tiger_tunable_lens_card
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+ | ====== Tiger Tunable Lens Card (TGTLC) ====== | ||
+ | ===== Description ===== | ||
+ | The TGTLC is a Tiger card that can power 2 Electrically Tunable Lenses (ETL) such as[[http:// | ||
+ | |||
+ | ETLs are polymer lenses whose curvature and thus focal length can be changed by applying current. They are available with diverse cover glass coating and optional offset lens. | ||
+ | |||
+ | ===== Features ===== | ||
+ | * TGTLC card can control up to 2 Electrically Tunable Lens (ETL) (such as C60-Tunable 4F assemblies) | ||
+ | * Control with serial commands, manual input devices (knob or joystick), or a 0-5V analog signal | ||
+ | * Open loop control | ||
+ | * Very fast, 15ms transient response. Resonant frequency at 150Hz and 600Hz. | ||
+ | |||
+ | ===== Applications ===== | ||
+ | |||
+ | * Potential substitute for piezo-based focus devices depending on specifics (especially low-mag, low NA), e.g. can acquire Z series without moving the objective | ||
+ | * Performs like a continuous focus device when used with the [[asi_xyz_tracker_plugin|ASI XYZ Tracker Plugin]] in Micro-Manager. | ||
+ | * Axial sweeping of beam focus in light sheet microscopy (e.g. be added to [[http:// | ||
+ | |||
+ | |||
+ | ===== Electrical Characteristics ===== | ||
+ | * Maximum output Voltage, 6 Volts | ||
+ | * Maximum output current, up to 290 mA per channel. (On RevA and A2 cards max current was only 200 mA) | ||
+ | * Current resolution, 4.4 μA. (On RevA and A2 cards current resolution is only 50 uA) | ||
+ | |||
+ | |||
+ | ==== Tiger Card ==== | ||
+ | |||
+ | [{{ tlc1.jpg? | ||
+ | |||
+ | ==== Front Panel ==== | ||
+ | |||
+ | [{{ :: | ||
+ | |||
+ | On RevA2 and above cards, the BNC connectors are dual purpose. By arranging [[tiger_tunable_lens_card# | ||
+ | |||
+ | [{{ tlc2.jpg? | ||
+ | |||
+ | On RevA cards, the BNC connectors are hardwired for External input control | ||
+ | |||
+ | <WRAP center round alert 60%> | ||
+ | **WARNING!! DO NOT** connect Tunable Lens to [[tgled|TGLED]] cards, it has same 3.5mm mono connectors. The TGLED card will fry it. The TGLED card outputs currents at 900 mA, while the Tunable lens can only handle currents up to 400 mA. This issue has been resolved in newer version of TGTLC cards where a 6pin Circular connector is used instead of 3.5mm mono connector. | ||
+ | </ | ||
+ | |||
+ | ===== Operation ===== | ||
+ | |||
+ | ==== Control ==== | ||
+ | TGTLC lets the user control a Electrically Tunable Lens(ETL) either in **Internal** mode or **External** mode. TGTLC card mode can be set with the [[commands: | ||
+ | |||
+ | In **Internal** mode, the user can adjust the ETL's focal length with serial commands like [[commands: | ||
+ | |||
+ | In **External** mode, the user can adjust the ETL's focal length with a 0-5V analog signal. | ||
+ | |||
+ | The TGTLC card is a constant current driver, it converts the user input into a currents (up to 290ma) that is applied to the ETL to produce a change in its curvature which results in the focal length change. | ||
+ | |||
+ | |||
+ | |||
+ | ==== Units/ | ||
+ | |||
+ | |||
+ | === Post firmware version 3.19 === | ||
+ | User has two options for unit ie user input when commanding their ETLs. First is a 16-bit abstract integer, another is diopters. User can pick their preferred units with [[commands: | ||
+ | |||
+ | * The abstract units, its a 16 bit integer. This replaces the previously 4000 count default axis profile B1. | ||
+ | * Upper limit is **32768** with 290 ma of current, lower limit is **-32768** with 0 ma of current, and default starting position is **0**. | ||
+ | * **1** is the smallest step change possible, which causes 4.4μA change in current applied to ETL. | ||
+ | |||
+ | * The second option is in 1/1000 of diopter(dpt). ETL's manufacture calibrated the ETL in factory and stored the diopter vs current curves on the ETL's EEPROM. TGTLC RevB and above cards are able to read this data, parse it and calculate the slope and intercept from this data. Its then able to accept user input in 1/1000 of a diopter and calculate the current it needs to apply to the ETL to get the desired diopter. | ||
+ | * This option is also available on older RevA and A2 cards, which can't read the eeprom data, instead they go by default values. | ||
+ | |||
+ | |||
+ | === Pre firmware version 3.19 === | ||
