Гальво двигатели


Galvo#2

Galvo#2                     Galvo #2: Делаем новые гальванометры

                    Внимание! Страница много весит . Придется подождать при загрузке.     Я продолжил свои эксперименты по созданию качественного лазерного проектора. Их результатом явилось создание новых легких и быстрых гальванометров. До этого я не писал о том, как эти гальванометры устроены, поэтому начну с теории.                                                                        Устройство гальванометра

Гальванометр состоит из вала, двух подшипников, магнита и  двух статорных катушек(см. рис.). Когда на катушки начинает подаваться ток, то в них возникает магнитное поле и они отталкиваются/притягиваются к магниту, который надет на вал. Т.о. вал приводится в движение. Для обеспечения большой точности и высокой скорости прорисовки изображения необходимо создание обратной связи, которая бы обеспечила точное позиционирование ротора в нужном положении и подавление нежелательных механических колебаний ротора. Сигнал обратной связи снимается с детекторов позиции, которые расположены на самих гальванометрах. В последнее время получили большую популярность оптические детекторы из-за их простоты изготовления.  Их я и использовал в своей конструкции.                                                                   Устройство оптического детектора

Такой детектор состоит из ИК светодиода, заслонки и двух ИК фотодиодов. Заслонка крепится на ротор гальванометра так, что при ее повороте в одну сторону на один фотодиод начинает попадать меньше ИК излучения, а на другой больше. Если ротор поворачивается в другом направлении, то все наоборот. Сигналы с фотодиодов усиливаются и подаются на дифференциальный усилитель, с выхода которого снимается сигнал обратной связи. Теперь можно переходить от теории к практике... Гальванометры, как и лазерная система в целом, не имеет мелочей. Поэтому нужно уделять особое внимание изготовлению каждого узла. От того, насколько качественно будут изготовлены составляющие системы, будет зависеть скорость и точность работы системы. Скорости у нас очень большие и большие вибрации(что не есть хорошо), поэтому конструкция должна быть очень жесткой. Для создания корпуса можно использовать фольгированный стеклотекстолит, который следует пропаять.                        Оптический детектор я расположил на одной из стенок гальванометра. Другая сторона стенки из фольгированного текстолита служит экраном от различных наводок. Провод от фотодетекторов обязательно должен быть экранированным. Фотодиоды нужно выбирать те, что плохо реагируют на обычный свет. Я использовал диоды Тип 1.                         В качестве вала я использовал подходящее сверло d=2mm. На него приклеены два маленьких неодимовых магнита, взятых из старого винчестера. Магниты должны быть как можно меньших размеров и располагаться симметрично относительно вала. Предпочтение следует отдавать более длинным, но менее толстым магнитам. Забугорные любители используют цилиндрические двухполюсные магниты с продольной поляризацией. Такие работают лучше. Катушки мотаем проводом ПЭЛ-0.5 по 60-70 витков в каждой, проклеиваем суперклеем(так меньше будут свистеть при работе) и закрепляем на боковых стенках. Затем начало одной нужно соединить с концом другой. Если вы не купили какие-нибудь специальные высокооборотные керамические подшипники по 20 евро за штуку, а собираетесь использовать те, что были куплены на базаре(как сделал я), то тут придется немного попотеть. Значит, покупаем обычных подшипников штук 15-20(из расчета на 2 гальванометра), замачиваем их в ацетоне(ну т.е. вымываем всю смазку), высушиваем их и начинаем выбирать те, которые легче крутятся. При вращении наперекос подшипник ни в коем случае не должен цеплять и хрустеть, а идти очень мягко. Клеить все это хозяйство лучше эпоксидным клеем, но если конструкция временная(на 1-2 дня, больше не выдерживает), то можно и суперклеем. Во время работы катушки могут очень сильно нагреваться поэтому термоклей лучше вообще не использовать.    После основной сборки приклеивается на ротор заслонка, а за ней кусочек губки, паралона или мягкая резинка. Это своего рода защита от попадания ротора в то положение из которого он самостоятельно выйти не сможет. Ротор должен быть минимально возможной длины, поэтому я отломал от него все лишнее. На конце клеится зеркало, выпилинное из алюминиевого блина от винчестера. У такого зеркала вес очень маленький.                         Гальванометры получились размером 2,5х3х4см. Так как я использовал оптическую обратную связь, то известную схему усилителя Chan'а пришлось изменить.                                                  Схема усилителя. Источник  http://elm-chan.org/works/vlp/report_e.html

