Individuals requiring letters of invitation to obtain travel visas to present their papers may access the online form at Invitation Letter Request Form
Questions about the Visa Invitation Letter application process, e-mail: email@example.com
- Please fill out a separate form for each person requesting a letter According
- All letters of invitation will be sent by a locked PDF unless otherwise requested.
- Please allow up to 15 business days to process your request.
- OSA is not able to contact Embassies in support of an individual attempting to gain entry to attend an OSA meeting.
- We recommend that you secure your travel visa before registering for the conference as cancellations after the preregistration cutoff can result in a cancellation fee.
OSA Management – Invitation Letter
The Optical Society
2010 Massachusetts Ave., NW
Washington, DC 20036
Apply now for your Visa
The visa application process to enter the United States has become subject to greater degrees of scrutiny than in the past. For this reason, the application process can take up to six months or more. You will need to apply for your visa as early as possible, but no later than three months before you wish to enter the United States.
Generally, a citizen of a foreign country who wishes to enter the United States must first obtain a visa, either a nonimmigrant visa for temporary stay, or an immigrant visa for permanent residence. Visitor visas are nonimmigrant visas for persons who want to enter the United States temporarily for business (visa category B-1), tourism, pleasure or visiting (visa category B-2), or a combination of both purposes (B-1/B-2).
There are several steps to apply for a visa. The order of these steps and how you complete them may vary at the U.S. Embassy or Consulate where you apply. Please consult the instructions available on the U.S. Embassy or Consulate website where you will apply.
Visa Waiver Program
There are 27 countries
that participate in the Visa Waiver Program
. If your country is on this list, and you are traveling to the United States for tourism or business for 90 days or less with a valid passport that meets U.S. requirements, and the listed conditions do not apply to you, you do NOT need a visa. Otherwise, you need to obtain a visa.
Electronic System for Travel Authorization (ESTA)
ESTA is an automated system that determines the eligibility of vistitors to travel to the United States under the Visa Waiver Program (VWP)
. Authorization via ESTA does not determine whether a traveler is admissible to the United States. U.S. Customs and Border Protection officers determine admissibility upon travelers' arrival. The ESTA application collections biographic information and answers to VWP eligibility questions. ESTA applications may be submitted at any time prior to travel, though it is recommended that travelers apply as soon as they begin preparing travel plans or prior to purchasing airline tickets.
Please note that as of January 2016, the Visa Waiver Program has changed. Under the new changes, the following categories of travelers are no longer eligible to travel or be admitted to the United States under the Visa Waiver Program, and will need to apply for, and go through the standard Visa application and interview process:
- Nationals of VWP countries who have traveled or been present in Iran, Iraq, Sudan, or Syria on or after March 1, 2011 (with limited exceptions).
- Nationals of VWP countries who are also nationals of Iran, Iraq, Sudan, or Syria. (Travelers who are known to fall into the dual national category noted above should have received notice via email on or about January 21, 2016 that their current ESTA is no longer valid).
These restrictions do not apply to VWP travelers whose presence in Iraq, Iran, Sudan, or Syria was to perform military service in the armed forces of a program country, or in order to carry out official duties as a full-time employee of the government of a program country. These military and official government services exceptions, however, do not apply to the dual national restriction.
The Act includes other changes to the VWP to promote enhanced information sharing of terrorism and criminal data, and use of INTERPOL databases and notices for border screening purposes. The vast majority of VWP eligible travelers will not be affected by the legislation.
Visa Application Guidelines
Complete the Online Visa Application
- Online Nonimmigrant Visa Application, Form DS-160 – Learn more about completing the DS-160. You must:
- 1) complete the online visa application
- 2) print the application form confirmation page to bring to your interview.
- Photo – You will upload your photo while completing the online Form DS-160. Your photo must be in the format explained in the Photograph Requirements.
