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Liquid Crystal Tunable Bandpass Filters![]()
KURIOS-VB1 Variable Bandwidth, Ø20 mm CA Application Idea Thorlabs' CM401 Hyperspectral Imaging System Includes the KURIOS-WL1 Fixed Bandwidth, Ø35 mm CA
Kurios® Controller Related Items ![]() Please Wait ![]() Click to Enlarge A hyperspectral image of a root cell taken using KURIOS-WB1. Two sample spectrums at the regions indicated are also shown. More details on this measurement are available in the Application Ideas tab. ![]() ![]() Click to Enlarge The back of the filter head contains the same mounting features as the front. The output polarization is rotated by 90° with respect to the input polarization. ![]() Click to Enlarge The front of the filter head contains internal SM1 or SM2 threads, four ![]() Click to Enlarge An image of our SLS401 Broadband Light Source coupled with a liquid light guide to our KURIOS-WL1/M Tunable Filter. The Ø35 mm clear aperture within the SM2-threaded housing is visible. Features
Kurios® Liquid Crystal Tunable Bandpass Filters provide a continuously tunable center wavelength (CWL) in the 420 - 730 nm, 430 - 730 nm, or 650 - 1100 nm range. Most Kurios models have a fixed bandwidth for any given center wavelength. Alternatively, the KURIOS-VB1(/M) has user-selectable bandwidth settings of Narrow, Medium, and Wide. The switching time varies depending upon the initial and final wavelengths and on the Kurios' bandwidth setting (for -VB1 only). See the plots in the tables below for details. With an included controller that provides Trigger In, Trigger Out, and Analog In functionality, these tunable optical bandpass filters are ideal for applications that perform multispectral or hyperspectral imaging, as demonstrated in the image to the right. For example, they can be used in conjunction with a monochrome scientific CCD camera to obtain images with a much higher accuracy for color representation than using a color CCD camera with a Bayer mosaic. This technique produces true spectral imaging and can thus show spectral features that would otherwise be impossible to detect. Thorlabs' Kurios tunable filters and CCD cameras are also compatible with our modular Cerna® microscopy platform that supports customizable microscopy solutions. For a complete, Cerna-based Hyperspectral Imaging System, see the CM401, which includes a KURIOS-VB1 tunable filter and a CCD camera. Similar in construction to Lyot and Solc filters, Kurios filters consist primarily of liquid crystal cells that are sandwiched between polarizing elements. Their integrated design enables quick and vibrationless tuning. For added operational stability, a closed-loop temperature control servo is used to maintain the filter head's operating temperature. An LED on the filter head displays red when the head is warming up and green when it is ready to be used. Wavelength Control with Included Controller The Trigger In connector allows Kurios to be controlled by another device via a TTL signal. It can be used, for instance, to synchronize Kurios with a scientific camera, such that every time the camera captures an image, the filter is immediately advanced to the next wavelength in the sequence. Kurios triggers on the falling edge of the 5 V TTL signal. The Trigger Out connector outputs a TTL signal that has the same duration as the calibrated switching time of the filter. This signal can be used, for example, to monitor the switching time and to cause events to coincide with or follow the switching event, such as imaging or shuttering. The Analog In connector allows the center wavelength to be set by a 0 to 5 V signal from an external voltage source and changed by an internal or external trigger. 0 V corresponds to the minimum wavelength of 420 nm, 430 nm, or 650 nm, while Kurios' sequence preload function, which is accessible from the front panel, the included GUI, and a command-line interface, permits the user to define a sequence of wavelengths (up to 1024 values). Providing an internal or external trigger switches the wavelength to the next value in the sequence. This function can be used, for example, in combination with the Trigger Out and Trigger In connectors to trigger a camera at the completion of each wavelength switch and then accept a trigger from the camera once the image is obtained. This sequence is stored within the controller's non-volatile memory, enabling the user to close the software GUI or unplug the USB cable without loss of the preloaded sequence. However, powering off the controller will cause the non-volatile memory to reset. The Bandwidth button on the front of the controller toggles through various operating modes. For the KURIOS-VB1(/M), this button toggles between Narrow, Medium, and Wide (the three selectable bandwidths), as well as beam-blocking mode ("Black"). For the fixed bandwidth models, the Bandwidth button toggles between the only bandwidth available and Black mode. Transmission and Polarization A lens-tube-mounted premium 750 nm shortpass filter is included with our KURIOS-WB1(/M), KURIOS-WL1(/M), Mounting Options