Здесь как и ранее я использовал вместо LM675 недорогие усилители мощности LM3886. Как показали мои эксперименты эти микросхемы довольно хороши и справляются с большинством задач на не слишком высоких скоростях. К восьмой ноге(Mute) LM3886 присоединен конденсатор, обеспечивающий включение схемы через 0,5-1 сек после подачи питания. Если такой конденсатор не ставить, то схема запускается когда напряжение питания еще не достигло необходимого уровня, что приводит к непредсказуемым последствиям для гальванометров. Для уменьшения стоимости и габаритов усилителей я применил широко распространенные счетверенные ОУ TL084. Но подойдут и любые другие общего назначения на подходящее напряжение питания, желательно чтобы были с внутренный компенсацией. Несмотря на все принятые меры по уменьшению массы роторов гальванометров и уменьшения времени их отклика, они получились довольно тяжелые и низкочастотные. Поэтому мне пришлось изменить значения элементов в схеме частотных компенсаторов(LF DUMP и HF DUMP). Возможно, что для каждого отдельно взятого гальванометра придется подбирать эти значения. Монтаж схемы должен быть хорошо продуман. Соединительные провода должны быть как можно меньшей длины. К ножкам питания каждого ОУ должен быть припаян блокировочный конденсатор. Настройка готовых усилителей особых проблем вызвать не должна. Сначала выставляем все подстроечники на ноль, подстроечник OFFSET должен находиться посередине. Затем подстроечником GAIN выставляем необходимое усиление. Если при этом схема сходит с ума и гальванометры начинают дергаться, то нужно просто поменять полярность их включения. Для точной настройки нужно подать сигналы испытательной таблицы ILDA и выставить необходимый уровень подавления LF DUMP(низкая частота) и HF DUMP(высокая частота). Если на ровных линиях, рисуемых лазером, появляются волны, то либо блок питания не справляется со своими обязанностями, либо усиление схемы слишком велико и она возбуждается. В первом случае придется обзавестись новым более мощным БП, а во втором случае нужно уменьшить усиление самого первого каскада схемы. Я не делал никакой схемы защиты гальванометров, но для надежной работы такая схема все же необходима. Так, нужно предусмотреть возможность автоматического отключения системы при падении напряжения питания и при выходе роторов гальванометров из допустимых пределов. Во время работы сканеры сильно греются, поэтому хорошо бы поставить на гальванометры температурные сенсоры, связанные с системой защиты. Не лишней будет установка маленького кулера около каждого сканера.                                                                Усилители для гальванометров

                                                    Готовая к работе установка спокойно разместилась на столе

После большой проделанной работы настало время долгожданных испытаний.                                                                        "Голова" в работе

                    Канадский флаг                                                      Попытка изобразить эмблему моего института

                                                                         Немножко анимации (13-15 FPS)

   Известная испытательная таблица ILDA Test Pattern. Сильно мерцала, поэтому удалось заснять только по кусочкам.  Частота обновления таблицы 6-7 FPS, 7500PPS

                                    Galvo #2: Последние штрихи

        Итак, вся основная работа уже позади. Теперь всю систему нужно засунуть в ящик. В качестве ящика хорошо подошел корпус от 486-го компьютера, который я нашел на улице около своего подъезда.   Радиаторы на платах усилителей имеют большую площадь, но при комнатной температуре около 45 градусов по Цельсию нагреваются так сильно, что к ним страшно прикасаться. Поэтому возле них планируется установка кулеров.                                 После небольшой модернизации гальванометров и тщательной настройки ситемы подавления я решил разогнать свой проектор до стандартной скорости 12KPPS. Однако, при такой скорости из гальванометров пошел запах горящего клея, а точность прорисовки контуров изображения сильно понизилась. Немного поэкспериментировав я пришел к выводу, что предел скорости для моей лазерной системы, при котором хорошо видны мелкие детали изображения без заметных искажений - 9K. Чтож, совсем неплохо для любительской системы. При такой скорости мой проектор рисует на стене изображение размером 1 метр на 1 метр с расстояния 3 метра.                                                                                                             Работающая установка

                           Мой позывной(уже бывший) 7500 и 9000 PPS  соответственно

         Волшебная испытательная таблица на 9K. Из-за сильного мерцания заснялась по кусочкам

                                                              Все остальные картинки 9К

                                                   У зверюги справа хвост не заснялся:)

В ходе экспериментов я столкнулся с тем фактом, что при большой сложности проецируемой картинки лазера мощностью в 1 милливатт уже недостаточно. Так уже несложную картинку размером 1 метр  можно увидить только если потушить свет. Для решения этой проблемы необходимо приобретение более мощного лазера, лучше зеленого цвета.