Schedule an Interview
Personal interviews can be critical to successfully and efficiently obtaining a visa to enter the United States
. One factor contributing to the increase in the processing time is a personal interview that is now required for most applicants as a standard part of visa processing. Group interviews are not recommended. Applicants need to be prepared to clearly present their intent to return from the U.S. as well as explain in detail how they will be spending their time while in the United States. It is not enough to just state “I will be attending a meeting”. Embassies are looking for more details as well as documents and information that demonstrate and support these intents.
Individuals are strongly encouraged to contact the embassy or consulate to schedule a personal interview as soon as it is known a visa is necessary for travel. Be aware that it may be difficult to qualify for a visa outside of your place of permanent residence. Wait times for interview appointments vary by location, season, and visa category, so you should apply for your visa early.
Helpful Information to prepare for your Interview
- There will be a non-refundable visa application fee. Review the instructions available on the website of the embassy or consulate where you will apply to learn more about the fee payment.
- Gather Required Documentation:
- Passport valid for travel to the United States - Your passport must be valid for at least six months beyond your period of stay in the United States, unless exempt by country-specific agreements (PDF - 57 KB). If more than one person is included in your passport, each person who needs a visa must submit a separate application.
- Nonimmigrant Visa Application, Form DS-160 confirmation page
- Application fee payment receipt, if you are required to pay before your interview.
- Photo – You will upload your photo while completing the online Form DS-160. If the photo upload fails, you must bring one printed photo in the format explained in the Photograph Requirements.
- Additional documents may be requested to establish if you are qualified. For example, additional requested documents may include evidence of:
- The purpose of your trip;
- Your intent to depart the United States after your trip; and/or
- Your ability to pay all costs of the trip.
- Evidence of your employment and/or your family ties may be sufficient to show the purpose of your trip and your intent to return to your home country. If you cannot cover all the costs for your trip, you may show evidence that another person will cover some or all costs for your trip.
Note: Visa applicants must qualify on the basis of the applicant's residence and ties abroad, rather than assurances from U.S. family and friends. A letter of invitation or Affidavit of Support is not needed to apply for a nonimmigrant tourist visa. If you do choose to bring a letter of invitation or Affidavit of Support to your interview, please remember that it is not one of the factors that we use in determining whether to issue or deny a nonimmigrant tourist visa.
Attend your Visa Interview
During your visa interview, a consular officer will determine whether you are qualified to receive a visa, and if so, which visa category is appropriate based on your purpose of travel. You will need to establish that you meet the requirements under U.S. law to receive the category of visa for which you are applying. Ink-free, digital fingerprint scans will be taken as part of your application process. They are usually taken during your interview, but this varies based on location. After your visa interview, your application may require further administrative processing
. You will be informed by the consular officer if further processing is necessary for your application. When the visa is approved, you may pay a visa issuance fee if applicable to your nationality, and will be informed how your passport with visa will be returned to you. Review the visa processing time
, to learn how soon your passport with visa will generally be ready for pick-up or delivery by the courier.
Whether you are applying for the first time or renewing your visa, you will use the same application process. Some applicants seeking to renew their visas in certain visa classes may be eligible for the Interview Waiver Program (IWP) which allows qualified individuals to apply for visa renewals without being interviewed in person by a U.S. consular officer. Review the instructions on the website of the U.S. Embassy or Consulate
where you will apply to determine if the IWP is available and if you qualify.
U.S. Customs and Border Information
Visa Waiver Program Frequently Asked Questions
U.S. State Department Visa Information
Department of Homeland Security
National Academies International Visitors Office
OSA Management is not able to contact U.S. embassies in support of an individual attempting to gain entry into the host country to attend the conference.
If your visa is delayed or denied, please contact the consulate where your application is being processed. Review Visa Denials for detailed information about visa ineligibilities, denials and waivers.
- Visitors are not permitted to accept employment or work in the United States.