+ | * With the default axis profile (B1), ETL's upper limit is **2000**, lower limit is **-2000**, and default starting position is **0**. | ||
+ | * Total travel is **4000** counts | ||
+ | * **1**is the smallest step change possible, which causes 50μA change in current applied to ETL. | ||
+ | |||
+ | |||
+ | <WRAP center round info 60%> | ||
+ | Note: An ETL has no feedback sensor. The TGTLC card is operating the ETLs in an open loop. The current applied is regulated. Between aging, temperature effects, there may be error in the user input and actual diopter observed. | ||
+ | </ | ||
+ | |||
+ | === Example === | ||
+ | |||
+ | Let's say the Electrically Tunable Lens (ETL) axis letter is **V**. | ||
+ | |||
+ | <asi> $ M V=-32768 | ||
+ | : | ||
+ | |||
+ | The above command would move the ETL to lower limit, where 0 amps of current would be applied ETL | ||
+ | |||
+ | <asi> $ M V=-32767 | ||
+ | : | ||
+ | |||
+ | The above command would move the ETL to slightly above lower limit, where 4.4μA of current would be applied ETL | ||
+ | |||
+ | <asi> $ M V=0 | ||
+ | : | ||
+ | |||
+ | The above command will move the ETL to middle of the travel range by applying 145mA of current. | ||
+ | |||
+ | <asi> $ M V=32768 | ||
+ | : | ||
+ | |||
+ | The above command will move the ETL to upper limit of the travel range by applying 290mA of current. | ||
+ | |||
+ | ==== Anti-Aliasing Filter ==== | ||
+ | |||
+ | <WRAP center round info 60%> | ||
+ | This option has been removed in TGTLC RevC cards and above. | ||
+ | </ | ||
+ | |||
+ | |||
+ | The '' | ||
+ | |||
+ | The default cut-off frequency is 300Hz. | ||
+ | |||
+ | ==== Serial Commands ==== | ||
+ | |||
+ | Apart from core serial commands like [[commands: | ||
+ | |||
+ | {{topic> | ||
+ | |||
+ | ==== Hardware Jumper Configuration ==== | ||
+ | |||
+ | [{{ :: | ||
+ | |||
+ | When the jumpers are arranged in above configuration (JP2 and JP3 have jumpers on pins 3 and 2). The BNC connectors can be used to control the Tunable Lens with an analog voltage of 0-5V. Use the [[commands: | ||
+ | |||
+ | |||
+ | [{{ :: | ||
+ | |||
+ | When the jumpers are arranged in above configuration (JP2 and JP3 have jumpers on pins 1 and 2). The BNC connectors can be used to TTL. More info [[commands: | ||
+ | |||
+ | [{{ tgtlc_reva.jpg? | ||
+ | |||
+ | |||
+ | ==== Tunable Lens Optics ==== | ||
+ | |||
+ | Although the Tunable Lens Card can be (and has been) used with other tunable lenes, ASI normally uses it with the [[https:// | ||
+ | |||
+ | The tunable lens power is specified in diopters which has units of 1/ | ||
+ | |||
+ | Because the tunable lens has strictly positive focusing power it is often useful to combine it with a negative lens to create a combined effect where a collimated input beam can be made to either converge or diverge via the ETL. With the 8-20 diopter ETL a -70 mm f.l. lens is commonly used, and a -150 mm f.l. lens for the 5-10 diopter stiff version. | ||
+ | |||
+ | Be aware that the tunable lens is less ideal optically than achromatic lenses, so for imaging applications make sure any aberrations are acceptable. | ||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | ===== 4f Tunable Lens Assembly ===== | ||
+ | |||
+ | [{{ :: | ||
+ | |||
+ | ASI's tunable Lens 4F assembly leverages the tunable lens to remotely focus an microscope image (i.e. adjust objective' | ||
+ | |||
+ | Here are the main features: | ||
+ | * Easy assembly; it screws into the C-mount (see photo) port of most microscopes. | ||
+ | * Only active component is the tunable lens, driven by the the Tunable Lens Card. | ||
+ | * The focal length of the standard tunable lens spans between 8 to 20 diopter. The resulting focus change will depend on your optics as described below. | ||
+ | |||
+ | The displacement of the objective' | ||
+ | |||
+ | \begin{equation}\delta_{focus} = \frac{-1}{M_{det}^2}*\frac{n*f_r^2}{f_{ETL}}\end{equation} | ||
+ | |||
+ | where // | ||
+ | //n// is refractive index of immersion medium; | ||
+ | f< | ||
+ | F< | ||
+ | |||
+ | (For more details see Fahrbach, Florian O., et al. “Rapid 3D Light-Sheet Microscopy with a Tunable Lens.” Optics Express, vol. 21, no. 18, 2013.) | ||
+ | |||
+ | Using the above equation it can be shown that the range of tuning of the objective' | ||
+ | |||
+ | \begin{equation}Range_{focus}= \frac{n*f_r^2*D_{ETL}}{M_{det}^2}\end{equation} | ||
+ | |||
+ | where $D_{ETL}$ is the range of the tunable lens expressed in diopters and $Range_{focus}$ is expressed in micrometers (um). Conveniently the range is independent of the offset lens chosen, but the offset lens changes the center point of the focus range. | ||