                                         

На главную

   

 

laserium.narod.ru

Так Мини Серии Galvo Электродвигатель/гальванометр/galvo Sanner

 

 

 

 

  

 

Specification for motor 

Working Temperature

25°C ± 20°C

Linearity

99.9%

Setting Time

≤ 0.23ms

Scale Drift

< 20PPM/°C

Zero Drift

< 10μRad. /°C

Long Term Drift Over 8 hours

< 0.5mRad

RMS Current

3A(Max)

Peak Current

15A(Max)

Maximum Scan Angle

± 20°

Storage Temperature

-10 to +60°C

Resolution

8μrad

Repeatability

12μrad

Input Aperture

3~7mm

Frequency

≤1400Hz

 

Specification for driver

 

Input Voltage

± 15/24VDC@4A MAX.RMS

Interface Signals

Digital:XY2-100 

Analog Signal Input Resistance

200K ± 1%Ω

Position Signal Input Resistance

1K ± 1%Ω

Position Signal Input Scale Factor

0.5V/°

Position Signal Output Scale Factor

0.5V/°

Working temperature

0°C - 40°C

  

 

 

 

Application 

 

 

 

Packing:

SO Mini Galvanometer Scanner will be packed in the wooden case or carton case.

Shipping:

1.Door to door, by the DHL,EMS, UPS,FedEx etc.

 

2.By air to the Air cargo or by sea to the seaport.

 

1. 1 year warranty.

2. Professional technician support on all our products.

3. We supply the sample,user manual, video operation.

4. Online trade-manager 24 hours.

we will continue to “quality first,customer first” principle of service, to update ,better product and quality service to customers.

 

Contact us:

 

www.sino-oper.com

 

 ringy0709

 

ring.y  AT sino-oper.com

 

+86-010-82790570   

 

Whatsapp:  008618618320050

 

 About us:

SINO-OPER just is a growing friend with you, and always concentrates on innovative 

laser scanning systems. 

We are honored that our company is supported by the people who are working for it. 

Reaching a goal requires a flexible, powerful, dynamic team that reacts on work together 

as one unit.

 

1.Minimum order quantity:1set

2.Payment terms: T/T in advance, western union

3.Delivery time: within 5 days after payment

4.Warranty: 1year

 

 

russian.alibaba.com

7 Мм Диафрагма Galvo Электродвигатель/гальванометр Сканер

 

 

 

Описание продукта

Спецификация для двигателя

Рабочая температура

25 °C ± 20 °C

Линейность

99.9%

Установка времени

&Le; 0.23 мс

Масштаб DRIFT

&Lt;20PPM/°C

Дрейф нуля

&Lt;10μrad. /&Deg;C

Долгосрочные Drift более 8 часов

&Lt;0.5 мрад

RMS ток

3A (макс.)

Пиковый ток

15A (макс.)

Максимальный угол сканирования

&Plusmn; 20 °

Температура хранения

-10 до + 60 °C

Разрешение

8μrad

Повторяемость

12μrad

Входного отверстия

3 ~ 7 мм

Частота

&Le;1400hz

 Спецификация для водителя

Входное напряжение

&Plusmn; 15/24VDC @ 4A Макс. RMS

Сигналов интерфейса

Цифровой: XY2-100

Аналоговый сигнал входное сопротивление

200 К ± 1% Ω

Положение сигнал входное сопротивление

1 К ± 1% Ω

Положение входной сигнал Масштабный коэффициент

0.5 В/°

Положение выходной сигнал Масштабный коэффициент

0.5 В/°

Рабочая температура

0 °C-40 °C

Применение

 

 

 

Упаковка и доставка

Упаковка:

7 мм Диафрагма сканирующей головки будут упакованы в деревянном корпусе или коробка дело.

Доставка:

1.От двери до двери, DHL, EMS, UPS, FedEx и т. д.

 

2.By air к air cargo или по морю к порту.

 

1. Гарантия 1 год.

2.Professional технической поддержки на все наши продукты.

3.Мы поставляем образец, руководство пользователя, операция видео.

4.Интернет-торговли-менеджер 24 часов.

Мы будем продолжать "качество первых, клиент первым" принцип обслуживания, чтобы обновить, лучший продукт и качества обслуживания клиентов.

 

Информация о компании

Свяжитесь с нами:

 

 Www.sino-oper.com

 

 Грейс. cao65

 

Грейс. C в sino-oper.com

 

+ 86-010-82790570

 

 О нас:

SINO-OPER просто растет друг с вами, и всегда концентрируется на инновационные

Лазерный сканирования систем.