- Unless canceled or revoked, a visa is valid until its expiration date. Therefore, a valid U.S. visa in an expired passport is still valid. If you have a valid visa in your expired passport, do not remove it from your expired passport. You may use your valid visa in your expired passport along with a new valid passport for travel and admission to the United States.
For detailed information about applying for a visa, refer to the On-line Resource links provided above.
Whether on foot, by car, by bike, or by light rail, there are plenty of options for getting around Denver.
To and From the Airport
The hotel does not offer shuttle service.
Denver International Airport - DEN
Hotel direction: 26 miles SW
Colorado Springs Airport - COS
- Airport Rail - At a cost of $9 each way, travelers can take the airport rail from DEN to Union Station and vice versa. The trains leave every 15 minutes between 6 a.m. and 8 p.m. and every 30 minutes outside of those hours. Download the Denver Union Station Arrival Guide here.
- Bus service, fee: 11 USD (one way)
- Estimated taxi fare: 60 USD (one way)
Hotel direction: 82 miles N
- Alternate transportation: SuperShuttle; fee: 22 USD (one way) ;reservation required
- Estimated taxi fare: 180 USD (one way)
Getting Around Denver
Denver’s public transportation is easy, inexpensive and convenient. You can get pretty much anywhere in The Mile High City by rail or bus, and often get there faster than by car.
Check out the Regional Transportation District's user-friendly homepage
for routes, fares and other pertinent info.
Uber and Lyft are car services operated by San Francisco locals. You must first download the app
, register, and set-up a credit card payment system. With Lyft, you can request a private car service, or use the shared car service called “Lyft Line”. This is useful when travelling with another person because you get a shared discounted rate. Uber has a similar service called “Uber Pool” with rides running at a flat rate of $7. To use any of these services, set a pick-up location and end destination and within minutes, you will be matched with a driver. Make sure to communicate with your driver; call, text, or wave down their car. Get more ride sharing tips.
As is customary in most U.S. cities, visitors may hail a taxi directly or use a smart phone app.
Want to tour the city on a bike? B-Cycle
makes Denver even more bike-friendly.
United Airlines is offering discounted flights for Congress Attendees. You may book online at http://www.united.com
and enter ZXJP194880
in the Offer Code box when searching for your flights. If booking through a travel professional or United Meetings at +1 800.426.1122, please provide them with the following Offer Code ZXJP194880.
This code is valid 2-20 July 2017 at Denver International (DEN) airport only.
Outside of the United States, please call your local United Airlines Reservation Office. Experience dependable, first-rate service and earn miles in MileagePlus®, United’s award-winning frequent flyer program. To enroll in MileagePlus®, log on to http://www.united.com
is offering discounts for domestic and international flights at Denver International Airport (DEN) when using the following codes:
(only valid 4 - 18 July 2017)
Reservations and ticketing are available via www.delta.com
or by calling the Delta Meeting Network Reservations at +1 800.328.1111. Please note that a Direct Ticketing Charge will apply for booking by phone. When booking online, select "Advanced Search" option and enter your Meeting ID Code in the box provided on the Search Flight page.
is pleased to offer low rates with unlimited mileage to participants attending CLEO. If you wish to reserve a car please contact Todd Alexander at +1 800.525.7537 Ext. 35003 or the Meetings and Convention Department at + 1 800.525.7537. They can ensure that you maximize your rental dollars. Please mention AWD # D340737
when you call. Reservations may also be made on the Avis website.
World Wide Telephone Numbers
Number is D340737
NOTE: This code is valid seven days before and after the conference.
is the nation's leading shared-ride airport shuttle, providing door-to-door ground transportation and provides service to and from 28 major airports in 23 cities. To go to the Congress SuperShuttle site, click here
is pleased to offer 10% discount off a roundtrip or one way reservation to participants attending the conference. Please refer to the discount CUJFZ
. Discounted reservations must be made on the SuperShuttle website.
Discount does not apply to exclusive vans (which are already discounted) or pre-existing reservations. Discounts cannot be applied retroactively. It is valid on select (Booking codes: ATF, EMG, EWC, and VAN) SuperShuttle and ExecuCar services nationwide.