Kurios® tunable bandpass filters have three operating modes for control of the center wavelength: Manual, Sequenced, and Analog. They also provide a beam blocking mode ("black mode"). Full details on the operation are available from the manual. ![]() Click to Enlarge The front panel of the KURIOS-WB1 controller while it is set to manual mode. ![]() Click to Enlarge The main window of the software when the KURIOS-VB1 Selectable Bandpass Tunable Filter is connected. (When using the KURIOS-WB1 or KURIOS-WL1, the Narrow and Medium buttons are grayed out. For the KURIOS-XL1 and KURIOS-XE2, the Medium and Wide buttons are grayed out.) Manual Mode
The Kurios controller defaults to the manual mode when it is powered on. If the controller is not in manual mode, it can be activated through any of the following methods:
Bandwidth (Item # KURIOS-VB1 Only)
Sequenced Mode
Analog Mode
Internal and External Triggering For internal triggering, the signal is provided by a clock within the controller and has a user-specified interval between triggers from 1 ms to 60 s. Moreover, when in sequenced mode, each wavelength in the sequence can have its own interval time. In contrast, when in analog mode, the controller updates the wavelength according to the analog input signal at the interval time set by the user. For external triggering, the 5 V TTL signal is provided through the Trigger In BNC connector on the front panel. Kurios triggers on the falling edge of the 5 V TTL signal. Beam Blocking Mode
![]() Click to Enlarge Schematic of the Hyperspectral Imaging Microscope ![]() Click for Details Our CM401 Hyperspectral Imaging System is built on Thorlabs' Cerna Microscopy Platform. Key components include the KURIOS-VB1 Tunable Bandpass Filter, our previous-generation 4070M-GE Monochrome Scientific Camera, and our previous-generation HPLS343 High-Power Plasma Light Source. Hyperspectral ImagingIn hyperspectral imaging, a stack of wavelength-separated, two-dimensional images is acquired. This technique is frequently used in microscopy, biomedical imaging, and machine vision, as it allows quick sample identification and analysis. Hyperspectral imaging obtains images with significantly better spectral resolution than that provided by standalone color cameras. Color cameras represent the entire spectral range of an image by using three relatively wide spectral channels—red, green, and blue. In contrast, hyperspectral imaging systems incorporate optical elements such as liquid crystal tunable bandpass filters or diffraction gratings, which create spectral channels with significantly narrower bandwidths. We have adapted our Cerna® microscopy platform, Kurios® tunable filters, and scientific-grade cameras to build a rig specifically designed for hyperspectral imaging. For detailed specifications, please see the full hyperspectral imaging system web presentation. Example Image Stacks Kurios tunable filters offer a number of advantages for hyperspectral imaging. Unlike approaches that rely upon angle-tunable filters or manual filter swapping, Kurios filters use no moving parts, enabling vibrationless wavelength switching on millisecond timescales. Because the filter is not moved or exchanged during the measurement, the data is not subject to "pixel shift" image registration issues. Our filters also include software and a benchtop controller with external triggers, making them easy to integrate with data acquisition and analysis programs. ![]() Click to Enlarge Figure 3: A color image of the mature capsella bursa-pastoris embryo, assembled using the entire field of view acquired in each spectral channel, as shown in Figure 1. By acquiring across multiple channels, a spectrum for each pixel in the image is obtained. ![]() Click to Enlarge Figure 1: Two images of a mature capsella bursa-pastoris embryo taken at different center wavelengths. The entire field of view is acquired for each spectral channel. Figure 2: This video shows the image obtained from the sample as a function of the center wavelength of the KURIOS-WB1 tunable filter. The center wavelength was incremented in 10 nm steps from 420 nm to 730 nm. (10 nm is not the spectral resolution; the spectral resolution is set by the FWHM bandwidth at each wavelength.) Tunable-Wavelength Illumination SourcesThe system below uses a Kurios tunable filter and a broadband illumination source to provide millisecond-timescale tuning between visible wavelengths (420 - 730 nm). The following tables correspond with either the imperial or metric list of components used in the application photograph.