Мы гордимся тем, что наша компания поддерживается людей, которые работают для него.

Достижения цели требуетГибкая, мощный, динамичный команда, которая реагирует на работать вместе

Как одно целое.

 

 

 

Часто задаваемые вопросы

 

1.Минимальное количество заказа: 1 компл.

2.Условия оплаты: t/t заранее, western union

3.Время доставки: в течение 5 дней после оплаты

4.Гарантия: 1 год

russian.alibaba.com

PRODUCT FOCUS: GALVANOMETER SCANNERS: What you need to know to buy a galvo-positioner

Valerie C. Coffey, contributing editor

Galvo-positioning requires an understanding of different types of actuators, position detectors, and servos; and specifications such as accuracy, repeatability, and stability over temperature and position.

Galvanometer scanners are found wherever laser beams are steered: materials processing, laser light shows, manufacturing, packaging, cutting, marking, welding, and numerous other applications. The market has seen some significant developments in the past year.

Originally, galvanometric devices measured the electric current flowing through a coil in a magnetic field–when current flows the coil experiences a torque proportional to the current. These devices were at the heart of all moving coil meters. In the laser world, the term "galvanometers," also known as galvoscanners, galvopositioners, or galvos, refers to a high-resolution rotary motor with a mirror mounted, instead of a pointer. And whereas nanopositioners (see Laser Focus World, May 2010, p. 75) primarily move a stage with high precision but can also steer laser beams, galvopositioners are less precise and therefore less expensive solutions for beam steering. Very low-precision galvos may simply be called optical scanners, like those found in grocery store scanners. China manufactures mainly low-precision galvoscanners, one application of which is laser light show systems where speed is the primary performance factor (see Fig. 1).

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FIGURE 1. Laser light show galvos don't require high precision, but they do need high speed to quickly move different colors of laser beams to form changing shapes. (Courtesy of Canton Laserphoto, GZ)

Galva-what-now?

A galvo system consists of three main components: the motor or galvanometer, the mirror or mirrors, and the "servo"–the driver board that controls the system. These three parts and their tradeoffs drive the performance of the system. "System positioning performance used to be measured in milliseconds," says Red Aylward, president, Cambridge Technology Inc. (CTI, Lexington, MA). "As galvo systems have reached 100 μs step times and root-mean-square (rms) frequencies greater than 2 kHz, many of the design rules that used to apply are no longer adequate."

The galvo part, an actuator that manipulates the mirror, comes in two configurations for today's high-performance systems, says Aylward. The moving magnet configuration, in which the magnet is part of the rotor and the coil is part of the stator (the stationary part of the motor), tends to have higher system-resonant frequencies–a desirable trait in galvos that ranges from single to more than 20 KHz (see Fig. 2, left). The other is the moving coil configuration where the coil is integral to the rotor and the magnet is part of the stator, which optimizes torque-to-inertia ratio and torque efficiency. A third type of actuator, the original moving iron configuration, had an iron rotor that offered high torque but limited high-speed performance and positioning accuracy.

According to Monika Herzog, marketing manager at Raylase AG (Wessling, Germany), a two-axis (2D) galvanometer scanner moves two mirrors along the x and y directions to deflect a laser beam to any position within the two dimensions, known as the "marking field." A beam input unit accepts input only from compatible lasers. Depending on the type of laser, the beam output is either open or fitted with a protection window or an f-theta lens–a scanning lens that provides a flat field at the image plane of the scanning system (see Fig. 2, right).

In cases where a suitable flat-field lens is not available, the laser focus must be positioned in three dimensions (3D), or x, y, and z. In a 3D scanning unit, the laser beam first encounters a moving lens, from which it diverges to one or two focusing lenses. The beam is then directed by a set of x and y mirrors moved by the galvanometer scanners. The orthogonal arrangement of the x and y mirrors directs the beam down toward and over the length and width of the working field.