Amtrak is offering Congress attendees a 10% discount off the best available rail fare between 6 - 16 July 2017. To book your reservation call Amtrak at + 1 800.872.7245 or contact your local travel agent.
Conventions cannot be booked via Internet. Please be sure to refer to Convention Fare Code X39D-961
when making your reservation. This offer is not valid on the Auto Train and Acela Service. Fare is valid on Amtrak Regional for all departures seven days a week, except for holiday blackouts. Offer valid with Sleepers, Business Class or First Class seats with payment of the full applicable accommodation charges.
Denver, Colorado is serviced by two international airports:
July Temperatures in Denver:
- Denver International Airport, DEN (pictured) is located approximately 19 miles ENE of Denver, DEN is a major airline hub, the sixth-busiest airport in the United States and 19th-busiest in the world, serving the third most destinations of U.S. airports. It’s now easier than ever to get from DEN to downtown Denver with the opening of the new Denver airport train line. Click here for more information!
- Colorado Springs Airport, COS – approximately 67 miles SSE of Denver. Click here for information on ground transportation from COS to downtown Denver.
The biggest surprise for visitors to Denver is the climate. The arid conditions bring only 8 to 15 inches of annual precipitation and locals wake up to more than 300 days of sunshine per year. That’s more annual hours of sun than Miami and San Diego!
Denver summers bring low relative humidity, making for beautiful, sun-filled days and cool, comfortable evenings. The mild weather is due in part to the city’s altitude: 5,280 feet above sea level, or exactly a mile high.
- Denver’s Average High Temps: 88oF / 31.1Co
- Denver’s Average Low Temps: 56oF / 13.3Co
- Denver’s Average Precipitation: 1.68 in / 42.7mm
For most current weather forecast in Denver, please click here
Denver, Colorado resides within the Mountain Standard Time.
Urban sophistication meets outdoor adventure in Denver. Get acquainted with The Mile High City, including history, transportation, and neighborhood guides. When you arrive, explore Denver with this new interactive Denver map
that will give you point-by-point directions in and around the city for the conference.
Denver, the capital of Colorado, is an American metropolis dating to the Old West era. Larimer Square, the city’s oldest block, features landmark 19th-century buildings. Museums include the Denver Art Museum, an ultramodern complex known for its collection of indigenous works, and the mansion of famed Titanic survivor Molly Brown. Denver is also a jumping-off point for ski resorts in the nearby Rocky Mountains.
Denver comes to life in the spring and summer. Whether you delve into Denver’s authentic Old West history, visit the numerous multi-cultural attractions, or enjoy the historic districts and neighborhoods the Mile-high city has to offer, your options are endless! Check out the Denver Blog
for the most up to date events before you leave home!
Home to award-winning chefs and restauranteurs, Denver has emerged as one of the top dining locations in the country. Mile-High City’s local culinary scene is thriving, offering everything from farm-to-table bistros to classic steak houses to historic Denver restaurants. Whether downtown on the 16th Street Mall or looking for a unique spot in Cherry Creek, visitors have a variety of great options to choose from. Click on dining to begin your culinary experience during your stay in Denver -- Enjoy!
Getting Around in Denver
: The “A Line”, which opened on April 22, 2016, whisks travelers to the heart of downtown, specifically the recently restored Union Station, which is the city’s new transportation hub and “living room,” thanks to its plush surroundings. From Union Station, travelers can access additional local and regional transportation services, such as light rail, regional and local buses, Amtrak rail service, taxis, and the free 16th
Street Mall shuttle (MallRide) and free downtown MetroRide buses that provides access to most downtown hotels. Union Station itself is a beautiful 1914 Beaux-Arts building and the location of hip, locally owned restaurants, bars, shops and a boutique hotel. Additionally, the new Denver airport rail has six stops along the way and takes approximately 37 minutes.