![]() Click to Enlarge The main window of the software when the KURIOS-VB1 Selectable Bandpass Tunable Filter is connected. (When using the KURIOS-WB1 or KURIOS-WL1, the Narrow and Medium buttons are grayed out. For the KURIOS-XL1 or KURIOS-XE2, the Medium and Wide buttons are grayed out.) SoftwareVersion 1.6.3 Includes a GUI for control of Kurios, as well as the required device drivers, C/C++ code examples, and LabVIEW VIs. To download, click the button below. Kurios® Software PackageGUI Interface In sequence and analog modes, the user may define sequences of up to 1024 wavelengths to be cycled through by the controller. Each step in the sequence has its own wavelength and duration (1 ms to 60 s), and for KURIOS-VB1, the bandwidth can also be changed from step to step. Sequences can be saved and loaded in CSV format using the "Save Profile" and "Load Profile" buttons. Custom Software Development
Damage Threshold Data for Kurios® Tunable Bandpass FiltersThe specifications to the right are measured data for Thorlabs' Kurios Tunable Filters.
Laser Induced Damage Threshold TutorialThe following is a general overview of how laser induced damage thresholds are measured and how the values may be utilized in determining the appropriateness of an optic for a given application. When choosing optics, it is important to understand the Laser Induced Damage Threshold (LIDT) of the optics being used. The LIDT for an optic greatly depends on the type of laser you are using. Continuous wave (CW) lasers typically cause damage from thermal effects (absorption either in the coating or in the substrate). Pulsed lasers, on the other hand, often strip electrons from the lattice structure of an optic before causing thermal damage. Note that the guideline presented here assumes room temperature operation and optics in new condition (i.e., within scratch-dig spec, surface free of contamination, etc.). Because dust or other particles on the surface of an optic can cause damage at lower thresholds, we recommend keeping surfaces clean and free of debris. For more information on cleaning optics, please see our Optics Cleaning tutorial. Testing MethodThorlabs' LIDT testing is done in compliance with ISO/DIS 11254 and ISO 21254 specifications. ![]() The photograph above is a protected aluminum-coated mirror after LIDT testing. In this particular test, it handled 0.43 J/cm2 (1064 nm, 10 ns pulse, 10 Hz, Ø1.000 mm) before damage. ![]()
According to the test, the damage threshold of the mirror was 2.00 J/cm2 (532 nm, 10 ns pulse, 10 Hz, Ø0.803 mm). Please keep in mind that these tests are performed on clean optics, as dirt and contamination can significantly lower the damage threshold of a component. While the test results are only representative of one coating run, Thorlabs specifies damage threshold values that account for coating variances. Continuous Wave and Long-Pulse LasersWhen an optic is damaged by a continuous wave (CW) laser, it is usually due to the melting of the surface as a result of absorbing the laser's energy or damage to the optical coating (antireflection) [1]. Pulsed lasers with pulse lengths longer than 1 µs can be treated as CW lasers for LIDT discussions. When pulse lengths are between 1 ns and 1 µs, laser-induced damage can occur either because of absorption or a dielectric breakdown (therefore, a user must check both CW and pulsed LIDT). Absorption is either due to an intrinsic property of the optic or due to surface irregularities; thus LIDT values are only valid for optics meeting or exceeding the surface quality specifications given by a manufacturer. While many optics can handle high power CW lasers, cemented (e.g., achromatic doublets) or highly absorptive (e.g., ND filters) optics tend to have lower CW damage thresholds. These lower thresholds are due to absorption or scattering in the cement or metal coating. LIDT in linear power density vs. pulse length and spot size. For long pulses to CW, linear power density becomes a constant with spot size. This graph was obtained from [1]. ![]() Pulsed lasers with high pulse repetition frequencies (PRF) may behave similarly to CW beams. Unfortunately, this is highly dependent on factors such as absorption and thermal diffusivity, so there is no reliable method for determining when a high PRF laser will damage an optic due to thermal effects. For beams with a high PRF both the average and peak powers must be compared to the equivalent CW power. Additionally, for highly transparent materials, there is little to no drop in the LIDT with increasing PRF. In order to use the specified CW damage threshold of an optic, it is necessary to know the following:
Thorlabs expresses LIDT for CW lasers as a linear power density measured in W/cm. In this regime, the LIDT given as a linear power density can be applied to any beam diameter; one does not need to compute an adjusted LIDT to adjust for changes in spot size, as demonstrated by the graph to the right. Average linear power density can be calculated using the equation below. The calculation above assumes a uniform beam intensity profile. You must now consider hotspots in the beam or other non-uniform intensity profiles and roughly calculate a maximum power density. For reference, a Gaussian beam typically has a maximum power density that is twice that of the uniform beam (see lower right). Now compare the maximum power density to that which is specified as the LIDT for the optic. If the optic was tested at a wavelength other than your operating wavelength, the damage threshold must be scaled appropriately. A good rule of thumb is that the damage threshold has a linear relationship with wavelength such that as you move to shorter wavelengths, the damage threshold decreases (i.e., a LIDT of 10 W/cm at 1310 nm scales to 5 W/cm at 655 nm): While this rule of thumb provides a general trend, it is not a quantitative analysis of LIDT vs wavelength. In CW applications, for instance, damage scales more strongly with absorption in the coating and substrate, which does not necessarily scale well with wavelength. While the above procedure provides a good rule of thumb for LIDT values, please contact Tech Support if your wavelength is different from the specified LIDT wavelength. If your power density is less than the adjusted LIDT of the optic, then the optic should work for your application. Please note that we have a buffer built in between the specified damage thresholds online and the tests which we have done, which accommodates variation between batches. Upon request, we can provide individual test information and a testing certificate. The damage analysis will be carried out on a similar optic (customer's optic will not be damaged). Testing may result in additional costs or lead times. Contact Tech Support for more information. Pulsed LasersAs previously stated, pulsed lasers typically induce a different type of damage to the optic than CW lasers. Pulsed lasers often do not heat the optic enough to damage it; instead, pulsed lasers produce strong electric fields capable of inducing dielectric breakdown in the material. Unfortunately, it can be very difficult to compare the LIDT specification of an optic to your laser. There are multiple regimes in which a pulsed laser can damage an optic and this is based on the laser's pulse length. The highlighted columns in the table below outline the relevant pulse lengths for our specified LIDT values. Pulses shorter than 10-9 s cannot be compared to our specified LIDT values with much reliability. In this ultra-short-pulse regime various mechanics, such as multiphoton-avalanche ionization, take over as the predominate damage mechanism [2]. In contrast, pulses between 10-7 s and 10-4 s may cause damage to an optic either because of dielectric breakdown or thermal effects. This means that both CW and pulsed damage thresholds must be compared to the laser beam to determine whether the optic is suitable for your application.
When comparing an LIDT specified for a pulsed laser to your laser, it is essential to know the following: LIDT in energy density vs. pulse length and spot size. For short pulses, energy density becomes a constant with spot size. This graph was obtained from [1].
The energy density of your beam should be calculated in terms of J/cm2. The graph to the right shows why expressing the LIDT as an energy density provides the best metric for short pulse sources. In this regime, the LIDT given as an energy density can be applied to any beam diameter; one does not need to compute an adjusted LIDT to adjust for changes in spot size. This calculation assumes a uniform beam intensity profile. You must now adjust this energy density to account for hotspots or other nonuniform intensity profiles and roughly calculate a maximum energy density. For reference a Gaussian beam typically has a maximum energy density that is twice that of the 1/e2 beam. Now compare the maximum energy density to that which is specified as the LIDT for the optic. If the optic was tested at a wavelength other than your operating wavelength, the damage threshold must be scaled appropriately [3]. A good rule of thumb is that the damage threshold has an inverse square root relationship with wavelength such that as you move to shorter wavelengths, the damage threshold decreases (i.e., a LIDT of 1 J/cm2 at 1064 nm scales to 0.7 J/cm2 at 532 nm): You now have a wavelength-adjusted energy density, which you will use in the following step. Beam diameter is also important to know when comparing damage thresholds. While the LIDT, when expressed in units of J/cm², scales independently of spot size; large beam sizes are more likely to illuminate a larger number of defects which can lead to greater variances in the LIDT [4]. For data presented here, a <1 mm beam size was used to measure the LIDT. For beams sizes greater than 5 mm, the LIDT (J/cm2) will not scale independently of beam diameter due to the larger size beam exposing more defects. The pulse length must now be compensated for. The longer the pulse duration, the more energy the optic can handle. For pulse widths between 1 - 100 ns, an approximation is as follows: Use this formula to calculate the Adjusted LIDT for an optic based on your pulse length. If your maximum