FIGURE 2. The Lightning II x-y scanner system from CTI (left) offers 24 bit resolution, low-drift, ultrahigh thermal stability galvo motors mounted in a resonant-dampening motor block. The 20 mm air-cooled version (shown) is ideal for very accurate micro-machining, while the water-cooled 25 mm version is ideal for via-hole drilling, each available with apertures ranging from 14 to 100 mm. (Courtesy of CTI) Raylase's Razorscan-AC series (right) of autocalibrating, high-stability galvanometers features a two-axis digital design for material processing such as rapid tooling, deep engraving, edge isolation, and trimming. The Razorscan-AC, available with apertures from 10 to 20 mm, offers μrad deflection control and an aluminum twin-shell design to ensure temperature equilibrium up to 40°C. (Courtesy of Raylase)

Positioning and servos

To measure the exact angular position of the mirrors mounted to the shaft, galvanometers are equipped with an extremely precise position detector, either an analog detector (which may be optical or capacitive), or a digital encoder. Explains Robert Milkowski, president, Nutfield Technology (Hudson, NH), "Capacitive detectors have a very good signal-to-noise ratio and good linearity, but the weight of the detector impacts its speed. Optical detection galvos are the inverse of capacitive; the upside is speed, while the downside is increased noise and less linearity."

Servo technologies can also be either analog or digital. Closed-loop galvos provide feedback to the servos, which can be analog PID-type driver boards or, within the past year, fully digital state-space driver boards. According to Aylward, "A closed-loop galvo is a limited-angle actuator (typically less than 40° of rotation) with an integral angular position detector, all designed for very fast (100 μs) and very accurate (single micro-radian repeatability) positioning when driven and controlled with a servo-control driver board. Open-loop galvos are generally lower accuracy and lower cost. And resonant scanners are also available for higher-speed applications up to 16 KHz. Complete closed-loop subsystems are the most common (also referred to as scan heads), with two mounted x-y galvos, two mirrors, and two servos packaged in a box and lens-ready for lots of applications like materials processing (the biggest app)."

With the recent advances in digital control, galvanometer systems are often divided by whether their position sensing technology and the driver-board technology are analog or digital. "The world of laser scanning is now moving to fully digital systems," says Dominik Brunner, sales manager at Scanlab AG (Puchheim, Germany; see Fig. 3, left).

Yet analog systems will remain on the market because they offer price for performance, says Milkowski at Nutfield. "For the average user, analog servos do the job at a lower cost. But they typically need to be hand-tuned by a technician. Digital servos do offer auto-tuning but offer little performance benefit. Digital position detectors offer more precision but are more expensive" (see Fig. 3, right).

Two servo configurations commonly compete to balance speed and accuracy requirements, says Aylward. An integrating servo, or Class 1, uses integrated position error to settle to the highest level of positioning accuracy with the least angular error. Applications that value precision over speed often rely on integrating Class 1 servo controllers. A nonintegrating servo, or Class 0, can provide higher system speeds because it avoids the integration time. This configuration is used when some precision (up to approximately 100 μrad) is sacrificed to increase the speed, often by 10% or more. Many of the highest-speed applications rely on nonintegrating Class 0 servos.

The categorization of galvanometers among manufacturers can be confusing. Different manufacturers categorize galvos differently, such as by application, closed-loop versus open loop, or technology type. At CTI, galvos are broken down by actuator type (moving magnet or moving coil) and type of position detector (capacitive, optical, or digital). "The most popular today is the moving magnet with an optical position detector. Digital position detection is the newest advance for applications requiring extreme accuracy but it comes at a price premium for that added accuracy," says Aylward. These digital systems are ideal for applications that require a particularly high level of thermal and positional stability, or dither.

Nutfield Technology divides the field into three categories by type: position detector, servo, and suspension. Suspension technologies are divided into bearing- or flexure-based systems. In bearing-based suspension systems, adequate for 90% of applications, the rotor is mounted using a classic round bearing technology. In flexure suspension systems, the rotor is mounted using steel flat springs, improving precision in imaging applications.

FIGURE 3. The intellicube10 scan head (left) from Scanlab features a compact sealed housing, digitally controlled scan systems, real-time monitoring of actual position, and advanced status information. Options include vector-tuning or jump-tuning, and on-the-fly processing of moving parts, ideal for marking, coding, and semiconductor and electronics manufacturing. (Courtesy of Scanlab) Nutfield Technology's rotor and mirror-mount design on the QS-12 galvo (right) creates higher rotor resonant frequencies to produce industry-leading scanning speed and accuracy for 10, 15, and 20 mm mirror applications. The QS-12 offers a small step response of 400 μs (settled to 99.9%) with a 15 mm x-mirror, and repeatability of less than 10 μrad. (Courtesy of Nutfield Technology)

Where to start?

The Raylase web site helps narrow down a customers' needs with some key questions. "We start by asking what industry focus a customer has: automobile, semiconductor, packaging, medical, and so on," says Herzog. "Then, what application: marking, cutting, perforating, drilling, welding, engraving, prototyping, tooling, and so on. We ask what nanometer of wavelength and wattage of power you are working with (which depends on your laser), what field size, and whether or not the target is moving. Are you more concerned with speed, low drift, or both? Then we find out whether you need a package including electronic board and software."

