizable Black anodized aluminum alloy housing		Fiber Optic Attenuator Wavelength 200 - 2500 nm Adjustable slit for attenuation
	Halogen Light Source Wavelength 360 - 2000 nm SMA905 output connector		Cuvette Holders for Abs., Fluo, Raman Use
	Fiber Collimator Wavelength 200 - 2000 nm Numerical aperture 0.22 - 0.37 NA fiber core diameter ≥ 100 µm		Sample Holder with Mounting for Reflectance Measurement
	Sample Holder with Mounting for Transmittance Measurement		Optical Mount for Transmittance and Reflectance Sample Measurement

1. How to choose between a long-pass filter (LP) and a Linear Variable Filter(LVF)?

The essence of grating diffraction is that "diffraction light from different slits interferes at a certain point in space", and the conditions for interference enhancement are determined by the grating equation: d·sinθ = k·λ, where λ represents the wavelength of the incident light, k is the diffraction order (k=±2 is second-order diffraction, k=±3 is third-order diffraction), θ is the diffraction Angle (i.e., the Angle between the diffracted light and the incident light), and d is the grating constant (the distance between adjacent grooves).

For example: For a spectrometer with a wavelength range of 200-700nm, when the diffraction angles θ of diffractive light of different wavelengths and different orders are the same:

For short-wavelength light of 200nm, the optical path difference corresponding to its third-order diffraction (k=3) is 3*200=600nm. Meanwhile, for long-wavelength light of 600nm, the optical path difference corresponding to its first-order diffraction (k=1) is 1*600=600nm. At this point, the first-order signal at 600nm will be affected by the third-order signal at 200nm, which will cause the measurement value to be distorted or higher.

If it is necessary to accurately measure long-wavelength light at 600nm, a long-pass filter (LP) with a cut-off wavelength < 600nm (such as a 500nm long-pass filter) can be installed: This filter will block short-wavelength light at 200nm (regardless of whether it is 1st, 2nd or 3rd order diffraction) from reaching the detector. At the same time, it transmits long-wavelength light of 600nm to ensure that the detector only receives the long-wavelength diffraction signal of the target, completely eliminating the interference of short-wavelength high-order diffraction.

Compared with the long-pass Filter (LP), the Linear Variable Filter (LVF) is a special "wavelength-selective component". Its core characteristic is that the transmission wavelength varies linearly with the spatial position (for example, from left to right, the transmission wavelength gradually changes from 400nm to 1000nm). Rather than the "fixed wavelength cut-off/bandpass" of traditional filter plates.

Therefore, for spectrometers with a wider wavelength range, the higher-order diffraction of multiple short waves will be close to the first-order diffraction of multiple long waves. For instance, for a spectrometer with a wavelength range of 200 to 1100nm, when the diffraction Angle θ is the same, that is, the optical path difference corresponding to the second-order diffraction (k=2) at 200nm is 200*2=400nm, which overlapped with the optical path difference of the first-order diffraction (k=1) at 400nm. When the optical path difference of the third-order diffraction (k=3) at 200nm is 200*3=600nm, and the optical path difference of the second-order diffraction (k=2) at 300nm is 300*2=600nm, and the first-order diffraction (k=1) at 600nm overlapped, etc., after installing the Linear Variable Filter, the short-wavelength high-order diffraction can be prevented from reaching the detector. Eliminate the influence of higher-order diffraction.

2. The realization of anti-temperature drift function?

The anti-temperature drift function of the spectrometer is the key design to ensure its measurement accuracy in environments with temperature changes, especially suitable for scenarios with large temperature fluctuations such as industrial sites and outdoor monitoring. Temperature changes can cause physical or performance alterations in the core components of a spectrometer, such as light sources, detectors, optical elements, and circuit systems, which in turn introduce measurement errors (i.e., "temperature drift"). Our anti-temperature drift function mainly offsets the influence of temperature through passive suppression. The principle is as follows:

Passive inhibition: Reduce temperature sensitivity

l Material optimization: The core optical components (grating/lens) are made of materials with low expansion coefficients (quartz, Yin steel) to reduce dimensional/shape offset caused by temperature changes, avoiding optical path offset or alteration of dispersion characteristics.

l Structural design: A constant temperature chamber or insulation layer is adopted to reduce the influence of external environmental temperature on the internal core components (the detector and light source are sealed in a constant temperature chamber, and the external temperature difference is isolated by insulation materials).

The anti-temperature drift function reduces the impact of temperature on core components at the physical level through "hardware suppression", ultimately achieving measurement stability and accuracy of the spectrometer within a wide temperature range. This is one of its core capabilities for adapting to complex environments.

Unlike the complex structure of traditional spectrometers, micro spectrometers typically adopt a symmetrical crossed Czerny-Turner spectroscopic structure, which is compact in size and can be held with one hand.

During its operation, the working principles of each component of the system are as follows:

1. Optical platform. These irregular structures on the optical platform can effectively prevent stray light from entering the detector and causing measurement errors.

2. Optical fiber interface. The micro spectrometer is designed with a standard optical fiber interface (usually SMA905, and an FC interface can also be customized), which is used in conjunction with optical fibers - the simplest optical transmission device - to enhance the ease of use of the spectrometer.

3. Incident slit. The slit in the spectrometer is equivalent to the entry pupil, shaping the incident light into a slender vertical spot, which corresponds to the pixel shape of the linear array detector after spectral separation. The smaller the slit, the narrower the image formed on the detector and the higher the spectral resolution.

4. Collimating reflector. The collimating mirror folds the optical fiber in the spectrometer to compress its size. Meanwhile, the reflector can convert the incident scattered light into parallel light and direct it towards the grating, while the other reflector focuses the dispersed light onto the detector.