energy density is less than this adjusted LIDT maximum energy density, then the optic should be suitable for your application. Keep in mind that this calculation is only used for pulses between 10-9 s and 10-7 s. For pulses between 10-7 s and 10-4 s, the CW LIDT must also be checked before deeming the optic appropriate for your application. Please note that we have a buffer built in between the specified damage thresholds online and the tests which we have done, which accommodates variation between batches. Upon request, we can provide individual test information and a testing certificate. Contact Tech Support for more information. [1] R. M. Wood, Optics and Laser Tech. 29, 517 (1998). In order to illustrate the process of determining whether a given laser system will damage an optic, a number of example calculations of laser induced damage threshold are given below. For assistance with performing similar calculations, we provide a spreadsheet calculator that can be downloaded by clicking the button to the right. To use the calculator, enter the specified LIDT value of the optic under consideration and the relevant parameters of your laser system in the green boxes. The spreadsheet will then calculate a linear power density for CW and pulsed systems, as well as an energy density value for pulsed systems. These values are used to calculate adjusted, scaled LIDT values for the optics based on accepted scaling laws. This calculator assumes a Gaussian beam profile, so a correction factor must be introduced for other beam shapes (uniform, etc.). The LIDT scaling laws are determined from empirical relationships; their accuracy is not guaranteed. Remember that absorption by optics or coatings can significantly reduce LIDT in some spectral regions. These LIDT values are not valid for ultrashort pulses less than one nanosecond in duration. ![]() A Gaussian beam profile has about twice the maximum intensity of a uniform beam profile. CW Laser Example However, the maximum power density of a Gaussian beam is about twice the maximum power density of a uniform beam, as shown in the graph to the right. Therefore, a more accurate determination of the maximum linear power density of the system is 1 W/cm. An AC127-030-C achromatic doublet lens has a specified CW LIDT of 350 W/cm, as tested at 1550 nm. CW damage threshold values typically scale directly with the wavelength of the laser source, so this yields an adjusted LIDT value: The adjusted LIDT value of 350 W/cm x (1319 nm / 1550 nm) = 298 W/cm is significantly higher than the calculated maximum linear power density of the laser system, so it would be safe to use this doublet lens for this application. Pulsed Nanosecond Laser Example: Scaling for Different Pulse Durations As described above, the maximum energy density of a Gaussian beam is about twice the average energy density. So, the maximum energy density of this beam is ~0.7 J/cm2. The energy density of the beam can be compared to the LIDT values of 1 J/cm2 and 3.5 J/cm2 for a BB1-E01 broadband dielectric mirror and an NB1-K08 Nd:YAG laser line mirror, respectively. Both of these LIDT values, while measured at 355 nm, were determined with a 10 ns pulsed laser at 10 Hz. Therefore, an adjustment must be applied for the shorter pulse duration of the system under consideration. As described on the previous tab, LIDT values in the nanosecond pulse regime scale with the square root of the laser pulse duration: This adjustment factor results in LIDT values of 0.45 J/cm2 for the BB1-E01 broadband mirror and 1.6 J/cm2 for the Nd:YAG laser line mirror, which are to be compared with the 0.7 J/cm2 maximum energy density of the beam. While the broadband mirror would likely be damaged by the laser, the more specialized laser line mirror is appropriate for use with this system. Pulsed Nanosecond Laser Example: Scaling for Different Wavelengths This scaling gives adjusted LIDT values of 0.08 J/cm2 for the reflective filter and 14 J/cm2 for the absorptive filter. In this case, the absorptive filter is the best choice in order to avoid optical damage. Pulsed Microsecond Laser Example If this relatively long-pulse laser emits a Gaussian 12.7 mm diameter beam (1/e2) at 980 nm, then the resulting output has a linear power density of 5.9 W/cm and an energy density of 1.2 x 10-4 J/cm2 per pulse. This can be compared to the LIDT values for a WPQ10E-980 polymer zero-order quarter-wave plate, which are 5 W/cm for CW radiation at 810 nm and 5 J/cm2 for a 10 ns pulse at 810 nm. As before, the CW LIDT of the optic scales linearly with the laser wavelength, resulting in an adjusted CW value of 6 W/cm at 980 nm. On the other hand, the pulsed LIDT scales with the square root of the laser wavelength and the square root of the pulse duration, resulting in an adjusted value of 55 J/cm2 for a 1 µs pulse at 980 nm. The pulsed LIDT of the optic is significantly greater than the energy density of the laser pulse, so individual pulses will not damage the wave plate. However, the large average linear power density of the laser system may cause thermal damage to the optic, much like a high-power CW beam.