Working fields range from 100 × 100 mm on the small end to 1.5 × 1.5 m on the large end. Spot sizes down to 300 μm are possible with CO2 lasers in a 500 × 500 mm working field for fast processing of different kinds of material. Another application is processing of objects with an uneven surface, addressed by the new Focus-Shifter family of products at Raylase, which allows the focus of the laser beam to move along the z-axis of the target.

Manufacturers agree that the top buying criteria are speed, accuracy, cost, and size. Speed or step response time is inversely related to the galvo/mirror inertia and resonant frequency, and is typically specified as the time to move to 99% of 0.1° (mechanical) positioning move. Maximum rms frequency or repetition rate is related to both the bandwidth and the capability of the galvo to dissipate the heat of high currents, rate, and duty cycle. Accuracy is given in terms of short-term repeatability, or the range of error that occurs when the galvo is repetitively commanded to the same position. For users doing alpha-numeric character marking, speed can be measured in characters per second. Generally, the higher the accuracy of a galvo system, the higher the cost. A larger beam and galvo reduce the speed and increase the cost.

Nonlinearity is another accuracy consideration involving the error difference from a perfectly linear slope of the command voltage to scan-angle position over the scan range (for example, when the command signal for -10 V gives -20°, 0 V gives 0°, and 10 V gives +20°). Size of the system is another important concern. Generally, the bigger the beam and the mirror to be deflected, the larger the galvo must be to deliver higher torque fast enough. Lifetime is also a consideration, given in terms of cycles (perhaps in the billions). Another factor to consider in very high-precision applications is thermal drift, with both offset and scale components–the position error related to changes in environmental temperature and over time.

Editor's note: The "Product Focus" series is intended to provide a broad overview of the product types discussed. Laser Focus World does not endorse or recommend any of the products mentioned in this article.

Galvo-positioning requires an understanding of different types of actuators, position detectors, and servos; and specifications such as accuracy, repeatability, and stability over temperature and position.

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electromagnetism - Building a coil for galvo motor

I'm building myown galvo motors and for that I need some coils that I'll have to build myself to fit into the dimensions I need. Is there any technique for winding the wire or is it just straight forward hand winding? Any trick or detail that you could share would be very useful as well.

The coil winding methods described inUsing miniature sensor coils for simultaneous measurement of orientation and position of small, fast-moving animals C. Schilstra, J.H. van Hateren * Department of Neurobiophysics, Uni6ersity of Groningen, Nijenborgh 4, Groningen, NL-9747 AG, The Netherlands 1998may be of substantial value.

They produced 3 orthogonally mounted coils, each of 2mm diameter and 40 to 80 turns & weighing 0.5 to 1.6 grams/coil. These were mounted on a blowfly to allow real time monitoring of its position and velocity when in flight. A later paper resports the mounting of a second coil set on a fly's head so that head movements relative to the fly's body can be measured while in flight.

The main equipment - sometimes the darkest of the arcane arts appears deceptively simple :-):

Amongst other details they say:

  • ... we use thin wire of 12-um (micro-metre) diameter (with two layers of insulation, 1 mm polyurethane and 1 um polyvinylbutyral; Lotan-Fix, Huber and Suhner, Switzerland).

    The coils are produced by winding the wire around a hollow axis of flexible material (Teflon; see Fig. 3 for the device used for winding coils). Before winding, a thin metal expansion rod is inserted into the hollow axis; the fit is such that this slightly increases the diameter of the axis.

    Approximately 1 m of wire, later used for connecting the coil, is first wound on a storage reel. Subsequently, the coil is wound, and glued together by slightly heating the outer layer of the wire insulation. Removal of the metal rod loosens the coil from the axis, after which it can be shifted from the axis with the help of a tightly fitting glider (Fig. 3).

    To prevent breaking of the wire, a tension loosener loosens the wire before the coil is shifted from the axis. Finally, the wire is unwound from the storage reel, and twisted, by means of a motor, with the other wire originating from the coil. The tension during the twisting is controlled by hanging small weights at the end of each wire (Koch, 1980). Careful twisting is essential to prevent induction of voltage in the resulting leads.

and

  • With the technique described above, we are able to make coils as small as 0.8 mm in diameter, but for most experiments we used coils of 2-mm diameter, with 40 or 80 windings. This gives a good compromise between weight (0.8–1.6 mg for the three coils) and signal-to noise ratio:

    Fig. 3 (inset) shows the resulting system of three coils. These were made with slightly different diameters (2.0, 2.1, and 2.2 mm) such that they fit within each other. The coils are fitted together as orthogonally as possible using a template with orthogonal grooves.

