The EM500 range of longitudinal field KD*P Pockels cells have been designed to offer the best possible performance in a package which as far as possible encloses the active region of the optical crystal in an earthed metallic casing. This provides good electrical shielding for reduced radiated emissions, and increases user safety. A further safety feature is the use of special high voltage rated HV BNC electrical connectors which have extended shields on the mating plugs which reduce the potential risks of electrical shock should the user handle the live cables when not connected to the Pockels cell. Although this arrangement provides many advantages to the user of these Pockels cells in an open environment (such as on an optical table in a research laboratory) it does increase the physical size of the Pockels cell.
For the manufacturer of Q-switched laser systems, the volume and mass of the optical components is often a major consideration, whilst issues such as radiated emissions and user safety are handled by the equipment enclosure into which the laser system is built. Size and weight therefore can take a higher priority for this user. We therefore produce a range of compact KD*P Pockels cells which lack the more bulky machined aluminium alloy housings of the EM500 series and use simpler pin or M3 stud contacts for the electrical connection. This connection reduces the load capacitance of the cell by eliminating the capacitance of the HV BNC connector which is in parallel with the active element.
These devices are housed in an industry standard 35mm diameter design which is allows this EO Q-switch to drop in to many existing laser head designs without modification. The device can be supplied with special end caps and also fitted wave-plates and polarizers if required. We are always happy to discuss any custom requirements for this OEM Q-switch. We are now able to supply this style of device with apertures of either 8, 10 or 12mm in the same sized housing. Larger 15mm and 20mm aperture Pockels cells are also available in 35mm diameter housings but of a different construction.
|Parameter||EM508M, EM510M AND EM512M|
|Aperture:||8mm, 10mm or 12mm|
|Wavelength Range:||0.3 - 1.2µm|
|Halfwave Voltage @ 1.06µm:||Approximately 6.0 kV static, 7.2kV dynamic|
|Optical Rise Time:||< 1.0 ns|
|Contrast Ratio @ 1.06µm:||> 1000:1|
|Capacitance Unterminated:||< 5 pF|
|Damage Threshold:||600 MW/cm2, 10ns at 1064nm|
|Insertion loss with AR coatings*:||typical 1.5-2.0%|
|Physical Dimensions:||35mm ∅, 49mm long|
* Our ultra-high transmission HHT versions of course render insertion losses down to in some cases immeasurably small amounts, please enquire as to whether these would be suitable for your application.
Larger aperture devices are of course available but in different package size. EM515M and EM520M (you've guessed by now how our numbering system works 😝) are both still in 35mm diameter packages but larger cells are available, currently up to 50mm aperture in a 100mm diameter package. Please enquire for large aperture cells.
Compact Double Pockels Cell
For applications where low working voltage is a priority (especially half wave applications like pulse picking) it is often desirable to use a double crystal Pockels cell in which the two crystals are optically in series but electrically in parallel. This halves the voltage required for a given retardation and can be very useful where a limited voltage is available from a chosen driver.