5. Grating. The grating is the most commonly used spectroscopic device in spectrometers. Its tiny periodic concave-convex structure on the surface can reflect light of different wavelengths that illuminate it at different angles, thereby achieving the function of spectral separation. Different gratings have different applicable wavelength ranges and dispersion capabilities. The number of periodic structures per unit length is called the line density of the grating. The higher the line density, the stronger the dispersion ability of the grating.

6. Detector. The linear array detector is arranged with thousands of pixels in the horizontal direction. Each pixel is responsible for receiving the light intensity signal of the specified wavelength and converting the light signal into an electronic signal for transmission.

7. Semiconductor cooler. Some micro-spectrometers are equipped with semiconductor coolers to control the temperature of the detector, thereby reducing the noise level of the detector and preventing instability caused by changes in environmental temperature during long-term operation.

8. Data transmission interface. Typically, a frame of spectral data from a micro-spectrometer is approximately 4KB in size, and the shortest spectral acquisition period can reach the microsecond level. Therefore, to ensure transmission speed and ease of use, most micro-spectrometers use USB interfaces for power supply and data transmission. Some spectrometers also offer other communication methods, such as RS-232, Bluetooth, Ethernet, Wifi, etc.

Software

Operation interface

1. Detection panel (function menu and operation buttons);

2. Equipment Panel (Equipment list and Parameter Settings);

3. Spectral Window (Spectral curve display and spectral window management);

4. Spectral Recording Panel (Spectral Curve Selection and Naming)

Software functions

1.Wavelength smoothing;

2.Defluorescence;

3.Remove background signals;

4.Transmission and reflection measurement;

5.Absorption measurement

6.Multiple measurements for different timepieces

Click here to get the download links for the driver and software. If you have any questions, please contact us for feedback.

Dimensions

L-55mm

L-100mm

Q1：What are the similarities and differences between refrigerated detectors and unrefrigerated detectors?

A1：In spectrometer systems, there are significant differences in function and performance between refrigerated and unrefrigerated detectors. For refrigerated detectors, the temperature of the detector is usually reduced by thermoelectric refrigeration/liquid nitrogen cooling. Working in a low temperature environment can significantly reduce thermal noise, improve the signal-to-noise ratio of the system, and then improve the sensitivity and resolution of the spectrum. The response to weak signals is more sensitive, and it is suitable for testing in a low light environment. Non-refrigerated detectors have no additional cooling system, operate at or near room temperature, usually have high noise levels, low sensitivity and signal-to-noise ratio, but simple operation and low maintenance costs. To sum up: If high sensitivity and low noise are needed, the refrigerated detector is the better choice, and if there are requirements for cost and convenience, the unrefrigerated detector is more suitable.

Q2：What is the difference between a backlit detector and a front-lit detector?

A2：A Back-illuminated Detector (BSI) and a Front-illuminated Detector (FSI) are two common types of photodetectors. The light-sensitive area of the backlit detector (BSI) is located on the back of the detector, and the light enters through the substrate of the detector, which can directly reach the light-sensitive material, thus reducing the scattering and reflection of the light, improving the light receiving efficiency, and having higher quantum efficiency. The forward light detector (FSI) photosensitive surface is located in front of the detector, the light enters through the transparent material, the circuit and metal layer inside the sensor are located in front of the light incident, due to the obstruction of the circuit structure, part of the incident light will be absorbed and reflected, reducing its receiving efficiency, and the circuit structure may also introduce more noise. To sum up: the sensitivity and image quality of back-illuminated detector (BSI) is usually better than that of front-illuminated detector (FSI), and the production cost of front-illuminated detector (FSI) is more advantageous, and the choice of which sensor mainly depends on the application needs and budget.

Q3：How to determine the appropriate dynamic range when selecting a spectrometer?

A3：The dynamic range of the spectrometer refers to the signal intensity range that the instrument can effectively measure. Under different test conditions, there are different requirements for the dynamic range of the spectrometer. When measuring the weak light signal (such as the fluorescence signal of biological samples), the sample strength changes greatly, the complex mixture, and the need to measure a large range of reflectivity data, the high dynamic range of the spectrometer is generally needed to ensure the accuracy of the measurement. For spectral analysis of a single component or application scenarios with a small signal intensity variation range, a low dynamic range spectrometer can be used. In addition, the comprehensive influence of factors such as sensitivity and noise level should be considered comprehensively to select the appropriate spectrometer.

Q4：Does the signal-to-noise ratio of the spectrometer affect its sensitivity?

A4：The signal-to-noise Ratio (SNR) of the spectrometer is an important indicator of its performance, representing the ratio between Signal strength and Noise strength. The higher the signal-to-noise ratio, the better the quality of the signal and the less noise interferes with the signal. Sensitivity usually refers to the ability of the spectrometer to detect the signal, that is, the minimum signal strength or concentration that it can detect. The high sensitivity means that the instrument can accurately identify and measure signals even at low concentrations or weak signals. In general, the higher the signal-to-noise ratio, the more obvious the signal is, and the signal is more prominent compared to the background noise. This means that the spectrometer is better able to distinguish between the target signal and the noise, and therefore, the sensitivity is increased. At the same time, in quantitative analysis, sensitivity is usually related to the Limit of Detection (LOD). LOD is the lowest concentration or signal strength that can be reliably detected. High SNR can significantly reduce LOD, thereby increasing the sensitivity of the instrument.

Q5：What is the difference between CCD spectrometer and CMOS spectrometer?

A5：Choose CCD type or CMOS type spectrometer according to the requirements for sensitivity and speed, if high sensitivity and high-quality imaging are required, CCD may be a better choice; If there are higher requirements for speed and cost, CMOS is more suitable.

If you need our technical team for guidance on product selection or customization, please help to provide below technical information, it helps to speed up the process.

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