The ability to use 12 um dia wire (0.012 mm), to produce coils down to 0.8mm in diameter and to make coils with diameter tolerances of 0.1 mm (2.0, 2.1, 2.2 mm) demonstrate a degree of mastery of the methods involved which should be far more than what is required for galvanometer winding. One would hope :-).

Supporting material but of far less detail is found in a follow on paper BLOWFLY FLIGHT AND OPTIC FLOW I. THORAX KINEMATICS AND FLIGHT DYNAMICS - 1999

Potentially useful information relating to use of coils is found in Induction coil sensors—a review - 2007.This is more about applications and electrical design but will be at leasts of injterest and the 95 refernces will provide some extra material.

electronics.stackexchange.com

DC Galvo Motor | Products & Suppliers

  • Achieving high-duty cycle sawtooth scanning with galvanometric scanners

    A galvanometric optical scanner ( galvo ) is a limited rotation DC motor with an integral position sensor.

  • A parametric piecewise-linear approach to laser projection

    In the LP20 galvo mirror system of Canton Laserphoto Electronic Equipment Co, Ltd., which is used in this study, an analog command input of up to ±5V DC results in ±8◦ mechanical degrees of scanner rotation at 20 Kpps. … end of the actuator, and deflects the light beam over the angular range of the motor shaft.

  • Laser processing of solder resist layers on laminated substrates

    The NdYAG laser with X-Y table. lb. with galvo scanner. A linear DC -servo motor enables fast X-Y moving.

  • Laser processing of polymer layers of laminated and flexible substrates

    … pm Figure 3.a. The Nd:YAG laser with X-Y table 3.b. with galvo scanner. A linear DC -servo motor enables fast X-Y moving.

  • Fabrication Methods for Precision Optics

    The ac or dc motor speed is controlled by turning a knob on the overhead control panel. The actual speed is electronically displayed on the panel either by an analog galvo tachometer (needle) or …

  • Utilization of laser technologies in the preparation of the physical structure of a miniature electrochemical cell used for biosensor researches

    Figure 9.TheNdYAG luer with X-Y tableand with galvo scanner A linear DC -servo motor enables fast X-Y moving.

  • In-vivo morphologic and spectroscopic investigation of Psoriasis

    The beam hits the scanning head which is composed of two galvo mirrors G1222 (Galvoline, Rome, Italy). It is mounted on a special movable mount which is controlled by a DC motor (M-501, Physik Instrumente GmbH, Karlsruhe, Germany) which controls the axial movement of the objective and therefore the depth inside the sample at which the laser beam …

  • Synchronized-scanning laser vibrometry

    Each galvo can rotate an attached mirror through mechanical (±30° optical). The target used was a light (01 10mm x 2mm), aluminium rotor with rigid cross-section mounted to a DC motor .

  • Laser Manufacturing of Mechanical Structures in Flexible Substrates

    A linear DC - servo motor enables fast X-Y moving. The system also has a galvo - motor controlled rotating mirror based X-Y beam deflection system, but …

  • Optical Recording On A Sealed Disk Assembly

    The axis of the galvo is imaged to the telecentric pupil of the microscope objective lens, thereby … The platen is mounted on a rotary air bearing driven by a brushless dc motor .

  • www.globalspec.com

    Mirror galvanometer - Wikipedia

    Thomson mirror galvanometer of tripod type, from around 1900 Galvanometer by H.W. Sullivan, London. Late 19th or early 20th century. This galvanometer was used at the transatlantic cable station, Halifax, NS, Canada Modern mirror galvanometer from Scanlab

    A mirror galvanometer is an electromechanical instrument that indicates that it has sensed an electric current by deflecting a light beam with a mirror. The beam of light projected on a scale acts as a long massless pointer. In 1826, Johann Christian Poggendorff developed the mirror galvanometer for detecting electric currents. The apparatus is also known as a spot galvanometer after the spot of light produced in some models.

    Mirror galvanometers were used extensively in scientific instruments before reliable, stable electronic amplifiers were available. The most common uses were as recording equipment for seismometers and submarine cables used for telegraphy.

    In modern times, the term mirror galvanometer is also used for devices that move laser beams by rotating a mirror through a galvanometer set-up. The name is often abbreviated as galvo.