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KURIOS-WB1(/M) and KURIOS-WL1(/M) are fixed wide-bandpass versions of our Kurios tunable bandpass filters. The center wavelength (CWL) is tunable from 420 nm to 730 nm. In general, the transmission and the width of the bandpass region increase with the CWL. The plots in the table to the right contain more details. To eliminate transmission in the near-IR and IR wavelength range, each of these tunable filters includes a premium shortpass filter with a 750 nm cut-off wavelength in an SM-threaded housing. This filter is recommended for use at the incident side of the filter head to protect the internal components from excessive IR exposure. The KURIOS-WB1 includes the FESH0750 filter and the KURIOS-WL1 includes a Ø2" version of the FESH0750 filter with the same optical properties. The fixed bandpass tunable filters provide switching times that vary depending upon the initial and final wavelengths. As shown in the contour plots in the table to the right, for small changes in the CWL (Δλ ≤ 30 nm), the switching time will be ≤5 ms. For greater changes in the CWL, the switching time will increase, reaching a maximum of 40 ms when switching from 420 nm to 730 nm. The KURIOS-WB1(/M) has a clear aperture of Ø20 mm. The housing has internal SM1 (1.035"-40) threading and is compatible with our 30 mm cage systems. Alternatively, the KURIOS-WL1(/M) has a clear aperture of Ø35 mm. Its housing has internal SM2 (2.035"-40) threading and is compatible with our 60 mm cage systems. Each Kurios tunable filter is factory calibrated and ships with a switching time map so that users may optimize their system for the specific filter. The map can be saved to disk through the included Windows® software. ![]()
KURIOS-XL1(/M) is a fixed narrow-bandpass version of our Kurios tunable bandpass filters. The center wavelength (CWL) is tunable from 430 nm to 730 nm. In general, the transmission and the width of the bandpass region increase with the CWL. The plots in the table to the right contain more details. To eliminate transmission in the near-IR and IR wavelength range, this tunable filter includes a Ø2" version of the FESH0750 premium shortpass filter with a 750 nm cut-off wavelength in an SM2-threaded housing. This filter is recommended for use at the incident side of the filter head to protect the internal components from excessive IR exposure. The fixed narrow bandpass tunable filter provides switching times that vary depending upon the initial and final wavelengths. As shown in the contour plot in the table to the right, for small changes in the CWL (Δλ ≤ 30 nm), the switching time will be ≤10 ms. For greater changes in the CWL, the switching time will increase, reaching a maximum of 70 ms when switching from 425 nm to 725 nm. The KURIOS-XL1(/M) has a clear aperture of Ø35 mm. Its housing has internal SM2 (2.035"-40) threading and is compatible with our 60 mm cage systems. Each Kurios tunable filter is factory calibrated and ships with a switching time map so that users may optimize their system for the specific filter. The map can be saved to disk through the included Windows® software. ![]()
KURIOS-XE2(/M) is a fixed bandpass Kurios tunable bandpass filter for near-IR wavelengths. The center wavelength (CWL) is tunable from 650 nm to 1100 nm. The fixed bandpass tunable filters provide switching times that vary depending upon the initial and final wavelengths. As shown in the contour plot in the table to the right, for small changes in the CWL (Δλ ≤ 30 nm), the switching time will be ≤10 ms. For greater changes in the CWL, the switching time will increase, reaching a maximum of 250 ms when switching from 650 nm to 1100 nm. The KURIOS-XE2(/M) has a clear aperture of Ø20 mm. The housing has internal SM1 (1.035"-40) threading and is compatible with our 30 mm cage systems. Each Kurios tunable filter is factory calibrated and ships with a switching time map so that users may optimize their system for the specific filter. The map can be saved to disk through the included Windows® software. ![]()
KURIOS-VB1 is the selectable bandpass version of our Kurios tunable bandpass filters. The center wavelength (CWL) is tunable from 420 nm to 730 nm, and the user may set a bandwidth of Narrow, Medium, or Wide. In general, for a given setting, the transmission and the width of the bandpass region increase with the CWL. The plots in the table to the right contain more details. To eliminate transmission in the near-IR and IR wavelength ranges, an FESH0750 Premium Shortpass Filter is included. This filter has a 750 nm cut-off wavelength, is mounted in an SM1-threaded (1.035"-40) housing, and is recommended for use at the incident side of the filter head to protect the internal components from excessive IR exposure. The switching time of the selectable bandpass Kurios depends upon the bandwidth setting and the initial and final wavelengths. The maximum switching time is 230 ms for the Narrow setting, 150 ms for the Medium setting, and 100 ms for the Wide setting. In general, the switching time will be longer for greater changes in wavelength. Each Kurios tunable filter is factory calibrated and ships with a switching time map so that the user may optimize their system for the specific filter. The map can be saved to disk through the included Windows® software. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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