+ | |||
+ | Using a 12 diopter range of the standard ETL and 60 mm as $f_r$, we can use the above equation to compute the following table of attainable focus shift with the C60-TUNELENS-4F assembly using air objectives. | ||
+ | |||
+ | ^Magnification ^ focus range (60mm $f_r$) ^ focus range (100mm $f_r$) ^ | ||
+ | |5x | 1.7 mm | 4.8 mm | | ||
+ | |10x | 432 um | 1.2 mm | | ||
+ | |20x | 108 um | 300 um | | ||
+ | |40x | 27 um | 75 um | | ||
+ | |60x | 12 um | 33 um | | ||
+ | |100x | 4 um | 12 um | | ||
+ | |||
+ | |||
+ | ==== Caveats ==== | ||
+ | |||
+ | Telecentric or " | ||
+ | |||
+ | The relay uses a 60 mm f.l. achromat lens which is a very short focal length which can potentially add aberrations. | ||
+ | |||
+ | More problematic for scientific imaging, the clear aperture of the relay lens can limit the allowable camera FOV. Vignetting will occur if the relay lens clear aperture is smaller than the sensor-side FOV plus the size of the objective back aperture demagnified by the ratio $f_r/ | ||
+ | |||
+ | The tunable lens can introduce optical aberrations which may be important for imaging applications but are negligible in tracking applications. | ||
+ | |||
+ | |||
+ | ===== Temperature Compensation ===== | ||
+ | |||
+ | Tunable Lens are susceptible to temperature change, their diopter decrease as temperature increases.Below is a graph of diopter vs current at two different temperatures | ||
+ | |||
+ | [{{ :: | ||
+ | |||
+ | This diopter per celcius change isn't constant and varies too. Below is a graph of the change diopter change per celsius vs current. | ||
+ | |||
+ | [{{ :: | ||
+ | |||
+ | Fortunately this effect is predictable and the manufacturer has built a temperature sensor into the Tunable lens and provided characterization data. At the factory , we analyze this data and build a model. The parameters for this model are saved on the Tunable Lens EEPROM itself. The Tunable Lens card reads the EEPROM on starup. These parameters can be read and altered through serial commands [[commands: | ||
+ | |||
+ | When Temperature compensation is enabled (through the [[commands: | ||
+ | |||
+ | ==== Calculation ==== | ||
+ | Below is how the temperature compensation is calculated and applied. | ||
+ | |||
+ | |||
+ | |||
+ | * First for a given current, Diopter per Celsius (//D/T//) at that current is calculated | ||
+ | |||
+ | \begin{equation}\frac{D}{T} = I_{user}*K_1+C_1\end{equation} | ||
+ | |||
+ | * Then current temperature is measured by reading the temperature onboard the Tunable lens , and subtracting that from the set point temperature. This set point temperature is where the Tunable lens was characterized at factory, and coefficients like K< | ||
+ | |||
+ | * This temperature change is multiplied with Diopter per Celsius (//D/T//) to get Diopter change | ||
+ | |||
+ | \begin{equation}D = \frac{D}{T}*(T_{current}-T_{setpoint})\end{equation} | ||
+ | |||
+ | * The Diopters are converted back to current by multiplying it with Diopter to current coefficient K< | ||
+ | |||
+ | \begin{equation}I_{applied} = I_{user}- D*K_{D2I}\end{equation} | ||
+ | |||
+ | The coefficients K< | ||
+ | |||
+ | * C< | ||
+ | |||
+ | * T< | ||
+ | |||
+ | * K< | ||
+ | |||
+ | * K< | ||
+ | |||
+ | \begin{equation} X=\frac{K_1*-1}{10000000} \end{equation} | ||
+ | |||
+ | |||
+ | ===== Applications ===== | ||
+ | |||
+ | One of the main applications of Tunable Lens system is with ASI XYZ Tracker plugin as a continuous focus device. For more info refer to the [[asi_xyz_tracker_plugin|ASI XYZ Tracker Micro-Manager plugin]] page. | ||
+ | |||
+ | |||
+ | ===== Serial Command Cheatsheet ===== | ||
+ | |||
+ | The commands shown here are assumed to be issued to the V axis. | ||
+ | |||
+ | Note: when setting the value of K< | ||
+ | |||
+ | ^ TGTLC Serial Commands |||| | ||
+ | ^ Property ^ Set ^ Get ^ Notes ^ | ||
+ | | Where | - | '' | ||
+ | | Mode | '' | ||
+ | | C< | ||
+ | | T< | ||
+ | | K< | ||
+ | | K< | ||
+ | | Absolute Move | '' | ||
+ | | Relative Move | '' | ||
+ | |||
+ | The BACKLASH command is deprecated, it used to change the Bessel filter prior to hardware revision C. | ||
+ | |||
+ | ===== Additional Reading ===== | ||
+ | |||
+ | * [[http:// | ||
+ | * [[http:// | ||
+ | |||
+ | |||
+ | {{tag> |
Address: 29391 W Enid Rd. Eugene, OR 97402, USA | Phone: +1 (541) 461-8181