    Kelvin's galvanometer[edit]

    The mirror galvanometer was later improved by William Thomson, later to become Lord Kelvin. He would patent the device in 1858.

    Thomson reacted to the need for an instrument that could indicate with sensibility all the variations of the current in a long cable. This instrument was far more sensitive than any which preceded it, enabling the detection of the slightest defect in the core of a cable during its manufacture and submersion. Moreover, it proved the best apparatus for receiving messages through a long cable.

    The following is adapted from a contemporary account of Thomson's instrument:[1]

    The mirror galvanometer consists of a long fine coil of silk-covered copper wire. In the heart of that coil, within a little air-chamber, a small round mirror is hung by a single fibre of floss silk, with four tiny magnets cemented to its back. A beam of light is thrown from a lamp upon the mirror, and reflected by it upon a white screen or scale a few feet distant, where it forms a bright spot of light. When there is no current on the instrument, the spot of light remains stationary at the zero position on the screen; but when a current flows through the traverses the long wire of the coil, the suspended magnets twist themselves horizontally out of their former position, the mirror is inclined with them, and the beam of light is deflected along the screen to one side or the other, according to the nature of the current. If a positive electric current gives a deflection to the right of zero, a negative current will give a deflection to the left of zero, and vice versa.

    The air in the little chamber surrounding the mirror is compressed at will, so as to act like a cushion, and deaden the movements of the mirror. The needle is thus prevented from idly swinging about at each deflection, and the separate signals are rendered abrupt. At a receiving station the current coming in from the cable has simply to be passed through the coil before it is sent into the ground, and the wandering light spot on the screen faithfully represents all its variations to the clerk, who, looking on, interprets these, and cries out the message word by word. The small weight of the mirror and magnets which form the moving part of this instrument, and the range to which the minute motions of the mirror can be magnified on the screen by the reflected beam of light, which acts as a long impalpable hand or pointer, render the mirror galvanometer marvellously sensitive to the current, especially when compared with other forms of receiving instruments. Messages could be sent from the United Kingdom to the United States through one Atlantic cable and back again through another, and there received on the mirror galvanometer, the electric current used being that from a toy battery made out of a lady's silver thimble, a grain of zinc, and a drop of acidulated water.

    The practical advantage of this extreme delicacy is that the signal waves of the current may follow each other so closely as almost entirely to coalesce, leaving only a very slight rise and fall of their crests, like ripples on the surface of a flowing stream, and yet the light spot will respond to each. The main flow of the current will of course shift the zero of the spot, but over and above this change of place the spot will follow the momentary fluctuations of the current which form the individual signals of the message. What with this shifting of the zero and the very slight rise and fall in the current produced by rapid signalling, the ordinary land line instruments are quite unserviceable for work upon long cables.

    Moving coil galvanometer[edit]

    Moving coil galvanometer was developed independently by Marcel Deprez and Jacques-Arsène d'Arsonval about 1880. Deprez's galvanometer was developed for high currents, while D'Arsonval designed his to measure weak currents. Unlike in the Kelvin's galvanometer, in this type of galvanometer the magnet is stationary and the coil is suspended in the magnet gap. The mirror attached to the coil frame rotates together with it. This form of instrument can be more sensitive and accurate and it replaced the Kelvin's galvanometer in most applications. The moving coil galvanometer is practically immune to ambient magnetic fields. Another important feature is self-damping generated by the electro-magnetic forces due to the currents induced in the coil by its movements the magnetic field. These are proportional to the angular velocity of the coil.

    Modern uses[edit]

    "EdSpot", a popular commercial mirror galvanometer, somewhat resembles this picture.

    In modern times, high-speed mirror galvanometers are employed in laser light shows to move the laser beams and produce colorful geometric patterns in fog around the audience. Such high speed mirror galvanometers have proved to be indispensable in industry for laser marking systems for everything from laser etching hand tools, containers, and parts to batch-coding semiconductor wafers in semiconductor device fabrication. They typically control X and Y directions on Nd:YAG and CO2 laser markers to control the position of the infrared power laser spot. Laser ablation, laser beam machining and wafer dicing are all industrial areas where high-speed mirror galvanometers can be found.

    This moving coil galvanometer is mainly used to measure very feeble or low currents of order 10−9 A.

    To linearise the magnetic field across the coil throughout the galvanometer's range of movement, the d'Arsonval design of a soft iron cylinder is placed inside the coil without touching it. This gives a consistent radial field, rather than a parallel linear field.

    See also[edit]

    References[edit]

    Further reading[edit]

    External links[edit]

    en.wikipedia.org


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